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Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2000 on: November 25, 2019, 01:28:36 PM »
I disagree with that Hefaistos. When I read e.g. "Full Stokes Model" it is a physics model. The tweaking and tuning is probably only to insert/add new found feedbacks and other influences/interactions.

What I most disagree with is: "Luckily, it's not the models that warm our globe."

Of course these models are built on physics. No argument there.
The issue here is that these models are demonstrably unreliable in terms of forecasting global warming - they're running hot.
So the physics they're built on isn't fully correct, or rather it isn't complete. I mentioned the main reasons in my previous reply: lack of theoretical foundations for some of the most fundamental and energy intense processes in earth climate, and plus to that a total lack of finely gridded data for same processes.
You could also sum it up: garbage in, garbage out.

Lennart van der Linde

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2001 on: November 25, 2019, 01:35:32 PM »
The issue here is that these models are demonstrably unreliable in terms of forecasting global warming - they're running hot.

Can you point us to some peer-reviewed science that demonstrates the models are running hot, and to what extent?
As far as I know they're pretty much on target, but maybe I've missed the relevant science.

Lennart van der Linde

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2002 on: November 25, 2019, 02:02:50 PM »
See for example Lewandowsky et al 2018:
https://iopscience.iop.org/article/10.1088/1748-9326/aaf372/pdf

Abstract
We review the evidence for a putative early 21st-century divergence between global mean surface temperature (GMST) and Coupled Model Intercomparison Project Phase 5 (CMIP5) projections. We provide a systematic comparison between temperatures and projections using historical versions of GMSTproducts and historical versions of model projections that existed at the times when claims about a divergence were made. The comparisons are conducted with a variety of statistical techniques that correct for problems in previous work, including using continuous trends and a Monte Carlo approach to simulate internal variability. The results show that there is no robust statistical evidence for a divergence between models and observations. The impression of a divergence early in the 21st century was caused by various biases in model interpretation and in the observations, and was unsupported by robust statistics.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2003 on: November 25, 2019, 05:02:45 PM »
Can you point us to some peer-reviewed science that demonstrates the models are running hot, and to what extent?
As far as I know they're pretty much on target, but maybe I've missed the relevant science.

First, the first linked document indicates that for peer-reviewed references on CMIP6 Model results to be included in AR6 they must be submitted by Dec 31, 2019, and published by Oct 15, 2020; so we can look forward to gaining access to more reviewable CMIP6 findings soon:

Title: "CMIP6 Model Analysis Workshop 25-28 March Barcelona"

https://cmip6workshop19.sciencesconf.org/data/CMIP6AnalysisWorkshop_FinalDiscussion_190328_FINAL.pdf


Second, the second linked article by Gavin Schmidt indicates that the CMIP6 models with relatively high ECS values (for values thru August 2019 see the first attached image) collectively show higher skill scores than those for earlier models (like CMIP5).  We will all have to wait and see what AR6 does with this new information:

Title: "Sensitive But Unclassified"

http://www.realclimate.org/index.php/archives/2019/11/sensitive-but-unclassified/


Lastly for this post, one would expect that NOAA knows something about ocean-atmosphere interactions, thus I single-out their GFDL CM4.0's projection of a most likely current value of ECS of about 5.0C (see the second attached image & following linked references).  NOAA's most significant changes for GFDL CM4.0 as compared to earlier model projections (with lower values of ECS) was improvements to the ocean, ice and aerosol modules; that lead to increasingly net positive cloud feedbacks (and much higher model skill levels as indicated by the third attached image).  This result is what only would expect from MISI-types of ice-climate feedback contributions to ECS; which leaves one to speculate what effective values of climate sensitivity would be projected if/when CMIP7/CMIP8 projections evaluate the impacts of MICI-types of ice-climate feedback mechanisms:

I.M. Held, H. Guo, A. Adcroft, J. P. Dunne, L.W. Horowitz, J. Krasting, E. Shevliakova, M. Winton, M. Shao, M. Bushuk, A.T. Wittenberg, B. Wyman, B. Xiang, R. Zhang, W. Anderson, V. Balaji, L. Donner, K. Dunne, J. Durachta, P. Gauthier, P. Ginoux, J-C. Golaz, S.M. Griffies, R. Hallberg, L. Harris, M. Harrison, W. Hurlin, J. John, P. Lin, S.J. Lin, S. Malyshev, R. Menzel, P.C.D. Milly, Y. Ming, V. Naik, D. Paynter, F. Paulot, V. Ramaswamy, B. Reichl, T. Robinson, A. Rosati, C. Seman, L. Silvers, S. Underwood, N. Zadeh (2019), "Structure and Performance of GFDL's CM4.0 Climate Model", Journal of Advances in Modeling Earth Systems (JAMES). DOI: 10.1029/2019MS001829

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001829

Abstract
We describe GFDL's CM4.0 physical climate model, with emphasis on those aspects that may be of particular importance to users of this model and its simulations. The model is built with the AM4.0/LM4.0 atmosphere/land model and OM4.0 ocean model. Topics include the rationale for key choices made in the model formulation, the stability as well as drift of the pre‐industrial control simulation, and comparison of key aspects of the historical simulations with observations from recent decades. Notable achievements include the relatively small biases in seasonal spatial patterns of top‐of‐atmosphere fluxes, surface temperature, and precipitation; reduced double Intertropical Convergence Zone bias; dramatically improved representation of ocean boundary currents; a high quality simulation of climatological Arctic sea ice extent and its recent decline; and excellent simulation of the El Niño‐Southern Oscillation spectrum and structure. Areas of concern include inadequate deep convection in the Nordic Seas; an inaccurate Antarctic sea ice simulation; precipitation and wind composites still affected by the equatorial cold tongue bias; muted variability in the Atlantic Meridional Overturning Circulation; strong 100 year quasi‐periodicity in Southern Ocean ventilation; and a lack of historical warming before 1990 and too rapid warming thereafter due to high climate sensitivity and strong aerosol forcing, in contrast to the observational record. Overall, CM4.0 scores very well in its fidelity against observations compared to the Coupled Model Intercomparison Project Phase 5 generation in terms of both mean state and modes of variability and should prove a valuable new addition for analysis across a broad array of applications.

Plain Language Summary
The Geophysical Fluid Dynamics Laboratory (GFDL) of the National Oceanic and Atmospheric Administration (NOAA) participates along with a number of model centers around the world in constructing state‐of‐the‐art climate models for use in studies for climate change and prediction. GFDL's latest multi‐purpose atmosphere‐ocean coupled climate model, CM4.0, is described here. It consists of GFDL's latest atmosphere and land models at about 100 km horizontal resolution, and ocean and sea ice models at roughly 25 km horizontal resolution. A handful of standard experiments have been conducted with CM4.0 for participation in the Coupled Model Intercomparison Project Phase 6, an archive of climate model results utilized by the Intergovernmental Panel on Climate Change and the climate research community more generally. The model results have been extensively evaluated against observations. This paper makes the case that CM4.0 ranks high among state‐of‐the‐art coupled climate models by many measures of bias in the simulated climatology and in its ability to capture modes of climate variability such as the El Niño‐Southern Oscillation and Madden‐Julian Oscillation. The paper also discusses some potential weaknesses, including unrealistically large internal variability in the Southern Ocean and insufficient warming before 1990 in the simulation of the 20th century.

See also:

Title: "Structure and Performance of GFDL’s CM4.0 Climate Model"

https://www.gfdl.noaa.gov/research_highlight/structure-and-performance-of-gfdls-cm4-0-climate-model/

Extract: "This paper describes the GFDL’s latest multi-purpose atmosphere-ocean coupled climate model, CM4.0. It consists of GFDL’s newest atmosphere and land models at about 100 km horizontal resolution, and ocean and sea ice models at roughly 25 km horizontal resolution. A handful of standard experiments have been conducted with CM4.0 for participation in the Coupled Model Inter-comparison Project Phase 6 (CMIP6), an archive of climate model results utilized by the Intergovernmental Panel on Climate Change (IPCC) and the climate research community more generally.

The model results have been extensively evaluated against observations. This paper makes the case that CM4.0 ranks high among state-of-the-art coupled climate models by many measures of bias in the simulated climatology and in its ability to capture modes of climate variability, such as the El Niño-Southern Oscillation and Madden-Julian Oscillation. The paper also discusses some potential weaknesses, including unrealistically large internal variability in the Southern Ocean and insufficient warming before 1990 in the simulation of the 20th century.

The two figures below illustrate the quality of CM4.0’s simulation of the current climate. The first figure compares the spatial pattern of the top-of-atmosphere (TOA) radiative fluxes with that of the CMIP5 coupled climate models used in the last IPCC assessment. CM4.0 has lower root-mean-square errors in (red dots) than nearly all CMIP5 models (box and whiskers). The second figure shows the realism of the pattern of sea surface temperature anomalies in a typical ENSO event in CM4.0, a marked improvement over other GFDL models used in IPCC assessments (not shown)."

&

JAMES' reference series on: "Geophysical Fluid Dynamics Laboratory CMIP6 Models"

https://agupubs.onlinelibrary.wiley.com/doi/toc/10.1002/(ISSN)1942-2466.CMIPMOD1


« Last Edit: November 25, 2019, 05:16:31 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2004 on: November 25, 2019, 05:12:26 PM »
As a follow-on to my last post, the two following references discuss the findings of two models included in CMIP6; which indicate that these models have both high values of ECS and higher skill levels than for the models included in CMIP5:

A. Gettelman, C. Hannay, J.T. Bacmeister, R.B. Neale, A.G. Pendergrass, G. Danabasoglu, J. Lamarque, J.T. Fasullo, D.A. Bailey, D.M. Lawrence, and M.J. Mills, "High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)", Geophysical Research Letters, vol. 46, pp. 8329-8337, 2019. http://dx.doi.org/10.1029/2019GL083978

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083978

Abstract
The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long‐term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5–4.5 K, is plausible.

&

A.A. Sellar, C.G. Jones, J. Mulcahy, Y. Tang, A. Yool, A. Wiltshire, F.M. O'Connor, M. Stringer, R. Hill, J. Palmieri, S. Woodward, L. Mora, T. Kuhlbrodt, S. Rumbold, D.I. Kelley, R. Ellis, C.E. Johnson, J. Walton, N.L. Abraham, M.B. Andrews, T. Andrews, A.T. Archibald, S. Berthou, E. Burke, E. Blockley, K. Carslaw, M. Dalvi, J. Edwards, G.A. Folberth, N. Gedney, P.T. Griffiths, A.B. Harper, M.A. Hendry, A.J. Hewitt, B. Johnson, A. Jones, C.D. Jones, J. Keeble, S. Liddicoat, O. Morgenstern, R.J. Parker, V. Predoi, E. Robertson, A. Siahaan, R.S. Smith, R. Swaminathan, M.T. Woodhouse, G. Zeng, and M. Zerroukat, "UKESM1: Description and evaluation of the UK Earth System Model", Journal of Advances in Modeling Earth Systems, 2019. http://dx.doi.org/10.1029/2019MS001739

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001739
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2019MS001739

Abstract

We document the development of the first version of the United Kingdom Earth System Model UKESM1. The model represents a major advance on its predecessor HadGEM2‐ES, with enhancements to all component models and new feedback mechanisms. These include: a new core physical model with a well‐resolved stratosphere; terrestrial biogeochemistry with coupled carbon and nitrogen cycles and enhanced land management; tropospheric‐stratospheric chemistry allowing the holistic simulation of radiative forcing from ozone, methane and nitrous oxide; two‐moment, five‐species, modal aerosol; and ocean biogeochemistry with two‐way coupling to the carbon cycle and atmospheric aerosols. The complexity of coupling between the ocean, land and atmosphere physical climate and biogeochemical cycles in UKESM1 is unprecedented for an Earth system model. We describe in detail the process by which the coupled model was developed and tuned to achieve acceptable performance in key physical and Earth system quantities, and discuss the challenges involved in mitigating biases in a model with complex connections between its components. Overall the model performs well, with a stable pre‐industrial state, and good agreement with observations in the latter period of its historical simulations. However, global mean surface temperature exhibits stronger‐than‐observed cooling from 1950 to 1970, followed by rapid warming from 1980 to 2014. Metrics from idealised simulations show a high climate sensitivity relative to previous generations of models: equilibrium climate sensitivity (ECS) is 5.4 K, transient climate response (TCR) ranges from 2.68 K to 2.85 K, and transient climate response to cumulative emissions (TCRE) is 2.49 K/TtC to 2.66 K/TtC.

Plain Language Summary
We describe the development and behaviour of UKESM1, a novel climate model that includes improved representations of processes in the atmosphere, ocean and on land. These processes are inter‐related: for example, dust is produced on the land and blown up into the atmosphere where it affects the amount of sunlight falling on the Earth. Dust can also be dissolved in the ocean, where it affects marine life. This in turn changes both the amount of carbon dioxide absorbed by the ocean and the material emitted from the surface into the atmosphere, which has an affect on the formation of clouds. UKESM1 includes many processes and interactions such as these, giving it a high level of complexity. Ensuring realistic process behaviour is a major challenge in the development of our model, and we have carefully tested this. UKESM1 performs well, correctly exhibiting stable results from a continuous pre‐industrial simulation (used to provide a reference for future experiments) and showing good agreement with observations towards the end of its historical simulations. Results for some properties‐‐‐including the degree to which average surface temperature changes with increased amounts of carbon dioxide in the atmosphere‐‐‐are examined in detail.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2005 on: November 25, 2019, 05:35:25 PM »
The linked July 2015 paper (see also the attached image) includes discussion of paleo-evidence that abrupt collapse of the WAIS helps to trigger Arctic amplification.  As DeConto is one of the primary authors and he is also one of the main authors of the Pollard, DeConto and Alley 2015 on ASLR from Antarctic cliff failures and hydrofracturing; I think that we should all take these paleo findings very seriously, including:

"The timing of significant warming in the circum-Arctic can be linked to major deglaciation events in Antarctica, demonstrating possible interhemispheric linkages between the Arctic and Antarctic climate on glacial–interglacial timescales, which have yet to be explained."

Coletti, A. J., DeConto, R. M., Brigham-Grette, J., and Melles, M.: A GCM comparison of Pleistocene super-interglacial periods in relation to Lake El'gygytgyn, NE Arctic Russia, Clim. Past, 11, 979-989, doi:10.5194/cp-11-979-2015, 2015.

http://www.clim-past.net/11/979/2015/cp-11-979-2015.pdf
http://www.clim-past.net/11/979/2015/cp-11-979-2015.html

Abstract: "Until now, the lack of time-continuous, terrestrial paleoenvironmental data from the Pleistocene Arctic has made model simulations of past interglacials difficult to assess. Here, we compare climate simulations of four warm interglacials at Marine Isotope Stages (MISs) 1 (9 ka), 5e (127 ka), 11c (409 ka) and 31 (1072 ka) with new proxy climate data recovered from Lake El'gygytgyn, NE Russia. Climate reconstructions of the mean temperature of the warmest month (MTWM) indicate conditions up to 0.4, 2.1, 0.5 and 3.1 °C warmer than today during MIS 1, 5e, 11c and 31, respectively. While the climate model captures much of the observed warming during each interglacial, largely in response to boreal summer (JJA) orbital forcing, the extraordinary warmth of MIS 11c compared to the other interglacials in the Lake El'gygytgyn temperature proxy reconstructions remains difficult to explain. To deconvolve the contribution of multiple influences on interglacial warming at Lake El'gygytgyn, we isolated the influence of vegetation, sea ice and circum-Arctic land ice feedbacks on the modeled climate of the Beringian interior. Simulations accounting for climate–vegetation–land-surface feedbacks during all four interglacials show expanding boreal forest cover with increasing summer insolation intensity. A deglaciated Greenland is shown to have a minimal effect on northeast Asian temperature during the warmth of stages 11c and 31 (Melles et al., 2012). A prescribed enhancement of oceanic heat transport into the Arctic Ocean does have some effect on Lake El'gygytgyn's regional climate, but the exceptional warmth of MIS l1c remains enigmatic compared to the modest orbital and greenhouse gas forcing during that interglacial."

Extract: "The timing of significant warming in the circum-Arctic can be linked to major deglaciation events in Antarctica, demonstrating possible interhemispheric linkages between the Arctic and Antarctic climate on glacial–interglacial timescales, which have yet to be explained."

&

The following link leads to the University of Alaska Fairbank's website focused on Lake Elgygytgn research, and the extract following the link is from an article Posted on February 4th, 2014 by Laura Nielsen on "Inter-hemispheric climate coupling". The extract emphasizes that in the paleo-past the Antarctic generally responded more quickly to orbital induced solar insolation variations, and that repeatedly paleo-collapses of the WAIS resulted in subsequent Arctic amplification, due both to changes in ocean currents, and to increases in sea level pushing more warm Pacific water through the Bering St. into the Arctic Ocean.  If the WAIS collapses this century, we may soon see a marked increase in Arctic amplification:

Title: "Inter-hemispheric climate coupling"

https://frontierscientists.com/2014/02/inter-hemispheric-climate-coupling/

Extract: "Antarctica and the Arctic

Climate at the North and South pole are connected. Sediment records from Antarctica show that the West Antarctic ice sheet melted at various times in history. Following many of those events, the Arctic warmed. These recurring intervals of paired warming show that climate in the two hemispheres is linked – it’s called inter-hemispheric climate coupling.

“When the West Antarctic ice sheet pulls back we see a corresponding warmth in the high lattitudes again, probably affecting the size of the Greenland ice sheet with major implications for changes in sea level,” says Julie Brigham-Grette. “Our results mesh with what glaciologists are seeing today. Seven of the 12 major ice shelves around the Antarctic are melting or are gone. We suspect the tipping point for the gradual de-glaciation of Greenland and the Arctic may be lower than glaciologists once thought.”

Complex systems


Earth is a complicated place. We can’t explain past warming using only orbital dynamics or levels of Carbon Dioxide. Scientists affiliated with the project outlined some past events that might explain the rapid warming the sediment records show occurred in both Antarctica and the Arctic around similar times.

When you imagine Antarctica, the picture includes large ice shelves that hang off the rocky edge of the ice-covered continent. Normally that ice keeps nearby ocean water very cold. The cold water travels along currents toward the north Pacific where it wells up to the surface. Ocean circulation can be affected, though. If Antarctic ice sheets disintegrate or melt away, they no longer enforce cold water currents that journey to the Arctic. Instead, surface ocean waters in the Arctic become warmer.

When Antarctica’s ice sheets disintegrate the ocean gains more water and sea levels rise globally. The Bering Strait usually restricts how much warm surface water approaches the Arctic from the south, but higher sea levels would mean warm surface water didn’t have to squeeze through such a narrow space, letting more warm water past the Bering Strait into the Arctic Ocean.

Either way, a warmer ocean means higher temperatures and more rainfall for the Arctic, which impacts paleoclimatology and sea ice history. Grasping the climate connections between the hemispheres gives us insight into our near future."

&

As I have noted that the MIS 11 (Holsteinian) era is particularly relevant to possible future scenarios for the impact of climate change, I provide the following paleo reference:

Florence Chen et al (2014), "Refining Estimates of Polar Ice Volumes during the MIS11 Interglacial Using Sea Level Records from South Africa", Journal of Climate, https://doi.org/10.1175/JCLI-D-14-00282.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00282.1
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-14-00282.1

Abstract: "Peak eustatic sea level (ESL), or minimum ice volume, during the protracted marine isotope stage 11 (MIS11) interglacial at ~420 ka remains a matter of contention. A recent study of high-stand markers of MIS11 age from the tectonically stable southern coast of South Africa estimated a peak ESL of 13 m. The present study refines this estimate by taking into account both the uncertainty in the correction for glacial isostatic adjustment (GIA) and the geographic variability of sea level change following polar ice sheet collapse. In regard to the latter, the authors demonstrate, using gravitationally self-consistent numerical predictions of postglacial sea level change, that rapid melting from any of the three major polar ice sheets (West Antarctic, Greenland, or East Antarctic) will lead to a local sea level rise in southern South Africa that is 15%–20% higher than the eustatic sea level rise associated with the ice sheet collapse. Taking this amplification and a range of possible GIA corrections into account and assuming that the tectonic correction applied in the earlier study is correct, the authors revise downward the estimate of peak ESL during MIS11 to 8–11.5 m."
« Last Edit: November 25, 2019, 06:32:52 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2006 on: November 25, 2019, 06:06:30 PM »
Per the linked article, the World Meteorological Organization, WMO, announced that thru 2018 there is no sign of a slowdown in GHG concentrations in the atmosphere:

Title: "WMO study: Greenhouse gases reached record levels in 2018"

https://www.upi.com/Top_News/World-News/2019/11/25/WMO-study-Greenhouse-gas-levels-reached-record-levels-in-2018/3641574683883/

Extract: "There is no sign of a slowdown, let alone a decline, in greenhouse gases concentration in the atmosphere despite all the commitments under the Paris Agreement on Climate Change," WMO Secretary-General Petteri Taalas said in releasing the report. "We need to translate the commitments into action and increase the level of ambition for the sake of the future welfare of the mankind."

The WMO found CO2 levels were the main culprit in last year's overall greenhouse gas increases.

In 2018, global averages of CO2 reached 407.8 parts per million, up from 405.5 parts per million in 2017. That increase was very similar to the one logged from 2016 to 2017 and registered just above the average for the last decade at 147 percent of the pre-industrial level of 1750.

Methane and nitrous oxide levels, meanwhile, also rose by more than the decade's average in 2018.

Methane reached a new high of about 1,869 parts per billion, or about 259 percent of pre-industrial levels, while nitrous oxide concentrations rose to 331.1 parts per billion, or 123 percent above the pre-industrial standard."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2007 on: November 25, 2019, 06:32:13 PM »
The linked article indicates that: "Clean-energy investments in the developing world plummeted last year … "

Title: "The developing world has hit the brakes on clean energy"

https://www.technologyreview.com/f/614750/the-developing-world-has-hit-the-brakes-on-clean-energy/

Extract: "Clean-energy investments in the developing world plummeted last year while coal use reached a record high.

Those are very bad signs for the climate. Most of the world’s economic expansion in the coming decades will be in nations like China, India, and other emerging markets. So powering that growth with fossil fuels, rather than renewables, threatens to lock in soaring levels of greenhouse gas emissions.

The really bad news: It now appears that China has kicked off a new coal building boom.
Last week, nonprofit Global Energy Monitor reported that the nation expanded its coal fleet by nearly 43 gigawatts between January 2018 and June 2019, far outpacing a roughly 8-gigawatt decline across the rest of the world in that period. And it has nearly 150 gigawatts under construction or likely to be revived—roughly equal to all the European Union’s coal plants.

“An increase in China’s coal power capacity is not compatible with the Paris climate agreement to hold warming well below 2 °C,” the report concluded."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2008 on: November 25, 2019, 06:57:11 PM »
As a follow-on to Reply #2004 , the linked open access peer-reviews article indicates that two UK models from CMIP6 have effective values of ECS of 5.5C and 5.4C; and explains why these values are higher than those for consensus climate models such as those in CMIP5 (see the attached images where the second image is an enlarged view of panel d from the first image).

Timothy Andrews et al. (24 November 2019", "Forcings, feedbacks and climate sensitivity in HadGEM3‐GC3.1 and UKESM1", JAMES, https://doi.org/10.1029/2019MS001866

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001866
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2019MS001866

Abstract

Climate forcing, sensitivity and feedback metrics are evaluated in both the UK's physical climate model HadGEM3‐GC3.1 at low (‐LL) and medium (‐MM) resolution and the UK's Earth System Model UKESM1. The Effective Climate Sensitivity (EffCS) to a doubling of CO2 is 5.5K for HadGEM3.1‐GC3.1‐LL and 5.4K for UKESM1. The transient climate response is 2.5K and 2.8K respectively. Whilst the EffCS is larger than that seen in the previous generation of models, none of the model's forcing or feedback processes are found to be atypical of models, though the cloud feedback is at the high end. The relatively large EffCS results from an unusual combination of a typical CO2 forcing with a relatively small feedback parameter. Compared to the previous UK climate model, HadGEM3‐GC2.0, the EffCS has increased from 3.2K to 5.5K due to an increase in CO2 forcing, surface albedo feedback and mid‐latitude cloud feedback. All changes are well understood and due to physical improvements in the model. At higher atmospheric and ocean resolution (HadGEM3‐GC3.1‐MM), there is a compensation between increased marine stratocumulous cloud feedback and reduced Antarctic sea‐ice feedback. In UKESM1 a CO2 fertilization effect induces a land surface vegetation change and albedo radiative effect. Historical aerosol forcing in HadGEM3‐GC3.1‐LL is ‐1.1 Wm‐2. In HadGEM3‐GC3.1‐LL historical simulations cloud feedback is found to be less positive than in abrupt‐4xCO2, in agreement with atmosphere‐only experiments forced with observed historical sea‐surface‐temperature and sea‐ice variations. However variability in the coupled model's historical sea‐ice trends hampers accurate diagnosis of the model's total historical feedback.

Plain language summary
A new generation of climate models ‐ called HadGEM3‐GC3.1 and UKESM1 ‐ have been developed in the United Kingdom and will be used widely in the Coupled Model Intercomparison Project phase 6 (CMIP6). Evaluating the models' benchmark climate sensitivity and feedback metrics is a useful first step to understanding their characteristic response to forcing. The effective climate sensitivities are found to be higher than that seen in the previous generation of models, in common with other recently developed climate models. Reasons for this are discussed.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2009 on: November 25, 2019, 07:04:13 PM »
Open mind has a new post
Climate Models
How well have climate models forecast global temperature?

Conclusion
Quote
Recent values are genuine predictions, in the sense that the observed values of global temperature weren’t known when the models were run (it can take a long time to run these models, even on a supercomputer).

Clearly actual temperature has followed the model results closely, staying within the 1-sigma range most of the time. The latest value (2019 year-to-date) is right in the bull’s eye.
https://tamino.wordpress.com/2019/11/25/climate-models/
« Last Edit: November 25, 2019, 08:09:51 PM by KiwiGriff »
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Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2010 on: November 25, 2019, 08:32:27 PM »
^^^^

These were the CMIP 5 models run with the RCP 4.5 emissions scenario.

AbruptSLR likes to selectively quote from Real Climate's recent post on the preliminary CMIP 6 model results.

http://www.realclimate.org/index.php/archives/2019/11/sensitive-but-unclassified/

Here's the part he quotes:

Quote
So what should people make of this? Here are some options:
These new higher numbers might be correct. As cloud micro-physical understanding has improved and models better match the real climate, they will converge on a higher ECS.

Here's the part he leaves out:

Quote
These new numbers are not correct. There are however many ways in which this might have manifest:
The high ECS models have all included something new and wrong.
They have all neglected a key process that should have been included with the package they did implement.
There has been some overfitting to imperfect observations.
The experimental set-up from which the ECS numbers are calculated is flawed.
There are arguments pro and con for each of these possibilities, and it is premature to decide which of them are relevant. It isn’t even clear that there is one answer that will explain all the high values – it might all be a coincidence – a catalogue of unfortunate choices that give this emergent pattern. We probably won’t find out for a while – though many people are now looking at this.
Why might the numbers be correct? All the preliminary analyses I’ve seen with respect to matches to present day climatologies and variability indicate that the skill scores of the new models (collectively, not just the high ECS ones) are improved over the previous versions. This is discussed in Gettelman et al. (2019) (CESM2), Sellar et al (2019) (UKESM1) etc. Indeed, this is a generic pattern in model development. However, up until now, there has not been any clear relationship between overall skill and climate sensitivity. Whether this will now change is (as yet) unclear.

Why might these numbers be wrong? Well, the independent constraints from the historical changes since the 19th C, or from paleo-climate or from emergent constraints in the CMIP5 models collectively suggest lower numbers (classically 2 to 4.5ºC) and new assessments of these constraints are likely to confirm it. For all these constraints to be wrong, a lot of things have to fall out just right (forcings at the LGM would have to be wrong by a factor of two, asymmetries between cooling and warming might need to be larger than we think, pattern effects need to be very important etc.). That seems unlikely.

Quote
There is some indication that for the models with higher ECS that the changes in the abrupt4xCO2 runs are changing so much (more than 10ºC warming) that the models might be exceeding the bounds for which some aspects are valid. Note these are the runs from which the ECS is calculated. What do I mean by this? Take the HadGEM3 model. The Hardiman et al. (2019) paper reports on an artifact in the standard runs related to the rising of the tropopause that ends up putting (fixed) high stratospheric ozone in the troposphere causing an incorrect warming of the tropopause and a massive change of stratospheric water vapor – leading to a positive (and erroneous) amplification of the warming (by about 0.6ºC). Are there other assumptions in these runs that are no longer valid at 10ºC warming? Almost certainly. Is that the explanation? Perhaps not – it turns out that most (though not all) high ECS models also have high transient climate responses (TCR) which happen at much smaller global mean changes (< 3ºC).

Many of the new CMIP 6 models claim that they're addressing cloud micro-physics better but they were developed a few years ago when studies seemed to indicate that clouds have more of cooling effect than they currently are shown to have.  Here's the abstract from the UKESM1 model development paper which states that it shows too much cooling from the 1950s to the 1980s while touting it's new cloud modelling.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001739

Quote
Abstract
We document the development of the first version of the United Kingdom Earth System Model UKESM1. The model represents a major advance on its predecessor HadGEM2‐ES, with enhancements to all component models and new feedback mechanisms. These include: a new core physical model with a well‐resolved stratosphere; terrestrial biogeochemistry with coupled carbon and nitrogen cycles and enhanced land management; tropospheric‐stratospheric chemistry allowing the holistic simulation of radiative forcing from ozone, methane and nitrous oxide; two‐moment, five‐species, modal aerosol; and ocean biogeochemistry with two‐way coupling to the carbon cycle and atmospheric aerosols. The complexity of coupling between the ocean, land and atmosphere physical climate and biogeochemical cycles in UKESM1 is unprecedented for an Earth system model. We describe in detail the process by which the coupled model was developed and tuned to achieve acceptable performance in key physical and Earth system quantities, and discuss the challenges involved in mitigating biases in a model with complex connections between its components. Overall the model performs well, with a stable pre‐industrial state, and good agreement with observations in the latter period of its historical simulations. However, global mean surface temperature exhibits stronger‐than‐observed cooling from 1950 to 1970, followed by rapid warming from 1980 to 2014. Metrics from idealised simulations show a high climate sensitivity relative to previous generations of models: equilibrium climate sensitivity (ECS) is 5.4 K, transient climate response (TCR) ranges from 2.68 K to 2.85 K, and transient climate response to cumulative emissions (TCRE) is 2.49 K/TtC to 2.66 K/TtC.

The details about how they were able to replicate pre-industrial conditions are enlightening:

Quote
The physical core of UKESM1 was already well-tuned before adding ESM components (Kuhlbrodt et al., 2018; Williams et al., 2018), and with the exception of the snow-vegetation interaction above it was not deemed necessary to re-tune the physical model parameters. The TOA radiation balance was however altered by the addition of ESM components, through a combination of changes in cloud, surface albedo and radiatively active gases. Without further tuning the net downward radiation at TOA in 1850 was −0.81 W m−2, which would have resulted in a significant downward drift in model temperatures. We brought the TOA radiation into balance by tuning parameters in the Anderson et al. (2001) parametrisation of DMS sea-water concentration to permit lower minimum values of DMS. The standard configuration of this parametrisation has a prescribed minimum value of 2.29 nM for seawater DMS concentration, while gridded observational DMS datasets, such as those of Kettle et al. (1999) or Lana et al. (2011), contain significantly smaller values than this over large regions of the ocean. Anderson et al. (2001) themselves point out that the data from which their parametrisation is derived is likely to contain a sampling bias towards higher values, so a lower minimum is reasonable. We reduced the minimum from 2.29 nM to 1.00 nM, extending the Anderson et al. (2001) linear relationship (between DMS concentration andlog10of chlorophyll concentration, surface SW and nutrient availability) to lower values of DMS. The ensuing reduction in DMS gave widespread decreases in cloud droplet number (and thus cloud albedo) across the Southern Ocean and stratocumulus regions, resulting in a drop in reflected SW at TOA of 2 to 5 Wm−2over large areas of the ocean.

Here's how the CMIP 6 model ECS, TCR and TCRE compare to the CMIP 5 results.  (Note the statement about cloud mcrophysics and cloud aerosol intereactions).

Quote
The UKESM1 values of ECS, TCR and TCRE are all higher than those of CMIP5 models (respectively, 2.1 K to 4.7 K, 1.0 K to 2.6 K, and 0.8 K/TtC to 2.4 K/TtC Andrews, Gregory, Webb, & Taylor, 2012; Gillett et al., 2013). Elsewhere in this special issue, Bodas-Salcedo et al. (2019) analyse the increase in atmospheric climate feedbacks in HadGEM3-GC3.1 relative to the previous version of HadGEM3, whose ECS (3.2 K; Senior et al., 2016) is within the range of CMIP5 models. They find that the feedbacks have become more positive as a result of improvements to cloud microphysics and cloud-aerosol interactions.

And they compare their results to observed surface temperatures.

Quote
Surface temperature is one of the few variables for which reliable observations cover the full period of the 1850-2014 historical simulation, which allows us to evaluate the model’s first-order climate response to the evolving forcing over this period. The UKESM1 global mean surface temperature anomaly in the historical ensemble shown in Figure 29, along-side the HadCRUT4 observation dataset (Morice, Kennedy, Rayner, & Jones, 2012). The observations represent only a single realisation of the internal variability of the climate system, so one should not expect the model ensemble to be centred on the observations, but rather that the range of observational uncertainty overlaps the ensemble range (under the assumption that the model ensemble is large enough to sample the relevant in-ternal variability). Most ensemble members begin to warm in the early 20th century, then cool strongly between 1950 and 1970 before warming rapidly through to the end of the simulation. The observations show a limited cooling of 0.1 K to 0.2 K during 1940 to 1970, but the model ensemble mean cools by nearly 0.4 K over the same period. All ensemble members also show a stronger cooling response to the large volcanic eruptions of 1883, 1963 and 1991 than is seen in the observations.

Figure 29 also separates the mean surface temperature into northern and south-904ern hemisphere timeseries. The stronger-than-observed cooling is restricted to the north-905ern hemisphere which, together with its temporal evolution, points to either aerosol or906land use forcing as the prime driver. Further investigation into this discrepancy will be907the subject of future work. In the southern hemisphere the model ensemble overlaps with908the observational uncertainty for the entire duration of the experiment, with the excep-909tion of the dip following the Mt. Pinatubo eruption in 1991 noted above.

« Last Edit: November 25, 2019, 08:42:20 PM by Ken Feldman »

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2011 on: November 25, 2019, 08:51:21 PM »
^^^^

These were the CMIP 5 models run with the RCP 4.5 emissions scenario.

AbruptSLR likes to selectively quote from Real Climate's recent post on the preliminary CMIP 6 model results.

http://www.realclimate.org/index.php/archives/2019/11/sensitive-but-unclassified/



No one expects consensus climate scientists to stop erring on the side of least drama, ESLD, anytime soon; however, if the preliminary CMIP6 findings are correct then it is likely that several significant tipping points may well have been crossed before consensus climate scientists publicly acknowledge the dangerous situation that we have collectively put ourselves in.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2012 on: November 25, 2019, 09:32:04 PM »
^^^^

These were the CMIP 5 models run with the RCP 4.5 emissions scenario.

AbruptSLR likes to selectively quote from Real Climate's recent post on the preliminary CMIP 6 model results.

http://www.realclimate.org/index.php/archives/2019/11/sensitive-but-unclassified/



No one expects consensus climate scientists to stop erring on the side of least drama, ESLD, anytime soon; however, if the preliminary CMIP6 findings are correct then it is likely that several significant tipping points may well have been crossed before consensus climate scientists publicly acknowledge the dangerous situation that we have collectively put ourselves in.

Here is the image from Tamino's post (the runs with the CMIP 5 models using the RCP 4.5 emissions scenario):



Catastrophist bloggers like to post about how the CMIP 6 models run even hotter than the CMIP 5 models and they also like to post a lot of studies using the RCP 8.5 emissions scenario.  As shown upthread, we are no longer projected to burn enough coal to meet the RCP 8.5 scenario.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2013 on: November 25, 2019, 09:54:31 PM »
Quote
Catastrophist bloggers like to post about ...

That NASA data looks like the makings of catastrophe.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2014 on: November 25, 2019, 10:17:07 PM »

4.5 is closest to our present emissions.
I do not see any evidence that we will remain on 4.5 into the future. On purely our emissions  8.5 is not probable however feed backs in the natural world may see us with an energy imbalance closer to the result of 8.5 than that implied by lessor scenarios .

First comment on open mind .
Quote
Robert Way | November 25, 2019 at 4:06 pm | Reply
Hi Tamino,
Is this a like-for-like comparison with SAT+SST for both or are you comparing SATs to SAT+SST (e.g. Cowtan et al 2015)?

[Response: It’s comparing SAT (from models) to SAT+SST (obsesrvations). A proper comparison (a al Cowtan & Way) makes the most recent observations even higher relative to the models.]

1 RCP are complex scenarios that we are not going to follow precisely. I do not see us reducing  emissions like in the future projections of  RCP 4.5. RCP 6.5 seems a more likely long term outlook at this point.
2 Using a metric that matches  the model output  finds the models if anything underestimate warming
3 Most of the energy goes into the oceans so surface temps are a poor measurement to use  to monitor our effects on the climate.
4 The emergent  effects of global warming seem to be happening at a faster rate than past consensus science has supported. We can include both sea Ice melt and sea level rise due to melting land ice in underestimated effects.
5 Do you feel lucky and are you willing to bet humanity's future on your optimistic feelings ?
« Last Edit: November 25, 2019, 10:31:52 PM by KiwiGriff »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2015 on: November 25, 2019, 10:34:23 PM »
Here is another peer-reviewed reference about preliminary CMIP6 projections (see also Replies #2003, 2004 and 2008) with a projected value of ECS around 5.3C:

Jean‐Christophe Golaz et al. (15 March 2019), "The DOE E3SM Coupled Model Version 1: Overview and Evaluation at Standard Resolution", JAMES, https://doi.org/10.1029/2018MS001603

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018MS001603

Abstract
This work documents the first version of the U.S. Department of Energy (DOE) new Energy Exascale Earth System Model (E3SMv1). We focus on the standard resolution of the fully coupled physical model designed to address DOE mission‐relevant water cycle questions. Its components include atmosphere and land (110‐km grid spacing), ocean and sea ice (60 km in the midlatitudes and 30 km at the equator and poles), and river transport (55 km) models. This base configuration will also serve as a foundation for additional configurations exploring higher horizontal resolution as well as augmented capabilities in the form of biogeochemistry and cryosphere configurations. The performance of E3SMv1 is evaluated by means of a standard set of Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima simulations consisting of a long preindustrial control, historical simulations (ensembles of fully coupled and prescribed SSTs) as well as idealized CO2 forcing simulations. The model performs well overall with biases typical of other CMIP‐class models, although the simulated Atlantic Meridional Overturning Circulation is weaker than many CMIP‐class models. While the E3SMv1 historical ensemble captures the bulk of the observed warming between preindustrial (1850) and present day, the trajectory of the warming diverges from observations in the second half of the twentieth century with a period of delayed warming followed by an excessive warming trend. Using a two‐layer energy balance model, we attribute this divergence to the model's strong aerosol‐related effective radiative forcing (ERFari+aci = −1.65 W/m2) and high equilibrium climate sensitivity (ECS = 5.3 K).

Plain Language Summary
The U.S. Department of Energy funded the development of a new state‐of‐the‐art Earth system model for research and applications relevant to its mission. The Energy Exascale Earth System Model version 1 (E3SMv1) consists of five interacting components for the global atmosphere, land surface, ocean, sea ice, and rivers. Three of these components (ocean, sea ice, and river) are new and have not been coupled into an Earth system model previously. The atmosphere and land surface components were created by extending existing components part of the Community Earth System Model, Version 1. E3SMv1's capabilities are demonstrated by performing a set of standardized simulation experiments described by the Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima protocol at standard horizontal spatial resolution of approximately 1° latitude and longitude. The model reproduces global and regional climate features well compared to observations. Simulated warming between 1850 and 2015 matches observations, but the model is too cold by about 0.5 °C between 1960 and 1990 and later warms at a rate greater than observed. A thermodynamic analysis of the model's response to greenhouse gas and aerosol radiative affects may explain the reasons for the discrepancy.
« Last Edit: November 25, 2019, 11:45:44 PM by AbruptSLR »
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Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2016 on: November 26, 2019, 08:09:33 AM »
The issue here is that these models are demonstrably unreliable in terms of forecasting global warming - they're running hot.

Can you point us to some peer-reviewed science that demonstrates the models are running hot, and to what extent?
As far as I know they're pretty much on target, but maybe I've missed the relevant science.

Nothing peer reviewed, but prof. Ed Hawkins makes regular updates to evaluate model performance. Models evidently running hot.

http://www.met.reading.ac.uk/~ed/home/index.php
https://www.climate-lab-book.ac.uk/comparing-cmip5-observations/

Lennart van der Linde

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2017 on: November 26, 2019, 02:01:10 PM »
Nothing peer reviewed, but prof. Ed Hawkins makes regular updates to evaluate model performance. Models evidently running hot.

http://www.met.reading.ac.uk/~ed/home/index.php
https://www.climate-lab-book.ac.uk/comparing-cmip5-observations/

It may be evident to you, but apparently not to Hawkins himself, and not to peer-reviewed Lewandowsky et al 2018 either.

Hawkins writes on his blog:
"The simulation data uses spatially complete coverage of surface air temperature whereas the observations use a spatially incomplete mix of air temperatures over land and sea surface temperatures over the ocean. It is expected that this factor alone would cause the observations to show smaller trends than the simulations."

He gives some other potential explanations for the apparent divergence as well:
"There are several possible explanations for why the earlier observations are at the lower end of the CMIP5 range. First, there is internal climate variability, which can cause temperatures to temporarily rise faster or slower than expected. Second, the radiative forcings used after 2005 are from the RCPs, rather than as observed. Given that there have been some small volcanic eruptions and a dip in solar activity, this has likely caused some of the apparent discrepancy. Third, the real world may have a climate sensitivity towards the lower end of the CMIP5 range. Next, the exact position of the observations within the CMIP5 range depends slightly on the reference period chosen. Lastly, this is not an apples-with-apples comparison because it is comparing air temperatures everywhere (simulations) with blended and sparse observations of air temperature and sea temperatures. A combination of some of these factors is likely responsible."

Lewandowsky et al 2018  elaborate on this:
https://iopscience.iop.org/article/10.1088/1748-9326/aaf372/meta

"The impression of a divergence early in the 21st century was caused by various biases in model interpretation and in the observations, and was unsupported by robust statistics [...] IPCC Assessment Report (AR5)... stated that '...111 out of 114 realizations show a GMST trend over 1998–2012 that is higher than the entire HadCRUT4 trend ensemble... This difference between simulated and observed trends could be caused by some combination of (a) internal climate variability, (b) missing or incorrect radiative forcing and (c) model response error' (Flato et al 2013, p 769). The consensus view expressed by the IPCC therefore pointed to a divergence between modeled and observed temperature trends, putatively caused by a mix of three factors. Subsequent to the IPCC report, the role of these three factors has become clearer [...] We have established that several biases in the observations and in model projections gave rise to the impression of a divergence between modeled and observed temperature trends. This impression was limited to the period 2011–2013, after which the ongoing debiasing eliminated any appearance of a divergence. During the period 2011–2013, the impression of a divergence could appear to be statistically significant, but only if the selection-bias issue was ignored. We have shown that ignoring of the selection-bias issue can drastically inflate Type-I error rates, which renders the inferences unreliable and in this case erroneous."

See their full paper for further details.
What do you think of their conclusions?

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2018 on: November 26, 2019, 02:47:44 PM »
I seems we probably don't need any extra feedbacks etc etc for global heating to reach uncomfortable levels.

Cross-posted from Paris 2015 thread.
UNEP have issued their 2019 emissions gap report.

Executive Summary - https://newclimate.org/wp-content/uploads/2019/11/EGR19ESEN.pdf
Full Report - https://newclimate.org/wp-content/uploads/2019/11/EGR2019.pdf

Press release - https://newclimate.org/2019/11/26/emissions-gap-report-2019/
Quote
Geneva, 26 November 2019 – unless global greenhouse gas emissions fall by 7.6 per cent each year between 2020 and 2030, the world will miss the opportunity to get on track towards the 1.5°C temperature goal of the Paris Agreement.

UNEP’s annual Emissions Gap Report says that even if all current unconditional commitments under the Paris Agreement are implemented, temperatures are expected to rise by 3.2°C, bringing even wider-ranging and more destructive climate impacts. Collective ambition must increase more than fivefold over current levels to deliver the cuts needed over the next decade for the 1.5°C goal.

Quote
“For ten years, the Emissions Gap Report has been sounding the alarm – and for ten years, the world has only increased its emissions,” said UN Secretary-General António Guterres.
“There has never been a more important time to listen to the science. Failure to heed these warnings and take drastic action to reverse emissions means we will continue to witness deadly and catastrophic heatwaves, storms and pollution.”[/size]

I think we are well and truly screwed.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2019 on: November 26, 2019, 04:39:19 PM »
...
 Models evidently running hot.
...

The first linked reference (and first two associated images) calibrated an effective/specific equilibrium climate sensitivity (S) based on warming cycles during the past 784,000 years.  There findings for the upper end risk (e.g. RCP 8.5) indicated that the projected GMSTA range could be between 4.78C to 7.36C by 2100, based on one set of calculations; which is in keeping with the preliminary high-end CMIP6 projections (see the third image).

Tobias Friedrich, Axel Timmermann, Michelle Tigchelaar, Oliver Elison Timm and Andrey Ganopolski (09 Nov 2016), "Nonlinear climate sensitivity and its implications for future greenhouse warming", Science Advances, Vol. 2, no. 11, e1501923, DOI: 10.1126/sciadv.1501923

http://advances.sciencemag.org/content/2/11/e1501923

Extract: "Global mean surface temperatures are rising in response to anthropogenic greenhouse gas emissions. The magnitude of this warming at equilibrium for a given radiative forcing—referred to as specific equilibrium climate sensitivity (S)—is still subject to uncertainties. We estimate global mean temperature variations and S using a 784,000-year-long field reconstruction of sea surface temperatures and a transient paleoclimate model simulation. Our results reveal that S is strongly dependent on the climate background state, with significantly larger values attained during warm phases. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, we find that the range of paleo-based estimates of Earth’s future warming by 2100 CE overlaps with the upper range of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Furthermore, we find that within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years. On the basis of temperature data from eight glacial cycles, our results provide an independent validation of the magnitude of current CMIP5 warming projections."

Furthermore, both the preliminary CMIP6 projections (see the third image again) and the CMIP3 projections (see the fourth image) following BAU pathways very closely match the observed record thru 2019.  Thus both paleo-based and modeled projections are matching the observed record (also remember that the faux hiatus is actually an indication of high climate variability; which implies an associated high level of climate sensitivity).
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2020 on: November 26, 2019, 05:31:29 PM »
The first linked article discusses the issue of 'why scientists defend dangerous industries' such as the fossil fuel industries; I note that most governments around the world significantly represent the interests of their largest industries, including fossil fuel industries.  Thus, I would paraphrase the title of this article to raise the topic of: 'Why scientists defend dangerous behavior of governmental bodies' such as the Intergovernmental Panel on Climate Change, IPCC.

In this regard, the second linked article (entitled: UNEP: 1.5C climate target ‘slipping out of reach’) about the UN's production gap report, propagates the dangerous (and/or exceedingly wishful) thinking that governments around the world will somehow implement trillions of dollars' worth of negative emissions technology in order to remain on some emissions trajectory to stay below (not well below as stated in the Paris goal, but only just below, which is another consensus science caveat) 2C (see the first attached image).  Consensus scientist frequently say that they are trying to give people hope, but I see this behavior as dangerous and not particularly scientific (as it assumes that governments will behave in a manner not supported by statistical evidence).

Title: "Why Scientists Defend Dangerous Industries"

https://www.chronicle.com/article/Why-Scientists-Defend/247598?key=j_DIeWIUtJsVs9ToXQRavlbGPXhFrlbMZ5YGwi74R_euUPz3gH5GFnQGxmYBpDRdUVplVDZvd3BHY1A4M2FUVEVadmtsNFZ6bWhZNDJrVUowOHp6VUsyRzZKQQ&cid=wcontentlist

Extract: "In his forthcoming book, The Triumph of Doubt: Dark Money and the Science of Deception (Oxford University Press), Michaels collects recent examples of industries not just questioning science but manipulating it. Often the manipulation involves private laboratories, but he also cites numerous examples of scientists at colleges taking industry grants and delivering skewed results that promote the interests of their funders.

How do academic scientists get wrapped up in this bad science?

There are academic scientists who receive funding, in some cases large amounts, to provide studies that are designed to find certain answers. We see that commonly, for example, in the nutrition literature, where the way a study is designed is very clearly going to give you a certain answer. Also scientists who do risk assessments, who build in assumptions that essentially guarantee that only the highest levels of exposures will be found to be dangerous. And then those scientists will appear in court, or in regulatory proceedings, for the corporation in question.

What made you think we need a book like The Triumph of Doubt now? You published a book called Doubt Is Their Product in 2008.

With the coming of the Trump administration, I saw two things. One was that some of the same product-defense scientists whom I had written about 10 years ago as trying to influence government regulatory agencies now were being put into positions to run those agencies. The other thing I saw was that this approach has become so common across all industries. It isn’t simply the oil industry and the chemical industry. It became used so widely. This is an insult to science and to scientists who have worked so hard on protecting the public."

&

Title: "UNEP: 1.5C climate target ‘slipping out of reach’"

https://www.carbonbrief.org/unep-1-5c-climate-target-slipping-out-of-reach

Extract: "Unless the world begins to rapidly reduce greenhouse gas emissions the 1.5C goal of the Paris Agreement “will slip out of reach,” according to the latest UN Environment Programme (UNEP) emissions gap report."

Edit: For those tempted to comment that the trajectories shown in the first attached image can be achieved without negative emissions technology, I note here that the attached image incorrectly addresses CO2 emissions as the only source of global warming, while when one correctly considers the impact of other GHGs like methane and nitrous oxide; which are difficult to remove artificially from the atmosphere, then negative emissions technology for CO2 need to be applied to make-up the difference).  For convenience, I attach the second image that shows the amount of negative emissions technology (BECCS) assumed in the AR5 scenarios.

Edit2: I also note that both images assume that ECS is approximately 3C; which is well below the preliminary CMIP6 projections for ECS.
« Last Edit: November 26, 2019, 06:13:33 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2021 on: November 26, 2019, 05:54:28 PM »
The linked articles describe how climate change can lead to abrupt changes in hypoxia in coastal fisheries (see the attached image and quote below):

http://www.nsf.gov/news/special_reports/deadzones/climatechange.pdf

http://www.theverge.com/2015/1/28/7930047/climate-change-could-mean-massive-ocean-dead-zones

Quote: "Though the exact mechanism driving dead zone expansion is unclear, studies show that it’s happening and will likely increase. One model predicts a 50 percent increase in low-oxygen water by the end of the century. As the zones spread, they reduce the number of habitats for many of the sea creatures we eat.

The disconcerting thing about Moffitt’s study is that it shows how quickly these changes can happen. Most policy discussions about climate change are conducted in terms of estimates and averages — 3 feet of sea level rise, 170 percent increase in ocean acidity — but what we’re dealing with are complex interlocking systems with tipping points and feedback loops we barely understand.

"It’s not just about temperature," says Moffitt. "It’s about disrupting fundamental earth processes that we as humans have understood to be very stable. They’re not stable. These systems have the capacity to be very unstable when you poke climate system with a sharp stick.""
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2022 on: November 26, 2019, 09:04:27 PM »
The linked reference indicates that when evaluating the range of plausible warming rates (ie plausible ranges of climate sensitivity) it is critical to include a proper evaluation of the nonlinear regional warming distributions.  That is to say that if strong regional superlinear warming drives nonlinear positive feedback mechanisms, consideration of this phenomena will result in higher estimates of climate sensitivity than currently estimated by AR5; which may be one of the reasons that the preliminary CMIP6 results are indicating higher values for ECS than did CMIP5:

Peter Good, Jason A. Lowe, Timothy Andrews, Andrew Wiltshire, Robin Chadwick, Jeff K. Ridley, Matthew B. Menary, Nathaelle Bouttes, Jean Louis Dufresne, Jonathan M. Gregory, Nathalie Schaller & Hideo Shiogama (2015), "Nonlinear regional warming with increasing CO2 concentrations", Nature Climate Change, Volume: 5, Pages: 138–142, doi:10.1038/nclimate2498

http://www.nature.com/nclimate/journal/v5/n2/full/nclimate2498.html

Abstract: "When considering adaptation measures and global climate mitigation goals, stakeholders need regional-scale climate projections, including the range of plausible warming rates. To assist these stakeholders, it is important to understand whether some locations may see disproportionately high or low warming from additional forcing above targets such as 2 K. There is a need to narrow uncertainty in this nonlinear warming, which requires understanding how climate changes as forcings increase from medium to high levels. However, quantifying and understanding regional nonlinear processes is challenging. Here we show that regional-scale warming can be strongly superlinear to successive CO2 doublings, using five different climate models. Ensemble-mean warming is superlinear over most land locations. Further, the inter-model spread tends to be amplified at higher forcing levels, as nonlinearities grow—especially when considering changes per kelvin of global warming. Regional nonlinearities in surface warming arise from nonlinearities in global-mean radiative balance, the Atlantic meridional overturning circulation, surface snow/ice cover and evapotranspiration. For robust adaptation and mitigation advice, therefore, potentially avoidable climate change (the difference between business-as-usual and mitigation scenarios) and unavoidable climate change (change under strong mitigation scenarios) may need different analysis methods."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2023 on: November 26, 2019, 10:55:50 PM »
The linked reference indicates that particularly the tropical South Pacific Ocean is a hotspot for natural nitrous oxide emissions; which, thus might increase with increase ENSO activity associated with global warming:

Massive nitrous oxide emissions from the tropical South Pacific Ocean by Arévalo-Martínez, D. L., A. Kock, C. R. Löscher, R. A. Schmitz, H. W. Bange published in Nature Geoscience doi:10.1038/ngeo2469

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2469.html

Abstract: "Nitrous oxide is a potent greenhouse gas and a key compound in stratospheric ozone depletion. In the ocean, nitrous oxide is produced at intermediate depths through nitrification and denitrification, in particular at low oxygen concentrations. Although a third of natural emissions of nitrous oxide to the atmosphere originate from the ocean, considerable uncertainties in the distribution and magnitude of the emissions still exist. Here we present high-resolution surface measurements and vertical profiles of nitrous oxide that include the highest reported nitrous oxide concentrations in marine surface waters, suggesting that there is a hotspot of nitrous oxide emissions in high-productivity upwelling ecosystems along the Peruvian coast. We estimate that off Peru, the extremely high nitrous oxide supersaturations we observed drive a massive efflux of 0.2–0.9 Tg of nitrogen emitted as nitrous oxide per year, equivalent to 5–22% of previous estimates of global marine nitrous oxide emissions. Nutrient and gene abundance data suggest that coupled nitrification–denitrification in the upper oxygen minimum zone and transport of resulting nitrous oxide to the surface by upwelling lead to the high nitrous oxide concentrations. Our estimate of nitrous oxide emissions from the Peruvian coast surpasses values from similar, highly productive area."

See also:
http://www.reportingclimatescience.com/news-stories/article/pacific-nitrous-oxide-emissions-more-than-thought.html

Caption for the attached image: "The graph shows in the dark blue to violet tones the oxygen minimum zone (OMZs) in the tropical oceans. They play a major role in the nitrogen cycle. For the SFB 754 they are the main working areas. Courtesy: SFB 754 and GEOMAR Helmholtz Centre for Ocean Research Kiel"
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2024 on: November 26, 2019, 11:28:48 PM »
The linked open access reference examines the coastal dynamics and creation of new submarine permafrost in shallow water of the central Laptev Sea (see the first attached image) and concludes: "For this region, it can be summarized that recent increases in coastal erosion rate and longer-term changes to benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP." (see the second attached image), where IBP means: ice-bonded permafrost.

Prior researchers have assumed that the IBP would be covered by a layer of somewhat protective non-ice-bonded sediment.  However, as Overduin (2015) make clear, wave driven coastal erosion (which will increase if/when the Arctic Sea Ice extent seasonally collapses) can/will expose the previously buried but new submarine IBP to relatively rapid warming from the sea water; which would likely result in a multi-decadal period of relatively rapid methane emissions as the associated methane hydrates in the new submarine permafrost region decompose:


Overduin, P., Wetterich, S., Günther, F., Grigoriev, M. N., Grosse, G., Schirrmeister, L., Hubberten, H.-W., and Makarov, A.: Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia, The Cryosphere Discuss., 9, 3741-3775, doi:10.5194/tcd-9-3741-2015, 2015.

http://www.the-cryosphere-discuss.net/9/3741/2015/tcd-9-3741-2015.html
http://www.the-cryosphere-discuss.net/9/3741/2015/tcd-9-3741-2015.pdf

Abstract: "Coastal erosion and relative sea-level rise transform terrestrial landscapes into marine environments. In the Arctic, these processes inundate terrestrial permafrost with seawater and create submarine permafrost. Permafrost begins to warm under marine conditions, which can destabilize the sea floor and may release greenhouse gases. We report on the transition of terrestrial to submarine permafrost at a site where the timing of inundation can be inferred from the rate of coastline retreat. On Muostakh Island in the central Laptev Sea, East Siberia, changes in annual coastline position have been measured for decades and vary highly spatially. We hypothesize that these rates are inversely related to the inclination of the upper surface of submarine ice-bonded permafrost (IBP) based on the consequent duration of inundation with increasing distance from the shoreline. We compared rapidly eroding and stable coastal sections of Muostakh Island and find permafrost-table inclinations, determined using direct current resistivity, of 1 and 5 %, respectively. Determinations of submarine IBP depth from a drilling transect in the early 1980s were compared to resistivity profiles from 2011. Based on boreholes drilled in 1982–1983, the thickness of unfrozen sediment overlying the IBP increased from 0 up to 14 m below sea level with increasing distance from the shoreline. The geoelectrical profiles showed thickening of the unfrozen sediment overlying ice-bonded permafrost over the 28 years since drilling took place. Parts of our geoelectrical profiles trace permafrost flooded, and showed that IBP degradation rates decreased from over 0.6 m a−1 following inundation to around 0.1 m a−1 as the duration of inundation increased to 250 years. We discuss that long-term rates are expected to be less than these values, as the depth to the IBP increases and thermal and pore water solute concentration gradients over depth decrease. For this region, it can be summarized that recent increases in coastal erosion rate and longer-term changes to benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP."
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Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2025 on: November 27, 2019, 02:30:07 PM »
Nothing peer reviewed, but prof. Ed Hawkins makes regular updates to evaluate model performance. Models evidently running hot.

http://www.met.reading.ac.uk/~ed/home/index.php
https://www.climate-lab-book.ac.uk/comparing-cmip5-observations/

It may be evident to you, but apparently not to Hawkins himself, and not to peer-reviewed Lewandowsky et al 2018 either.

Hawkins writes on his blog:
"The simulation data uses spatially complete coverage of surface air temperature whereas the observations use a spatially incomplete mix of air temperatures over land and sea surface temperatures over the ocean. It is expected that this factor alone would cause the observations to show smaller trends than the simulations."

He gives some other potential explanations for the apparent divergence as well:
"There are several possible explanations for why the earlier observations are at the lower end of the CMIP5 range. First, there is internal climate variability, which can cause temperatures to temporarily rise faster or slower than expected. Second, the radiative forcings used after 2005 are from the RCPs, rather than as observed. Given that there have been some small volcanic eruptions and a dip in solar activity, this has likely caused some of the apparent discrepancy. Third, the real world may have a climate sensitivity towards the lower end of the CMIP5 range. Next, the exact position of the observations within the CMIP5 range depends slightly on the reference period chosen. Lastly, this is not an apples-with-apples comparison because it is comparing air temperatures everywhere (simulations) with blended and sparse observations of air temperature and sea temperatures. A combination of some of these factors is likely responsible."

Lewandowsky et al 2018  elaborate on this:
https://iopscience.iop.org/article/10.1088/1748-9326/aaf372/meta

"The impression of a divergence early in the 21st century was caused by various biases in model interpretation and in the observations, and was unsupported by robust statistics [...] IPCC Assessment Report (AR5)... stated that '...111 out of 114 realizations show a GMST trend over 1998–2012 that is higher than the entire HadCRUT4 trend ensemble... This difference between simulated and observed trends could be caused by some combination of (a) internal climate variability, (b) missing or incorrect radiative forcing and (c) model response error' (Flato et al 2013, p 769). The consensus view expressed by the IPCC therefore pointed to a divergence between modeled and observed temperature trends, putatively caused by a mix of three factors. Subsequent to the IPCC report, the role of these three factors has become clearer [...] We have established that several biases in the observations and in model projections gave rise to the impression of a divergence between modeled and observed temperature trends. This impression was limited to the period 2011–2013, after which the ongoing debiasing eliminated any appearance of a divergence. During the period 2011–2013, the impression of a divergence could appear to be statistically significant, but only if the selection-bias issue was ignored. We have shown that ignoring of the selection-bias issue can drastically inflate Type-I error rates, which renders the inferences unreliable and in this case erroneous."

See their full paper for further details.
What do you think of their conclusions?

Hawkins lists various reasons why there is a discrepancy. Nr 3: "the real world may have a climate sensitivity towards the lower end of the CMIP5 range."
I guess he nailed it there.
If that was true for CMIP5, the CMIP6 models with much higher ECS around or above 5 will have an even tougher fight with reality.

Lewandowsky et al 2018  analyze data up until 2016. If you go back to the figure I attached in Reply #2016 the discrepancy looked less worrying with those data ending in 2016. But when we include 2017 and 2018 in the dataset and compare with the models, we get the impression that actual temperatures follow a lower trajectory, a lower trend, than the models. They write:
"...several biases in the observations and in model projections gave rise to the impression of a divergence between modeled and observed temperature trends. This impression was limited to the period 2011–2013, after which the ongoing debiasing eliminated any appearance of a divergence. During the period 2011–2013, the impression of a divergence could appear to be statistically significant, but only if the selection-bias issue was ignored. "

They might have been correct about selection bias, if it wasn't for a repeat of same in 2017-18. With two more years of data, the divergence seems to become only stronger.
« Last Edit: November 27, 2019, 02:36:28 PM by Hefaistos »

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2026 on: November 27, 2019, 03:59:07 PM »
...
They might have been correct about selection bias, if it wasn't for a repeat of same in 2017-18. With two more years of data, the divergence seems to become only stronger.

The two attached images of GMSTA projections by Gavin Schmidt make it clear that 2019 will be warmer than either 2017 or 2018, and there is currently no prospect of an El Nino event in the 2019-2020 season that we are currently in.  Thus 2017-18 may well support James Hansen's hypothesis that strong La Nina events are currently becoming weaker, which, if true, indicates that GMSTA is now warmer faster than its prior trendline as shown in the third image.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2027 on: November 27, 2019, 04:12:34 PM »
I seems we probably don't need any extra feedbacks etc etc for global heating to reach uncomfortable levels.



I have read accounts that in the early 1960's, Lyndon Baines Johnson was advised about the risks that climate change would follow the exact BAU pathway that we have subsequently followed, but he felt that geoengineering could solve the problem without rocking the socio-economic boat.  Therefore, policy makers have been aware of the severity of our collective climate change problem for a long time and they have chosen to take the easy route for well over five decades.  Furthermore, it is not clear to me that policy makers now have any more integrity than LBJ did in the 1960's; which is why I recommend that consensus climate scientists stop sugar-coating the harsh reality of our current situation.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2028 on: November 27, 2019, 04:32:59 PM »
The linked websites provide information on the acceleration of the migration of the magnetic poles (the image shows the recent migration of the south magnetic pole, see caption.  Note the south dip pole is located in the Southern Ocean).  I would be nice if the Trump administration would give NOAA enough money to update their historical data, and their model projections, up to at least 2018 so that we could better evaluate the impact of the recent loss of ice mass from the WAIS:

http://www.ngdc.noaa.gov/geomag/GeomagneticPoles.shtml

http://maps.ngdc.noaa.gov/viewers/historical_declination/

Caption: "Observed south dip poles during 1903 – 2000 are yellow squares. Modeled pole locations from 1590 to 2020 are circles progressing from blue to yellow"

Extract: "It has been long understood that dip poles migrate over time. In 1831, James Clark Ross located the north dip pole position in northern Canada. Natural Resources Canada (NRCan) tracked the North Magnetic Pole, which is slowly drifting across the Canadian Arctic, by periodically carrying out magnetic surveys to reestablish the Pole's location from 1948 to 1994. An international collaboration, led by a French fundraising association, Poly-Arctique, and involving NRCan, Institut de Physique du Globe de Paris and Bureau de Recherche Geologique et Miniere, added two locations of the North Magnetic Pole in 2001 and 2007. The most recent survey determined that the Pole is moving approximately north-northwest at 55 km per year.

The magnetic poles or dip pole are computed from all the Gauss coefficients using an iterative method. Magnetic poles derived in this fashion are geographically closer to the experimentally observed poles. Based on the current WMM model, the 2015 location of the north magnetic pole is 86.27°N and 159.18°W and the south magnetic pole is 64.26°S and 136.59°E."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2029 on: November 27, 2019, 05:03:08 PM »
Per the linked open access reference: "… Arctic sea ice may have critical points beyond which a return to the previous state is less likely."  Current AR5/CMIP5 models do not adequately exhibit this behavior:

Goldstein, M. A., Lynch, A. H., Arbetter, T. E., and Fetterer, F.: Abrupt transitions in Arctic open water area, The Cryosphere Discuss., doi:10.5194/tc-2016-108, in review, 2016.

http://www.the-cryosphere-discuss.net/tc-2016-108/

Abstract. September open water fraction in the Arctic is analyzed using the satellite era record of ice concentration (1979–2014). This analysis suggests that there is a statistically significant breakpoint (shift in the mean) and increase in the variance around 1988 and another breakpoint around 2007 in the Pacific sector. These structural breaks are robust to the choice of algorithm used for deriving sea ice concentration from satellite data, and are also apparent in other measures of open water, such as operational ice charts and the record of navigable days from Barrow to Prudhoe Bay. Breakpoints in the Atlantic sector record of open water are evident in 1988 and 2007 but more weakly significant. The breakpoints appear to be associated with concomitant shifts in average ice age, and tend to lead change in Arctic circulation regimes. These results support the thesis that Arctic sea ice may have critical points beyond which a return to the previous state is less likely.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2030 on: November 27, 2019, 05:13:26 PM »
The two linked articles discuss the increasing risks associated with scientific reticence, w.r.t. climate change:

"Dangerous Scientific Reticence" by James Hansen (2016)

http://csas.ei.columbia.edu/2016/03/24/dangerous-scientific-reticence/

&

"Beware the "fat tail": Climate risk and scientific reticence" by David Spratt (2016)

http://www.climatecodered.org/2016/03/climate-risk-and-scientific-reticence.html
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2031 on: November 27, 2019, 05:46:33 PM »
I like the idea of using machine learning to identify various interconnections between the numerous different Earth Systems in order to help improve the skill of the next generation of climate models (such as for CMIP7), as discussed in the linked reference:

Chris Huntingford et al. (22 November 2019), "Machine learning and artificial intelligence to aid climate change research and preparedness", Environmental Research Letters, Volume 14, Number 12, https//doi.org/10.1088/1748-9326/ab4e55

https://iopscience.iop.org/article/10.1088/1748-9326/ab4e55

Abstract
Climate change challenges societal functioning, likely requiring considerable adaptation to cope with future altered weather patterns. Machine learning (ML) algorithms have advanced dramatically, triggering breakthroughs in other research sectors, and recently suggested as aiding climate analysis (Reichstein et al 2019 Nature 566 195–204, Schneider et al 2017 Geophys. Res. Lett. 44 12396–417). Although a considerable number of isolated Earth System features have been analysed with ML techniques, more generic application to understand better the full climate system has not occurred. For instance, ML may aid teleconnection identification, where complex feedbacks make characterisation difficult from direct equation analysis or visualisation of measurements and Earth System model (ESM) diagnostics. Artificial intelligence (AI) can then build on discovered climate connections to provide enhanced warnings of approaching weather features, including extreme events. While ESM development is of paramount importance, we suggest a parallel emphasis on utilising ML and AI to understand and capitalise far more on existing data and simulations.
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Lennart van der Linde

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2032 on: November 27, 2019, 06:32:00 PM »
Hawkins lists various reasons why there is a discrepancy. Nr 3: "the real world may have a climate sensitivity towards the lower end of the CMIP5 range."
I guess he nailed it there.
If that was true for CMIP5, the CMIP6 models with much higher ECS around or above 5 will have an even tougher fight with reality.

Lewandowsky et al 2018  analyze data up until 2016. If you go back to the figure I attached in Reply #2016 the discrepancy looked less worrying with those data ending in 2016. But when we include 2017 and 2018 in the dataset and compare with the models, we get the impression that actual temperatures follow a lower trajectory, a lower trend, than the models. They write:
"...several biases in the observations and in model projections gave rise to the impression of a divergence between modeled and observed temperature trends. This impression was limited to the period 2011–2013, after which the ongoing debiasing eliminated any appearance of a divergence. During the period 2011–2013, the impression of a divergence could appear to be statistically significant, but only if the selection-bias issue was ignored. "

They might have been correct about selection bias, if it wasn't for a repeat of same in 2017-18. With two more years of data, the divergence seems to become only stronger.

It seems to me you're jumping to conclusions from hypotheses that have not been confirmed or not properly investigated yet. Hawkins lists several hypothetical explanations for the discrepancy between observations and simulations without saying which explanation he thinks is responsible for which part of the discrepancy, if at all. So your guess is as good as any, but needs to be properly investigated first. Lewandowsky et al give some first results from their investigation and do not confirm your guess. Maybe this is because they have not taken the latest years into account yet, but that remains to be seen. If two more years of data would indeed show a significant divergence, then two or more years of data after 2018 may change the picture once again. So it seems a little early to jump to the conclusion that the models are running hot, the more so as ASLR has shown several studies that indicate the ECS may be or may become higher with further warming. Proper risk management would take this possibility into account and demands a little more critical reasoning than you've been showing here so far, if you ask me.

KiwiGriff

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2033 on: November 27, 2019, 07:56:11 PM »
Classic denial cherry picking
Only look at what confirms your prejudice and ignore every thing else.
2019 is warm and it is an ENSO neutral year.
Some evidence points towards increasing frequency of extreme El Niño

Increasing frequency of extreme El Niño events due to greenhouse warming
Wenju Cai, Simon Borlace, Matthieu Lengaigne, Peter van Rensch, Mat Collins, Gabriel Vecchi, Axel Timmermann, Agus Santoso, Michael J. McPhaden, Lixin Wu, Matthew H. England, Guojian Wang, Eric Guilyardi & Fei-Fei Jin
Nature Climate Change volume 4, pages111–116(2014)
https://www.nature.com/articles/nclimate2100
Abstract
Quote
El Niño events are a prominent feature of climate variability with global climatic impacts. The 1997/98 episode, often referred to as ‘the climate event of the twentieth century’1,2, and the 1982/83 extreme El Niño3, featured a pronounced eastward extension of the west Pacific warm pool and development of atmospheric convection, and hence a huge rainfall increase, in the usually cold and dry equatorial eastern Pacific. Such a massive reorganization of atmospheric convection, which we define as an extreme El Niño, severely disrupted global weather patterns, affecting ecosystems4,5, agriculture6, tropical cyclones, drought, bushfires, floods and other extreme weather events worldwide3,7,8,9. Potential future changes in such extreme El Niño occurrences could have profound socio-economic consequences. Here we present climate modelling evidence for a doubling in the occurrences in the future in response to greenhouse warming. We estimate the change by aggregating results from climate models in the Coupled Model Intercomparison Project phases 3 (CMIP3; ref. 10) and 5 (CMIP5; ref. 11) multi-model databases, and a perturbed physics ensemble12. The increased frequency arises from a projected surface warming over the eastern equatorial Pacific that occurs faster than in the surrounding ocean waters13,14, facilitating more occurrences of atmospheric convection in the eastern equatorial region.

Historical change of El Niño properties sheds light on future changes of extreme El Niño
Bin Wang, Xiao Luo, Young-Min Yang, Weiyi Sun, Mark A. Cane, Wenju Cai, Sang-Wook Yeh, and  View ORCID ProfileJian Liu
PNAS November 5, 2019
https://www.pnas.org/content/116/45/22512
Abstract
Quote
El Niño’s intensity change under anthropogenic warming is of great importance to society, yet current climate models’ projections remain largely uncertain. The current classification of El Niño does not distinguish the strong from the moderate El Niño events, making it difficult to project future change of El Niño’s intensity. Here we classify 33 El Niño events from 1901 to 2017 by cluster analysis of the onset and amplification processes, and the resultant 4 types of El Niño distinguish the strong from the moderate events and the onset from successive events. The 3 categories of El Niño onset exhibit distinct development mechanisms. We find El Niño onset regime has changed from eastern Pacific origin to western Pacific origin with more frequent occurrence of extreme events since the 1970s. This regime change is hypothesized to arise from a background warming in the western Pacific and the associated increased zonal and vertical sea-surface temperature (SST) gradients in the equatorial central Pacific, which reveals a controlling factor that could lead to increased extreme El Niño events in the future. The Coupled Model Intercomparison Project phase 5 (CMIP5) models’ projections demonstrate that both the frequency and intensity of the strong El Niño events will increase significantly if the projected central Pacific zonal SST gradients become enhanced. If the currently observed background changes continue under future anthropogenic forcing, more frequent strong El Niño events are anticipated. The models’ uncertainty in the projected equatorial zonal SST gradients, however, remains a major roadblock for faithful prediction of El Niño’s future changes.

Higher frequency of Central Pacific El Niño events in recent decades relative to past centuries
Mandy B. Freund, Benjamin J. Henley, David J. Karoly, Helen V. McGregor, Nerilie J. Abram & Dietmar Dommenget
Nature Geoscience volume  12
https://www.nature.com/articles/s41561-019-0353-3
Abstract
Quote
Niño events differ substantially in their spatial pattern and intensity. Canonical Eastern Pacific El Niño events have sea surface temperature anomalies that are strongest in the far eastern equatorial Pacific, whereas peak ocean warming occurs further west during Central Pacific El Niño events. The event types differ in their impacts on the location and intensity of temperature and precipitation anomalies globally. Evidence is emerging that Central Pacific El Niño events have become more common, a trend that is projected by some studies to continue with ongoing climate change. Here we identify spatial and temporal patterns in observed sea surface temperatures that distinguish the evolution of Eastern and Central Pacific El Niño events in the tropical Pacific. We show that these patterns are recorded by a network of 27 seasonally resolved coral records, which we then use to reconstruct Central and Eastern Pacific El Niño activity for the past four centuries. We find a simultaneous increase in Central Pacific events and a decrease in Eastern Pacific events since the late twentieth century that leads to a ratio of Central to Eastern Pacific events that is unusual in a multicentury context. Compared to the past four centuries, the most recent 30 year period includes fewer, but more intense, Eastern Pacific El Niño events.



Animals can be driven crazy by placing too many in too small a pen. Homo sapiens is the only animal that voluntarily does this to himself.
Notebooks of Lazarus Long.
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wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2034 on: November 27, 2019, 09:12:03 PM »
ASLR makes it explicit that he is presenting the right tailed risks, not settled science. While it is difficult to accept so much scientific uncertainty (scientific reticence), the message that ASLR conveys in his posts is one of prudence.

I can think of no better demonstration for why extreme right tailed risks must prompt precautionary action even in the face of great uncertainty than the attached image. It shows the shifting attitude within successive IPCC reports to the likelihood of the temperature at which the onset of climate tipping points begins.

Taken from a comment in Nature from today (Nov. 27), by Lenton et. al

Climate tipping points — too risky to bet against
https://www.nature.com/articles/d41586-019-03595-0

Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2035 on: November 27, 2019, 11:28:38 PM »
ASLR makes it explicit that he is presenting the right tailed risks, not settled science. While it is difficult to accept so much scientific uncertainty (scientific reticence), the message that ASLR conveys in his posts is one of prudence.

I can think of no better demonstration for why extreme right tailed risks must prompt precautionary action even in the face of great uncertainty than the attached image.

I totally agree with this, wdmn!
We have a real problem, we should take precautionary action, be prudent.

I just don't see the case for alarmism. And I don't like that most GCM models are tweaked and tuned to give us alarmist forecasts.

As with ASLR presenting the right tailed risks, from what is not settled science, the forecasts from GCMs is not science at all.
Vital parts of climate theory is not settled (specifically critical is the hydrological cycle /deep convection in the tropics), and the data isn't there yet, and the track record of GCMs in CMIP5 is highly questionable.

« Last Edit: November 27, 2019, 11:36:52 PM by Hefaistos »

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2036 on: November 27, 2019, 11:34:39 PM »
ASLR makes it explicit that he is presenting the right tailed risks, not settled science. While it is difficult to accept so much scientific uncertainty (scientific reticence), the message that ASLR conveys in his posts is one of prudence.

I can think of no better demonstration for why extreme right tailed risks must prompt precautionary action even in the face of great uncertainty than the attached image. It shows the shifting attitude within successive IPCC reports to the likelihood of the temperature at which the onset of climate tipping points begins.

Taken from a comment in Nature from today (Nov. 27), by Lenton et. al

Climate tipping points — too risky to bet against
https://www.nature.com/articles/d41586-019-03595-0

ASLR does a very good job in pointing out the possible consequences of unchecked fossil fuel emissions.  Unfortunately, he also writes disparagingly of "consensus" scientists and conveys a situation that seems much more dire than it is.  Yes, we need to get off of fossil fuels as soon as possible.  However, he often ignores that we're making great progress in doing so. 

He ignores the fact that most of the highly speculative and sensationalist disaster scenarios he writes about are based on the RCP 8.5 emissions scenario which assumes that renewables will be more expensive than fossil fuels through the 21st century when if fact, renewables are now cheaper than coal.

In fact, 2018 may have been the peak of global coal consumption.

https://foreignpolicy.com/2019/11/26/coal-fired-power-is-declining-thanks-to-a-slowdown-in-india-and-china-climate-change/

Quote
Coal-Fired Power Is Declining Thanks to a Slowdown in India and China
2019 could end with a deceleration in overall carbon emissions.
By C.K. Hickey
November 26, 2019, 4:36 PM

After more than a century as the world’s dominant source of electricity, coal may finally be losing its importance. Coal-fired power production is projected to fall 3 percent this year—the largest annual decline on record. According to a new report from three think tanks and published by Carbon Brief, this reduction represents an amount of electricity greater than that generated by coal from Germany, Spain, and the U.K. combined.

Quote
As coal’s contribution to electricity usage falls, electricity generated by non-fossil sources is on the rise across the globe. As seen in the chart below, wind power saw the largest growth among energy sources over the last year.

Quote
Coal plants still fuel 38 percent of the world’s electricity, however, and so curtailing the carbon emissions from its production remains essential for limiting a rise in global temperatures. The sharp drop projected in coal-fired electricity suggests 2019 could end with a slowdown in overall carbon emissions, according to the report.

AbruptSLR likes to post about MICI, a highly speculative hyptothesis that the authors have backed away from recently.  He likes to post about the CMIP 6 models that have higher ECS, ignoring the CMIP 6 models that have ECS in line with consensus science (that would be half of them). 

But again, the most egregious error he makes (and many of the catastrophists on this site make) is that since current emissions are close to RCP 8.5 emissions, that the emissions for the rest of the century will continue on the RCP 8.5 path.  Since RCP 8.5 assumes an acceleration of the use of coal and that renewables will be more expensive than coal, the RCP 8.5 emissions scenario just isn't possible.

Here's a graphical representation of the RCP scenarios:



The big black area in the middle of that graph is coal use.   You can see that in 2100 it's responsible for more than half of the emissions in the RCP 8.5 scenario.  It's likely to be zero decades before then.

Natural gas is already in dire straits.  Much of the natural gas infrastructure being planned today will be stranded assets well before the end of it's useful life.

https://www.utilitydive.com/news/renewables-storage-poised-to-undercut-natural-gas-prices-increase-strande/562674/

Quote
Renewables, storage poised to undercut natural gas prices, increase stranded assets: RMI

If all proposed gas plants are built, 70% of those investments will be rendered uneconomic by 2035, according to the Rocky Mountain Institute.

Carbon-free resources are now cost competitive with new natural gas plants, according to a pair of reports released Monday by the Rocky Mountain Institute.

Wind, solar and storage projects, combined with demand-side management, have reached a "tipping point," one report finds, meaning they're now able to compete alongside natural gas on price while providing the same reliability services. But unlike the fluctuating price of fuels, these technologies' prices are expected to continue dropping, the reports' authors told Utility Dive.

This reality could leave many natural gas investors and utilities with stranded infrastructure assets, the second RMI report finds, and new gas investments should be made with caution.

Even with the additional carbon being released in the Arctic due to warming, the reduction in CO2 and methane from eliminating those two sources of anthropogenic emissions will result in emissions closer to the RCP 2.6 scenario than the RCP 8.5 scenario.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2037 on: November 28, 2019, 12:09:19 AM »
...
But again, the most egregious error he makes (and many of the catastrophists on this site make) is that since current emissions are close to RCP 8.5 emissions, that the emissions for the rest of the century will continue on the RCP 8.5 path.
...

In fact I have postulated that the global socio-economic system will sustain a major contraction comparable to that shown in the attached image from the 40-year update of Limits to Growth.  Therefore, in Reply #1927 (with follow-on in #1941) I have recommended that for input to AR7 that the IPCC make a sixth family of forcing scenarios that only follows the GHG emissions per RCP 8.5 (or SSP5 - 8.5) until 2050 and then collapses to almost no fossil-fuel-based anthropogenic GHG emissions; and which also incorporates ice-climate feedbacks [such as those cited by Hansen et al. (2016)] starting now.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2038 on: November 28, 2019, 12:20:10 AM »
...
As with ASLR presenting the right tailed risks, from what is not settled science, the forecasts from GCMs is not science at all.


Some posters on this forum think that I am too hard on consensus climate scientists, but at least I fully acknowledge that their Earth System Models (ESMs) represent heavily caveated science.  I just recommend that they make it clearer that their current ESM projections do not adequately represent right-tailed risks as indicated by the two attached images.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2039 on: November 28, 2019, 12:30:02 AM »
ASLR does a very good job in pointing out the possible consequences of unchecked fossil fuel emissions.  Unfortunately, he also writes disparagingly of "consensus" scientists and conveys a situation that seems much more dire than it is.  Yes, we need to get off of fossil fuels as soon as possible.  However, he often ignores that we're making great progress in doing so. 

It's almost like you didn't look at the graphic I attached. The situation has proven to be more dire than consensus scientists have conveyed. Within 5 years our understanding shifted so much that we lost 75-100 years to the time from when we thought we would be exposed to high risk from climate tipping points. Deep uncertainty requires precaution!

The graphic demonstrates clearly how subjective probabilities in a situation of deep uncertainty, coupled with scientific reticence can lead to dangerous delays by decision makers, particularly when they are being lobbied extensively by organizations that have an interest in delaying action.

Lennart van der Linde

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2040 on: November 28, 2019, 12:31:02 AM »
Yes, we need to get off of fossil fuels as soon as possible.  However [...] we're making great progress in doing so [...] Even with the additional carbon being released in the Arctic due to warming, the reduction in CO2 and methane from eliminating those two sources of anthropogenic emissions will result in emissions closer to the RCP 2.6 scenario than the RCP 8.5 scenario.

Lenton et al 2019 say:
"If current national pledges to reduce greenhouse-gas emissions are implemented — and that’s a big ‘if’ — they are likely to result in at least 3 °C of global warming. This is despite the goal of the 2015 Paris agreement to limit warming to well below 2 °C. Some economists, assuming that climate tipping points are of very low probability (even if they would be catastrophic), have suggested that 3 °C warming is optimal from a cost–benefit perspective. However, if tipping points are looking more likely, then the ‘optimal policy’ recommendation of simple cost–benefit climate-economy models aligns with those of the recent IPCC report. In other words, warming must be limited to 1.5 °C. This requires an emergency response [...] Early results from the latest climate models — run for the IPCC’s sixth assessment report, due in 2021 — indicate a much larger climate sensitivity (defined as the temperature response to doubling of atmospheric CO2) than in previous models. Many more results are pending and further investigation is required, but to us, these preliminary results hint that a global tipping point is possible [...] Some scientists counter that the possibility of global tipping remains highly speculative. It is our position that, given its huge impact and irreversible nature, any serious risk assessment must consider the evidence, however limited our understanding might still be. To err on the side of danger is not a responsible option. If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization. No amount of economic cost–benefit analysis is going to help us. We need to change our approach to the climate problem. In our view, the evidence from tipping points alone suggests that we are in a state of planetary emergency: both the risk and urgency of the situation are acute."

Let's take the science seriously and recognize the urgency that Lenton et al, ASLR and others describe and justly emphasize as a planetary emergency and existential threat. Downplaying this inconvenient truth may be a natural impulse, but has been done for too long and is nog helping us. Let's face reality and the risks it entails and do what we have to do to minimize those risks, while we still can.
« Last Edit: November 28, 2019, 12:53:13 AM by Lennart van der Linde »

KiwiGriff

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2041 on: November 28, 2019, 01:00:55 AM »
Quote
Yes, we need to get off of fossil fuels as soon as possible.  However [...] we're making great progress in doing so

We are not making progress at all.
Again on this thread .
 Until this clearly shows a change in the rate of CO2 addition no amount of dodgy carbon accounting or talk of  impossible RCP's is going to impact on the reality of our predicament.
The keeling curve is still smegging  accelerating.



PS. Keep it up ASLR I find your contribution  both convincing and informative.  I don't like coming on your thread and distracting you from your excellent series of posts. However....

Animals can be driven crazy by placing too many in too small a pen. Homo sapiens is the only animal that voluntarily does this to himself.
Notebooks of Lazarus Long.
Robert Heinlein.

JMP

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2042 on: November 28, 2019, 04:56:17 AM »
I agree. We are practically making no progress at all.
Emissions continue to rise.  Renewables (actually down from 2017 to 2018) are now just barely increasing, and future investment is not nearly what is needed to reach goals. 

'A report from the Climate Policy Initiative (CPI) found that work to mitigate climate change through a transition to low-carbon energy is lagging behind, and must be accelerated across the board to come close to achieving the non-binding goals of the Paris Agreement.'

'The new report from the CPI found that global investment in renewables peaked at $612 billion in 2017, and dropped 11% in 2018. The 2017 peak, it said, was thanks largely to an increase in green energy spending in China, the U.S. and India, while last year’s drop could be attributed to changes in lending patterns and a global economic slowdown.

“While climate finance has reached record levels, action still falls far short of what is needed under a 1.5˚C scenario,” the report’s authors note, citing the global average temperature goal recognized by the Paris Agreement.
The authors note that the United Nations Intergovernmental Panel on Climate Change (IPCC) estimates that between $1.6 trillion and $3.8 trillion will need to be spent every year until 2050 to achieve a transition to global low-carbon energy supply.

Among its conclusions, the CPI states: “There is a need for a tectonic shift beyond ‘climate finance as usual.’ Annual investment must increase many times over, and rapidly, to achieve globally agreed climate goals.” '

https://www.forbes.com/sites/davidrvetter/2019/11/07/69-uk-emissions-drop-nice-but-global-renewables-investment-down-reports/#1a6eb7a041c0
« Last Edit: November 28, 2019, 05:40:02 AM by JMP »

JMP

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2043 on: November 28, 2019, 05:19:12 AM »
Renewables are barely going up .8% - but for instance Natural Gas jumped 5% in the same time period.  Total energy production is still increasing and so CO2 is too and I'm not seeing figures on this site for CH4 which we know is also increasing terribly.   

"Acceleration in energy consumption in 2018 (+2.3%) driven by high growth in electricity and gas demand

Global energy consumption grew significantly in 2018, spurred by the sustained economic growth and rising demand in China, the world’s largest energy consumer since 2009. Chinese energy consumption posted its highest growth since 2012, mainly driven by power generation, strong industrial demand and increasing transport fuel consumption encouraged by a growing vehicle fleet.
Total energy consumption in the United States reached a record high of 2.3 Gtoe in 2018, up 3.5% from 2017, partially driven by weather conditions (hot summer, cold winter).

On the contrary, energy consumption decreased in the European Union (-1%) and in particular in Germany (-3.5%) partly due to decreasing consumption in the power sector, a milder winter, reducing consumption, and energy efficiency improvements."

https://yearbook.enerdata.net/total-energy/world-consumption-statistics.html


Renewables are not yet making up for total energy growth.  Yet, officials still pretend we're going to not only stop emissions growth, not only reduce emissions, some believe we will somehow be able to reverse course and actually have negative emissions... because... they wish it so.  Show us. 
     
   

(Hope this isn't too far off topic - but in the interest of being reality based.
Now, meanwhile back in the Antarctic....) 


« Last Edit: November 28, 2019, 05:37:05 AM by JMP »

Aporia_filia

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2044 on: November 28, 2019, 12:31:47 PM »
Thanks a lot ASLR for his tireless contribution.
"Let's take the science seriously and recognize the urgency that Lenton et al, ASLR and others describe and justly emphasize as a planetary emergency and existential threat. Downplaying this inconvenient truth may be a natural impulse, but has been done for too long and is nog helping us. Let's face reality and the risks it entails and do what we have to do to minimize those risks, while we still can."
As usual, very wise comment from Lennart.
And cross posting from Holocene Extinction this 'compelling' article:
Quote from: Aporia_filia on November 25, 2019, 08:01:50 PM
The chill of reality. UBC ecological economist William E. Rees, co-creator of the ecological footprint concept, has some bad news for techno-optimists.
 I find his views very realistic, as he wants to be:

https://stanford.us4.list-manage.com/track/click?u=88e1f9157b8a1070712b4dd12&id=54d87b4ae2&e=abc543e6fa
...
Compelling summary of our behavior and its consequences (thanks to Tor)
« Last Edit: November 28, 2019, 07:45:29 PM by Aporia_filia »

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2045 on: November 28, 2019, 03:20:02 PM »
...
AbruptSLR likes to post about MICI, a highly speculative hyptothesis that the authors have backed away from recently.
...

As Tamsin Edwards et al. (2019) presents a lower bound assessment of paleo-slr it is not clear to me that their analysis could replicate the more recent finding that during the Eemian sea level rose abruptly as indicated in the attached image.  Furthermore, DeConto & Pollard updated their 2016 work to reflex consensus values of ECS; however, if the final CMIP6 results cause the AR6 range for ECS to increase, then it would have been better if DeConto & Pollard never revised their 2016 value for ECS.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2046 on: November 30, 2019, 07:04:26 PM »
For those who think that climate change risk is too abstract to personally assess, especially because of deep uncertainty, please consider that the people attending the annual World Economic Forum in Davos assess risk professionally and at the beginning of 2019 they reported (see links and the associated attached image) that they decided that climate change risks (and associated issues) were the world's greatest risk:

Title: "The Global Risks Report 2019"

https://www.weforum.org/reports/the-global-risks-report-2019

Extract: "The world faced a growing number of complex and interconnected challenges in 2018. From climate change and slowing global growth to economic inequality, we will struggle if we do not work together in the face of these simultaneous challenges. The Global Risks Report 2019 provides an opportunity to place the global risk landscape into context at the beginning of the new year and identify priority areas for action in 2019."

See also:

Title: "WEF 2019 Global Risk Report once again highlights climate threat"

https://www.acclimatise.uk.com/2019/01/16/wef-2019-global-risk-report-once-again-highlights-climate-threat/

“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2047 on: November 30, 2019, 09:19:23 PM »
The linked reference indicates how much agriculture and fisheries will be impacted by climate change by the end of this century assuming that ECS is approximately 3C.  If ECS is actually over 5C then these projections could happen many decades earlier than currently projected.

Title: "Model: Possible simultaneous impact of global warming on agriculture and marine fisheries"

https://phys.org/news/2019-11-simultaneous-impact-global-agriculture-marine.html

Extract: "The researchers report that the model showed that the worst-case scenario was rather dire—90 percent of the global population will be living in an area where production from agriculture and fisheries is falling by the end of this century. More specifically, the model showed a 25 percent reduction in average global productivity in the agriculture sector. For fisheries, the model showed declines of up to 60 percent."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2048 on: November 30, 2019, 11:51:22 PM »

I can think of no better demonstration for why extreme right tailed risks must prompt precautionary action even in the face of great uncertainty than the attached image. It shows the shifting attitude within successive IPCC reports to the likelihood of the temperature at which the onset of climate tipping points begins.


I concur with wdmn that the opinions expressed in Lenton et al. (2019) are important, and thus bear repeating (see the attached image and the following linked reference):

Lenton et al. (2019), "Climate tipping points — too risky to bet against", Nature, 575, 592-595,
doi: 10.1038/d41586-019-03595-0

https://www.nature.com/articles/d41586-019-03595-0

Extract: "Politicians, economists and even some natural scientists have tended to assume that tipping points in the Earth system — such as the loss of the Amazon rainforest or the West Antarctic ice sheet — are of low probability and little understood. Yet evidence is mounting that these events could be more likely than was thought, have high impacts and are interconnected across different biophysical systems, potentially committing the world to long-term irreversible changes.

The Intergovernmental Panel on Climate Change (IPCC) introduced the idea of tipping points two decades ago. At that time, these ‘large-scale discontinuities’ in the climate system were considered likely only if global warming exceeded 5 °C above pre-industrial levels. Information summarized in the two most recent IPCC Special Reports (published in 2018 and in September this year) suggests that tipping points could be exceeded even between 1 and 2 °C of warming (see ‘Too close for comfort’)."

As Lenton et al. (2019) cite findings from the IPCC, I do believe that they ignore numerous significant ice-climate feedback mechanisms; nevertheless, I like how they emphasis that the risk of triggering a cascade of tipping point increases with each passing year.  Indeed, regardless of the preliminary CMIP6 model findings and recent paleo-findings of abrupt climate change; as the world continues to warm and various Earth Systems risk becoming increasingly non-linear; the pdf for abrupt climate change is shifting to the right each year as illustrated by:

a. Increases in GMSTA in the past decade; and in 2019 GMSTA will be over 1.1C.

b. Increases in Antarctic ice shelf mass loss (activating other ice-climate feedbacks).

c. Increases in average cloud altitude as observed by satellite records.

d. Faster than expected permafrost degradation.

e. Faster than expected decrease in intense La Nina events.

f. Faster than expected forest degradation, particularly in the Amazon.

g. Etc.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2049 on: December 01, 2019, 12:05:25 AM »
As a follow-on to my last post, I provide links to the following two references; which discuss both the increasing climate risks as GMSTA approaches and/or exceeds 1.5C, and the fact that climate change risks are non-stationary and are currently increasing with time, respectively.

O. Hoegh-Guldberg et al. (20 Sep 2019), "The human imperative of stabilizing global climate change at 1.5°C", Science, Vol. 365, Issue 6459, eaaw6974, DOI: 10.1126/science.aaw6974

https://science.sciencemag.org/content/365/6459/eaaw6974

Structured Abstract
BACKGROUND

The United Nations Framework Convention on Climate Change (UNFCCC) was established in 1992 to pursue the “stabilization of greenhouse gas concentrations at a level that would prevent dangerous anthropogenic interferences with the climate system.” Since 1992, five major climate change assessment cycles have been completed by the UN Intergovernmental Panel on Climate Change (IPCC). These reports identified rapidly growing climate-related impacts and risks, including more intense storms, collapsing ecosystems, and record heatwaves, among many others. Once thought to be tolerable, increases in global mean surface temperature (GMST) of 2.0°C or higher than the pre-industrial period look increasingly unmanageable and hence dangerous to natural and human systems.

The Paris Climate Agreement is the most recent attempt to establish international cooperation over climate change. This agreement, ratified or acceded to by 185 countries, was designed to bring nations together voluntarily to take ambitious action on mitigating climate change, while also developing adaptation options and strategies as well as guaranteeing the means of implementation (e.g., climate finance). The Agreement is aimed at “holding the increase in the global average temperature to well below 2.0°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change.” Many unanswered questions regarding a 1.5°C target surround the feasibility, costs, and inherent risks to natural and human systems. Consequently, countries invited the IPCC to prepare a Special Report on “the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty.” The Special Report was completed and approved by the 48th Session of the IPCC in October 2018.

ADVANCES
Multiple lines of evidence indicate that the next 0.5°C above today (which will take GMST from 1.0°C to 1.5°C above the pre-industrial period) will involve greater risks per unit temperature than those seen in the last 0.5°C increase. This principle of “accelerating risk” is also likely to drive proportionally and possibly exponentially higher risk levels in the transition from 1.5°C to 2.0°C above the pre-industrial period. We argue that this is a consequence of impacts accelerating as a function of distance from the optimal temperature for an organism or an ecosystem process. Coral reefs, for example, often appear healthy right up until the onset of mass coral bleaching and mortality, which can then destroy a reef within a few months. This also explains the observation of “tipping points” where the condition of a group of organisms or an ecosystem can appear “healthy” right up to the point of collapse, suggesting caution in extrapolating from measures of ecosystem condition to predict the future. Information of this nature needs to be combined with an appreciation of organisms’ distance from their optimal temperature.

Finally, we explore elements of the costs and benefits associated with acting in response to climate change, and come to the preliminary conclusion that restraining average global temperature to 1.5°C above the pre-industrial period would be much less costly than the damage due to inaction on global climate change.

OUTLOOK
As an IPCC expert group, we were asked to assess the impact of recent climate change (1.0°C, 2017) and the likely impact over the next 0.5° to 1.0°C of additional global warming. At the beginning of this exercise, many of us were concerned that the task would be hindered by a lack of expert literature available for 1.5°C and 2.0°C warmer worlds. Although this was the case at the time of the Paris Agreement, it has not been our experience 4 years later. With an accelerating amount of peer-reviewed scientific literature since the IPCC Special Report Global Warming of 1.5°C, it is very clear that there is an even more compelling case for deepening commitment and actions for stabilizing GMST at 1.5°C above the pre-industrial period."

Extract: "Climate change is one of the greatest challenges for humanity. Global mean surface temperature (GMST) is increasing at the rate of 0.2° ± 0.1°C per decade, reaching 1.0°C above the pre-industrial period (reference period 1850–1900) in 2017."

&

Sarhadi, A., Ausín, M. & Wiper, M. A New Time-varying Concept of Risk in a Changing Climate. Sci Rep 6, 35755 (2016) doi:10.1038/srep35755

https://www.nature.com/articles/srep35755

Abstract: "In a changing climate arising from anthropogenic global warming, the nature of extreme climatic events is changing over time. Existing analytical stationary-based risk methods, however, assume multi-dimensional extreme climate phenomena will not significantly vary over time. To strengthen the reliability of infrastructure designs and the management of water systems in the changing environment, multidimensional stationary risk studies should be replaced with a new adaptive perspective. The results of a comparison indicate that current multi-dimensional stationary risk frameworks are no longer applicable to projecting the changing behaviour of multi-dimensional extreme climate processes. Using static stationary-based multivariate risk methods may lead to undesirable consequences in designing water system infrastructures. The static stationary concept should be replaced with a flexible multi-dimensional time-varying risk framework. The present study introduces a new multi-dimensional time-varying risk concept to be incorporated in updating infrastructure design strategies under changing environments arising from human-induced climate change. The proposed generalized time-varying risk concept can be applied for all stochastic multi-dimensional systems that are under the influence of changing environments."
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“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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