Conservative Scientists & its Consequences

[AbruptSLR]

New evidence supports earlier findings that continued global warming increases bacteria and fungi actively in the soil which in turn leads to the increased release for CO₂ from organics in the soil:

Title: "Warmer soil releasing more carbon, worsening climate change"

https://apnews.com/36dc726138144232b23ff0361c284bb9/Warmer-soil-releasing-more-carbon,-worsening-climate-change

[mostly_lurking]

https://www.counterpunch.org/2018/08/03/the-end-of-the-line-a-climate-in-crisis/

http://www.lifeworth.com/deepadaptation.pdf

Advanced fear mongering at it's best.

[Shared Humanity]

The West’s response to environmental issues has been restricted by the dominance of neoliberal economics since the 1970s. That led to hyper-individualist, market fundamentalist, incremental and atomistic approaches.

By hyper-individualist, I mean a focus on individual action as consumers, switching light bulbs or buying sustainable furniture, rather than promoting political action as engaged citizens.

By market fundamentalist, I mean a focus on market mechanisms like the complex, costly and largely useless carbon cap and trade systems, rather than exploring what more government intervention could achieve.

By incremental, I mean a focus on celebrating small steps forward such as a company publishing a sustainability report, rather than strategies designed for a speed and scale of change suggested by the science.

By atomistic, I mean a focus on seeing climate action as a separate issue from the governance of markets, finance and banking, rather than exploring what kind of economic system could permit or enable sustainability.

This (Neoliberal) ideology has now influenced the workloads and priorities of academics in most
universities, which restricts how we can respond to the climate tragedy. In my own case, I took an unpaid sabbatical, and writing this paper is one of the outcomes of that decision. We no longer have time for the career games of aiming to publish in top-ranked journals to impress our line managers or improve our CV for if we enter the job market. Nor do we have a need for the narrow specialisms that are required to publish in such journals.

So, yes, I am suggesting that in order to let oneself evolve in response to the climate tragedy one may have to quit a job – and even a career. However, if one is prepared to do that, then one can engage with an employer and professional community from a new place of confidence.

on page 21 (long article)  Deep Adaptation: A Map for Navigating Climate Tragedy

http://www.lifeworth.com/deepadaptation.pdf

Can't disagree with any of that.

[AbruptSLR]

Can't disagree with any of that.

It seems to me that this line of discussion fits better into the 'Adapting to the Anthropocene' thread in the Science folder:

https://forum.arctic-sea-ice.net/index.php/topic,1308.350.html#lastPost

[AbruptSLR]

Per the linked article, consensus science is currently overestimating the amount of methane absorbed by northern hemisphere forest soils:

Title: "Methane uptake from forest soils has ‘fallen by 77% in three decades’"

https://www.carbonbrief.org/methane-uptake-from-forest-soils-has-fallen-77-per-cent-three-decades

Extract: "The amount of methane absorbed by forest soils has fallen by an average of 77% in the northern hemisphere over the past 27 years, a new study finds.

The research, which analysed soil data taken from more than 300 studies, suggests that the world is currently “overestimating the role that forest soils play in trapping gas”, the lead author tells Carbon Brief."

[jai mitchell]

If aerosol impacts are stronger then the climate sensitivity to CO2 (with near term feedbacks) is also stronger.  This leads to much more rapid warming as aerosols are removed going forward.

The way to check if this is true is to correlate past global temperature behavior with aerosol emissions and forcing.  Under a strong aerosol impact, during the industrial boom of post WWII the temperatures would dip below the 1930s average and then shoot back up, into an accelerated curve. 

If Aerosol impacts are low (and climate sensitivity is also low) then there would be no major dip during the 1950s-1960s and the future warming would be much more moderate.

so I ask you, which of the historic temperature curve portions in the following graphic best fits the actual temperature curve below?

[bbr2314]

If aerosol impacts are stronger then the climate sensitivity to CO2 (with near term feedbacks) is also stronger.  This leads to much more rapid warming as aerosols are removed going forward.

The way to check if this is true is to correlate past global temperature behavior with aerosol emissions and forcing.  Under a strong aerosol impact, during the industrial boom of post WWII the temperatures would dip below the 1930s average and then shoot back up, into an accelerated curve. 

If Aerosol impacts are low (and climate sensitivity is also low) then there would be no major dip during the 1950s-1960s and the future warming would be much more moderate.

so I ask you, which of the historic temperature curve portions in the following graphic best fits the actual temperature curve below?

[gerontocrat]

It's that CH4 stuff again.

https://www.carbonbrief.org/methane-uptake-from-forest-soils-has-fallen-77-per-cent-three-decades

Methane uptake from forest soils has ‘fallen by 77% in three decades’

......the release of methane is largely offset by other natural processes which absorb methane from the atmosphere.

The troposphere – the lowest level of the atmosphere – is the largest sink for methane. In this part of the atmosphere, methane reacts with naturally occurring compounds known as “hydroxyl radicals” to form water and, to a lesser extent, CO2.

Down on the ground, soils – particularly forest soils – play a smaller, but still significant role in absorbing methane. These soils are home to specialised bacteria known as “methanotrophs” – literally meaning “methane eaters”. The bacteria absorb atmospheric methane that has diffused into the soil and break it down into smaller compounds that they can use as energy.

However, the activity of these microorganisms appears to have slowed “dramatically” in the past three decades, says Dr Peter Groffman, a microbial biologist and co-author of the research published in the Proceedings of the National Academy of Scientists. He tells Carbon Brief:

“Our analysis of methane uptake around the globe shows that methane uptake in forest soils has decreased by an average of 77% from 1988 to 2015. We conclude that the soil methane sink may be declining and overestimated in several regions across the globe.”

The findings suggest that the “global methane budget” – the balance of emissions and uptake of methane across the Earth’s surface – will need to account for a decrease in soil methane uptake, Groffman says:

“These findings suggest that global budgets for atmospheric methane – which are used to inform policy around methane-producing activities – are overestimating the role that forest soils play in trapping gas. Declining methane uptake by forest soils should be factored into these models to avoid exacerbating climate warming, as methane in the atmosphere may rise more quickly and reach higher levels than current models predict.”

The research should also serve as a reminder that relying on natural processes to soak up excess methane is a risky strategy, he adds:

“We can’t rely on natural processes to solve our greenhouse gas problems. Just as trees and oceans may not always be able to absorb CO2, forest soils may not always be able to take up methane and keep it out of the atmosphere.

“If we are going to stabilise the atmospheric concentration of methane, we are going to have to work harder to control anthropogenic sources such as leaks from natural gas extraction.”

[AbruptSLR]

Consensus climate models do not account for the fact that with continued global warming the Arctic carbon cycle is accelerating:

Title : "Arctic carbon cycle is speeding up"

https://climate.nasa.gov/news/2776/arctic-carbon-cycle-is-speeding-up/

[AbruptSLR]

These scientists suggest that as we continue on a BAU pathway, nitrous oxide feedbacks may become more important than current consensus climate models account for:

Title: "Back to the future of climate change"

https://www.sciencedaily.com/releases/2018/08/180809125546.htm

Extract: ""The suggestion of a nitrous oxide feedback on climate warming adds a new layer of intrigue to this discussion and highlights the role a changing nitrogen cycle might have on our future Earth.
…
"Indeed, there are gaps in our understanding between the model worlds and the fossil worlds. The past enables us to test and hone models on which future projections are based. It also helps us determine what processes are missing from our current Earth system models," he says. "These things combined help us understand and prepare for what is on the horizon."

[CDN_dude]

Open-access paper "Wildfire as a major driver of recent permafrost thaw in boreal peatlands"

https://www.nature.com/articles/s41467-018-05457-1

"Permafrost vulnerability to climate change may be underestimated unless effects of wildfire are considered. Here we assess impacts of wildfire on soil thermal regime and rate of thermokarst bog expansion resulting from complete permafrost thaw in western Canadian permafrost peatlands. Effects of wildfire on permafrost peatlands last for 30 years and include a warmer and deeper active layer, and spatial expansion of continuously thawed soil layers (taliks). These impacts on the soil thermal regime are associated with a tripled rate of thermokarst bog expansion along permafrost edges. Our results suggest that wildfire is directly responsible for 2200 ± 1500 km2 (95% CI) of thermokarst bog development in the study region over the last 30 years, representing ~25% of all thermokarst bog expansion during this period. With increasing fire frequency under a warming climate, this study emphasizes the need to consider wildfires when projecting future circumpolar permafrost thaw."

[sidd]

Thanks for the reference, i was waiting for something like this. I take the liberty of reposting this link in the Wildfires thread.

sidd

[AbruptSLR]

The findings of the linked article imply that policymakers would be wise to apply a high factor of safety when evaluating the policy implications of consensus ice sheet model projections such as those cited in AR5:

Dolan AM; De Boer B; Bernales J; Hill DJ; Haywood AM (2018) High climate model dependency of Pliocene Antarctic ice-sheet predictions, Nature Communications, 9, doi: 10.1038/s41467-018-05179-4

http://www.nature.com/articles/s41467-018-05179-4

Extract: "… the collapse of the vulnerable marine basins of Antarctica is dependent on the ice-sheet model used.  These results demonstrate that great caution is required in order to avoid making unsound statements about the nature of the Pliocene Antarctic ice-sheet based on model results that do not account for structural uncertainty in both the climate and ice sheet models."

[AbruptSLR]

Dessler & Forster (2018) demonstrate rather convincingly that the likely range for ECS in the period from 2000 to 2017 was 2.4 to 4.6C as opposed to AR5's cited likely range of 1.5 to 4.5C.  Furthermore, it is important to remember that ECS is not a fixed value but rather is projected to increase with continued global warming, this century:

A. E. Dessler and P.M. Forster (07 August 2018), "An estimate of equilibrium climate sensitivity from interannual variability', Journal of Geophysical Research Atmospheres, https://doi.org/10.1029/2018JD028481

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD028481?campaign=wolacceptedarticle

Abstract
Estimating the equilibrium climate sensitivity (ECS; the equilibrium warming in response to a doubling of CO2) from observations is one of the big problems in climate science. Using observations of interannual climate variations covering the period 2000 to 2017 and a model‐derived relationship between interannual variations and forced climate change, we estimate ECS is likely 2.4‐4.6 K (17‐83% confidence interval), with a mode and median value of 2.9 and 3.3 K, respectively. This analysis provides no support for low values of ECS (below 2 K) suggested by other analyses. The main uncertainty in our estimate is not observational uncertainty, but rather uncertainty in converting observations of short‐term, mainly unforced climate variability to an estimate of the response of the climate system to long‐term forced warming.

Plain language summary
Equilibrium climate sensitivity (ECS) is the amount of warming resulting from doubling carbon dioxide. It is one of the important metrics in climate science because it is a primary determinant of how much warming we will experience in the future. Despite decades of work, this quantity remains uncertain: the last IPCC report stated a range for ECS of 1.5‐4.5 deg. Celsius. Using observations of interannual climate variations covering the period 2000 to 2017, we estimate ECS is likely 2.4‐4.6 K. Thus, our analysis provides no support for the bottom of the IPCC's range."

You can obtain a copy of the paper here:

https://drive.google.com/file/d/1nt4YEMLc0AwWEAHtHAcwDEVzHkyKj1G-/view

[CDN_dude]

Arctic understanding limited by patchy field work, scientist says. Areas of Canadian Arctic poorly sampled, could mean faulty assumptions about rate of climate change

https://www.cbc.ca/news/canada/north/arctic-study-understanding-limited-climate-change-1.4781405

"Metcalfe's research suggests scientists are oversampling locations warming slowly, while places warming much more rapidly, such as the Canadian Arctic, may be releasing stored carbon at a greater rate and in a greater quantity than assumed.

Metcalfe says this could mean scientists are underestimating the global impact of warming in the Arctic."

[AbruptSLR]

The linked reference indicates that prior estimates of effective ECS based on energy budgets were too low:

Timothy Andrews et al. (30 July 2018), "Accounting for changing temperature patterns increases historical estimates of climate sensitivity; Geophysical Research Letters, https://doi.org/10.1029/2018GL078887

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078887

Abstract

Eight Atmospheric General Circulation Models (AGCMs) are forced with observed historical (1871‐2010) monthly sea‐surface‐temperature (SST) and sea‐ice variations using the AMIP II dataset. The AGCMs therefore have a similar temperature pattern and trend to that of observed historical climate change. The AGCMs simulate a spread in climate feedback similar to that seen in coupled simulations of the response to CO2 quadrupling. However the feedbacks are robustly more stabilizing and the effective climate sensitivity (EffCS) smaller. This is due to a ‘pattern effect’ whereby the pattern of observed historical SST change gives rise to more negative cloud and LW clear‐sky feedbacks. Assuming the patterns of long‐term temperature change simulated by models, and the radiative response to them, are credible, this implies that existing constraints on EffCS from historical energy budget variations give values that are too low and overly constrained, particularly at the upper end. For example, the pattern effect increases the long‐term Otto et al. (2013) EffCS median and 5‐95% confidence interval from 1.9K (0.9‐5.0K) to 3.2K (1.5‐8.1K).

Plain Language Summary

Recent decades have seen cooling over the eastern tropical Pacific and Southern Ocean while temperatures rise globally. Climate models indicate that these regional features, and others, are not expected to continue into the future under sustained forcing from atmospheric carbon dioxide increases. This matters, because climate sensitivity depends on the pattern of warming, so if the past has warmed differently from what we expect in the future then climate sensitivity estimated from the historical record may not apply to the future. We investigate this with a suite of climate models and show that climate sensitivity simulated for observed historical climate change is smaller than for long‐term carbon dioxide increases. The results imply that historical energy budget changes only weakly constrain climate sensitivity.

[AbruptSLR]

Make no mistake about it, the findings of this references indicates a trend that threatens the viability of the Amazon Rainforest.  A loss of the Amazon Rainforest would meaningfully impair an important carbon sink, beyond what is assumed in AR5 projections:

Elisa T. Sena et al. (8 August 2018), "Reduced wet season length detected by satellite retrievals of cloudiness over Brazilian Amazonia: a new methodology", Journal of Climate, https://doi.org/10.1175/JCLI-D-17-0702.1

https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-17-0702.1

Abstract: "This study investigates the variability of the seasonal cycle of convection in the Brazilian Amazon Basin during the last decades, and examines physical mechanisms that potentially trigger these modifications. A new methodology to evaluate the onset and length of the rainy season using long-term cloud fraction observations from geostationary satellites is proposed and the connection between cloud cycle variability, surface properties, thermodynamic and dynamic conditions is explored. The results show that cloud cover has significantly decreased over the last decades. The decline in cloudiness is steeper at 12 UTC (8 LT), when a trend of up to -6%/decade is observed over Central and Eastern Amazon. High cloud cover reduction is the major contributor to the observed decline in total cloud fraction. Delayed onsets and a reduction of up to 4 days/year in Northern and Central Amazon wet season length are observed. Correlation analyses indicate the El Niño phenomenon affects the interannual variability of cloudiness in the Amazon, leading to delayed onset and early demise of the rainy season. Tropical South Atlantic, the Pacific Warm Pool and the North Atlantic Tripole also play a small, but significant, role in the Amazon’s cloudiness variability. The decrease in cloudiness over the Amazon Basin reduces the amount of solar radiation reflected back to space, while increasing irradiance at the surface. This local warming alters surface heat fluxes and the atmospheric thermodynamic profile, further affecting cloud development. The strong tendencies reported here indicate a significant shift in the Amazonian hydroclimate during the last few decades."

[jai mitchell]

Dessler & Forster (2018) demonstrate rather convincingly that the likely range for ECS in the period from 2000 to 2017 was 2.4 to 4.6C as opposed to AR5's cited likely range of 1.5 to 4.5C.  Furthermore, it is important to remember that ECS is not a fixed value but rather is projected to increase with continued global warming, this century:

A. E. Dessler and P.M. Forster (07 August 2018), "An estimate of equilibrium climate sensitivity from interannual variability', Journal of Geophysical Research Atmospheres, https://doi.org/10.1029/2018JD028481

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD028481?campaign=wolacceptedarticle

Abstract
Estimating the equilibrium climate sensitivity (ECS; the equilibrium warming in response to a doubling of CO2) from observations is one of the big problems in climate science. Using observations of interannual climate variations covering the period 2000 to 2017 and a model‐derived relationship between interannual variations and forced climate change, we estimate ECS is likely 2.4‐4.6 K (17‐83% confidence interval), with a mode and median value of 2.9 and 3.3 K, respectively. This analysis provides no support for low values of ECS (below 2 K) suggested by other analyses. The main uncertainty in our estimate is not observational uncertainty, but rather uncertainty in converting observations of short‐term, mainly unforced climate variability to an estimate of the response of the climate system to long‐term forced warming.

Plain language summary
Equilibrium climate sensitivity (ECS) is the amount of warming resulting from doubling carbon dioxide. It is one of the important metrics in climate science because it is a primary determinant of how much warming we will experience in the future. Despite decades of work, this quantity remains uncertain: the last IPCC report stated a range for ECS of 1.5‐4.5 deg. Celsius. Using observations of interannual climate variations covering the period 2000 to 2017, we estimate ECS is likely 2.4‐4.6 K. Thus, our analysis provides no support for the bottom of the IPCC's range."

You can obtain a copy of the paper here:

https://drive.google.com/file/d/1nt4YEMLc0AwWEAHtHAcwDEVzHkyKj1G-/view

this work combined with Brown & Caldeira 2017 https://www.nature.com/articles/nature24672 and Caldwell 2018 https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0631.1 are definitive and should firmly place ECS at 3.5 or greater.

[AbruptSLR]

The linked reference indicates that Permafrost carbon feedback (PCF) will be stronger than currently assumed by consensus climate change models:

Katey Walter Anthony, Thomas Schneider von Deimling, Ingmar Nitze, Steve Frolking, Abraham Emond, Ronald Daanen, Peter Anthony, Prajna Lindgren, Benjamin Jones, Guido Grosse. 21st-century modeled permafrost carbon emissions accelerated by abrupt thaw beneath lakes. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-05738-9

http://www.nature.com/articles/s41467-018-05738-9

Extract: "These finding demonstrate the need to incorporate abrupt thaw processes in earth system models for more comprehensive projection of the PCF this century."

See also:

Title: "'Abrupt thaw' of permafrost beneath lakes could significantly affect climate change models"

https://www.sciencedaily.com/releases/2018/08/180816143035.htm

[TeaPotty]

This is really really bad on several levels.

Methane and carbon dioxide emissions from abrupt thaw beneath thermokarst lakes will more than double radiative forcing from circumpolar permafrost-soil carbon fluxes this century

So first, they are pointing at our ongoing "abrupt thaw" as a driver of an increased ratio of CH4 vs CO2. Possibly because the bacteria cant break down the CH4 fast enough? This would seem to makes sense.

In the gradual thaw setting for RCP4.5, atmospheric carbon uptake by plants growing in active layer soils is stimulated more than decomposition of soil organic matter. However, the same degree of warming triggers an acceleration of abrupt thaw via thermokarst-lake formation on up to 4.9% (3.0–6.6%, 68% uncertainty range) of the permafrost-dominated landscape

Then, they point out that the CH4 to CO2 ratio increase from abrupt thaws under IPCC's RCP4.5 (moderate) warming is fairly similar to RCP8.5. Of course, our current path is pretty much BAU, so this is doubly bad news. The feedbacks have feedbacks! (sorry, I couldnt help but use some humor here)


Now, couple this research with this:

”We find a 64–70% probability that a decline in OH has contributed to the post-2007 methane rise.”

Role of atmospheric oxidation in recent methane growth
http://www.pnas.org/content/114/21/5373.short

And:

”Based on our analysis, the mathematically most likely explanation for the renewed growth in atmospheric methane, counterintuitively, involves a 25-Tg/y decrease in methane emissions from 2003 to 2016 that is offset by a 7% decrease in global mean hydroxyl (OH) concentrations, the primary sink for atmospheric methane, over the same period.”

Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl
http://www.pnas.org/content/114/21/5367.short

The big picture on CH4 looks grim. We're not really sure why its accelerating, and we're not sure why OH is already declining significantly too. And now we know that the permafrost is extremely sensitive to our current climate pathway. To sum it up, here's another quote from the original article (my bold):

In contrast to shallow, gradual thaw that may rapidly re-form permafrost upon climate cooling, deep, CH4-yielding abrupt thaw is irreversible this century. Once formed, lake taliks continue to deepen even under colder climates, mobilizing carbon that was sequestered from the atmosphere over tens of thousands of years. The release of this carbon as CH4 and CO2 is irreversible in the 21st century.

[SteveMDFP]

This is really really bad on several levels.
 
So first, they are pointing at our ongoing "abrupt thaw" as a driver of an increased ratio of CH4 vs CO2. Possibly because the bacteria cant break down the CH4 fast enough? This would seem to makes sense.
 

Yep.  More precisely, some bacteria turn organic material to methane.  Others turn organic material to C02, but need oxygen to do so.  There's very limited oxygen at the bottom of these thermokarst lakes, so methane it is.  Meanwhile, once formed, a thermokarst lake delivers 4C temperatures to the underlying permafrost, continuously--when not frozen through-and-through.

We don't necessarily need a methane clathrate gun to be screwed by methane emissions.

[AbruptSLR]

The linked research indicates that the expected reductions in anthropogenic aerosol emissions in the coming decades will warm the North Atlantic Ocean; which in turn will slow the AMOC; which in turn will accelerate Hansen's hypothesis discussed in James Hansen's book: "Storms of My Grandchildren".  Consensus climate model projections all need to be updated to include this feedback mechanism:

Title: "Research Highlight: Climate Model Predicts Faster Warming for the North Atlantic Ocean"

https://www.skepticalscience.com/2018-SkS-Weekly-News-Roundup_33.html

Extract: "Researchers at Scripps Institution of Oceanography at UC San Diego have predicted faster rates of warming than previously predicted for the North Atlantic Ocean in a recent paper published in the Journal of Climate. This warming could disrupt major oceanic cycles and have worldwide impacts on climate systems.

The researchers modeled scenarios based on possible future greenhouse gas and aerosol emission rates. One likely scenario focuses on future decline in aerosols and continued increase of greenhouse gases in the atmosphere. Aerosols are minute particles suspended in the atmosphere. Some scatter sunlight, thereby actually acting as cooling agents."

See also:

https://scripps.ucsd.edu/news/research-highlight-climate-model-predicts-faster-warming-north-atlantic-ocean

Extract: "A warmer North Atlantic could significantly weaken the AMOC. The system is driven by changes in salinity and temperature; as the warm water moves north, it evaporates to become saltier and gets cooler in the northern latitudes, making it denser so it sinks. Changes in water temperature in the North Atlantic could throw a wrench into this whole process. In fact, recent studies have shown that the AMOC may have started weakening over the past decade. Greater weakening could have widespread impacts on climate and weather patterns. While all of the exact consequences are still unknown, for instance, warmer water on the surface could fuel stronger hurricanes.

“The changing pattern of ocean heat uptake will cause the atmospheric circulation to reorganize, bringing changes in rainfall and storms,” Xie said."

[AbruptSLR]

TeaPotty,
To reinforce your point about methane emissions from thermokarst lakes, the first image from Deimling et al (2015), shows high such methane emission by 2050 when following a BAU pathway:

Schneider von Deimling, T., Grosse, G., Strauss, J., Schirrmeister, L., Morgenstern, A., Schaphoff, S., Meinshausen, M., and Boike, J.: Observation-based modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity, Biogeosciences, 12, 3469-3488, doi:10.5194/bg-12-3469-2015, 2015.

http://www.biogeosciences.net/12/3469/2015/bg-12-3469-2015.html

To reinforce your point about the impact of diminishing OH radicals in the atmosphere, Isaksen et al. (2011) indicates that the GWP 100 of CH4 could increase from its present value of about 35 (see the second image) to over a value of 50 sometime after 2050.

Isaksen, I. S. A., Gauss M., Myhre, G., Walter Anthony, K. M.  and Ruppel, C.,  (2011), "Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions", Global Biogeochem. Cycles, 25, GB2002, doi:10.1029/2010GB003845.

http://onlinelibrary.wiley.com/doi/10.1029/2010GB003845/abstract

The last image reminds us all that due to cascading tipping points ECS could well increase from its current mean values of circa 3.5C to over 6C by the end of this century.

Best,
ASLR

[rboyd]

The GWP100 numbers for methane seem to be completely irrelevant with respect to any accurate discussion of climate change, as the methane that is removed from the atmosphere is being more than constantly replaced by new methane (anthropogenic and naturally sourced, with the latter increasing over time).

As long as atmospheric methane levels are increasing a better assessment of the CC impacts of methane levels would be a GWP20 or even perhaps a GWPimmediate number. The proposed reduction in OH levels just intensifies the issue. The possibility of non-linear feedbacks adds to this issue, given the near-term intensity of the methane-induced warming.

This level of short-term warming also makes me think that the aerosol cooling effect must be significantly larger than consensus, otherwise we would be warming at an even faster rate.

[AbruptSLR]

The GWP100 numbers for methane seem to be completely irrelevant with respect to any accurate discussion of climate change, as the methane that is removed from the atmosphere is being more than constantly replaced by new methane (anthropogenic and naturally sourced, with the latter increasing over time).

As long as atmospheric methane levels are increasing a better assessment of the CC impacts of methane levels would be a GWP20 or even perhaps a GWPimmediate number. The proposed reduction in OH levels just intensifies the issue. The possibility of non-linear feedbacks adds to this issue, given the near-term intensity of the methane-induced warming.

This level of short-term warming also makes me think that the aerosol cooling effect must be significantly larger than consensus, otherwise we would be warming at an even faster rate.

While in general terms I agree with your points, I did provide a graph with all relevant values of GWP for methane, and I note that high-end ESMs always use the correct value of methane, which they calculate based on chemistry.  Thus the real question is what standard are we going to hold policymakers to; as to date they simply state that they are entitled to assume that future methane emissions will be low so NOAA actually uses a value of GWP100 for methane of 25 when they calculate CO2e that they publish as the standard for policymakers to use.

[TeaPotty]

I note that high-end ESMs always use the correct value of methane, which they calculate based on chemistry.  Thus the real question is what standard are we going to hold policymakers to; as to date they simply state that they are entitled to assume that future methane emissions will be low

Exactly. But lets not forget that our policymakers will continue taking foolish strides hand in hand with out scientific elite, as till now. Remember how just a few years ago many in the scientific elite bullied methane researchers? Gavin Schmidt was especially cocky about it. He denies it all now of course.

Many scientists are still speaking up whenever methane research comes up, and stating thats its a mistake to take any "attention" off CO2. Such petulant little children, virtually zero self-reflection, and an embarrassment to science.

[AbruptSLR]

Yet another indication that the Arctic permafrost will likely degrade faster than consensus scientists previously assumed:

Title: "Exclusive: Some Arctic Ground No Longer Freezing—Even in Winter"

https://www.nationalgeographic.com/environment/2018/08/news-arctic-permafrost-may-thaw-faster-than-expected/

Extract: "New data from two Arctic sites suggest some surface layers are no longer freezing. If that continues, greenhouse gases from permafrost could accelerate climate change.
…
"This is a big deal," says Ted Schuur, a permafrost expert at Northern Arizona University."

[kassy]

Wasn't there a recent interview where Micheal Mann said he expected some rational action but it just never came. This is the problem. Our politicians are not that rational anymore and in most western nations they are promoting the politics of the elite not the people.

Bottom line:

Anyone that thinks that conservative scientists are the problem
instead of our politicians who put their future before their electorates future
is deluded


ETA: some spelling mistakes but also:

Ask not what conservative scientists can do for you but ask what you can do for conservative scientists? (and your grandchildren etc).

[TeaPotty]

Anyone that thinks that conservative scientists are the problem
instead of our politicians who put their future before their electorates future
is deluded

1) Anyone with good knowledge of politics of knows that politicians don’t do what’s rational and best for their citizens. Sorry, but this reeks of isolated naivety.

2) Conservative scientists provide the ultimate excuse for inaction.

3) At this point in time, talking to the public about 2C is outright deception.

4) In our ultra-capitalist society, money shapes and corrupts every industry. Science and academia is no different. Conservative scientsts hold most of the top positions because their interests align better with the big money.

[kassy]

1) No that comes first. Imhofe had a snowball. He had no need for conservative scientists.

2) Nope, the snowball got there first.

Also any measure for conservative scientists providing the ultimate excuse for inaction vs the perfectly alarmed/or dryly on message ones that get ignored?

The politicians mainly protest about the cost and job losses ignoring the fact we are subsidizing fossil fuels while ignoring the long term climate costs. Some coal miners want to keep mining coal and people are people. Although we could educate them better.

People in general don't read much science any way and if you look at the big picture there are some other points:
-The weather guys hardly ever touch on the bigger patterns (stuck weather)
-And main stream coverage of the subject is crap compared to your average Trump tweet (not a coincidence either).

The politicians decide stuff based on who gives them money while scientists have to publish their stuff in peer reviewed publications.

So the scientists are too conservative while we change the global target due to dollars which was a political choice.

Influence people to become a less ultra-capitalist society that is way more useful then ranting about scientists.

[TeaPotty]

Whatever helps these ppl sleep better at night.

A politician has the same loyalty as a prostitute, and historically always has. Conservative scientists are part of the system driving us to collapse, and they believe it is their duty to mislead the public. They think the public cant handle the truth, and would just break down in despair.

I’m done arguing with you. Everyone shares responsibility for their part.

[AbruptSLR]

I think that the information in Reply #2320 is so important that AR6 is likely to adopt Dessler & Forster (2018) recommended likely range for the current value of ECS to be 2.4 to 4.6C; therefore, I decided to repeat that post below:

"Dessler & Forster (2018) demonstrate rather convincingly that the likely range for ECS in the period from 2000 to 2017 was 2.4 to 4.6C as opposed to AR5's cited likely range of 1.5 to 4.5C.  Furthermore, it is important to remember that ECS is not a fixed value but rather is projected to increase with continued global warming, this century:

A. E. Dessler and P.M. Forster (07 August 2018), "An estimate of equilibrium climate sensitivity from interannual variability', Journal of Geophysical Research Atmospheres, https://doi.org/10.1029/2018JD028481

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD028481?campaign=wolacceptedarticle

Abstract
Estimating the equilibrium climate sensitivity (ECS; the equilibrium warming in response to a doubling of CO2) from observations is one of the big problems in climate science. Using observations of interannual climate variations covering the period 2000 to 2017 and a model‐derived relationship between interannual variations and forced climate change, we estimate ECS is likely 2.4‐4.6 K (17‐83% confidence interval), with a mode and median value of 2.9 and 3.3 K, respectively. This analysis provides no support for low values of ECS (below 2 K) suggested by other analyses. The main uncertainty in our estimate is not observational uncertainty, but rather uncertainty in converting observations of short‐term, mainly unforced climate variability to an estimate of the response of the climate system to long‐term forced warming.

Plain language summary
Equilibrium climate sensitivity (ECS) is the amount of warming resulting from doubling carbon dioxide. It is one of the important metrics in climate science because it is a primary determinant of how much warming we will experience in the future. Despite decades of work, this quantity remains uncertain: the last IPCC report stated a range for ECS of 1.5‐4.5 deg. Celsius. Using observations of interannual climate variations covering the period 2000 to 2017, we estimate ECS is likely 2.4‐4.6 K. Thus, our analysis provides no support for the bottom of the IPCC's range."

You can obtain a copy of the paper here:

https://drive.google.com/file/d/1nt4YEMLc0AwWEAHtHAcwDEVzHkyKj1G-/view
"

[AbruptSLR]

The linked reference confirms that low values for ECS based on historical estimates.  This implies that it is likely that the true range of values for ECS is higher than that reported in AR5:

Timothy Andrews et al. (30 July 2018), "Accounting for Changing Temperature Patterns Increases Historical Estimates of Climate Sensitivity", Geophysical Research Letters, https://doi.org/10.1029/2018GL078887

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078887

Abstract
Eight atmospheric general circulation models (AGCMs) are forced with observed historical (1871–2010) monthly sea surface temperature and sea ice variations using the Atmospheric Model Intercomparison Project II data set. The AGCMs therefore have a similar temperature pattern and trend to that of observed historical climate change. The AGCMs simulate a spread in climate feedback similar to that seen in coupled simulations of the response to CO2 quadrupling. However, the feedbacks are robustly more stabilizing and the effective climate sensitivity (EffCS) smaller. This is due to a pattern effect, whereby the pattern of observed historical sea surface temperature change gives rise to more negative cloud and longwave clear‐sky feedbacks. Assuming the patterns of long‐term temperature change simulated by models, and the radiative response to them, are credible; this implies that existing constraints on EffCS from historical energy budget variations give values that are too low and overly constrained, particularly at the upper end. For example, the pattern effect increases the long‐term Otto et al. (2013, https://doi.org/10.1038/ngeo1836) EffCS median and 5–95% confidence interval from 1.9 K (0.9–5.0 K) to 3.2 K (1.5–8.1 K).

Plain Language Summary
Recent decades have seen cooling over the eastern tropical Pacific and Southern Oceans while temperatures rise globally. Climate models indicate that these regional features, and others, are not expected to continue into the future under sustained forcing from atmospheric carbon dioxide increases. This matters because climate sensitivity depends on the pattern of warming, so if the past has warmed differently from what we expect in the future, then climate sensitivity estimated from the historical record may not apply to the future. We investigate this with a suite of climate models and show that climate sensitivity simulated for observed historical climate change is smaller than for long‐term carbon dioxide increases. The results imply that historical energy budget changes only weakly constrain climate sensitivity.

[AbruptSLR]

AR5 did not consider the large peatland area in the Congo Basin, when estimating their 'land use' contributions to global warming in the coming decades:

Title: "Guest post: A plan to solve the mysteries of Congo’s vast tropical peatland"

https://www.carbonbrief.org/guest-post-a-plan-to-solve-mysteries-of-congos-vast-tropical-peatland

Extract: "Last year, I led a team of scientists in publishing the first-ever map of a vast peatland in the central Congo Basin. Covering 145,500 square kilometres – an area larger than England – it is the world’s most extensive tropical peatland.

Peat is a type of wetland soil made of semi-decomposed plant matter and so is rich in carbon. We estimate that about 30bn tonnes of carbon is stored in the peatland we found – an amount equivalent to three years of global fossil-fuel emissions.
…
However, while mostly intact and increasingly protected on paper, the peatlands are in reality threatened by road building, logging, drainage for industrial palm oil plantations, and oil exploration. Additionally, rising temperatures could tip the balance of the peatland from absorbing carbon from the atmosphere to releasing it. However, while mostly intact and increasingly protected on paper, the peatlands are in reality threatened by road building, logging, drainage for industrial palm oil plantations, and oil exploration. Additionally, rising temperatures could tip the balance of the peatland from absorbing carbon from the atmosphere to releasing it."

[AbruptSLR]

It is likely that both the RCP, and the SSP, radiative forcing scenarios underestimate future methane emissions from shallow agricultural reservoirs:

Thomas A. Davidson et al, Synergy between nutrients and warming enhances methane ebullition from experimental lakes, Nature Climate Change (2018). DOI: 10.1038/s41558-017-0063-z


http://www.nature.com/articles/s41558-017-0063-z

Abstract: "Lakes and ponds are important natural sources of the potent greenhouse gas methane (CH4), with small shallow waters identified as particular hotspots. Ebullition (bubbles) of CH4 makes up a large proportion of total CH4 flux. However, difficulty measuring such episodic events5 makes prediction of how ebullition responds to nutrient enrichment and rising temperatures challenging. Here, the world’s longest running, mesocosm-based, shallow lake climate change experiment was used to investigate how the combination of warming and eutrophication (that is, nutrient enrichment) affects CH4 ebullition. Eutrophication without heating increased the relative contribution of ebullition from 51% to 75%. More strikingly the combination of nutrient enrichment and experimental warming treatments of +2–3 °C and +4–5 °C had a synergistic effect, increasing mean annual ebullition by at least 1900 mg CH4-C m−2 yr−1. In contrast, diffusive flux showed no response to eutrophication and only a small increase at higher temperatures (average 63 mg CH4–C m−2 yr−1). As shallow lakes are the most common lake type globally, abundant in highly climate sensitive regions and most vulnerable to eutrophication, these results suggest their current and future contributions to atmospheric CH4 concentrations may be significantly underestimated."

See also, Title: "Combined nutrients and warming massively increase methane emissions from lakes"

https://phys.org/news/2018-01-combined-nutrients-massively-methane-emissions.html

Extract: "Shallow lakes in agricultural landscapes will emit significantly greater amounts of methane, mostly in the form of bubbles (ebullition) in a warmer world, which is a potential positive feedback mechanism to climate warming.
…
The results here were striking as they showed that the combination of increased nutrient loading and warming had a synergistic effect on the ebullition of methane. In the absence of nutrient enrichment, warming alone increased annual methane ebullition by around 50 percent and its relative contribution to total methane emission rose from about 50 percent to 75 percent.

In stark contrast, when nutrient levels were high, warming increased total methane emission by at least six-fold, and in some cases, 17-fold, and the proportion of ebullition increased to 95 percent of total annual methane flux."

[AbruptSLR]

As a follow-on to my last post about underestimates likely future emissions from freshwater reservoirs (especially agricultural reservoirs), the linked article cites an article about a new scientific study that estimates that the U.S. EPA is currently underestimating about 60% of anthropogenic fossil fuel related methane emissions.  This difference gains importance when considering that radiative forcing from methane calculated on an emissions basis is about twice that as on an atmospheric concentration basis:

Title: "US emissions of methane – a potent greenhouse gas – are 60% higher than EPA thinks"

https://www.usatoday.com/story/news/nation/2018/06/21/emissions-greenhouse-gas-methane-higher-than-epa-thinks/722391002/

Extract: "The U.S. oil and gas industry emits 13 million metric tons of methane from its operations each year – nearly 60 percent more than currently estimated by the Environmental Protection Agency, a new study in the journal Science finds."

See also:

http://science.sciencemag.org/content/early/2018/06/20/science.aar7204.full

[AbruptSLR]

The linked reference provides evidence that CMIP5 model projections 'have underestimated the cooling effect that aerosol particles have had on climate in recent decades"; which 'suggests that the models are not sensitive enough to increasing greenhouse gas concentrations in the atmosphere'.  In other words, this reference finds that the CMIP5 models (as a group) underestimate both TCR & ECS:


Trude Storelvmo et al. (29 August 2018), "Lethargic response to aerosol emissions in current climate models", Geophysical Research Letters, https://doi.org/10.1029/2018GL078298

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078298

"Abstract
The global temperature trend observed over the last century is largely the result of two opposing effects – cooling from aerosol particles and greenhouse gas (GHG) warming. While the effect of increasing GHG concentrations on Earth's radiation budget is well‐constrained, that due to anthropogenic aerosols is not, partly due to a lack of observations. However, long‐term surface measurements of changes in downward solar radiation (SDSR), an often‐used proxy for aerosol radiative impact, are available worldwide over the last half‐century. We compare SDSR changes from ∼1,400 stations to those from the CMIP5 global climate simulations over the period 1961‐2005. The observed SDSR shows a strong early downward trend followed by a weaker trend‐reversal, broadly consistent with historical aerosol emissions. However, despite considerable changes to known aerosol emissions over time, the models show negligible SDSR trends, revealing a lethargic response to aerosol emissions, and casting doubt on the accuracy of their future climate projections.

Plain Language Summary
Observations of incoming solar radiation, as measured at approximately 1400 surface stations worldwide, show a strong downward trend from the 1960s to the 1980s, followed by a weaker trend reversal thereafter. These trends are thought to be due to changes in the amount of aerosol particles in the atmosphere, and we find support for that here in the temporal evolution of anthropogenic aerosol emissions. This is expected because aerosol particles reflect and/or absorb sunlight back to space, and have a net cooling effect on Earth's climate. However, we find that the current generation of climate models simulate negligible solar radiation trends over the last half‐century, suggesting that they have underestimated the cooling effect that aerosol particles have had on climate in recent decades. Despite this, climate models tend to reproduce surface air temperature over the time period in question reasonably well. This, in turn, suggests that the models are not sensitive enough to increasing greenhouse gas concentrations in the atmosphere, with important implications for their ability to simulate future climate."

[AbruptSLR]

The linked reference provide evidence that the ocean's 'biological carbon pump' is likely a positive feedback on climate change.  This likely positive feedback is underestimated in current consensus science climate models:

F.Boscolo-Galazz et al. (30 August 2018), "Temperature dependency of metabolic rates in the upper ocean: A positive feedback to global climate change?", Global and Planetary Change, https://doi.org/10.1016/j.gloplacha.2018.08.017

https://www.sciencedirect.com/science/article/pii/S0921818118301905

Abstract: "The temperature of seawater can affect marine plankton in various ways, including by affecting rates of metabolic processes. This can change the way carbon and nutrients are fixed and recycled and hence the chemical and biological profile of the water column. A variety of feedbacks on global climate are possible, especially by altering patterns of uptake and return of carbon dioxide to the atmosphere. Here we summarize and synthesize recent studies in the field of ecology, oceanography and ocean carbon cycling pertaining to possible feedbacks involving metabolic processes. By altering the rates of cellular growth and respiration, temperature-dependency may affect nutrient uptake and food demand in plankton and ultimately the equilibrium of pelagic food webs, with cascade effects on the flux of organic carbon between the upper and inner ocean (the “biological carbon pump”) and the global carbon cycle. Insights from modern ecology can be applied to investigate how temperature-dependent changes in ocean biogeochemical cycling over thousands to millions of years may have shaped the long-term evolution of Earth's climate and life. Investigating temperature-dependency over geological time scales, including through globally warm and cold climate states, can help to identify processes that are relevant for a variety of future scenarios."

Extract: "- Heterotrophic respiration rates respond twice as fast as to ocean temperature changes than photosynthesis.

- This may alter the ratio of particulate organic carbon to export production in the ocean, with more carbon sequestered to the deep ocean when it is cooler.

- Temperature dependency of metabolic rates has potential for being a key internal feedback for Earth's climate"

[AbruptSLR]

The linked reference indicates that the current methodology used by consensus science for sea level rise projections underestimate the risks of high-end low probability events (which can lead to abrupt sea level rise):

Dewi Le Bars (27 August 2018), "Uncertainty in sea level rise projections due to the dependence between contributors", Earth's Future, https://doi.org/10.1029/2018EF000849

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018EF000849

"Abstract
Sea level rises at an accelerating pace threatening coastal communities all over the world. In this context sea level projections are key tools to help risk mitigation and adaptation. Projections are often made using models of the main contributors to sea level rise (e.g. thermal expansion, glaciers, ice sheets). To obtain the total sea level these contributions are added, therefore the uncertainty of total sea level depends on the correlation between the uncertainties of the contributors. This fact is important to understand the differences in the uncertainty of sea level projections from different methods. Using two process‐based models to project sea level for the 21st century, we show how to model the correlation structure and its time dependence. In these models the correlation primarily arises from uncertainty of future global mean surface temperature that correlates with almost all contributors. Assuming that sea level contributors are independent of each other, an assumption made in many sea level projections, underestimates the uncertainty in sea level projections. As a result, high‐end low probability events that are important for decision making are underestimated. The uncertainty in the strength of the dependence between contributors is also explored. New dependence relations between the uncertainty of dynamical processes, and surface mass balance in glaciers and ice sheets are introduced in our model. Total sea level uncertainty is found to be as sensitive to the dependence between contributors as to uncertainty in certain individual contributors like thermal expansion and Greenland ice sheet."

[AbruptSLR]

The linked reference confirms both that the low end value of climate sensitivity given in AR5 is too low and that climate sensitivity increases with continued warming on the century scale:

Philip Goodwin (10 September 2018), "On the time evolution of climate sensitivity and future warming", Earth's Future, https://doi.org/10.1029/2018EF000889

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018EF000889

Abstract
The Earth's climate sensitivity to radiative forcing remains a key source of uncertainty in future warming projections. There is a growing realisation in recent literature that research must go beyond an equilibrium and CO2‐only viewpoint, towards considering how climate sensitivity will evolve over time in response to anthropogenic and natural radiative forcing from multiple sources. Here, the transient behaviour of climate sensitivity is explored using a modified energy balance model, in which multiple climate feedbacks evolve independently over time to multiple sources of radiative forcing, combined with constraints from observations and from the Climate Model Intercomparison Project phase 5 (CMIP5). First, a large initial ensemble of 107 simulations is generated, with a distribution of climate feedback strengths from sub‐annual to 102 year timescales constrained by the CMIP5 ensemble; including the Planck feedback, the combined water‐vapour lapse‐rate feedback, snow and sea‐ice albedo feedback, fast cloud feedbacks, and the cloud response to SST‐adjustment feedback. These 107 simulations are then tested against observational metrics representing decadal trends in warming, heat and carbon uptake, leaving only 4.6×103 history‐matched simulations consistent with both the CMIP5 ensemble and historical observations. The results reveal an annual‐timescale climate sensitivity of 2.1 °C (ranging from 1.6 to 2.8 °C at 95% uncertainty), rising to 2.9 °C (from 1.9 to 4.6 °C) on century timescales. These findings provide a link between lower estimates of climate sensitivity, based on the current transient state of the climate system, and higher estimates based on long‐term behaviour of complex models and palaeoclimate evidence.

[AbruptSLR]

The linked article provides a convenient summary of many of the ways in which the 'the IPCC has been Systematically Underestimating Climate Change Risk'; however, it is my opinion that even this assessment errs on the side of least drama:

Title: "New Evidence That Climate Change Poses a Much Greater Threat to Humanity Than Recently Understood Because the IPCC has been Systematically Underestimating Climate Change Risks: An Ethical Analysis"

https://ethicsandclimate.org/2018/09/21/new-evidence-that-climate-change-poses-a-much-greater-threat-to-humanity-than-recently-understood-because-the-intergovernmental-panel-on-climate-change-has-been-systematically-underestimating-climate/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+EthicsAndClimate+%28ETHICS+and+CLIMATE%29

Extract: "Three papers have been recently published that lead to the conclusion that human-induced climate change poses a much more urgent and serious threat to life on Earth than many have thought who have been relying primarily on the conclusions of the Intergovernmental Panel on Climate Change (IPCC). This paper first reviews these papers and then examine the ethical questions by the issues discussed in these papers.
…
This paper summarizes major conclusions from a third recent paper which analyzes IPCC’s consistent underestimation of climate change impacts. The paper, What Lies Beneath: On the Understatement of Climate Change Risks, (hereinafter “WLB”), recently published by the Breakthrough Institute, claims both that the risks posed by climate change are far greater than is evident from the conclusions of IPCC and examines why IPCC has frequently underestimated threats from climate change.
…
IPCC has published few projections regarding tipping-point thresholds, nor emphasized the importance of building robust risk-management assessments of them in absence of adequate quantitative data.
…
The IPCC reports fail to mention that the ECS measure omits key “long-term” feedbacks that a rise in the planet’s temperature can trigger. (WLB, p. 22) These include the permafrost feedback, other changes in the terrestrial carbon cycle, a decrease in the ocean’s carbon-sink efficiency, and the melting of polar ice sheets creating a cold ocean-surface layer underneath that accelerates the melting of ice shelves and hastens the rate of ice-mass loss.
…
Conclusions about climate sensitivity should take into account that:

1.   Biogeochemical feedbacks (such as less efficient land-ocean sinks, including permafrost loss) effectively increases carbon emissions to 2100 by about 20% and can enhance warming by up to 0.5°C, compared to the baseline scenario. (WLB, p. 23)
2.   Warming has been projected to increase methane emissions from wetlands by 0 – 100% compared with present-day wetland methane emissions. A 50% increase in wetland methane emissions by 2100 is expected in response to high-end warming of 4.1 – 5°C which could add at least another 0.5°C warming. (WLB, p. 23)
3.   It is important to use high-end climate sensitivity because some studies have suggested the climate models have underestimated three major positive climate feedbacks: positive ice albedo feedback from the retreat of Arctic sea ice; positive cloud albedo feedbacks from retreating storm track clouds in mid-latitudes, and positive albedo feedback by the next phase (water and ice) clouds. When these are taken into account the ECS is more than 40% higher than the IPCC mid-figure, at 4.5 to 4.7° C. (WLB, p. 23)
…
Carbon budgets are usually based on mid-term climate sensitivity numbers of around 30 C. (WLB, p. 22)

Yet there are reasons to believe climate sensitivity is closer to 40  C. In fact, as we have seen, climate sensitivity may be between 4-60 C. (WLB, p. 22)
…
The IPCC reports fail to say that once projected emissions from future food production and deforestation are taken into account there is no carbon budget for fossil-fuel emissions for a 20C target. (WLB, p. 24).

There are also problems with carbon budgets which incorporate “overshoot” scenarios, in which warming exceeds the target before being cooled by carbon drawdown. (WLB, p.24)  Pam Pearson, Dir. of International Cryo-sphere Climate Initiative, said that most cryo-sphere thresholds are determined by peak temperatures, and the length of time spent at the peak warning rather than “later decreasing temperatures after the peak are largely irrelevant, especially with higher temperatures and longer duration peaks.” Thus “overshoot scenarios” which are now becoming the norm in policymaking hold much greater risks. (WLB, p. 24)
…
Conclusion-Ethical Issues Raised by IPCC’s Consistent Underestimation of Climate Change Impacts.

A. Failure to Apply a Precautionary Science"

[Sebastian Jones]

Have not parsed this as yet, too much to look at and compare now but will.
.......
https://ethicsandclimate.org/2018/09/21/new-evidence-that-climate-change-poses-a-much-greater-threat-to-humanity-than-recently-understood-because-the-intergovernmental-panel-on-climate-change-has-been-systematically-underestimating-climate/amp/

Impressions? just waffle?

I have, in fact I came here to share the paper.
It is not waffle, it is an important synthesis and analysis of the cited papers.
Its conclusions?
Briefly, we are hooped.
Sea level rise? at least 2m by 2100.
Temperature rise? We have already baked in at least 4C.
Effects on civilization? 80-90% population decline as a result of desertification, uninhabitable zones, heat stress and botched migrations.

[AbruptSLR]

Have not parsed this as yet, too much to look at and compare now but will.
.......
https://ethicsandclimate.org/2018/09/21/new-evidence-that-climate-change-poses-a-much-greater-threat-to-humanity-than-recently-understood-because-the-intergovernmental-panel-on-climate-change-has-been-systematically-underestimating-climate/amp/

Impressions? just waffle?

I have, in fact I came here to share the paper.
It is not waffle, it is an important synthesis and analysis of the cited papers.
Its conclusions?
Briefly, we are hooped.
Sea level rise? at least 2m by 2100.
Temperature rise? We have already baked in at least 4C.
Effects on civilization? 80-90% population decline as a result of desertification, uninhabitable zones, heat stress and botched migrations.

I concur that this is a serious and valuable paper; however, in addition to my comments in Reply #2348, I note that reasons to suspect that it errs on the side of least drama include that it does not consider:

1. Hansen's ice-climate feedback mechanism combined with ice cliff and hydrofacturing ice sheet failure mechanisms.
2. Short-term increases in both natural and anthropogenic methane emissions in the next few decades.
3.The like rapid reduction of higher than expected negative forcing from anthropogenic aerosols that have been masking higher than acknowledged TCR and ECS values; and
4. More rapid increases in both TCR and ECS with continued warming than currently acknowledged.

[gerontocrat]

Have not parsed this as yet, too much to look at and compare now but will.
.......
https://ethicsandclimate.org/2018/09/21/new-evidence-that-climate-change-poses-a-much-greater-threat-to-humanity-than-recently-understood-because-the-intergovernmental-panel-on-climate-change-has-been-systematically-underestimating-climate/amp/

Impressions? just waffle?

I have, in fact I came here to share the paper.
It is not waffle, it is an important synthesis and analysis of the cited papers.
Its conclusions?
Briefly, we are hooped.
Sea level rise? at least 2m by 2100.
Temperature rise? We have already baked in at least 4C.
Effects on civilization? 80-90% population decline as a result of desertification, uninhabitable zones, heat stress and botched migrations.

Far too convincing for comfort

It is as if (ASIF) someone had wandered around the ASIF threads and collected all the references to papers and data that undermine the IPCC consensus and plonked them into the 44 pages of this report.

A pity they didn't do a precis - say two pages of one-liners. It would be, I think, a very powerful document. I don't think I dare.

[Sigmetnow]

A compilation:

Michael E. Mann on Twitter: "I invite anyone who thinks that scientists like myself are ignoring worst case scenarios or downplaying risk & urgency to read my articles & commentaries over the past few years:
https://t.co/jaqXpPM68v
https://t.co/MoVbMr5vSQ
https://t.co/f8UHcbI2P9
https://t.co/yK30woXDvD
https://t.co/VZCQywe3Sj "

https://mobile.twitter.com/michaelemann/status/1046572666352783360

Links are to compilations of articles, by year.

[AbruptSLR]

A compilation:

Michael E. Mann on Twitter: "I invite anyone who thinks that scientists like myself are ignoring worst case scenarios or downplaying risk & urgency to read my articles & commentaries over the past few years:
https://t.co/jaqXpPM68v
https://t.co/MoVbMr5vSQ
https://t.co/f8UHcbI2P9
https://t.co/yK30woXDvD
https://t.co/VZCQywe3Sj "

https://mobile.twitter.com/michaelemann/status/1046572666352783360

Links are to compilations of articles, by year.

As much as I feel for scientists like Mann, Mother Nature only cares about what mankind collectively figures out to do, and we all need to face reality.

[AbruptSLR]

Here is a scientist/man/individual who in my opinion is intellectually honest:

Title: "James Hansen"

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

[Archimid]

A true hero of mankind. Without him (and others like him) we would be heading 100% blind into climate change. He has persevered on this all his life. He pushed when everyone thought him crazy. Great human.

[GeoffBeacon]

A pity they didn't do a precis - say two pages of one-liners. It would be, I think, a very powerful document. I don't think I dare.

I really wish you would G..

Yes please. I'd add too many expletives.

[TerryM]

Geoff
Some of us prefer a little spice with so heavy a meal.
Terry