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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1950 on: November 18, 2019, 06:25:31 PM »
I appreciate Naomi Oreskes' insights in the linked article about the decades long energy companies' '… climate-change scam that beat science, big time.; including the insight that: 'Scientists working on the issue have often told me that, once upon a time, they assumed, if they did their jobs, politicians would act upon the information. That, of course, hasn’t happened.'

In a perfect world, consensus climate scientists would be immune to politics; but w.r.t climate-change, history has proven that this is far from the actual case:

Title: "Why science failed to stop climate change - How the energy companies took us all"

https://www.salon.com/2019/11/18/why-science-failed-to-stop-climate-change_partner/

Extract: "It’s a tale for all time. What might be the greatest scam in history or, at least, the one that threatens to take history down with it. Think of it as the climate-change scam that beat science, big time.

Scientists have been seriously investigating the subject of human-made climate change since the late 1950s and political leaders have been discussing it for nearly as long. In 1961, Alvin Weinberg, the director of the Oak Ridge National Laboratory, called carbon dioxide one of the “big problems” of the world “on whose solution the entire future of the human race depends.” Fast-forward nearly 30 years and, in 1992, President George H.W. Bush signed the U.N. Framework Convention on Climate Change (UNFCCC), promising “concrete action to protect the planet.”

Scientists working on the issue have often told me that, once upon a time, they assumed, if they did their jobs, politicians would act upon the information. That, of course, hasn’t happened. Anything but, across much of the planet. Worse yet, science failed to have the necessary impact in significant part because of disinformation promoted by the major fossil-fuel companies, which have succeeded in diverting attention from climate change and successfully blocking meaningful action."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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nanning

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1951 on: November 18, 2019, 06:42:40 PM »
<snip>
It is a small planet with limited resources to maintain life. That resource is in decline.

Thank you for that view gerontocrat.
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
   Simple: minimize your possessions and be free and kind    It's just a mindset.       Refugees welcome

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1952 on: November 19, 2019, 12:32:29 AM »
Gavin Schmidt recently posted the first image indicating that 2019 will almost certainly be the second warmest year in the observed record, even though ENSO is currently neutral.



For what it is worth, I provide the two attached images that Gavin Schmidt provided in July 2019 (referenced to a 'pre-industrial' baseline) where based on January to June 2019 GISTEMP data he was projecting the 2019 would likely be tied for second place for the warmest year on record; while his November 2019 indicates that 2019 will most likely have second place all by itself.

Edit1: I note that in these images 2016 is shown as having an annual GMSTA with a 'pre-industrial' baseline of about 1.23C; while 2019 is likely to have an annual GMSTA with a 'pre-industrial' baseline of above 1.1C.

Edit2: For convenience, I provide the third image as a re-post of the quoted image.

Edit3: See also:

Title: "Assessing the Global Climate in October 2019:

https://www.ncei.noaa.gov/news/global-climate-201910

Extract: "The year-to-date globally averaged sea surface temperature was the second highest for January–October in the 1880–2019 record …"
« Last Edit: November 20, 2019, 05:39:46 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1953 on: November 19, 2019, 03:39:50 AM »
...
 Furthermore, the 40-year update of Limits to Growth provides projections very much inline with our current BAU situation, and which projects a coming major socioeconomic contraction very much inline with my proposed sixth family of IPCC forcing scenarios (see the last two images, respectively).

Not only did Limits to Growth project a socio-economic collapse circa 2050, but so have the Australians:

Title: "Climate Change Could End Human Civilisation as We Know It by 2050, Analysis Finds"

https://www.sciencealert.com/by-2050-climate-change-could-alter-human-civilisation-as-we-know-it

Extract: "The new report, co-written by a former executive in the fossil fuel industry, is a harrowing follow-up to the Breakthrough National Centre for Climate Restoration's 2018 paper, which found that climate models often underestimate the most extreme scenarios.

Endorsed by former Australian defence chief Admiral Chris Barrie, the message is simple: if we do not take climate action in the next 30 years, it is entirely plausible that our planet warms by 3°C and that human civilisation as we know it collapses.

Under this scenario, the authors explain, the world will be locked into a "hothouse Earth" scenario, where 35 percent of the global land area, and 55 percent of the global population, will be subject to more than 20 days a year of "lethal heat conditions, beyond the threshold of human survivability."

With a runaway event like this, climate change will not present as a normal distribution, but instead will be skewed by a fat tail – indicating a greater likelihood of warming that is well in excess of average climate models.
Under a business-as-usual scenario, the authors explain, warming is set to reach 2.4°C by 2050. If feedback cycles are taken into account, however, there may be another 0.6°C that current models do not assume.

"It should be noted," the paper adds, "that this is far from an extreme scenario: the low-probability, high-impact warming (five percent probability) can exceed 3.5–4°C by 2050.""

Edit: For ease of reference, I provide the two attached Limits to Growth images updated on its 40th anniversary
« Last Edit: November 19, 2019, 04:03:09 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1954 on: November 19, 2019, 05:20:02 PM »
The Pine Island Ice Shelf, PIIS, plays a major role in the future stability of the Pine Island Glacier, PIG, and as the first attached image of the PIIS for Nov. 19, 2019 indicates that the PIIS will sustain a major calving event any week/month now, I thought that it would be helpful to review some key issues regarding the PIIS, the PIG and their relationship to the Thwaites drainage basin, thus:

The second image shows the condition of the PIIS and the associated grounding line from March 2012, and the associated shear strains in the PIIS.

The third image shows the condition of the PIIS and associated grounding line from Mid-January 2014, showing both a retreat of the calving front and a retreat of the grounding line from 2012.

The fourth image shows a screen grab of the PIIS calving front retreat history from 1973 to 2018, which is close to the calving front configuration today.  Also, I note that the calving front is currently retreating faster than the grounding line; which suggests that in coming decades the PIG may have an un-buttressed ice cliff face subject to MICI-types of failure mechanisms
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1955 on: November 19, 2019, 05:34:02 PM »
As a follow-on to my last post about the retreat history of the PIIS and the PIG, the first attached image shows the PIG basal topography and the relationship of the PIG drainage basin to the Thwaites drainage basin; which indicates that a MICI-type of collapse in either basin would act to undermine the glacial ice in the other basin.

The second image shows a close-up of both the PIG and the Southwest 'SW' Tributary glacier basal topographies.

The third image shows the relations of the ice shear strains between the SW Tributary Glacier and the eastern shear margin of the Thwaites Glacier.  Further as the PIIS no longer blocks the flow path of the SW Glacier ice shelf; it is reasonable to assume that the SW Tributary Glacier ice flow velocity is increasing (& note that the upcoming major calving event for the PIIS may well trigger minor calving from the SW Tributary Glacier ice shelf), the shear margin for the SW Tributary Glacier may soon connect directly with the Thwaites eastern shear margin; which would likely cause the ice flow velocity for Thwaites to accelerate.

The fourth image shows a close-up of the ice flow velocities in the SW Tributary Glacier prior to 2016.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1956 on: November 19, 2019, 05:49:36 PM »
As a follow-on to my last to posts, the first attached shows the ice velocity pattern for several key ASE marine glaciers prior to 2012.

The second image shows a representative water circulation pattern beneath the PIIS between 2009 and 2012, showing a gyre both in the front and the rear of the sub-ice-shelf cavity, that serve to periodically advection either warmer modified CDW or cooler modified CDW into this cavity.  Note that 2009 was associated with an introduction of warmer modified CDW (due to a moderate El Nino event) and that 2012 was associated with an introduction of cooler modified CDW (due to a moderate La Nina event).

The third image shows a profile view of that advection of warm modified CDW beneath the PIIS circa 2009 where the temperatures shown are the difference of the water temperature from that required to melt ice (which varies with depth).

The fourth (& final) image in this series, shows a schematic of typical primary stresses and associated crevasse patterns for ice shelves like the PIIS, and I note that the PIIS calving from is currently in the 'Compressive flow with shear at sides' zone, but that in coming decades this calving front will likely retreat thru the 'Shear at valley walls' zone into the 'Extending flow' zone where/when an un-buttressed ice cliff face may likely become exposed.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1957 on: November 19, 2019, 06:39:25 PM »
The linked reference indicates that since 2009 nitrous oxide emissions have been increasing at about twice the rate assumed by the IPCC:

R. L. Thompson et al. (2019), "Acceleration of global N2O emissions seen from two decades of atmospheric inversion", Nature Climate Change, DOI: https://doi.org/10.1038/s41558-019-0613-7

https://www.nature.com/articles/s41558-019-0613-7

Abstract: "Nitrous oxide (N2O) is the third most important long-lived GHG and an important stratospheric ozone depleting substance. Agricultural practices and the use of N-fertilizers have greatly enhanced emissions of N2O. Here, we present estimates of N2O emissions determined from three global atmospheric inversion frameworks during the period 1998–2016. We find that global N2O emissions increased substantially from 2009 and at a faster rate than estimated by the IPCC emission factor approach. The regions of East Asia and South America made the largest contributions to the global increase. From the inversion-based emissions, we estimate a global emission factor of 2.3 ± 0.6%, which is significantly larger than the IPCC Tier-1 default for combined direct and indirect emissions of 1.375%. The larger emission factor and accelerating emission increase found from the inversions suggest that N2O emission may have a nonlinear response at global and regional scales with high levels of N-input."

Edit, see also:

Title: "Nitrogen fertilizers are incredibly efficient, but they make climate change a lot worse"

https://phys.org/news/2019-11-nitrogen-fertilizers-incredibly-efficient-climate.html

Extract: "In a paper published today in Nature Climate Change, we found global emissions are higher and growing faster than are being reported."
« Last Edit: November 20, 2019, 10:42:53 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1958 on: November 19, 2019, 09:30:56 PM »
The linked reference indicates that consensus climate science has previously seriously underestimated the amount of future GHG emission from freshwater lakes by up to a factor of 2.7 times:

Andrew J. Tanentzap et al. Chemical and microbial diversity covary in fresh water to influence ecosystem functioning, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073/pnas.1904896116

https://www.pnas.org/content/early/2019/11/12/1904896116

Significance

Every drop of fresh water contains hundreds of different organic compounds, yet the biological role of this vast chemical diversity is largely a mystery. One hypothesis is that greater diversity may provide more opportunities for microbes to coexist, namely “diversity begets diversity.” Here we find a close association between mixtures of chemicals and both the diversity of microorganisms in lake sediments and their potential to decompose plant litterfall. Increases in chemical diversity also elevated greenhouse gas concentrations by an average of 1.5 to 2.7 times under scenarios that simulated future environmental change. Overall, our findings advance our understanding of how life is connected to the chemical environment in ways that can influence important processes, such as carbon cycling.

Abstract

Invisible to the naked eye lies a tremendous diversity of organic molecules and organisms that make major contributions to important biogeochemical cycles. However, how the diversity and composition of these two communities are interlinked remains poorly characterized in fresh waters, despite the potential for chemical and microbial diversity to promote one another. Here we exploited gradients in chemodiversity within a common microbial pool to test how chemical and biological diversity covary and characterized the implications for ecosystem functioning. We found that both chemodiversity and genes associated with organic matter decomposition increased as more plant litterfall accumulated in experimental lake sediments, consistent with scenarios of future environmental change. Chemical and microbial diversity were also positively correlated, with dissolved organic matter having stronger effects on microbes than vice versa. Under our experimental scenarios that increased sediment organic matter from 5 to 25% or darkened overlying waters by 2.5 times, the resulting increases in chemodiversity could increase greenhouse gas concentrations in lake sediments by an average of 1.5 to 2.7 times, when all of the other effects of litterfall and water color were considered. Our results open a major new avenue for research in aquatic ecosystems by exposing connections between chemical and microbial diversity and their implications for the global carbon cycle in greater detail than ever before.

See also:

Title: "Freshwater lakes already emit a quarter of global carbon—and climate change could double that"

https://phys.org/news/2019-11-freshwater-lakes-emit-quarter-global.html

Extract: "The amount of greenhouse gases released from lakes by microbes and sunlight is huge. Initial estimates were about 9% of the net carbon released from the Earth's surface to the atmosphere—that is, the amount released over and above the Earth's carbon-storing processes.

But, thanks to improved measurements, recent research has revised the figure to as high as 25%. These numbers are substantial given that that lakes only comprise about 4% of the global land surface."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1959 on: November 19, 2019, 11:52:21 PM »
The linked January 24, 2019 article makes is clear that the Bulletin of Atomic Scientists' Science and Security Board believes that we are within 2 minutes on the Doomsday Clock to a hypothetical apocalypse associated with threats from both nuclear weapons and climate change and that the risks associated with these threats are amplified '… by the increased use of information warfare to undermine democracy around the world …":

Title: "A new abnormal: It is still 2 minutes to midnight"

https://thebulletin.org/doomsday-clock/current-time/

Extract: "Humanity now faces two simultaneous existential threats, either of which would be cause for extreme concern and immediate attention. These major threats—nuclear weapons and climate change—were exacerbated this past year by the increased use of information warfare to undermine democracy around the world, amplifying risk from these and other threats and putting the future of civilization in extraordinary danger."

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1960 on: November 20, 2019, 04:20:57 PM »
The linked reference indicates that stratospheric ozone trends have not been recovering as quickly as assumed by consensus climate models, indicating that:

'These decreases do not reveal an inefficacy of the Montreal Protocol; rather, they suggest that other effects are at work, mainly dynamical variability on long or short timescales, counteracting the positive effects of the Montreal Protocol on stratospheric ozone recovery.'

&

'However, this variability is not represented in current regression analyses.'

Ball, W. T., Alsing, J., Staehelin, J., Davis, S. M., Froidevaux, L., and Peter, T.: Stratospheric ozone trends for 1985–2018: sensitivity to recent large variability, Atmos. Chem. Phys., 19, 12731–12748, https://doi.org/10.5194/acp-19-12731-2019, 2019.

https://www.atmos-chem-phys.net/19/12731/2019/

Abstract: "The Montreal Protocol, and its subsequent amendments, has successfully prevented catastrophic losses of stratospheric ozone, and signs of recovery are now evident. Nevertheless, recent work has suggested that ozone in the lower stratosphere (< 24 km) continued to decline over the 1998–2016 period, offsetting recovery at higher altitudes and preventing a statistically significant increase in quasi-global (60∘ S–60∘ N) total column ozone. In 2017, a large lower stratospheric ozone resurgence over less than 12 months was estimated (using a chemistry transport model; CTM) to have offset the long-term decline in the quasi-global integrated lower stratospheric ozone column. Here, we extend the analysis of space-based ozone observations to December 2018 using the BASICSG ozone composite. We find that the observed 2017 resurgence was only around half that modelled by the CTM, was of comparable magnitude to other strong interannual changes in the past, and was restricted to Southern Hemisphere (SH) midlatitudes (60–30∘ S). In the SH midlatitude lower stratosphere, the data suggest that by the end of 2018 ozone is still likely lower than in 1998 (probability ∼80 %). In contrast, tropical and Northern Hemisphere (NH) ozone continue to display ongoing decreases, exceeding 90 % probability. Robust tropical (>95 %, 30∘ S–30∘ N) decreases dominate the quasi-global integrated decrease (99 % probability); the integrated tropical stratospheric column (1–100 hPa, 30∘ S–30∘ N) displays a significant overall ozone decrease, with 95 % probability. These decreases do not reveal an inefficacy of the Montreal Protocol; rather, they suggest that other effects are at work, mainly dynamical variability on long or short timescales, counteracting the positive effects of the Montreal Protocol on stratospheric ozone recovery. We demonstrate that large interannual midlatitude (30–60∘) variations, such as the 2017 resurgence, are driven by non-linear quasi-biennial oscillation (QBO) phase-dependent seasonal variability. However, this variability is not represented in current regression analyses. To understand if observed lower stratospheric ozone decreases are a transient or long-term phenomenon, progress needs to be made in accounting for this dynamically driven variability."

Maybe by CMIP7 we will have learned how to model ozone more accurately.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1961 on: November 20, 2019, 04:48:49 PM »
The linked reference indicates that:

'These multiple lines of evidence lead to a 68% confidence interval for the total aerosol effective radiative forcing of ‐1.60 to ‐0.65 W m‐2, or ‐2.0 to ‐0.4 W m‐2 with a 90% likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessment but shifted towards more negative values.'

Thus effective aerosol radiative forcing has been more negative than assumed by AR5; which, implies that it has been masking a higher ECS than assumed by AR5; and that as future aerosol emissions are decreased, GMSTA will increase faster than assumed by AR5:

N. Bellouin et al. (01 November 2019), "Bounding global aerosol radiative forcing of climate change", Reviews of Geophysics, https://doi.org/10.1029/2019RG000660

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019RG000660

Abstract
Aerosols interact with radiation and clouds. Substantial progress made over the past 40 years in observing, understanding, and modeling these processes helped quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols, called aerosol radiative forcing, but uncertainties remain large. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable and arguable lines of evidence, including modelling approaches, theoretical considerations, and observations. Improved understanding of aerosol absorption and the causes of trends in surface radiative fluxes constrain the forcing from aerosol‐radiation interactions. A robust theoretical foundation and convincing evidence constrain the forcing caused by aerosol‐driven increases in liquid cloud droplet number concentration. However, the influence of anthropogenic aerosols on cloud liquid water content and cloud fraction is less clear, and the influence on mixed‐phase and ice clouds remains poorly constrained. Observed changes in surface temperature and radiative fluxes provide additional constraints. These multiple lines of evidence lead to a 68% confidence interval for the total aerosol effective radiative forcing of ‐1.60 to ‐0.65 W m‐2, or ‐2.0 to ‐0.4 W m‐2 with a 90% likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessment but shifted towards more negative values. The uncertainty will narrow in the future by continuing to critically combine multiple lines of evidence, especially those addressing industrial‐era changes in aerosol sources and aerosol effects on liquid cloud amount and on ice clouds.

Plain language summary
Human activities emit into the atmosphere small liquid and solid particles called aerosols. Those aerosols change the energy budget of the Earth, and trigger climate changes, by scattering and absorbing solar and terrestrial radiation and playing important roles in the formation of cloud droplets and ice crystals. But because aerosols are much more varied in their chemical composition and much more heterogeneous in their spatial and temporal distributions than greenhouse gases, their perturbation to the energy budget, called radiative forcing, is much more uncertain. This review uses traceable and arguable lines of evidence, supported by aerosol studies published over the past 40 years, to quantify that uncertainty. It finds that there are 2 chances out of three that aerosols from human activities have increased scattering and absorption of solar radiation by 14 to 29% and cloud droplet number concentration by 6 to 18% in the period 2005‐‐2015 compared to the year 1850. Those increases exert a radiative forcing that offsets between a fifth and a half of the radiative forcing by greenhouse gases. The degree to which human activities affect natural aerosol levels, and the response of clouds, and especially ice clouds, to aerosol perturbations remain particularly uncertain.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1962 on: November 20, 2019, 05:19:16 PM »
The attached image from a French CMIP6 projections of GMSTA (with a pre-industrial baseline) for the different SSP scenarios, and indicate that by following either SSP5 8.5 or SSP3 7.0, GMSTA could be approaching 2.5C by 2040; which would likely be sufficient to trigger hydrofracturing on some key West Antarctic ice shelves, by that date:
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1963 on: November 20, 2019, 06:15:18 PM »
The linked reference indicates that since the industrial era the ocean has been accumulating more heat content then consensus climate scientists previously assumed.  Furthermore, the associate Fig. 2 (shown in two attached images for panel A and B, respectively), show that the Southern Ocean has been responsible for the lion's share of cumulative heat uptake (see the first image), while much of the heat accumulated in the Atlantic Ocean since 1950 has come from other regions.  This recent data suggests that many consensus climate models have likely underestimated the about of heat stored in the Southern Ocean; which is available for ice melting of key Antarctic marine glacial ice and ice shelf ice.

Laure Zanna, Samar Khatiwala, Jonathan M. Gregory, Jonathan Ison, and Patrick Heimbach (January 22, 2019), "Global reconstruction of historical ocean heat storage and transport", PNAS, 116 (4), 1126-1131, https://doi.org/10.1073/pnas.1808838115

https://www.pnas.org/content/116/4/1126

Significance
Since the 19th century, rising greenhouse gas concentrations have caused the ocean to absorb most of the Earth’s excess heat and warm up. Before the 1990s, most ocean temperature measurements were above 700 m and therefore, insufficient for an accurate global estimate of ocean warming. We present a method to reconstruct ocean temperature changes with global, full-depth ocean coverage, revealing warming of 436 ×10 21  ×1021 J since 1871. Our reconstruction, which agrees with other estimates for the well-observed period, demonstrates that the ocean absorbed as much heat during 1921–1946 as during 1990–2015. Since the 1950s, up to one-half of excess heat in the Atlantic Ocean at midlatitudes has come from other regions via circulation-related changes in heat transport.

Abstract
Most of the excess energy stored in the climate system due to anthropogenic greenhouse gas emissions has been taken up by the oceans, leading to thermal expansion and sea-level rise. The oceans thus have an important role in the Earth’s energy imbalance. Observational constraints on future anthropogenic warming critically depend on accurate estimates of past ocean heat content (OHC) change. We present a reconstruction of OHC since 1871, with global coverage of the full ocean depth. Our estimates combine timeseries of observed sea surface temperatures with much longer historical coverage than those in the ocean interior together with a representation (a Green’s function) of time-independent ocean transport processes. For 1955–2017, our estimates are comparable with direct estimates made by infilling the available 3D time-dependent ocean temperature observations. We find that the global ocean absorbed heat during this period at a rate of 0.30 ± 0.06 W/m 2  m2 in the upper 2,000 m and 0.028 ± 0.026 W/m 2  m2 below 2,000 m, with large decadal fluctuations. The total OHC change since 1871 is estimated at 436 ± 91 ×10 21  ×1021 J, with an increase during 1921–1946 (145 ± 62 ×10 21  ×1021 J) that is as large as during 1990–2015. By comparing with direct estimates, we also infer that, during 1955–2017, up to one-half of the Atlantic Ocean warming and thermosteric sea-level rise at low latitudes to midlatitudes emerged due to heat convergence from changes in ocean transport.

Caption: "Fig. 2. Cumulative heat uptake from 1871 to 2017 (joules per year) shown for each patch (numbered here and shown in SI Appendix, Fig. S1), contributing to the integrated passive heat storage (A) globally and (B) in the Atlantic Ocean. Note the different scales for the two panels."

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1964 on: November 20, 2019, 07:27:03 PM »
The linked open access publication indicates that current consensus science estimates of right-tailed climate economic impacts are '… grossly underestimating many of the most serious consequences for lives and livelihoods because these risks are difficult to quantify precisely and lie outside of human experience.'  Obviously, as risk is equal to probability times consequences, this means that right-tailed risks are currently be grossly underestimated:

Title: "The missing economic risks in assessments of climate change impacts"

http://www.lse.ac.uk/GranthamInstitute/publication/the-missing-economic-risks-in-assessments-of-climate-change-impacts/
http://www.lse.ac.uk/GranthamInstitute/wp-content/uploads/2019/09/The-missing-economic-risks-in-assessments-of-climate-change-impacts-2.pdf

   Extract: "Economic assessments of the potential future risks of climate change have been omitting or grossly underestimating many of the most serious consequences for lives and livelihoods because these risks are difficult to quantify precisely and lie outside of human experience.

   Political and business leaders need to understand the scale of these ‘missing risks’ because they could have drastic and potentially catastrophic impacts on citizens, communities and companies.

   Scientists are growing in confidence about the evidence for the largest potential impacts of climate change and the rising probability that major thresholds in the Earth’s climate system will be breached as global mean surface temperature rises, particularly if warming exceeds 2°C above the pre-industrial level. These impacts include:
   Destabilisation of ice sheets and glaciers and consequent sea level rise
   Stronger tropical cyclones
   Extreme heat impacts
   More frequent and intense floods and droughts
   Disruptions to oceanic and atmospheric circulation
   Destruction of biodiversity and collapse of ecosystems
   
        Many of these impacts will grow and occur concurrently across the world as global temperature climbs.

   Some of these impacts involve thresholds in the climate system beyond which major impacts accelerate, or become irreversible and unstoppable.

   When a threshold is breached, it might cause one or more other thresholds to be exceeded as well, leading to a cascade of impacts.

   Many of these impacts could exceed the capacity of human populations to adapt, and would significantly affect and disrupt the lives and livelihoods of hundreds of millions, if not billions, of people worldwide.

   These impacts would also undermine economic growth and development, exacerbate poverty and destabilise communities.

   Economic assessments fail to take account of the potential for large concurrent impacts across the world that would cause mass migration, displacement and conflict, with huge loss of life.

   Economic assessments that are expressed solely in terms of effects on output (e.g. gross domestic product), or that only extrapolate from past experience, or that use inappropriate discounting, do not provide a clear indication of the potential risks to lives and livelihoods.

   It is likely that there are additional risks that we are not yet anticipating simply because scientists have not yet detected their possibility, as we have entered a period of climate change that is unprecedented in human history.

   Some advances are being made in improving economic assessments of climate change impacts but much more progress is required if assessments are to offer reliable guidance for political and business leaders on the biggest risks.

   The lack of firm quantifications is not a reason to ignore these risks, and when the missing risks are taken into account, the case for strong and urgent action to reduce greenhouse gas emissions becomes even more compelling."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1965 on: November 20, 2019, 08:18:29 PM »
The linked reference indicates that earlier models of methane (& CO2) fluxes from Arctic tundra ecosystems underestimate the importance of the temperatures of deeper layers of soil w.r.t. fluxes in non-summer seasons:

Howard, D., Agnan, Y., Helmig, D., Yang, Y., and Obrist, D.: Environmental controls on ecosystem-scale cold season methane and carbon dioxide fluxes in an Arctic tundra ecosystem, Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-437, in review, 2019.

https://www.biogeosciences-discuss.net/bg-2019-437/

https://www.biogeosciences-discuss.net/bg-2019-437/bg-2019-437.pdf

Abstract. Understanding the processes that influence and control carbon cycling in Arctic tundra ecosystems is essential for making accurate predictions about what role these ecosystems will play in potential future climate change scenarios. Particularly, air–surface fluxes of methane and carbon dioxide are of interest as recent observations suggest that the vast stores of soil carbon found in the Arctic tundra are becoming more available to release to the atmosphere in the form of these greenhouse gases. Further, harsh wintertime conditions and complex logistics have limited the number of year-round and cold season studies and hence too our understanding of carbon cycle processes during these periods. We present here a two-year micrometeorological data set of methane and carbon dioxide fluxes that provides near-continuous data throughout the active summer and cold winter seasons. Net emission of methane and carbon dioxide in one of the study years totalled 3.7 and 89 g C m−2 a−1 respectively, with cold season methane emission representing 54% of the annual total. In the other year, net emission totals of methane and carbon dioxide were 4.9 and 485 g C m−2 a−1 respectively, with cold season methane emission here representing 82 % of the annual total – a larger proportion than has been previously reported in the Arctic tundra. Regression tree analysis suggests that, due to relatively warmer air temperatures and deeper snow depths, deeper soil horizons – where most microbial methanogenic activity takes place – remained warm enough to maintain efficient methane production whilst surface soil temperatures were simultaneously cold enough to limit microbial methanotrophic activity. These results provide valuable insight into how a changing Arctic climate may impact methane emission, and highlight a need to focus on soil temperatures throughout the entire active soil profile, rather than rely on air temperature as a proxy for modelling temperature–methane flux dynamics.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1966 on: November 20, 2019, 09:37:05 PM »
The linked report indicates that government plans for fossil fuel production leaves a large 'Production Gap' between associated global carbon dioxide emissions that the emissions required to meet the goals of the Paris Agreement (see the attached image).  Also, I note that this analysis does not consider the potentially much higher values of climate sensitivity indicated by many CMIP6 models:

Title: "The Production Gap"

http://productiongap.org/

http://productiongap.org/wp-content/uploads/2019/11/Production-Gap-Report-2019.pdf

Extract: "Governments are planning to produce about 50% more fossil fuels by 2030 than would be consistent with limiting warming to 2°C and 120% more than would be consistent with limiting warming to 1.5°C.

The global production gap is even larger than the already-significant global emissions gap, due to minimal policy attention on curbing fossil fuel production."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1967 on: November 20, 2019, 10:09:00 PM »
More bad news about projected nitrous oxide emissions:

Title: "Nitrous oxide emissions set to rise in the Pacific Ocean"

https://phys.org/news/2019-11-nitrous-oxide-emissions-pacific-ocean.html

Extract: "The acidification of the Pacific Ocean in northern Japan is increasing the natural production rate of N2O, an ozone-depleting greenhouse gas. That's the finding of a study carried out jointly by scientists at EPFL, Tokyo Institute of Technology and Japan Agency for Marine-Earth Science and Technology and appearing recently in Nature Climate Change."

See also:

Florian Breider et al. Response of N2O production rate to ocean acidification in the western North Pacific, Nature Climate Change (2019). DOI: 10.1038/s41558-019-0605-7

https://www.nature.com/articles/s41558-019-0605-7

Extract: "Collectively, these results suggest that if seawater pH continues to decline at the same rate, ocean acidification could increase marine N2O production during nitrification in the subarctic North Pacific by 185 to 491% by the end of the century."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1968 on: November 20, 2019, 10:24:33 PM »
The linked article/reference indicates that the Arctic Ocean could be seasonally ice free between 2044 and 2067, by constraining the relationship between sea ice extent and sea ice albedo feedback (SIAF) and found that: 'The relationship is strengthened when models with unrealistically thin historical ice are excluded.'  Obviously, this stronger relationship projects greater Arctic Amplification and consequently greater values of ECS than previously assumed by consensus climate science:

Title: "Arctic Ocean could be ice-free for part of the year as soon as 2044"

https://phys.org/news/2019-11-arctic-ocean-ice-free-year.html

Extract: "But according to a new study by UCLA climate scientists, human-caused climate change is on track to make the Arctic Ocean functionally ice-free for part of each year starting sometime between 2044 and 2067.

For their study, Thackeray and co-author Alex Hall, a UCLA professor of atmospheric and oceanic sciences, set out to determine which models are most realistic in how they weigh the effects of sea ice albedo feedback, which they figured would lead them to the most realistic projections for sea ice loss.

Thackeray and Hall assessed 23 models' depiction of seasonal ice melt between 1980 and 2015 and compared them with the satellite observations. They retained the six models that best captured the actual historical results and discarded the ones that had proven to be off base, enabling them to narrow the range of predictions for ice-free Septembers in the Arctic."

See also:

Chad W. Thackeray et al. An emergent constraint on future Arctic sea-ice albedo feedback, Nature Climate Change (2019). DOI: 10.1038/s41558-019-0619-1

https://www.nature.com/articles/s41558-019-0619-1

Abstract: "Arctic sea ice has decreased substantially over recent decades, a trend projected to continue. Shrinking ice reduces surface albedo, leading to greater surface solar absorption, thus amplifying warming and driving further melt. This sea-ice albedo feedback (SIAF) is a key driver of Arctic climate change and an important uncertainty source in climate model projections. Using an ensemble of models, we demonstrate an emergent relationship between future SIAF and an observable version of SIAF in the current climate’s seasonal cycle. This relationship is robust in constraining SIAF over the coming decades (Pearson’s r = 0.76), and then it degrades. The degradation occurs because some models begin producing ice-free conditions, signalling a transition to a new ice regime. The relationship is strengthened when models with unrealistically thin historical ice are excluded. Because of this tight relationship, reducing model errors in the current climate’s seasonal SIAF and ice thickness can narrow SIAF spread under climate change."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1969 on: November 20, 2019, 11:08:57 PM »
I managed to find the original of the graphic in the above post by AbruptSLR.

You can download it from here :- http://newsroom.ucla.edu/releases/arctic-sea-ice-melting-2044

Attached is part of the full graphic that is, I hope, easier to read.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1970 on: November 21, 2019, 02:06:33 PM »
I posted this on the Paris 2015 & Beyond thread.

But the chances of abrupt sea level rise and accelerated global heating seem to be somewhat higher than consensus.
__________________________________________________________
Going backwards. Of the reports that have come out this year this UNEP report is perhaps the worse.

The contrast between what could be done to reduce Global Heating and what seems will be done to accelerate Global Heating is profound and certainly more than confirmed my most pessimistic thoughts and feelings.

Quote
Governments are planning to produce about 50% more fossil fuels by 2030 than would be consistent with limiting warming to 2°C and 120% more than would be consistent with limiting warming to 1.5°C.

To estimate the production gap, this report puts forward a method analogous to that used in the Emissions Gap Report. It uses publicly available data to estimate the difference between what countries are planning and what would be consistent with 1.5°C and 2°C pathways, based on scenarios from the recent Intergovernmental Panel on Climate Change (IPCC) Special Report on Global Warming of 1.5°C. In aggregate, countries’ planned fossil fuel production by 2030 will lead to the emission of 39 billion tonnes (gigatonnes) of carbon dioxide (GtCO2). That is 13 GtCO2, or 53%, more than would be consistent with a 2°C pathway, and 21 GtCO2 (120%) more than would be consistent with a 1.5°C pathway. This gap widens significantly by 2040.

Many countries appear to be banking on export markets to justify major increases in production (e.g., the United States, Russia, and Canada) while others are seeking to limit or largely end imports through scaled-up production (e.g., India and China). The net result could be significant over-investment, increasing the risk of stranded assets, workers, and communities, as well as locking in a higher emissions trajectory.
Links.........
https://www.theguardian.com/environment/2019/nov/20/fossil-fuel-production-on-track-for-double-the-safe-climate-limit

UNEP Reports
https://productiongap.org/2019report/
http://productiongap.org/wp-content/uploads/2019/11/Production-Gap-Report-2019-Executive-Summary.pdf
http://productiongap.org/wp-content/uploads/2019/11/Production-Gap-Report-2019-Executive-Summary.pdf
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1971 on: November 21, 2019, 04:31:25 PM »
I managed to find the original of the graphic in the above post by AbruptSLR.

You can download it from here :- http://newsroom.ucla.edu/releases/arctic-sea-ice-melting-2044

Attached is part of the full graphic that is, I hope, easier to read.

When CMIP6 is complete I would like to see Chad W. Thackeray et al. re-do their analysis using the CMIP6 model projections, as the likely higher climate sensitivity indicated by the preliminary CMIP6 results would likely advance the date for a seasonally ice-free Arctic Ocean to a significantly earlier date than 2044; where it might trigger a cascade of other possible ice-climate mechanisms such as:

1. An abrupt release of relatively freshwater from the Beaufort Gyre into the North Atlantic, which might abruptly slow the MOC.

2. An abrupt slowing of the MOC (see point 1) might abruptly increase upwelling of relatively warm CDW beneath key Antarctic ice shelves and adjacent to the grounding lines for key Antarctic marine glaciers.

3. Abruptly increase Arctic rainfall that could result in further melting of Arctic sea ice and snow on coastal Arctic areas.

Furthermore, the models identified by such a hypothetical analysis by Chad W. Thackeray et al. on the CMIP6 results, could be used as input to the boundary conditions for regional models of Antarctica and the Southern Ocean that include MICI-mechanisms (whether from the International Thwaites Glacier Collaboration or from Pollard & DeConto, etc.)
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1972 on: November 21, 2019, 04:42:13 PM »
Are we getting increased precipitation in SO? No, see attached, there is no trend there.

I don't see much evidence in satellite data for their claim.

I re-post Reply #290:

The first image is from Hansen et al (2016), showing the ocean stratification and precipitation portions of the ice-climate feedback mechanism.  I repost this image to remind readers that this mechanism proposes: a cooling of the sea surface temperature, SST, an increase in sea ice extent, SIE, and a reduction of sea surface salinity, SSS, not only due to ice melt but also due to precipitation (and its difference with evaporation).  The first two linked references confirm these trends (see the second and third images); however, as most consensus climate models ignore the ice-climate feedback mechanism, they both discuss possible alternate mechanisms.  Nevertheless, since ~1980, this SST, SIE and SSS data is fully consistent with the ice-climate mechanism, and I also note that the associated change in SST tends to mask the full strength of climate sensitivity when measured by GMSTA:

Zhang, L., Delworth, T. L., Cooke, W., & Yang, X. (2018). Natural variability of Southern Ocean convection as a driver of observed climate trends. Nature Climate Change. doi:10.1038/s41558-018-0350-3, https://doi.org/10.1038/s41558-018-0350-3

https://www.nature.com/articles/s41558-018-0350-3

Abstract: "Observed Southern Ocean surface cooling and sea-ice expansion over the past several decades are inconsistent with many historical simulations from climate models. Here we show that natural multidecadal variability involving Southern Ocean convection may have contributed strongly to the observed temperature and sea-ice trends. These observed trends are consistent with a particular phase of natural variability of the Southern Ocean as derived from climate model simulations. Ensembles of simulations are conducted starting from differing phases of this variability. The observed spatial pattern of trends is reproduced in simulations that start from an active phase of Southern Ocean convection. Simulations starting from a neutral phase do not reproduce the observed changes, similarly to the multimodel mean results of CMIP5 models. The long timescales associated with this natural variability show potential for skillful decadal prediction."

Extract: "However, we cannot conclude that internally generated SO deep convection is the only driver, even in recent observations. The SO deep-convection change could work together with various other mechanisms identified in earlier studies3–16, such as wind-driven ice transport and cold/warm-temperature advection, and anthropogenic surface freshening due to an amplified hydrological cycle and ice-sheet melting. As mentioned above, the surface wind trend favours warm SST and decreasing sea ice over the Antarctic Peninsula through warm advection and over the Amundsen– Bellingshausen seas through enhanced vertical mixing caused by anomalous negative wind stress curl. Our model also shows that the long-lasting westerly winds over the SO induce upwelling and a spin-up of the AABW cell, which in turn generates the warm SST.  The surface freshwater changes due to shifted storm tracks and melting ice sheet in future may slow down the SO MOC15, which also cannot be excluded. It is also possible that melting of land-based ice sheets, a process usually not included in climate models, could cause surface freshening and the subsequent suppressed convection and SST cooling."
&

Purich, A., England, M. H., Cai, W., Sullivan, A., & Durack, P. J. (2018). Impacts of Broad-Scale Surface Freshening of the Southern Ocean in a Coupled Climate Model. Journal of Climate, 31(7), 2613–2632. doi:10.1175/jcli-d-17-0092.1, https://doi.org/10.1175/JCLI-D-17-0092.1

https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0092.1

Abstract: "The Southern Ocean surface has freshened in recent decades, increasing water column stability and reducing upwelling of warmer subsurface waters. The majority of CMIP5 models underestimate or fail to capture this historical surface freshening, yet little is known about the impact of this model bias on regional ocean circulation and hydrography. Here experiments are performed using a global coupled climate model with additional freshwater applied to the Southern Ocean to assess the influence of recent surface freshening. The simulations explore the impact of persistent and long-term broad-scale freshening as a result of processes including precipitation minus evaporation changes. Thus, unlike previous studies, the freshening is applied as far north as 55°S, beyond the Antarctic ice margin. It is found that imposing a large-scale surface freshening causes a surface cooling and sea ice increase under preindustrial conditions, because of a reduction in ocean convection and weakened entrainment of warm subsurface waters into the surface ocean. This is consistent with intermodel relationships between CMIP5 models and the simulations, suggesting that models with larger surface freshening also exhibit stronger surface cooling and increased sea ice. Additional experiments are conducted with surface salinity restoration applied to capture observed regional salinity trends. Remarkably, without any mechanical wind trend forcing, these simulations accurately represent the spatial pattern of observed surface temperature and sea ice trends around Antarctica. This study highlights the importance of accurately simulating changes in Southern Ocean salinity to capture changes in ocean circulation, sea surface temperature, and sea ice."

Caption for the third attached image: "FIG. 1. Trends over 1950–2000. (a) Observed SSS trends from Durack and Wijffels (2010); (b) zonal-mean SSS trends for observations (Durack and Wijffels 2010) and CMIP5 models; (c) zonal-mean precipitation trends for observations (ERA-Interim, COREv2, GPCPv2.2, CMAP standard, CMAP enhanced) and CMIP5 models; and (d) zonal-mean P–E trends for observations (ERA-Interim, COREv2) and CMIP5 models. In (a), stippling indicates significance at the 95% level. In (b) observations are shown in dashed black. In (c)–(d) observations are shown in colors, and vary in the time periods they cover (refer to the data and methods section). In (b)–(d) CMIP5 models are shown in grey, and the ACCESS1.0 CMIP5 run is shown in dark blue."

Note: Sea Surface Salinity, SSS, can be measured remotely in units of PSU, see the extract for the linked website:

http://www.salinityremotesensing.ifremer.fr/sea-surface-salinity/definition-and-units

Extract: "Ocean salinity is generally defined as the salt concentration (e.g., Sodium and Chloride) in sea water. It is measured in unit of PSU (Practical Salinity Unit), which is a unit based on the properties of sea water conductivity. It is equivalent to per thousand or (o/00) or to g/kg."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1973 on: November 21, 2019, 04:59:45 PM »
While many of my posts have focused on the risks associated a possible/probable higher than AR5/CMIP5 range for climate sensitivity, in this post I highlight three initial model boundary conditions that might cause climate models (including those in CMIP6) to underestimate the near-term (say between 2020 and 2050) risks to WAIS stability:

1. As indicated by Replies #1957, #1958 and #1960, respectively indicate that the RCP radiative forcing scenarios underestimate input from nitrous oxide (see the attached image and following associated article), freshwater GHG emissions and over estimated the rate of recovery of ozone in the stratosphere.  Here I note that atmospheric nitrous oxide slows the recovery of ozone in the atmosphere; thus the higher than expected nitrous oxide emissions from fertilizers (see the attached image) should slow the recovery of the Antarctic ozone hole from that assumed in most climate models including CMIP6.

2. As indicated by Reply #1877 consensus climate models have not yet accounted for the importance in modeling the variability of the Westerlies over the Southern Ocean w.r.t. estimating wind stress on the ocean surface that has been accelerating the ACC (by 40% over the past 40-years); which, has been inducing more upwelling of warm CDW than assumed by consensus climate models.  This in turn has been promoting more ice mass loss from key marine glaciers and associated ice shelves; which has triggered earlier activation of several ice-climate feedback mechanisms than assumed by consensus climate models.

3. The integrity of the ASE ice shelves and Thwaites Ice Tongue is typically over-estimated in regional models of the AIS (note that the recent observed calving of the PIIS, the Thwaites Eastern Ice Shelf and the Thwaites Ice Tongue all exceed consensus expectations), and thus for CMIP7 it would be advisable to use models that reflex the true fragility of such ice shelves and ice tongues:

Title: "Nitrogen fertilizers are incredibly efficient, but they make climate change a lot worse"

https://phys.org/news/2019-11-nitrogen-fertilizers-incredibly-efficient-climate.html

Extract: "In a paper published today in Nature Climate Change, we found global emissions are higher and growing faster than are being reported."
« Last Edit: November 21, 2019, 05:13:36 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1974 on: November 21, 2019, 05:04:29 PM »
Quote
(not that the recent observed calving of the PIIS, the Thwaites Eastern Ice Shelf and the Thwaites Ice Tongue all exceed consensus expectations),

Did you mean note that?
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1975 on: November 21, 2019, 05:14:34 PM »
Quote
(not that the recent observed calving of the PIIS, the Thwaites Eastern Ice Shelf and the Thwaites Ice Tongue all exceed consensus expectations),

Did you mean note that?

Tom,

Corrected

Thanks,
ASLR
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1976 on: November 21, 2019, 05:37:58 PM »
I posted this on the Paris 2015 & Beyond thread.

But the chances of abrupt sea level rise and accelerated global heating seem to be somewhat higher than consensus.


For what it worth, I note that some left-tail advocates look at observed mean SLR data such as the first attached image showing all related satellite data from Aviso, from Dec 1992 to August 2019, and indicate that they do not see much, if any, acceleration in mean SLR, and thus they imply that the risk of abrupt sea level rise this century can be discounted.

In this regard, I attach the second image from AR5 that shows that SLR contribution from mountain glaciers has recently been decelerating while the ice sheet contribution has been accelerating; which tends to mask the nonlinear acceleration (without MICI-type of input yet) of the ice sheet contributions to SLR.  Furthermore, the third image (from the linked article) shows changes in terrestrial storage of water as measured by the GRACE satellite from 2012 to 2016; which, also must be considered when evaluating changes in the mean SLR trends.

Title: "A Map of the Future of Water"

https://trend.pewtrusts.org/en/archive/spring-2019/a-map-of-the-future-of-water

Extract related to third image: "We know this thanks to 14 years’ worth of satellite data collected by a unique NASA Earth-observing mission called the Gravity Recovery and Climate Experiment—which has the gratifying acronym GRACE. Unlike some satellite missions that rely on images, GRACE, which was launched in 2002 and decommissioned at the end of 2017, was more a “scale in the sky.” It measured the very tiny space-time variations in Earth’s gravity field, effectively weighing changes in water mass over large river basins and groundwater aquifers—those porous, subterranean rock and soil layers that store water that must be pumped to the surface."

Edit: As I am primarily concerned with WAIS contributions to SLR this century, when correcting for net terrestrial water storage, one should subtract associated contributions from both the GIS and the EAIS in order to determine the net WAIS terrestrial contribution.
« Last Edit: November 21, 2019, 06:37:17 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1977 on: November 21, 2019, 06:26:25 PM »
Quote
Tom,

Corrected

Thanks,
ASLR
Glad to do it. I am a mediocre speller and an atrocious typist.
Especially when I use my iPhone (Autocorrect to Tom: "It's not a bug, it's a feature!")
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1978 on: November 21, 2019, 07:39:18 PM »
I'll post this here even though it's not about sea level.

"Kevin Anderson Truth about Climate Crisis Part 1"

A very good interview because of Kevin's answers.
Especially starting 12m00 and 12m20 but the rest is interesting as well. He has the ability to think straight. I think that he hasn't emotionally connected yet to the long term consequences.

(38m24)

edit: added emotional connection to long term consequences.
« Last Edit: November 21, 2019, 08:56:45 PM by nanning »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1979 on: November 21, 2019, 08:01:02 PM »
The linked reference finds that: "We find that the energy of the vortices has increased over the past two decades. Using our method, we are able to pinpoint that the energy increase occurs due to an increase in the mean amplitude of the vortices rather than in an increase in their number. Finally, the vortices show a clear response to the strengthening of winds in the Southern Ocean."

This increase of mesoscale eddy kinetic energy in the Southern Ocean over the past two decades in important for several reasons including that these mesoscale eddies advect warm surface waters (such as from Agulhas leakage of warm surface water from the Indian Ocean around the Cape of Good Hope, see the two attached images, where the first image show water temperature at a depth of 250 to 400m and the second shows surface currents/eddies) down into the CDW where subsequent upwelling can convey this heat to the basal side of ice shelves and to the grounding lines of key Antarctic marine glaciers:

Josué Martínez‐Moreno et al. (10 September 2019), "Kinetic Energy of Eddy‐Like Features From Sea Surface Altimetry", JAMES, https://doi.org/10.1029/2019MS001769

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001769

Abstract
The mesoscale eddy field plays a key role in the mixing and transport of physical and biological properties and redistribution of energy in the ocean. Eddy kinetic energy is commonly defined as the kinetic energy of the time‐varying component of the velocity field. However, this definition contains all processes that vary in time, including coherent mesoscale eddies, jets, waves, and large‐scale motions. The focus of this paper is on the eddy kinetic energy contained in coherent mesoscale eddies. We present a new method to decompose eddy kinetic energy into oceanic processes. The proposed method uses a new eddy identification algorithm (TrackEddy). This algorithm is based on the premise that the sea level signature of a coherent eddy can be approximated as a Gaussian feature. The eddy Gaussian signature then allows for the calculation of kinetic energy of the eddy field through the geostrophic approximation. TrackEddy has been validated using synthetic sea surface height data and then used to investigate trends of eddy kinetic energy in the Southern Ocean using satellite sea surface height anomaly (AVISO+). We detect an increasing trend of eddy kinetic energy associated with mesoscale eddies in the Southern Ocean. This trend is correlated with an increase in the coherent eddy amplitude and the strengthening of wind stress over the last two decades.

Plain Language Summary
It is well accepted that climate change results in the intensification of the winds, in particular of those blowing over the Southern Ocean. Despite previous research showing an increase in the high‐frequency motions in the Southern Ocean due to the intensification of the winds, we still do not know how swirling vortices of tens to hundreds of kilometers in the ocean have responded to climate change. In this study, we use satellite observations of the sea surface height from 1993 to 2017 to look for changes in the swirling vortices. The focus of our study is on the Southern Ocean as it is one of the areas with more vortices and also plays a key role in controlling the climate. We find that the energy of the vortices has increased over the past two decades. Using our method, we are able to pinpoint that the energy increase occurs due to an increase in the mean amplitude of the vortices rather than in an increase in their number. Finally, the vortices show a clear response to the strengthening of winds in the Southern Ocean.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1980 on: November 21, 2019, 08:44:10 PM »
The linked reference indicates that previous consensus estimates overestimated the amounts of carbon dioxide absorbed by the Southern Ocean:

Seth M. Bushinsky et al. (28 October 2019), "Reassessing Southern Ocean Air‐Sea CO2 Flux Estimates With the Addition of Biogeochemical Float Observations", Global Biogeochemical Cycles, https://doi.org/10.1029/2019GB006176

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GB006176

Abstract
New estimates of pCO2 from profiling floats deployed by the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project have demonstrated the importance of wintertime outgassing south of the Polar Front, challenging the accepted magnitude of Southern Ocean carbon uptake (Gray et al., 2018, https://doi:10.1029/2018GL078013). Here, we put 3.5 years of SOCCOM observations into broader context with the global surface carbon dioxide database (Surface Ocean CO2 Atlas, SOCAT) by using the two interpolation methods currently used to assess the ocean models in the Global Carbon Budget (Le Quéré et al., 2018, https://doi:10.5194/essd‐10‐2141‐2018) to create a ship‐only, a float‐weighted, and a combined estimate of Southern Ocean carbon fluxes (<35°S). In our ship‐only estimate, we calculate a mean uptake of −1.14 ± 0.19 Pg C/yr for 2015–2017, consistent with prior studies. The float‐weighted estimate yields a significantly lower Southern Ocean uptake of −0.35 ± 0.19 Pg C/yr. Subsampling of high‐resolution ocean biogeochemical process models indicates that some of the differences between float and ship‐only estimates of the Southern Ocean carbon flux can be explained by spatial and temporal sampling differences. The combined ship and float estimate minimizes the root‐mean‐square pCO2 difference between the mapped product and both data sets, giving a new Southern Ocean uptake of −0.75 ± 0.22 Pg C/yr, though with uncertainties that overlap the ship‐only estimate. An atmospheric inversion reveals that a shift of this magnitude in the contemporary Southern Ocean carbon flux must be compensated for by ocean or land sinks within the Southern Hemisphere.

Plain Language Summary
The Southern Ocean is thought to take up a significant amount of carbon dioxide each year but is a difficult region to observe due to its remote location and harsh winter weather. Recently, autonomous robots deployed by the Southern Ocean Carbon and Climate Observations and Modeling project have been making year‐round measurements of ocean carbonate chemistry, from which we can estimate surface carbon dioxide. These provide new data at times and locations where we previously had very little. We found that combining the float observations with traditional shipboard data reduced our estimate for the amount carbon that the Southern Ocean takes up each year, though by less than had been previously estimated when considering float observations alone. We also show that some of the new signals is likely due to the differences in when and where floats make measurements. The magnitude of difference between prior estimates of the Southern Ocean carbon flux and our new approach is significant, ~20% of the contemporary global ocean carbon flux. It is therefore crucial to understand how this may impact the global carbon cycle, and we show that a compensating flux must be found somewhere within the Southern Hemisphere.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1981 on: November 21, 2019, 11:31:23 PM »
So that readers can better appreciate how the IPCC forcing scenarios have compared with the observed CO2 emissions I provide the first third images for the SRES, RCP and SSP scenarios, respectively, vs the indicated observed data (note the impact on CO2 emission of the 2007-2008 global recession).  Note that the observed emissions consistently follow a BAU pathway.

Also, for reference I provide the fourth image of atmospheric CO2 concentrations at Mauna Loa thru the week ending Nov 16 2019 (where we can no longer see Mt. Fuji).
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1982 on: November 22, 2019, 04:01:39 PM »
Obviously, the headlines from the linked article that Oxford Dictionary has declared 'Climate Emergency' the word of the year as its 2019 usage increased by over 10,000%, is good news for potential climate action.  However, what strikes me most is the concluding sentence that:

'Now that we’re almost at the end of this carbon-ravaged year, let’s hope the Oxford Dictionary's nomination adds weight to the wave of concern “climate crisis” encompasses.'

Title: "The Oxford Dictionary Has Declared ‘Climate Emergency’ the Word of the Year"

https://www.vice.com/en_in/article/a35b3e/the-oxford-dictionary-has-declared-climate-emergency-the-word-of-the-year

Extract: "According to judges, the Oxford Dictionary Word of the Year is one that best encompasses the prevailing mood, with the 2018 choice being "toxic" (a pretty apt description of that year). The Dictionary also defines a “climate emergency” as “a situation in which urgent action is required to reduce or halt climate change and avoid potentially irreversible environmental damage.” According to the people at Oxford, this term went from relative obscurity to “one of the most prominent—and prominently debated—terms of 2019,” with usage increasing by some 10,796 percent this year alone.

Now that we’re almost at the end of this carbon-ravaged year, let’s hope the Oxford Dictionary's nomination adds weight to the wave of concern “climate crisis” encompasses."

In this regard, the term 'climate emergency' assumes that collectively we can act to '… avoid potentially irreversible environmental damage.'; while the term 'climate crisis' more accurately reflects the true state of Earth Systems, both now and in the future.  This distinction can be better understood by considering the influence of 'climate lag' which is defined as the delay that can occur in a change of some aspect of a climate (or Earth System) due to the influence of factors that are slow-acting.  Thus, climate change that is apparent now is not a good indication of the eventual change, as indicated by the following linked reference that finds:

"Time‐dependent feedbacks underscore the need of a measure of climate sensitivity that accounts for the degree of equilibration, so that models, observations, and paleo proxies can be adequately compared and aggregated to estimate future warming."

This finding is particularly true for ice-climate feedback mechanisms that current consensus climate models ignore as they are assumed to become engaged on timescales of millennia; without investigating the 'degree of equilibration' of such ice-climate feedback mechanisms such as the current fragile condition of the Thwaites Ice Tongue, the existence of the rapidly enlarging subglacial cavity in the Thwaites gateway (the Big Ear) and the high risk of floatation of the thin grounded glacial ice between the ice tongue and the Big Ear; which collectively could trigger a MICI-type of collapse of the BSB in the coming decades.  To illustrate this point I attach the first image showing that the E3SMv1 model projects that ECS is currently 5.3C; while the second image (from Hansen et al.) shows that due to a potential albedo flip from the loss of sea ice and ice sheets could increase ECS to over 7C during the period of rapid ice loss.

Maria Rugenstein et al. (19 November 2019), "Equilibrium climate sensitivity estimated by equilibrating climate models", Geophysical Research Letters, https://doi.org/10.1029/2019GL083898

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083898

Abstract
The methods to quantify equilibrium climate sensitivity are still debated. We collect millennial‐length simulations of coupled climate models and show that the global mean equilibrium warming is higher than those obtained using extrapolation methods from shorter simulations. Specifically, 27 simulations with 15 climate models forced with a range of CO2 concentrations show a median 17% larger equilibrium warming than estimated from the first 150 years of the simulations. The spatial patterns of radiative feedbacks change continuously, in most regions reducing their tendency to stabilizing the climate. In the equatorial Pacific, however, feedbacks become more stabilizing with time. The global feedback evolution is initially dominated by the tropics, with eventual substantial contributions from the mid‐latitudes. Time‐dependent feedbacks underscore the need of a measure of climate sensitivity that accounts for the degree of equilibration, so that models, observations, and paleo proxies can be adequately compared and aggregated to estimate future warming.

Key points
•   27 simulations of 15 general circulation models are integrated to near equilibrium
•   All models simulate a higher equilibrium warming than predicted by using extrapolation methods
•   Tropics and mid‐latitudes dominate the change of the feedback parameter on different timescales & on millennial timescales
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1983 on: November 22, 2019, 07:12:07 PM »
For those who are interested, I provide the following linked Wikipedia article without comment:

Title: "Memory of Mankind"

https://en.wikipedia.org/wiki/Memory_of_Mankind

Extract: "Memory of Mankind (MOM) is a preservation project funded in 2012 …"
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1984 on: November 22, 2019, 07:40:29 PM »
In an ideal world, western countries would currently be actively transferring both funding and technology to make Third World (including those in Africa, see the linked article) economies sustainable as quickly as practicable.  However, I believe that most western countries are not prepared to act adequately to our collective climate situation:

Title: "A fossil fuel-powered future for Africa will come at a drastic human cost"

https://qz.com/africa/1752506/air-pollution-in-africa-will-worsen-over-the-next-ten-years/

Extract: "Over the course of the next three decades, Africa will record faster population growth than anywhere else.

The obvious implications range from the need for more industrialization—to create jobs and products—to increased congestion across several urban centers. And despite the growing availability of renewable energy sources, fossil fuels remain the dominant energy source powering African countries."

« Last Edit: November 22, 2019, 10:35:34 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1985 on: November 22, 2019, 08:32:31 PM »
As some readers may become confused by the IPCC's families of Shared Socio-economic Pathway forcing scenarios, the first image shows five of the fourteen SSP5 scenarios with a very wide range of peak radiative forcing values; however, SSP5 - 8.5 is considered to be the Baseline scenario, and as shown in the second attached image of a French CMIP6 GMSTA projections, this Baseline scenario projects a value for GMSTA of about 6.5C by 2100, instead of the 5C estimated by the IPCC when they first developed the SSP5 - 8.5 scenario.

Edit: If it is not clear to some readers why the IPCC has SSP5 scenarios with peak radiative forcing ranging from 2.6 to 8.5W/sqm, it is because this scenarios do not have any associated probability of occurrence, but rather provide a wide range of options to choose from depending on the persons sense of agency to control/influence the behavior of other people.
« Last Edit: November 22, 2019, 10:36:10 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1986 on: November 23, 2019, 06:09:32 PM »
Holocene has been a period of relatively stable global temperatures (possibly due to early anthropogenic activities) as compared to other recent interglacial periods such as the Eemian or Holsteinian [see the first image from Hansen & Sato (2011) and the second image from Wikipedia, and w.r.t. the second image I note that with a baseline of pre-industrial temperatures the GMSTA for 2016 was 1.23C so that readers can adjust from the average Holocene temperature baseline shown in the second image (& I note that 2019 will be more than 1.1C above pre-industrial].  Previously, I have noted that this over 11,000-year period of relatively warm ocean temperatures has warmed subsea Arctic permafrost layers containing methane hydrates bringing the hydrates to a metastable condition that could be destabilized by a pulse of relatively warm water from the North Atlantic due to future slowing of the AMOC; however, here I note that this over 11,000-year warm period (which did not occur prior to the Eemian peak) has also warmed the seafloor in the ASE adding one more heat source (see the third image for other heat sources) near the current grounding lines of ASE marine glaciers that could help to accelerate the thinning of the lightly grounded glacial ice near the base of the Thwaites Ice Tongue; which is also subject to warming from ocean water on both its upstream (from the Big Ear Cavity) and the downstream (from the ocean) sides as shown in the fourth image.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1987 on: November 24, 2019, 02:26:21 AM »
You imagine how a rain-dominated Arctic [& I note that the following linked information from Bintanja et al. (2017) assumes that ECS =3C and that no ice-climate feedback mechanisms occur] would impact Arctic Amplification and consequently ECS in the coming decades:

R. Bintanja et al. (2017), "Towards a rain-dominated Arctic", Nature Climate Change, DOI: 10.1038/nclimate3240

http://www.nature.com/nclimate/journal/v7/n4/full/nclimate3240.html

Extract: "Rain causes more (extensive) permafrost melt [Refs. 7,26], which most likely leads to enhanced emissions of terrestrial methane [Ref. 27] (a powerful greenhouse gas), more direct runoff (a smaller seasonal delay) and concurrent freshening of the Arctic Ocean [Ref 18]. Rainfall also diminishes snow cover extent and considerably lowers the surface albedo of seasonal snow, ice sheets and sea ice [Ref. 9], reinforcing surface warming and amplifying the retreat of ice and snow; in fact, enhanced rainfall will most likely accelerate sea-ice retreat by lowering its albedo (compared with that of fresh snowfall)."

See also:

Richard Bintanja and Olivier Andry (2017), “Towards a rain-dominated Arctic”, Geophysical Research Abstracts Vol. 19, EGU2017-4402

http://meetingorganizer.copernicus.org/EGU2017/EGU2017-4402.pdf

Abstract: “Current climate models project a strong increase in Arctic precipitation over the coming century, which has been attributed primarily to enhanced surface evaporation associated with sea-ice retreat. Since the Arctic is still quite cold, especially in winter, it is often (implicitly) assumed that the additional precipitation will fall mostly as snow. However, very little is known about future changes in rain/snow distribution in the Arctic, notwithstanding the importance for hydrology and biology. Here we use 37 state-of-the-art climate models in standardised twenty-first century (2006–2100) simulations to show that 70◦ – 90◦N average annual Arctic snowfall will actually decrease, despite the strong increase in precipitation, and that most of the additional precipitation in the future (2091– 2100) will fall as rain. In fact, rain is even projected to become the dominant form of precipitation in the Arctic region. This is because Arctic atmospheric warming causes a greater fraction of snowfall to melt before it reaches the surface, in particular over the North Atlantic and the Barents Sea. The reduction in Arctic snowfall is most pronounced during summer and autumn when temperatures are close to the melting point, but also winter rainfall is found to intensify considerably. Projected (seasonal) trends in rain/snowfall will heavily impact Arctic hydrology (e.g. river discharge, permafrost melt), climatology (e.g. snow, sea ice albedo and melt) and ecology (e.g. water and food availability).”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1988 on: November 24, 2019, 02:33:48 AM »
The following linked references cite research on forests, as an illustration of how sensitive such carbon sinks can be to future climate disruption (such as :wet-dry cycles, pests, fires, etc) especially as our current rate of increase of radiative forcing is much higher than at any time since the PETM; and thus vegetation (both on land & in the ocean) will not have adequate time to adapt to such rapidly changing climate conditions:

James Hansen, Pushker Kharecha, Makiko Sato (2013), "Doubling Down on Our Faustian Bargain", Environmental Research Letters.

http://iopscience.iop.org/article/10.1088/1748-9326/8/1/011006/meta
&
http://www.columbia.edu/~jeh1/mailings/2013/20130329_FaustianBargain.pdf

Abstract: "Rahmstorf et al 's (2012) conclusion that observed climate change is comparable to projections, and in some cases exceeds projections, allows further inferences if we can quantify changing climate forcings and compare those with projections. The largest climate forcing is caused by well-mixed long-lived greenhouse gases. Here we illustrate trends of these gases and their climate forcings, and we discuss implications. We focus on quantities that are accurately measured, and we include comparison with fixed scenarios, which helps reduce common misimpressions about how climate forcings are changing.

Annual fossil fuel CO2 emissions have shot up in the past decade at about 3% yr-1, double the rate of the prior three decades (figure 1). The growth rate falls above the range of the IPCC (2001) 'Marker' scenarios, although emissions are still within the entire range considered by the IPCC SRES (2000). The surge in emissions is due to increased coal use (blue curve in figure 1), which now accounts for more than 40% of fossil fuel CO2 emissions."

The second linked article is entitled: "Forests 'held their breath' during global warming hiatus, research shows".  This illustrates Hansen's Faustian Bargain.

https://phys.org/news/2017-01-forests-held-global-hiatus.html

Extract: "The study shows that, during extended period of slower warming, worldwide forests 'breathe in' carbon dioxide through photosynthesis, but reduced the rate at which they 'breathe out'—or release the gas back to the atmosphere."


The third linked reference indicates that forests play a more important role in keeping the planet cool than was previously appreciated.  Thus, if one assumes that they are entitled to make self-serving assumptions one could assume that decision makers will not only preserve forests but will expand them in the future.  However, the reality is that we are currently losing forests at a rate appropriate for a BAU scenario; and which could accelerate in the future.  Thus, if we keep losing forest, the AR5 projections may err on the side of least drama:

Ryan M. Bright et al. Local temperature response to land cover and management change driven by non-radiative processes, Nature Climate Change (2017). DOI: 10.1038/nclimate3250

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3250.html

Abstract: "Following a land cover and land management change (LCMC), local surface temperature responds to both a change in available energy and a change in the way energy is redistributed by various non-radiative mechanisms. However, the extent to which non-radiative mechanisms contribute to the local direct temperature response for different types of LCMC across the world remains uncertain. Here, we combine extensive records of remote sensing and in situ observation to show that non-radiative mechanisms dominate the local response in most regions for eight of nine common LCMC perturbations. We find that forest cover gains lead to an annual cooling in all regions south of the upper conterminous United States, northern Europe, and Siberia—reinforcing the attractiveness of re-/afforestation as a local mitigation and adaptation measure in these regions. Our results affirm the importance of accounting for non-radiative mechanisms when evaluating local land-based mitigation or adaptation policies."

The fourth reference (see also the attached image) indicates a two-fold increase of carbon cycle sensitivity to tropical temperature variations:

Wang, X., Piao, S., Ciais, P., Friedlingstein, P., Myneni, R.B., Cox, P., Heimann, M., Miller, J., Peng, S.P., Wang, T., Yang, H. and Chen, A., (2014), "A two-fold increase of carbon cycle sensitivity to tropical temperature variations", Nature, 2014; DOI: 10.1038/nature12915.

http://www.nature.com/nature/journal/v506/n7487/full/nature12915.html#extended-data

http://sites.bu.edu/cliveg/files/2014/01/wang-nature-2014.pdf

Abstract: "Earth system models project that the tropical land carbon sink will decrease in size in response to an increase in warming and drought during this century, probably causing a positive climate feedback. But available data are too limited at present to test the predicted changes in the tropical carbon balance in response to climate change. Long-term atmospheric carbon dioxide data provide a global record that integrates the interannual variability of the global carbon balance. Multiple lines of evidence demonstrate that most of this variability originates in the terrestrial biosphere. In particular, the year-to-year variations in the atmospheric carbon dioxide growth rate (CGR) are thought to be the result of fluctuations in the carbon fluxes of tropical land areas. Recently, the response of CGR to tropical climate interannual variability was used to put a constraint on the sensitivity of tropical land carbon to climate change. Here we use the long-term CGR record from Mauna Loa and the South Pole to show that the sensitivity of CGR to tropical temperature interannual variability has increased by a factor of 1.9 ± 0.3 in the past five decades. We find that this sensitivity was greater when tropical land regions experienced drier conditions. This suggests that the sensitivity of CGR to interannual temperature variations is regulated by moisture conditions, even though the direct correlation between CGR and tropical precipitation is weak. We also find that present terrestrial carbon cycle models do not capture the observed enhancement in CGR sensitivity in the past five decades. More realistic model predictions of future carbon cycle and climate feedbacks require a better understanding of the processes driving the response of tropical ecosystems to drought and warming."

Caption for the attached image: "Figure 1 | Change in detrended anomalies in CGR and tropical MAT, in dCGR/dMAT and in ªintCGR over the past five decades. a, Change in detrended CGR anomalies at Mauna Loa Observatory (black) and in detrended tropical MAT anomalies (red) derived from the CRU data set16. Tropical MAT is calculated as the spatial average over vegetated tropical lands (23uN to 23u S).  The highest correlations between detrended CGR and detrended tropicalMAT are obtained when no time lags are applied (R50.53, P,0.01). b, Change in dCGR/dMAT during the past five decades. c, Change in cintCGR during the past five decades. In b and c, different colours showdCGR/dMATor cint CGR estimated with moving time windows of different lengths (20 yr and 25 yr). Years on the horizontal axis indicate the central year of the moving time window used to derive dCGR/dMAT or cintCGR (for example, 1970 represents period 1960–1979 in the 20-yr time window). The shaded areas show the confidence interval of dCGR/dMATand cintCGR, as appropriate, derived using 20-yr or 25-yr moving windows in 500 bootstrap estimates."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1989 on: November 24, 2019, 02:50:05 AM »
The linked reference indicates that freshwater hosing events (either by ice meltwater from Greenland and/or a freshwater release from the Beaufort Gyre) in the North Atlantic can result in warming of the Nordic Seas by the warm Gulf Stream water flowing beneath the thin surface layer of cool fresh water from the hosing event (see the attached image); which can accelerate Arctic Amplification & which is another example of dynamical climate sensitivity:

Mélanie Wary et. al. (2017), "Regional seesaw between North Atlantic and Nordic Seas
during the last glacial abrupt climate events", Clim. Past Discuss., doi:10.5194/cp-2017-14

http://www.clim-past-discuss.net/cp-2017-14/cp-2017-14.pdf

Abstract. Dansgaard-Oeschger oscillations constitute one of the most enigmatic features of the last glacial cycle.  Their cold atmospheric phases have been commonly associated with cold sea-surface temperatures and expansion of sea ice in the North Atlantic and adjacent seas. Here, based on dinocyst analyses from the 48-30 ka BP interval of four sediment cores from the northern Northeast Atlantic and southern Norwegian Sea, we provide direct and quantitative evidence of a regional paradoxical seesaw pattern: cold Greenland and North Atlantic phases coincide with warmer sea-surface conditions and shorter seasonal sea-ice cover durations in the Norwegian Sea as compared to warm phases. Combined with additional paleorecords and multi-model hosing simulations, our results suggest that during cold Greenland phases, reduced Atlantic meridional overturning circulation and cold North Atlantic sea-surface conditions were accompanied by the subsurface propagation of warm Atlantic waters that re-emerged in the Nordic Seas and provided moisture towards Greenland summit.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1990 on: November 24, 2019, 03:01:12 AM »
The linked first article entitled: "SkS Analogy 4 - Ocean Time Lag", illustrates how consensus science can greatly underplay the risks associated with dynamical climate sensitivity as illustrated by the second linked reference associated with the influences that the IPO as short-term GMSTA.  The first attached image is from the first reference & indicates that due to a 30-year lag we will not reach 2C warming until 2035 + 30 – 2065.  However, the second & third images, from the second reference, indicate respectively that we appear to have entered a warm IPO period (which may well last until ~2035); which indicates that we could reach +1.8C by 2034 (when considering the indicated confidence range, and that this analysis assumes that ECS = 3C).

https://www.skepticalscience.com/SkS_Analogy_04_Ocean_Time_Lag.html

Extract: "Greenhouse gases (GHG) determine amount of warming, but oceans delay the warming.

This figure therefore shows the temperature anomaly starting in 1970, the year when the temperature increase due to greenhouse gases began to emerge from the background noise. This figure indicates 3 things: (1) the time lag between emitting greenhouse gases and when we see the principle effect is about 30 years, due mostly to the time required to heat the oceans, (2) the rate of temperature increase predicted by a climate sensitivity of 3°C tracks well with the observed rate of temperature increase, and (3) we have already locked in more than 1.5°C warming. As of 2017 we have reached 406 ppm CO2. At the current increase of 2 ppm CO2/yr., this implies that we will reach 440 ppm and lock in 2°C warming by 2035 … if we don’t act now."

The second reference is:

Henley, B. J and King, A. D. (2017) Trajectories toward the 1.5C Paris target: Modulation by the Interdecadal Pacific Oscillation, Geophysical Research Letters, doi:10.1002/2017GL073480

http://onlinelibrary.wiley.com/doi/10.1002/2017GL073480/abstract

Abstract: "Global temperature is rapidly approaching the 1.5°C Paris target. In the absence of external cooling influences, such as volcanic eruptions, temperature projections are centered on a breaching of the 1.5°C target, relative to 1850–1900, before 2029. The phase of the Interdecadal Pacific Oscillation (IPO) will regulate the rate at which mean temperature approaches the 1.5°C level. A transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026. If the Pacific Ocean remains in its negative decadal phase, the target will be reached around 5 years later, in 2031. Given the temporary slowdown in global warming between 2000 and 2014, and recent initialized decadal predictions suggestive of a turnaround in the IPO, a sustained period of rapid temperature rise might be underway. In that case, the world will reach the 1.5°C level of warming several years sooner than if the negative IPO phase persists."

Plain Language Summary
Global temperature is rapidly approaching the 1.5°C Paris target. In this study, we find that in the absence of external cooling influences, such as volcanic eruptions, the midpoint of the spread of temperature projections exceeds the 1.5°C target before 2029, based on temperatures relative to 1850–1900. We find that the phase of the Interdecadal Pacific Oscillation (IPO), a slow-moving natural oscillation in the climate system, will regulate the rate at which global temperature approaches the 1.5°C level. A transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026. If the Pacific Ocean remains in its negative phase, however, the projections are centered on reaching the target around 5 years later, in 2031. Given the temporary slowdown in global warming between 2000 and 2014, and recent climate model predictions suggestive of a turnaround in the IPO, a sustained period of rapid temperature rise might be underway. In that case, the world will reach the 1.5°C level of warming several years sooner than if the negative IPO phase persists.

See also the associated following article entitled: "Pacific Ocean shift could see 1.5C limit breached within a decade":

https://www.carbonbrief.org/pacific-ocean-shift-could-see-1point5-limit-breached-within-decade
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1991 on: November 24, 2019, 03:16:51 AM »
The total radiative forcings, RFs, from the linked ORNL website article by Blasing, T.J. (that updates such RF values reported in April 2016, see the attached table) are used in the linked Wikipedia article to calculate a CO2e value of 526.6ppm in 2016; which assuming the current rate of annual increase in CO2e of about 3.5ppm indicates that by early 2017 CO2e exceeded 530ppm and has continued to increase since that time:

https://en.wikipedia.org/wiki/Carbon_dioxide_equivalent

Extract: "To calculate the CO2e of the additional radiative forcing calculated from April 2016's updated data: ∑ RF(GHGs) = 3.3793, thus CO2e = 280 e3.3793/5.35 ppmv = 526.6 ppmv."

http://cdiac.ornl.gov/pns/current_ghg.html


This relatively high value of 530ppm for CO2e appears to be associated with RF associated with tropospheric ozone and its chemical interaction in the atmosphere with GHGs like methane, as discussed in the following linked references.

Stevenson et al (2013), "Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP),"Atmos. Chem. Phys., 13, 3063–3085, doi:10.5194/acp-13-3063-2013

https://core.ac.uk/download/pdf/9666974.pdf

Abstract. Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410mWm−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17 %. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields) of ±10 %. Applying two different tropopause definitions gives differences in RFs of ±3 %. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12 %), nitrogen oxides (31±9 %), carbon monoxide (15±3 %) and non-methane volatile organic compounds (9±2 %); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42mWm−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mWm−2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF."

See also:

https://tes.jpl.nasa.gov/mission/climateO3/

Extract: "Tropospheric O3 is also the source of the hydroxyl radical (OH), which controls the abundance and distribution of many atmospheric constituents (including greenhouse gases such as methane and hydrochlorofluorocarbons). Ozone makes a significant contribution to the radiative balance of the upper troposphere and lower stratosphere, such that changes in the distribution of O3 in these atmospheric regions affect the radiative forcing of climate.

Climate Feedback and Forcing for Tropospheric Ozone

Climate forcing by O3 remains uncertain because O3 change as a function of altitude has been under-measured. In order to better understand the role of tropospheric O3 in climate, accurate temperature measurements are needed along with co-located O3 and CO profiles."
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Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1992 on: November 24, 2019, 04:10:00 AM »
Quote from: AbruptSLR link=topic=2205.msg238141#msg238141
The second reference is:
Henley, B. J and King, A. D. (2017) Trajectories toward the 1.5C Paris target: Modulation by the Interdecadal Pacific Oscillation, Geophysical Research Letters, doi:10.1002/2017GL073480

http://onlinelibrary.wiley.com/doi/10.1002/2017GL073480/abstract

...
 A transition to the positive phase of the IPO would lead to a projected exceedance of the target centered around 2026.

According to later data from the Met/Hadley, the IPO has been positive for some time already. So we should reach +1.5 in the shorter timeframe then, in only 6 years. I doubt it, but we'll see.

IPO is positive up until mid 2017 according to this report:

http://cola.gmu.edu/c20c/IPO_Aug2017_NZ_UPDATED_FOR_C20C+.pdf

http://archive.stats.govt.nz/browse_for_stats/environment/environmental-reporting-series/environmental-indicators/Home/Atmosphere-and-climate/interdecadal-pacific-oscillations.aspx
« Last Edit: November 24, 2019, 04:24:51 AM by Hefaistos »

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1993 on: November 24, 2019, 04:29:46 PM »
The linked reference states that: "Our results provide empirical support for recent climate model projections showing an intensification of ENSO extremes under greenhouse forcing.".  Also, I note that intensification of extreme ENSO events is a signature for a relatively high value for ECS:

Pamela R. Grothe et al, Enhanced El Niño‐Southern Oscillation variability in recent decades, Geophysical Research Letters (2019). DOI: 10.1029/2019GL083906

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083906

Abstract
The El Niño‐Southern Oscillation (ENSO) represents the largest source of year‐to‐year global climate variability. While earth system models suggest a range of possible shifts in ENSO properties under continued greenhouse gas forcing, many centuries of preindustrial climate data are required to detect a potential shift in the properties of recent ENSO extremes. Here, we reconstruct the strength of ENSO variations over the last 7,000 years with a new ensemble of fossil coral oxygen isotope records from the Line Islands, located in the central equatorial Pacific. The corals document a significant decrease in ENSO variance of ~20% from 3,000 to 5,000 years ago, coinciding with changes in spring/fall precessional insolation. We find that ENSO variability over the last five decades is ~25% stronger than during the preindustrial. Our results provide empirical support for recent climate model projections showing an intensification of ENSO extremes under greenhouse forcing.

Plain Language Summary
Recent modeling studies suggest El Niño will intensify due to greenhouse warming. Here, new coral reconstructions of the El Niño‐Southern Oscillation (ENSO) record sustained, significant changes in ENSO variability over the last 7,000yrs, and imply that ENSO extremes of the last 50 years are significantly stronger than those of the pre‐industrial era in the central tropical Pacific. These records suggest that El Niño events already may be intensifying due to anthropogenic climate change.

Key Points

•   Line Island corals provide 1,751 years of monthly‐resolved ENSO variability from the mid‐Holocene to present
•   ENSO strength is significantly weaker between 3,000 and 5,000 years ago compared to the 2,000‐year periods both before and after
•   ENSO extremes of the last 50 years are significantly stronger than those of the pre‐industrial era in the central tropical Pacific
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1994 on: November 24, 2019, 08:22:54 PM »
Sorry if this gets irrirating for some but I must communicate the meaning of all this new research that ASLR, vox_mundi and others have posted in the past half year.

I keep reading about more and more positive feedbacks, and climate change effects are worsening (much) faster than expected earlier by scientists. The biosphere is acceleratingly collapsing.

I think civilisation doesn't need to put any more CO2e in the atmosphere, in order to be certain of biosphere and social collapse. All CO2e emissions from now on are a 'bonus'.
If only half of those positive feedbacks start acting soon...
Earth is going to run a fever.

Sorry children, the GDP and costs were more important to grown-ups.
In retrospect, the rich grown-ups didn't like to change. Didn't like to abstain from bad behaviour. Sorry?
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1995 on: November 25, 2019, 12:11:37 AM »

According to later data from the Met/Hadley, the IPO has been positive for some time already. So we should reach +1.5 in the shorter timeframe then, in only 6 years. I doubt it, but we'll see.


While know one knows for certain what GMSTA will be in 6 years from now; if the attached model projection, contributing to CMIP6, is correct, then without consideration of how much the IPO varies, or trends, GMSTA will have reached, or exceeded, +1.5C (above pre-industrial) within that 6-year timeframe no matter which SSP scenario is followed.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1996 on: November 25, 2019, 12:50:27 AM »
The linked reference provides paleo evidence from about 11,500 year ago, that indicates that portions of the WAIS are very sensitivity to collapse, even under conditions that were cooler than today:

J. Kingslake et al. (2018), "Extensive retreat and re-advance of the West Antarctic Ice Sheet during the Holocene", Nature, https://doi.org/10.1038/s41586-018-0208-x

http://www.nature.com/articles/s41586-018-0208-x.epdf?referrer_access_token=lOkN7hgTt7KBVbuYuXMwc9RgN0jAjWel9jnR3ZoTv0PagDqQuHClF_KBoNEwt0qCDswVby5xisTUuro2GVqEdVyNRmUsMYB32-gwCy-WQGiOJuRHvpbmk3l6OEkAKwxOiPNDPRAKMIlDGFP4EHQgKD_G1qFJE2DhzFl3IkCeDuHh2Xln7I7LeJAB1tog4tIasE0yBRLzYo4hLBA3XhRCpg%3D%3D&tracking_referrer=news.nationalgeographic.com

Abstract: "To predict the future contributions of the Antarctic ice sheets to sea-level rise, numerical models use reconstructions of past ice-sheet retreat after the Last Glacial Maximum to tune model parameters. Reconstructions of the West Antarctic Ice Sheet have assumed that it retreated progressively throughout the Holocene epoch (the past 11,500 years or so). Here we show, however, that over this period the grounding line of the West Antarctic Ice Sheet (which marks the point at which it is no longer in contact with the ground and becomes a floating ice shelf) retreated several hundred kilometres inland of today’s grounding line, before isostatic rebound caused it to re-advance to its present position. Our evidence includes, first, radiocarbon dating of sediment cores recovered from beneath the ice streams of the Ross Sea sector, indicating widespread Holocene marine exposure; and second, ice-penetrating radar observations of englacial structure in the Weddell Sea sector, indicating ice-shelf grounding. We explore the implications of these findings with an ice-sheet model. Modelled re-advance of the grounding line in the Holocene requires ice-shelf grounding caused by isostatic rebound. Our findings overturn the assumption of progressive retreat of the grounding line during the Holocene in West Antarctica, and corroborate previous suggestions of ice-sheet re-advance. Rebound-driven stabilizing processes were apparently able to halt and reverse climate-initiated ice loss. Whether these processes can reverse present-day ice loss on millennial timescales will depend on bedrock topography and mantle viscosity—parameters that are difficult to measure and to incorporate into ice-sheet models."

See also:

Title: "The West Antarctic Ice Sheet Seems to Be Good at Collapsing"

https://news.nationalgeographic.com/2018/06/west-antarctic-ice-sheet-collapse-climate-change/

Extract: "SCIENTISTS HAVE DISCOVERED that the West Antarctic Ice Sheet underwent a major retreat between 10,000 and 12,000 years ago, at a time when the world was actually cooler than it is today. The collapse happened at the close of the last Ice Age, and it left the ice sheet 135,000 square miles smaller than it is today – a difference nearly as large as the state of Montana.

“That the ice sheet could retreat beyond where it is today, in a climate that was likely quite a bit colder than today, points to extraordinary sensitivity,” says Robert DeConto, a glaciologist at the University of Massachusetts Amherst, who was not involved in the research."
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Tom_Mazanec

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1997 on: November 25, 2019, 02:36:36 AM »
Quote
While know one knows for certain what GMSTA will be in 6 years from now; if the attached model projection, contributing to CMIP6, is correct, then without consideration of how much the IPO varies, or trends, GMSTA will have reached, or exceeded, +1.5C (above pre-industrial) within that 6-year timeframe no matter which SSP scenario is followed.
And it seems inevitable that it will exceed 2˚ within twenty years or so.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1998 on: November 25, 2019, 03:24:10 AM »
Quote
While know one knows for certain what GMSTA will be in 6 years from now; if the attached model projection, contributing to CMIP6, is correct, then without consideration of how much the IPO varies, or trends, GMSTA will have reached, or exceeded, +1.5C (above pre-industrial) within that 6-year timeframe no matter which SSP scenario is followed.
And it seems inevitable that it will exceed 2˚ within twenty years or so.

These GCM model projections should be disregarded, they're unreliable. Most CMIP5 models are shown to be running hot compared to actual temperatures. CMIP6 models seem to be running even hotter, at least the 3 or 4 that I have looked at. These models have profound issues with a lack of theory on the hydrological cycle, esp. deep convection in the tropics; they also lack data on those things because there are no satellite data for the grid size where deep convection takes place. We also know that model builders do a lot of tweaking and tuning to the models to make them perform as they want, as reported by themselves in papers accompanying the models. Upthread I described two of them as "alarmist constructs", see Reply #1935 .

Luckily, it's not the models that warm our globe.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #1999 on: November 25, 2019, 12:31:36 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."
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