Support the Arctic Sea Ice Forum and Blog

Author Topic: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)  (Read 66314 times)

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #750 on: March 14, 2019, 11:16:17 PM »
Re 744.

Have you seen the news in #64 here.

https://forum.arctic-sea-ice.net/index.php/topic,2449.msg191933.html

"The plant assemblages indicate that there was an abrupt and major shift in the vegetation from wet, cold conditions at Pilauco to warm, dry conditions," Kennett said. According to him, the atmospheric zonal climatic belts shifted "like a seesaw," with a synergistic mechanism, bringing warming to the Southern Hemisphere even as the Northern Hemisphere experienced cooling and expanding sea ice.

They could be related?

kassy,

Thanks for the link, as I had not seen that article before; however the Younger Dryas was from approximately 12,900 to about 11,700 years BP; so the partial WAIS discussed in 11,500BP in Reply #744, may, or may not, be related.

Best,
ASLR
« Last Edit: March 15, 2019, 06:28:09 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #751 on: March 15, 2019, 06:11:54 PM »
CMIP6 is already being conducted with at best consideration of MISI types of ice mass loss from both the GIS & AIS, and completely without consideration of MICI types of ice mass losses, therefore, a discussion of the implications of the growing number of consensus climate scientists who are pointing to the findings of Edwards et al. (2019) as justification for ignoring MICI types of ice mass loss in their model projections this century may be academic.  Nevertheless, here I point out that Edwards et al. (2019) used a statistical emulator of ice sheet mass loss over the past 1 million years to indicate that most likely MISI behavior could account for the paleo record; however, this finding is a far different matter than concluding that MICI types of behavior can be discounted in model projections for the rest of this century.

First, as SSP5-Baseline indicates that we may well be at Mid-Pliocene (3.3 Ma–3 Ma) conditions by (or before) 2040, the Edwards et al. (2019) emulation of the past 1Ma are likely not relevant; while Pollard, DeConto & Alley (2018)'s evaluation of MICI under Mid-Pliocene conditions are more relevant.

Second, we are approaching Mid-Pliocene conditions thousands of times faster than occurred during the Mid-Pliocene; which Pollard, DeConto & Alley (2018) took into account by abruptly introducing Mid-Pliocene conditions onto modern AIS conditions in their model.

Third, both Edwards et al (2019) and Pollard, DeConto & Alley (2018) use AIS boundary & starting conditions for the modern AIS that are less aggressive than what is currently observed in 2019 w.r.t. such factors as: a) the large subglacial cavity at the base of the Thwaites Ice Tongue; b) the loss of ice shelf buttressing of the Southwest Tributary Glacier in Pine Island Bay; and c) the amount of ice-climate feedback mechanisms that are already being activated (including MOC slowing, shifting of the ENSO towards more frequent El Nino events & increased advection of warm CDW towards the grounding lines of key AIS marine glaciers).

I understand that CMIP6 is already pushing the computational capacity of the participation ESMs; I think that it is wasteful of research funds to be investigating scenarios with little chance of occurring, and also I note that currently the cost of using Exascale computers is dropping by half about every 3 months.  Therefore, I believe that rather than likely committing a Type 2 error (a false negative, i.e. assuming that MICI ice mass loss will not occur this century when it actually might occur after 2040); it would be better for consensus climate scientists to work harder (possibly by using Exascale computing resources) on including MICI mechanisms in at least some of their scenarios so as to at least evaluate right-tail risks.

Finally, I provide the attached images related to use of the scientific method (without comment), as I believe that the proper use of this method would not result in MICI behavior being discounted in on-going ESM modeling efforts.

Edit: I forgot to mention that the emulator used by Edwards et al. (2019) did not include the impact of the Antarctic ozone holes (as this did not occur in paleo-times); which this ozone hole has accelerated ice mass loss from Antarctica and projections of the impact of continuing GHG emissions on the westerly winds over the Southern Ocean, indicate that as the ozone hole heals the regional impact of increasing GHG atmospheric concentrations will keep these regional westerly winds in an optimal zone for promoting ice mass loss for at least the next few decades.
« Last Edit: March 15, 2019, 06:33:16 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #752 on: March 15, 2019, 07:46:03 PM »
The linked open access commentary provides a convenient summary of the nature and likely impacts of Arctic Amplification:

Twila A. Moon et al. (07 March 2019), "The expanding footprint of rapid Arctic change", Earth's Future, https://doi.org/10.1029/2018EF001088

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018EF001088

Abstract
Arctic land ice is melting, sea ice is decreasing, and permafrost is thawing. Changes in these Arctic elements are interconnected, and most interactions accelerate the rate of change. The changes affect infrastructure, economics, and cultures of people inside and outside of the Arctic, including in temperate and tropical regions, through sea level rise, worsening storm and hurricane impacts, and enhanced warming. Coastal communities worldwide are already experiencing more regular flooding, drinking water contamination, and coastal erosion. We describe and summarize the nature of change for Arctic permafrost, land ice, and sea ice, and its influences on lower latitudes, particularly the United States. We emphasize that impacts will worsen in the future unless individuals, businesses, communities, and policy makers proactively engage in mitigation and adaptation activities to reduce the effects of Arctic changes and safeguard people and society.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #753 on: March 15, 2019, 08:06:47 PM »
We shouldn't forget that shrubs thrive (relative to trees as explained in the linked reference) in relatively cold regions, and there continued expansion into the tundra decreases albedo & thus increases Arctic Amplification:

Treml et al. (2019), "Differences in growth between shrubs and trees: How does the stature of woody plants influence their ability to thrive in cold regions?", Agricultural and Forest Meteorology, https://doi.org/10.1016/j.agrformet.2019.02.036

https://www.sciencedirect.com/science/article/pii/S0168192319300954

Abstract
Shrubs can be found far above or beyond cold tree limits. However, the mechanisms shrubs employ to thrive at sites not allowing the development of trees remain poorly understood. We hypothesize that shrubs are advantaged over trees thanks to: (i) their low stature reflected in a better thermal environment; (ii) differences in temperature thresholds of wood formation; and (iii) a shorter period of wood formation in the slender stems of shrubs with narrow cells compared to tree stems with large cells. We studied wood formation of Picea abies (trees) and Pinus mugo (shrubs) growing on the same site in the treeline ecotone of the Krkonoše Mts in the Czech Republic. We measured air temperature near tree (shrub) tops, stem temperature and soil temperature in the root zone. In addition, we determined the number of cells in individual phases of wood phenology. We then computed the duration of individual wood-phenology phases and temperature thresholds for the onset of wood formation. Our results show that in the growing season, shrubs experience higher amplitude of air and stem temperatures compared to trees. Mean growing season air and stem temperatures are similar between the two growth forms whereas mean soil temperatures are lower for shrubs because their dense canopies shade the ground. Temperature thresholds for wood formation are either similar (3 °C for soil temperature, onset of cell division) or greater by 1.2–2.6 K (onset of cell enlargement) for P. mugo shrubs than for P. abies trees, depending on the temperature metrics considered. Although we found ambiguous differences in the onset of wood formation, this was completed earlier in P. mugo than in P. abies, leading to a generally shorter growing period of shrubs (103 days) than trees (125 days). In conclusion, the main advantage of shrubs over trees resides in the earlier completion of wood formation and thus a shorter growing season. Trees with wide cells at stem base require more time for cell differentiation and maturation than shrubs with narrow cells. Other differences are either of lesser importance (the ambient thermal environment) or probably species-specific (temperature thresholds for wood formation).

Edit: I also not that the continuing expansion of digging creatures (like ground squirrels, etc.) into the tundra (with continued warming) accelerates permafrost degradation and thus also contributes to increasing Arctic Amplification.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #754 on: March 16, 2019, 02:52:05 AM »
I do not have time to comment adequately about the information provided by the WAIS Divide ice core project, but perhaps come of the extracts below from the linked open access reference provides some idea of the sensitivity of the WAIS over the time period to 68 ka:

Kendrick Taylor (10 September 2016), "Introduction to special section on the WAIS Divide Special Issue of Paleoceanography", Paleoceanography and Paleoclimatology,  https://doi.org/10.1002/2016PA002995

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016PA002995

Extract: "The high temporal resolution of the atmospheric carbon dioxide record revealed three abrupt increases in carbon dioxide at the times of major climate events (Heinrich Stadial 1, the Bølling warming, and the termination of the Younger Dryas). These enigmatic features of the deglaciation have spurred a discussion of the possible sources of carbon capable of responding to climate on the centennial scale [Bauska et al., 2016]. The high temporal resolution also allowed detailed records of late Holocene variability in the concentration [Ahn et al., 2012] and isotopic composition [Bauska et al., 2015] of atmospheric carbon dioxide, revealing multidecadal changes in land carbon storage.

The detailed atmospheric methane record defined new modes of variability, including sharp increases during some of the cold Greenland “Heinrich” stadials. This led to a hypothesis that extreme southward migration of the Intertropical Convergence Zone during the Greenland stadials activated Southern Hemisphere methane sources [Rhodes et al., 2015]. During Heinrich Stadial 1, this possible Southern Hemisphere source of methane is directly associated with an abrupt rise in atmospheric carbon dioxide. Additional work constrained the anthropogenic contribution to atmospheric methane during the late Holocene [Mitchell et al., 2013], possibly including preindustrial human influence [Mischler et al., 2009] and other details of methane during the Holocene period [Sowers, 2010]."

Edit, note that per the linked reference a significant discharge of icebergs can cause an abrupt increase in tropical methane production:

Rhodes, R. H., E. J. Brook, J. C. H. Chiang, T. Blunier, O. J. Maselli, J. M. McConnell, D. Romanini, and J. P. Severinghaus (2015), Enhanced tropical methane production in response to iceberg discharge in the North Atlantic, Science, 348(6238), 1016–1019, doi:10.1126/science.1262005.

http://science.sciencemag.org/content/348/6238/1016

The tropical impact of iceberg armadas
The massive discharges of icebergs from the Greenland ice sheet during the Last Glacial Period are called Heinrich events. But did Heinrich events cause abrupt climate change, or were they a product of it? Methane levels represent a proxy for climate, because methane production increases mostly due to wetter conditions in the tropics. Rhodes et al. report a highly resolved record of atmospheric methane concentrations, derived from an ice core from Antarctica. Methane levels varied—i.e., the tropical climate changed—in response to cooling in the Northern Hemisphere caused by Heinrich events.

Abstract
The causal mechanisms responsible for the abrupt climate changes of the Last Glacial Period remain unclear. One major difficulty is dating ice-rafted debris deposits associated with Heinrich events: Extensive iceberg influxes into the North Atlantic Ocean linked to global impacts on climate and biogeochemistry. In a new ice core record of atmospheric methane with ultrahigh temporal resolution, we find abrupt methane increases within Heinrich stadials 1, 2, 4, and 5 that, uniquely, have no counterparts in Greenland temperature proxies. Using a heuristic model of tropical rainfall distribution, we propose that Hudson Strait Heinrich events caused rainfall intensification over Southern Hemisphere land areas, thereby producing excess methane in tropical wetlands. Our findings suggest that the climatic impacts of Heinrich events persisted for 740 to 1520 years.

Edit 2, the following link leads to the table of content of all articles in the special issue of Paleoceanography and Paleoclimatology on the WAIS Divide ice core project:

https://agupubs.onlinelibrary.wiley.com/doi/toc/10.1002/(ISSN)1944-9186.WAISDIV

Edit 3, in particular see also:

Rachael H. Rhodes  Edward J. Brook  Joseph R. McConnell  Thomas Blunier  Louise C. Sime  Xavier Faïn  Robert Mulvaney (14 March 2017), "Atmospheric methane variability: Centennial‐scale signals in the Last Glacial Period", Global Biogeochemical Cycles, https://doi.org/10.1002/2016GB005570

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016GB005570

Abstract
In order to understand atmospheric methane (CH4) biogeochemistry now and in the future, we must apprehend its natural variability, without anthropogenic influence. Samples of ancient air trapped within ice cores provide the means to do this. Here we analyze the ultrahigh‐resolution CH4 record of the West Antarctic Ice Sheet Divide ice core 67.2–9.8 ka and find novel, atmospheric CH4 variability at centennial time scales throughout the record. This signal is characterized by recurrence intervals within a broad 80–500 year range, but we find that age‐scale uncertainties complicate the possible isolation of any periodic frequency. Lower signal amplitudes in the Last Glacial relative to the Holocene may be related to incongruent effects of firn‐based signal smoothing processes. Within interstadial and stadial periods, the peak‐to‐peak signal amplitudes vary in proportion to the underlying millennial‐scale oscillations in CH4 concentration—the relative amplitude change is constant. We propose that the centennial CH4 signal is related to tropical climate variability that influences predominantly low‐latitude wetland CH4 emissions.

Plain Language Summary
Using a new method to measure methane concentrations of ancient air trapped in ice cores, we have detected variability in atmospheric methane concentration on centennial time scales in the Last Glacial Period for the first time. We know these signals represent past changes in atmospheric methane because they appear in several ice core records. We propose that changes in methane emissions from tropical wetlands are responsible. How this new variability might be related to similar signals found in the late Holocene ice core records and the instrumental record of atmospheric methane is an open question.

Edit 4, see also:

Title: "How complexity science can quickly detect climate record anomalies", 2018

https://www.santafe.edu/news-center/news/how-complexity-science-can-quickly-detect-anomalies-climate-records

Extract: "In previous cores, Garland notes that decades, even centuries, were aggregated into a single point. The WAIS data, by contrast, sometimes gives more than forty data points per year. But as scientists move to analyze the data at shorter time scales, even small anomalies can be problematic.

“As fine-grained data becomes available, fine-grained analyses can be performed,” Garland notes. “But it also makes the analysis susceptible to fine-grained anomalies.”

To quickly identify which anomalies require further investigation, the team uses information theoretic techniques to measure how much complexity appears at each point in the time sequence. A sudden spike in the complexity could mean that there was either a major, unexpected climate event, like a super volcano, or that there was an issue in the data or the data processing pipeline."
« Last Edit: March 16, 2019, 03:14:28 AM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #755 on: March 16, 2019, 04:15:30 PM »
As noted previously in this thread E3SMv1 has a reported mean ECS of 5.3C (see the attached image & associated caption), and now JAMES has a paper with all of the details (which are too numerous for me to address here), and I note that Andrew Dessler reports that several other CMIP6 models also have values of ECS greater than 5C.  If so this increases the calculated probability of a MICI type of WAIS collapse beginning circa 2040:

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#.XIv0M0dysFU.twitter
&
https://agupubs.onlinelibrary.wiley.com/doi/epdf/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 (110km grid spacing), ocean and sea ice (60km in the mid‐latitudes and 30km at the equator and poles), and river transport (55km) 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 Diagnosis, Evaluation, and Characterization of Klima (CMIP6 DECK) simulations consisting of a long pre‐industrial 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 pre‐industrial (1850) and present‐day, the trajectory of the warming diverges from observations in the second half of the 20th 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 m‐2) and high equilibrium climate sensitivity (ECS = 5.3 K).

Plain Language Summary
The United States 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 Diagnosis, Evaluation, and Characterization of Klima (CMIP6 DECK) protocol at standard horizontal spatial resolution of approximately 1 degree 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.

Caption: "Figure 27. Time evolution of annual global mean air surface temperature anomalies for the idealized CO₂ forcing simulations abrupt-4xCO2 (red), 1pctCO2 (blue) and the control simulation (piControl; green). Solid lines are fits obtained with a two-layer energy balance model (discussed in sub-section 6.3). Also depicted are estimates of ECS and TCR."

« Last Edit: March 16, 2019, 04:56:00 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #756 on: March 16, 2019, 04:52:29 PM »
I have previously noted that earlier consensus climate science reports like AR5 have made liberal use of caveats to exclude several right-tailed feedback mechanisms from the confidence ranges that they report for various climate change parameters (see also my comments in at least Replies #707 & #751).  Furthermore, in at least Reply #719 I recommended that consensus science generate families of Maximum-credible Climate-risk Scenarios (MCSs) in order to better assess right-tail climate risks.

In this post I briefly note consensus science only formally cites two limit states (i.e. the aspirational 1.5C GMSTA target and the 'Well below' 2C GMSTA limit by 2100).  To my Civil Engineering way of thinking the 1.5C target can be associated with an 'Operations' limit state where the proper function of our socioeconomic systems begin to fail; while the 'Well below' 2C limit can be associated where significant human life safety becomes threatened.

However, also to my Civil Engineering way of thinking, modern civil society depends on numerous other limit states (in civil engineering designs there are several other limit states such as: 'Progressive Collapse', 'Fatigue' and 'Durability limit states), that it would be good for consensus science to formally specify acceptable limit states for this century such as: a) Sea Level Rise and the associated rate of Sea Level Rise; b) Tropical Pacific SSTA, and c) Cascades of tipping points leading to abrupt changes in climate state.  Also, I note that in limit state design engineers assign partial load factors of safety for each separate forcing according to its uncertainty and partial resistance factors of safety to reflex the fragility of each separate system component according to its uncertainty.  Furthermore, I note that all civil engineering designs to adapt to climate change use the incomplete forcing from consensus science reports like AR5/CMIP5 and use load and resistance safety factors that were empirically established for quasi-static climate change, and that little or no attempts have been made to develop such factors of safety appropriate to maintain civil society under conditions of rapid/dynamic climate change.

Finally, I provide the linked UC Berkeley article and associated images on how the real process of science works; which per the attached images includes community feedback and societal expectations of benefits from scientific work.  In this sense the real consensus climate science process is politicized by community resistance to change and by societal expectation that science bring benefits ('good science') rather than reporting increasing risks/dangers ('bad science'):

Title: "The real process of science"

https://undsci.berkeley.edu/article/howscienceworks_02

Extract: "At first this process might seem overwhelming. Even within the scope of a single investigation, science may involve many different people engaged in all sorts of different activities in different orders and at different points in time — it is simply much more dynamic, flexible, unpredictable, and rich than many textbooks represent it as."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #757 on: March 16, 2019, 05:13:34 PM »
In my last post I suggested that consensus science formally set limits for socioeconomically acceptable levels of changes in Tropical Pacific SST, as this region of the Earth is critical from driving climate change.  In this regard, the linked reference provides discussions of how this regions manages to influence so much of the Earth's climate and also notes that during El Nino events (which are projected to become more frequent with continued warming) heat is extracted from the Tropical Pacific ocean water via increase evaporation, and I note that water vapor is a key driver of climate change:

Lijing Cheng (14 March 2019), "Evolution of ocean heat content related to ENSO", Journal of Climate, https://doi.org/10.1175/JCLI-D-18-0607.1

https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-18-0607.1

Abstract
As the strongest inter-annual perturbation to the climate system, the El Niño-Southern Oscillation (ENSO) dominates the year-to-year variability of the ocean energy budget. Here we combine ocean observations, re-analyses, and surface flux data with Earth system model simulations to obtain estimates of the different terms affecting the redistribution of energy in the Earth system during ENSO events, including exchanges between ocean and atmosphere, among different ocean basins, lateral and vertical rearrangements. This comprehensive inventory allows better understanding of the regional and global evolution of ocean heat related to ENSO, and provides observational metrics to benchmark performance of climate models. Results confirm that there is a strong negative ocean heat content tendency (OHCT) in the tropical Pacific Ocean during El Niño, mainly through enhanced air-sea heat fluxes (Q) into the atmosphere driven by high sea surface temperatures. As well as this diabatic component, there is an adiabatic redistribution of heat both laterally and vertically (0-100m and 100-300m) in the tropical Pacific and Indian oceans that dominates the local OHCT. Heat is also transported and discharged from 20oS-5oN into off-equatorial regions within 5-20oN during and after El Niño. OHCT and Q changes outside of the tropical Pacific Ocean indicates the ENSO-driven atmospheric teleconnections and changes of ocean heat transport (i.e. Indonesian Throughflow). The tropical Atlantic and Indian oceans warm during El Niño, partly offsetting the tropical Pacific cooling for the tropical oceans as a whole. While there are distinct regional OHCT changes, many compensate each other resulting in a weak but robust net global ocean cooling during and after El Niño.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #758 on: March 16, 2019, 05:34:40 PM »
Ed Hawkins provides insight on how to correctly interpret various different climate parameters at 'Climate Lab Book'"

https://www.climate-lab-book.ac.uk/author/ehawkins/

See also:

Title: "What does ‘mean’ actually mean?"

https://www.climate-lab-book.ac.uk/2018/what-does-mean-actually-mean/#more-5569
&

See also:

Kevin Cowtan et al. (20 July 2018), Statistical analysis of coverage error in simple global temperature estimators", Dynamics and Statistics of the Climate System, Volume 3, Issue 1, dzy003, https://doi.org/10.1093/climsys/dzy003

https://academic.oup.com/climatesystem/article/3/1/dzy003/5056434

Abstract


Background
Global mean surface temperature is widely used in the climate literature as a measure of the impact of human activity on the climate system. While the concept of a spatial average is simple, the estimation of that average from spatially incomplete data is not. Correlation between nearby map grid cells means that missing data cannot simply be ignored. Estimators that (often implicitly) assume uncorrelated observations can be biased when naively applied to the observed data, and in particular, the commonly used area weighted average is a biased estimator under these circumstances. Some surface temperature products use different forms of infilling or imputation to estimate temperatures for regions distant from the nearest observation, however the impacts of such methods on estimation of the global mean are not necessarily obvious or themselves unbiased. This issue was addressed in the 1970s by Ruvim Kagan, however his work has not been widely adopted, possibly due to its complexity and dependence on subjective choices in estimating the dependence between geographically proximate observations.

Objectives
The aim of this work is to present a simple estimator for global mean surface temperature from spatially incomplete data which retains many of the benefits of the work of Kagan, while being fully specified by two equations and a single parameter. The main purpose of the simplified estimator is to better explain to users of temperature data the problems associated with estimating an unbiased global mean from spatially incomplete data, however the estimator may also be useful for problems with specific requirements for reproducibility and performance.

Methods
The new estimator is based on generalized least squares, and uses the correlation matrix of the observations to weight each observation in accordance with the independent information it contributes. It can be implemented in fewer than 20 lines of computer code. The performance of the estimator is evaluated for different levels of observational coverage using reanalysis data with artificial noise.

Results
For recent decades the generalized least squares estimator mitigates most of the error associated with the use of a naive area weighted average. The improvement arises from the fact that coverage bias in the historical temperature record does not arise from an absolute shortage of observations (at least for recent decades), but rather from spatial heterogeneity in the distribution of observations, with some regions being relatively undersampled and others oversampled. The estimator addresses this problem by reducing the weight of the oversampled regions, in contrast to some existing global temperature datasets which extrapolate temperatures into the unobserved regions. The results are almost identical to the use of kriging (Gaussian process interpolation) to impute missing data to global coverage, followed by an area weighted average of the resulting field. However, the new formulation allows direct diagnosis of the contribution of individual observations and sources of error.

Conclusions
More sophisticated solutions to the problem of missing data in global temperature estimation already exist. However the simple estimator presented here, and the error analysis that it enables, demonstrate why such solutions are necessary. The 2013 Fifth Assessment Report of the Intergovernmental Panel on Climate Change discussed a slowdown in warming for the period 1998-2012, quoting the trend in the HadCRUT4 historical temperature dataset from the United Kingdom Meteorological Office in collaboration with the Climatic Research Unit of the University of East Anglia, along with other records. Use of the new estimator for global mean surface temperature would have reduced the apparent slowdown in warming of the early 21st century by one third in the spatially incomplete HadCRUT4 product.
&

Title: "Reconciling estimates of climate sensitivity"

https://www.climate-lab-book.ac.uk/2016/reconciling-estimates-of-climate-sensitivity/#more-4441
&

Ed Hawkins Twitter

https://twitter.com/ed_hawkins?ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Eauthor

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

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #759 on: March 16, 2019, 05:51:12 PM »
I think that the linked 2018 YouTube video by Jim White is worth watching (if you have a spare 1.15 hours), as he provides discussions of: how Earth Systems work, how people impact those systems and what are some abrupt change risks):

Title: "Climate Change: Dr Jim White (January 2018)"



See also:

https://nas-sites.org/americasclimatechoices/other-reports-on-climate-change/abrupt-impacts-of-climate-change/
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #760 on: March 16, 2019, 11:15:00 PM »
An Ice Apocalypse includes an albedo flip associated with a seasonally sea ice free Arctic Ocean, and the linked reference indicates how such a future Arctic sea ice free season will grow faster in the autumn than in the spring:

Lebrun, M., Vancoppenolle, M., Madec, G., and Massonnet, F.: Arctic sea-ice-free season projected to extend into autumn, The Cryosphere, 13, 79-96, https://doi.org/10.5194/tc-13-79-2019, 2019.

https://www.the-cryosphere.net/13/79/2019/

Abstract
The recent Arctic sea ice reduction comes with an increase in the ice-free season duration, with comparable contributions of earlier ice retreat and later advance. CMIP5 models all project that the trend towards later advance should progressively exceed and ultimately double the trend towards earlier retreat, causing the ice-free season to shift into autumn. We show that such a shift is a basic feature of the thermodynamic response of seasonal ice to warming. The detailed analysis of an idealised thermodynamic ice–ocean model stresses the role of two seasonal amplifying feedbacks. The summer feedback generates a 1.6-day-later advance in response to a 1-day-earlier retreat. The underlying physics are the property of the upper ocean to absorb solar radiation more efficiently than it can release heat right before ice advance. The winter feedback is comparatively weak, prompting a 0.3-day-earlier retreat in response to a 1-day shift towards later advance. This is because a shorter growth season implies thinner ice, which subsequently melts away faster. However, the winter feedback is dampened by the relatively long ice growth period and by the inverse relationship between ice growth rate and thickness. At inter-annual timescales, the thermodynamic response of ice seasonality to warming is obscured by inter-annual variability. Nevertheless, in the long term, because all feedback mechanisms relate to basic and stable elements of the Arctic climate system, there is little inter-model uncertainty on the projected long-term shift into autumn of the ice-free season.

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

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #761 on: March 16, 2019, 11:38:56 PM »
The linked open access reference is relevant to projecting the future stability of Arctic sea ice and the underlying ocean stratification and warming of the inflowing waters:

H. Sadatzki, T. M. Dokken, S. M. P. Berben, F. Muschitiello, R. Stein, K. Fahl, L. Menviel, A. Timmermann, E. Jansen, Sea ice variability in the southern Norwegian Sea during glacial Dansgaard-Oeschger climate cycles. Sci. Adv. 5, eaau6174 (2019).

http://advances.sciencemag.org/content/5/3/eaau6174

Abstract
The last glacial period was marked by pronounced millennial-scale variability in ocean circulation and global climate. Shifts in sea ice cover within the Nordic Seas are believed to have amplified the glacial climate variability in northern high latitudes and contributed to abrupt, high-amplitude temperature changes over Greenland. We present unprecedented empirical evidence that resolves the nature, timing, and role of sea ice fluctuations for abrupt ocean and climate change 32 to 40 thousand years ago, using biomarker sea ice reconstructions from the southern Norwegian Sea. Our results document that initial sea ice reductions at the core site preceded the major reinvigoration of convective deep-water formation in the Nordic Seas and abrupt Greenland warming; sea ice expansions preceded the buildup of a deep oceanic heat reservoir. Our findings suggest that the sea ice variability shaped regime shifts between surface stratification and deep convection in the Nordic Seas during abrupt climate changes.

See also: "New PhD thesis solves mysteries around large abrupt climate changes"

https://www.bjerknes.uib.no/en/article/news/new-phd-thesis-solves-mysteries-around-large-abrupt-climate-changes


Extract: "Henrik Sadatzki defends on Friday 15.02.2019 his thesis for the PhD degree at the University of Bergen. The thesis is entitled: “Sea ice variability in the Nordic Seas over Dansgaard–Oeschger climate cycles during the last glacial – A biomarker approach”.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #762 on: March 17, 2019, 03:46:42 PM »
The first two (associated) linked sources indicate that due to global warming intense El Nino events will become more frequent (estimated to occur about every 10 years); while the third linked source indicates that there is a good chance that there will be an intense El Nino event in the 2019-2020 season; which would be only four years after the 2015-16 intense El Nino event.  This is a clear indication that the likely range for ECS is higher than AR5 indicates; and this adds to the probability that the WAIS may initiate a MICI type of collapse circa 2040:

Wenju Cai et al. (2018), "Increased variability of eastern Pacific El Nino under greenhouse warming", Nature 564, 201-206, https://doi.org/10.1038/s41586-018-0776-9

https://www.nature.com/articles/s41586-018-0776-9?WT.feed_name=subjects_ocean-sciences

Extract: "An increase in SST variance implies an increase in the number of 'strong' EP-El Nino events (corresponding to large SST anomalies) and associated extreme weather events."

See also:

Title: "El Nino events to become 'stronger' and more intense, study finds"

https://www.smh.com.au/environment/climate-change/el-nino-events-to-become-stronger-and-more-intense-study-finds-20181212-p50lrv.html

"They are stronger and more frequent," Dr Cai said, adding the likelihood of intense El Nino events as measured by sea-surface temperatures will increase from about one every 15 years now to every 10 years on average during this century.

Big El Ninos of recent decades include 1982-83, 1997-98 and 2015-16."

Also, particularly see:

Title: "'Monster' El Nino a chance later this year, pointing to extended dry times"

https://www.smh.com.au/environment/climate-change/monster-el-nino-a-chance-later-this-year-pointing-to-extended-dry-times-20190315-p514hi.html

Extract: "The prospect of a big El Nino later this year was raised at an international conference of climate scientists in Chile earlier this month.

They considered parallel years, such as 2014 when a near-El Nino was reached before conditions revived a year later, creating one of the three most powerful such events in the past half century.

"There is more heat now below the surface waiting to be tapped than there was in early 2015," said Michael McPhaden, a senior scientist with US National Atmospheric and Oceanic Administration who attended the Chilean event.

"If westerly wind bursts of sufficient amplitude, duration and zonal extent develop along the equator in the next couple of months, 2019-20 could be very exciting," he said.

"While it's not a slam dunk that El Nino is going to persist, I think that the odds have certainly increased over one to two months ago," Phil Klotzbach, a research scientist at Colorado State University, said. " We've had a big build up of heat in the eastern and central Pacific."

Cai Wenju, a senior CSIRO scientist who has published widely on the El Nino Southern Oscillation climate pattern, said the chance of El Nino returning is high.

A return of westerlies by about June to halt the easterly tradewinds “could spark the fire and there’s a lot of fuel", Dr Cai said.

“If it’s similar to 2015, the impact this time will be big," he said."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #763 on: March 18, 2019, 03:54:31 PM »
I have made a point that I do not think that the WAIS will begin a MICI type of collapse until about 2040 (note that SSP5-Baseline projects a GMSTA of about 2C, relative to 1986-2005, by 2040); however, that do not mean that I do not think that we will activate numerous nonlinear positive self-reinforcing feedback mechanisms between now and then, which not only increases the probability of a MICI type of WAIS collapse this century, but also increases the probably that we cross a tipping point for abrupt climate change well before 2040 as cited in the two linked sources and illustrated by the attached image of abrupt regional feedback mechanisms.

Title: "Climate report understates threat"

https://thebulletin.org/2018/10/climate-report-understates-threat/

Extract: "The UN’s Intergovernmental Panel on Climate Change’s Special Report on Global Warming of 1.5 degrees Celsius, released on Monday, is a major advance over previous efforts to alert world leaders and citizens to the growing climate risk. But the report, dire as it is, misses a key point: Self-reinforcing feedbacks and tipping points—the wildcards of the climate system—could cause the climate to destabilize even further.

To put it bluntly, there is a significant risk of self-reinforcing climate feedback loops pushing the planet into chaos beyond human control.

These cascading feedbacks include the loss of the Arctic’s sea ice, which could disappear entirely in summer in the next 15 years. The ice serves as a shield, reflecting heat back into the atmosphere, but is increasingly being melted into water that absorbs heat instead. Losing the ice would tremendously increase the Arctic’s warming, which is already at least twice the global average rate. This, in turn, would accelerate the collapse of permafrost, releasing its ancient stores of methane, a super climate pollutant 30 times more potent in causing warming than carbon dioxide.

By largely ignoring such feedbacks, the IPCC report fails to adequately warn leaders about the cluster of six similar climate tipping points that could be crossed between today’s temperature and an increase to 1.5 degrees—let alone nearly another dozen tipping points between 1.5 and 2 degrees."

See also:

Drijfhout et al. (2015), "Catalogue of abrupt shifts in Intergovernmental Panel on Climate Change climate models", PNAS https://doi.org/10.1073/pnas.1511451112

https://www.pnas.org/content/112/43/E5777

Abstract: "Abrupt transitions of regional climate in response to the gradual rise in atmospheric greenhouse gas concentrations are notoriously difficult to foresee. However, such events could be particularly challenging in view of the capacity required for society and ecosystems to adapt to them. We present, to our knowledge, the first systematic screening of the massive climate model ensemble informing the recent Intergovernmental Panel on Climate Change report, and reveal evidence of 37 forced regional abrupt changes in the ocean, sea ice, snow cover, permafrost, and terrestrial biosphere that arise after a certain global temperature increase. Eighteen out of 37 events occur for global warming levels of less than 2°, a threshold sometimes presented as a safe limit. Although most models predict one or more such events, any specific occurrence typically appears in only a few models. We find no compelling evidence for a general relation between the overall number of abrupt shifts and the level of global warming. However, we do note that abrupt changes in ocean circulation occur more often for moderate warming (less than 2°), whereas over land they occur more often for warming larger than 2°. Using a basic proportion test, however, we find that the number of abrupt shifts identified in Representative Concentration Pathway (RCP) 8.5 scenarios is significantly larger than in other scenarios of lower radiative forcing. This suggests the potential for a gradual trend of destabilization of the climate with respect to such shifts, due to increasing global mean temperature change."


Caption for the attached image: "Abrupt shifts as a function of global temperature increase. Shown are the number of abrupt climate changes occurring in the CMIP5 database for different intervals of warming relative to the preindustrial climate."
« Last Edit: March 18, 2019, 04:43:43 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #764 on: March 18, 2019, 04:27:44 PM »
Here is an example of how a proposed geoengineering measure could lead to unintended consequences:

Gürses, Ö., Kolatschek, V., Wang, Q., and Rodehacke, C. B.: Brief communication: A submarine wall protecting the Amundsen Sea intensifies melting of neighboring ice shelves, The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-32, in review, 2019.

https://www.the-cryosphere-discuss.net/tc-2019-32/

Abstract. Disintegration of ice shelves in the Amundsen Sea has the potential to cause sea level rise by inducing an acceleration of grounded ice streams. Moore et al. (2018) proposed that using a submarine wall to block the penetration of warm water into the ice shelf cavities could reduce this risk. We use a global sea ice-ocean model to show that a wall shielding the Amundsen Sea below 350 m depth successfully suppresses the inflow of warm water and reduces ice shelf melting. However, the warm water gets redirected towards neighboring ice shelves, which reduces the effectiveness of the wall.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

gerontocrat

  • ASIF Governor
  • Posts: 4272
    • View Profile
  • Liked: 477
  • Likes Given: 10
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #765 on: March 18, 2019, 05:29:45 PM »
Here is an example of how a proposed geoengineering measure could lead to unintended consequences:

Moore et al. (2018) proposed that using a submarine wall to block the penetration of warm water into the ice shelf cavities could reduce this risk. We use a global sea ice-ocean model to show that a wall shielding the Amundsen Sea below 350 m depth successfully suppresses the inflow of warm water and reduces ice shelf melting. However, the warm water gets redirected towards neighboring ice shelves, which reduces the effectiveness of the wall.

I recommend Part 3 of John Wyndhm's SF novel - "The Kraken Wakes" especially to those who think we can fix stuff with massive infrastructure and other engineering projects.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Shared Humanity

  • ASIF Governor
  • Posts: 3254
    • View Profile
  • Liked: 123
  • Likes Given: 16
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #766 on: March 18, 2019, 05:59:46 PM »
We are not yet certain what the impacts of our current geoengineering project over the last 200 years will look like and we have been studying this fairly intently for the better part of 40 years. There is no way we can predict fully the effects of future projects. We should expect unintended, unanticipated and quite painful consequences of our hubris in approaching climate change as an engineering problem to be solved.

Never the less, given our refusal to halt the current project, we should expect many increasingly frantic projects, implemented far to quickly in the very near future.

May the Goddess help us.

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #767 on: March 18, 2019, 06:10:09 PM »
We are not yet certain what the impacts of our current geoengineering project over the last 200 years will look like and we have been studying this fairly intently for the better part of 40 years. There is no way we can predict fully the effects of future projects. We should expect unintended, unanticipated and quite painful consequences of our hubris in approaching climate change as an engineering problem to be solved.
...

In addition to the abrupt feedback mechanisms identified by CMIP5 (see Reply #763), I not that CMIP5 does not consider many ice-climate feedback mechanism (some of which are being included in CMIP6 that has several ESMs with ECS over 5C).  Therefore, all of the findings earlier studies of geoengineering are likely irrelevant, and if the WAIS begins a MICI type of collapse circa 2040, then likely CMIP6, 7 & 8 findings may well associate be of no use in assessing geoengineering impacts (nevertheless policy makers assume that they will be able to at least implement BECCS).
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #768 on: March 18, 2019, 07:44:56 PM »
The linked article indicates that the USA and Saudi Arabia recently blocked a U.N. resolution to make the UNEA (U.N. Environment Assembly) the governing body for regulating any future potential implementation of geoengineering.  Apparently, the USA and Saudi Arabia did not want a U.N. body to limit/regulate the impacts of geoengineering on the overall environment and on small countries:

Title: "U.S. Blocks U.N. Resolution on Geoengineering"

https://www.scientificamerican.com/article/u-s-blocks-u-n-resolution-on-geoengineering/
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

gerontocrat

  • ASIF Governor
  • Posts: 4272
    • View Profile
  • Liked: 477
  • Likes Given: 10
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #769 on: March 18, 2019, 08:05:56 PM »
The linked article indicates that the USA and Saudi Arabia recently blocked a U.N. resolution to make the UNEA (U.N. Environment Assembly) the governing body for regulating any future potential implementation of geoengineering.  Apparently, the USA and Saudi Arabia did not want a U.N. body to limit/regulate the impacts of geoengineering on the overall environment and on small countries:

Title: "U.S. Blocks U.N. Resolution on Geoengineering"

https://www.scientificamerican.com/article/u-s-blocks-u-n-resolution-on-geoengineering/
Here we have the USA - in search of energy dominance based on oil and gas as official Government policy, and Saudi Arabia - facing bankruptcy if/when demand for the black stuff collapses.

So not a surprise if they want unfettered freedom to try geo-engineering by any means to capture CO2 so fossil fuel production can not only continue unabated but increase. It won't work but.......

The lunatics have taken over the asylum - the brakes on the Trumpistan roller-coaster have failed.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #770 on: March 19, 2019, 03:43:21 PM »
While the laws of nature will be followed no matter what, it is the judicial system that determines what is legal fact with regard to human actions (e.g. see the linked article about goverments suing regarding professionally irresponsible behavior and or fraud by the fossil fuel industry); and consensus climate science evaluations play a major role with regard to what judges and juries determine to be legally liable facts about anthropogenic radiative forcing.

Consensus science has helped to establish a legal expectation that staying well below a GMSTA of 2C (relative to pre-industrial) is acceptable; however, James Hansen has stated that establishing an acceptable limit of 350ppm of atmospheric CO₂ concentrations would be advisable.  If consensus science would follow the Precautionary Principle, then it would be easier for youth groups to be successful in their lawsuits; and Greta Thunberg's youth movement might then file multiple lawsuits against governments for failing to adequately safeguard their collective futures (including lawsuits to block irresponsible implementation of geoengineering):

Title: "DC moves closer to climate lawsuit against Exxon"

https://thehill.com/policy/energy-environment/434590-dc-building-team-for-exxon-climate-challenge

Extract: "The D.C. government is beefing up its legal team ahead of an anticipated legal challenge against Exxon.

If D.C. moves forward with a lawsuit against Exxon, it will be joining a handful of other states and municipalities looking into how the oil and gas giant may have failed to publicize science it had linking emissions to global warming.

New York sued Exxon in October for allegedly engaging in "a longstanding fraudulent scheme.""

Edit: To be clear, if youth groups were successful in hundreds of lawsuits against hundreds of governments worldwide, then we would likely see these governments enact progressive carbon tax programs around the world.

Edit2, With regards to Hansen's 350ppm acceptable limit for atmospheric CO2 concentrations, the first attached image shows that we past that limit around 1987; and thus I assume that Hansen also meant that atmospheric CH4 concentrations should have an acceptable limit around 1685ppb where they were around 1987 as indicated by the second attached image.
« Last Edit: March 19, 2019, 05:42:17 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #771 on: March 19, 2019, 04:22:45 PM »
I have made a point that I do not think that the WAIS will begin a MICI type of collapse until about 2040 (note that SSP5-Baseline projects a GMSTA of about 2C, relative to 1986-2005, by 2040); however, that do not mean that I do not think that we will activate numerous nonlinear positive self-reinforcing feedback mechanisms between now and then, which not only increases the probability of a MICI type of WAIS collapse this century, but also increases the probably that we cross a tipping point for abrupt climate change well before 2040 as cited in the two linked sources and illustrated by the attached image of abrupt regional feedback mechanisms.

Title: "Climate report understates threat"

https://thebulletin.org/2018/10/climate-report-understates-threat/

...

I would like to note that most of the abrupt regional feedback mechanisms identified in quote above came from CMIP5; however, if CMIP6 has several ESMs with ECS greater than 5C, then CMIP6 will most likely identify many more abrupt feedback mechanisms including several related to ice-climate feedback mechanisms (omitted in CMIP5) even though CMIP6 only considers MISI types of ice sheet collapse mechanisms and omits consideration of MICI type collapse mechanisms.

Furthermore, I note CMIP5 many very well have underestimated the negative feedback from both natural and anthropogenic aerosols, which means that if rainforests (especially the Amazon) degrades rapidly and/or anthropogenic aerosol emissions are rapidly decreased in the coming decades, we are likely to cross many more tipping point thresholds earlier than identified in CMIP5.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #772 on: March 19, 2019, 07:13:28 PM »
While the linked reference does not consider a MICI type of WAIS collapse beginning circa 2040, it does provide valuable insights into transient responses of both atmospheric and oceanic heat transports up to about 2040.  In this regards, the attached image indicates that as the AMOC slows down it will transport more ocean heat content into the North Atlantic which could contribute to a regional ice albedo flip around Greenland, that could in turn significantly increase surface ice melting in Greenland circa 2040, which would be reinforced by the bipolar seesaw if a MICI type of WAIS collapse begins around 2040:

He, C., Liu, Z., & Hu, A. (2019). The transient response of atmospheric and oceanic heat transports to anthropogenic warming. Nature Climate Change. doi:10.1038/s41558-018-0387-3

https://www.nature.com/articles/s41558-018-0387-3

Abstract: "Model projections of the near-future response to anthropogenic warming show compensation between meridional heat transports by the atmosphere (AHT) and ocean (OHT) that are largely symmetric about the equator, the causes of which remain unclear. Here, using both the Coupled Model Intercomparison Project Phase 5 archive and Community Climate System Model version 4 simulations forced with Representative Concentration Pathway 8.5 to 2600, we show that this transient compensation—specifically during the initial stage of warming—is caused by combined changes in both atmospheric and oceanic circulations. In particular, it is caused by a southward OHT associated with a weakened Atlantic Meridional Overturning Circulation, a northward apparent OHT associated with an ocean heat storage maximum around the Southern Ocean, and a symmetric coupled response of the Hadley and Subtropical cells in the Indo-Pacific basin. It is further shown that the true advective OHT differs from the flux-inferred OHT in the initial warming due to the inhomogeneous responses of ocean heat storage. These results provide new insights to further our understanding of future heat transport responses, and thereby global climatic processes such as the redistribution of ocean heat."

Edit, the above comments assume that we follow at least a RCP 8.5 pathway thru at least 2035.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Sleepy

  • ASIF Upper Class
  • Posts: 1174
  • Retired, again...
    • View Profile
  • Liked: 72
  • Likes Given: 0
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #773 on: March 19, 2019, 08:55:16 PM »
Nice mini-thread by Glen Peters here on emission scenarios:
https://twitter.com/Peters_Glen/status/1107923815508701184
For fossil CO₂ emissions, we started to move onto track, but that quickly changed…
Omnia mirari, etiam tritissima.
-
Science is a jealous mistress and takes little account of a man's feelings.

AbruptSLR

  • ASIF Emperor
  • Posts: 16789
    • View Profile
  • Liked: 287
  • Likes Given: 89
Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #774 on: March 19, 2019, 10:37:49 PM »
The linked reference (& associated article), how Emergent Constraints (ECs), see the two attached panels and the associated caption, can be used to improve ESM projections"

Hall et al. (2019), "Progressing emergent constraints on future climate change", Nature Climate Change (2019). DOI: 10.1038/s41558-019-0436-6 , https://www.nature.com/articles/s41558-019-0436-6

https://www.nature.com/articles/s41558-019-0436-6

Abstract: "In recent years, an evaluation technique for Earth System Models (ESMs) has arisen—emergent constraints (ECs)—which rely on strong statistical relationships between aspects of current climate and future change across an ESM ensemble. Combining the EC relationship with observations could reduce uncertainty surrounding future change. Here, we articulate a framework to assess ECs, and provide indicators whereby a proposed EC may move from a strong statistical relationship to confirmation. The primary indicators are verified mechanisms and out-of-sample testing. Confirmed ECs have the potential to improve ESMs by focusing attention on the variables most relevant to climate projections. Looking forward, there may be undiscovered ECs for extremes and teleconnections, and ECs may help identify climate system tipping points."

Caption for attached images: "Fig. 2 | emergent relationships for two ECs relating to physical and biogeochemical components of the climate system. a,b, An EC for snow-albedo feedbacks is shown in a, while b shows an EC for carbon loss from tropical land. In both cases the observational constraint is shown as a vertical bar. In a the y-axis is the strength of springtime snow-albedo feedback strength over Northern Hemisphere land masses, as measured in the climate change context (% albedo change per unit warming), while the x-axis is the snow-albedo feedback strength associated with springtime warming in the current climate’s seasonal cycle (same units). In b, the y-axis is the sensitivity of tropical land carbon losses to anthropogenic warming (Pg C K–1), and the x-axis is the sensitivity of interannual CO2 growth rate to inter-annual warming anomalies (Pg C yr–1 K–1). The models in a are from the CMIP3 and CMIP5 ensembles. The models in b are the C4MIP (black symbols) and CMIP5 (coloured asterisks) models. Panel b is adapted from ref. 21, Wiley."

Title: "Uncertain projections help to reveal the truth about future climate change"

https://phys.org/news/2019-03-uncertain-reveal-truth-future-climate.html

Extract: "Overall the tone of the study is a very positive about emergent constraints which enable the ensemble of climate models being developed worldwide, to be more than the sum of the parts.

Professor Chris Huntingford, study co-author based at the UK Centre for Ecology and Hydrology summarised this shared perspective: "An enormous amount of effort has gone into developing climate models by research groups around the world. Unfortunately, there remain significant differences between their projections.

"This uncertainty has to be reduced to help policymakers plan. At present, the only game in town to aid uncertainty removal is that of Emergent Constraints.""
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson