Conservative Scientists & its Consequences

[Sleepy]

Thanks for cheering me up wili.
It's like going into a mine field.

Africa related, when they have little rain they get even less, tried to find the actual paper but its paywalled. The authors page contains links to both the NASA article and another article from The Conversation.
http://miketosca.com/work/#/recent/

Using temporally spaced, yet spatially coincident satellite and meteorological data I was able to show that anthropogenic fire aerosols in tropical Africa inhibited convective processes (i.e. rainfall) via solar absorption. This result was the first time aerosol-driven changes in cloud dynamics were resolved using observations.

A quote from the NASA article.
http://www.jpl.nasa.gov/news/news.php?feature=4681

African smoke contains a high percentage of black carbon particles from incompletely burned vegetation. Their dark color makes them very efficient at absorbing sunlight and heating the air around them, creating a layer of warm, soot-filled air. When air rising from Earth's sun-warmed surface hits this layer, it stops moving upward and spreads out horizontally instead. Without vigorous updrafts, the circular, up-and-down airflow that builds rain-producing clouds -- known as convection -- is suppressed.

[wili]

That last one is a good reminder that there is more than just GW messing with local and regional climate.

Generally, though, the Saharan and Arabian deserts are on the move northwards.

That is making northern African states like Libya less livable, but also states like Syria north of the Arabian peninsula. Meanwhile, the southern-most areas of the Sahara are scheduled to actually get more rain, iirc. That seems to already be happening in parts of the Arab peninsula. But the rain tends to come in deluges that the land there is ill equipped to absorb, so you get very nasty floods coming down from rocky land, floods full of sand and full of dust-turned-to-mud.

[AbruptSLR]

My interpretation of the linked reference is that if current cloud feedback is more positive than expected by the CMIP5 ensemble mean, then the long-term cloud feedback will also be more positive than currently expect, thus indicating that ECS could become more positive with continued warming this century:

Chen Zhou, Mark D. Zelinka, Andrew E. Dessler and Stephen A. Klein (2015), "The relationship between inter-annual and long-term cloud feedbacks", Geophysical Research Letters, DOI: 10.1002/2015GL066698


http://onlinelibrary.wiley.com/doi/10.1002/2015GL066698/abstract

Abstract: "Analyses of CMIP5 simulations suggest that climate models with more positive cloud feedback in response to inter-annual climate fluctuations also have more positive cloud feedback in response to long-term global warming. Ensemble mean vertical profiles of cloud change in response to inter-annual and long-term surface warming are similar, and the ensemble mean cloud feedback is positive on both timescales. However, the average long-term cloud feedback is smaller than the inter-annual cloud feedback, likely due to differences in surface warming pattern on the two timescales. Low cloud cover (LCC) change in response to inter-annual and long-term global surface warming is found to be well correlated across models, and explains over half of the covariance between inter-annual and long-term cloud feedback. The inter-model correlation of LCC across timescales likely results from model-specific sensitivities of LCC to sea surface warming."

[AbruptSLR]

The two linked (open access) references represent the conventional IPCC (and Gavin Schmidt) type of thinking represented in AR5 for climate sensitivity; while the first reference by Annan acknowledges that AR5 likely over-reached when it included very low ECS values based on values determined using observational data taken during the faux hiatus, and discusses a path forward to try to reduce the currently relatively high uncertainties about climate sensitivity:

J. D. Annan (December 2015), "Recent Developments in Bayesian Estimation of Climate Sensitivity", Current Climate Change Reports, Constraints on Climate Sensitivity (R Knutti, Section Editor), Volume 1, Issue 4, pp 263-267, DOI: 10.1007/s40641-015-0023-5


http://download.springer.com/static/pdf/667/art%253A10.1007%252Fs40641-015-0023-5.pdf?originUrl=http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2Fs40641-015-0023-5&token2=exp=1448043870~acl=%2Fstatic%2Fpdf%2F667%2Fart%25253A10.1007%25252Fs40641-015-0023-5.pdf%3ForiginUrl%3Dhttp%253A%252F%252Flink.springer.com%252Farticle%252F10.1007%252Fs40641-015-0023-5*~hmac=84199aa301d315d16eb2111b1b4b13a69eb7515938306caa1035713800ff96e1

Abstract: "How sensitive the climate system is to the atmospheric concentration of CO2 is one of the most important and long-standing questions in climate science. This problem is well-suited to the Bayesian approach. Early estimates were highly uncertain, but recent research appears to show some convergence with both high and low values excluded with increasing confidence. There is, however, increasing evidence that many of these estimates ignore some significant sources of uncertainty, correctly accounting for which would probably broaden the estimates somewhat. Conversely, different lines of evidence tend to generate consistent results, and it should be possible to synthesise these so as to decrease our uncertainties."

Extract: "The subjective Bayesian approach is now widely utilised for estimation of the equilibrium climate sensitivity. Progress has been steady, although even the newest estimates can be seen to have limitations. While estimates based on the recent observational record are increasingly converging to a moderate value with a best estimate rarely far from 2 to 2.5 ∘C, and a range which is confidently bounded between about 1 and 4.5 ∘C (or less), these estimates are themselves conditional on approximations that are now recognised to introduce significant additional uncertainties (and perhaps a bias) into the results. The real climate system is more complex than any model, and the concept of an equilibrium sensitivity may not be precisely definable in the real world. Therefore, there must be a limit to how accurately this parameter can be meaningfully estimated. Nevertheless, there is no reason to presume we have yet reached this limit, and it provides a useful basis for predicting the magnitude of future climate change. There are many opportunities for improving our estimates, and better understanding and quantifying our uncertainties. One area for research that has not been explored in much detail is the possibility of synthesising different lines of research, all of which inform on the equilibrium sensitivity. Such an analysis has the potential for generating a more precise and credible result."

Andrew H. MacDougall (2015), "The Transient Response to Cumulative CO2 Emissions: a Review", Current Climate Change Reports,

http://link.springer.com/article/10.1007%2Fs40641-015-0030-6

Abstract: "The transient climate response to cumulative CO2 emissions (TCRE) is a metric of climate change that directly relates the primary cause of climate change (cumulative CO2 emissions) to global mean temperature change. The metric was developed once researchers noticed that the cumulative CO2 versus temperature change curve was nearly linear for almost all Earth system model output. Here, recent literature on the origin, limits, and value of TCRE is reviewed. TCRE appears to emerge from the diminishing radiative forcing per unit mass of atmospheric CO2 being compensated by diminishing efficiency of ocean heat uptake and the modulation of airborne fraction of carbon by ocean processes. The best estimate of the value of TCRE is between 0.8 to 2.5 K EgC−1. Overall, TCRE has been shown to be a conceptually simple and robust metric of climate warming with many applications in formulating climate policy."

[AbruptSLR]

The linked reference cites a positive feedback (for both global warming & for Arctic Sea Ice loss) mechanism associated with the thinning Arctic Sea Ice losing insulating power, that was not included in the AR5 climate change models:

Melissa A. Burt, David A. Randall, and Mark D. Branson  (2015), "Dark Warming", Journal of Climate, doi: http://dx.doi.org/10.1175/JCLI-D-15-0147.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0147.1

Abstract: "As the Arctic sea ice thins and ultimately disappears in a warming climate, its insulating power decreases. This causes the surface air temperature to approach the temperature of the relatively warm ocean water below the ice. The resulting increases in air temperature, water vapor and cloudiness lead to an increase in the surface downwelling longwave radiation (DLR), which enables a further thinning of the ice. This positive ice-insulation feedback operates mainly in the autumn and winter. A climate-change simulation with the Community Earth System Model shows that, averaged over the year, the increase in Arctic DLR is three times stronger than the increase in Arctic absorbed solar radiation at the surface.
The warming of the surface air over the Arctic Ocean during fall and winter creates a strong thermal contrast with the colder surrounding continents. Sea-level pressure falls over the Arctic Ocean, and the high-latitude circulation reorganizes into a shallow “winter monsoon.” The resulting increase in surface wind speed promotes stronger surface evaporation and higher humidity over portions of the Arctic Ocean, thus reinforcing the ice-insulation feedback."

See also:
https://www.sciencenews.org/article/thinning-ice-leads-winter-warming-arctic?tgt=nr

[sidd]

Thanx for the Burt paper, the concept of winter monsoon in the the Arctic is intriguing. They did this in the CESM model, so mebbe someone can do an intermodel comparison sometime.

[AbruptSLR]

In the linked Sci. Am. article entitled: "Consilience and Consensus Or why climate skeptics are wrong", Michael Shermer discusses the reasoning as to why anthropogenic climate change is real (see extract below).  However, I believe that all of the points that he raises about climate skeptics will soon be proven to apply to the political consensus position on the AR5 projections.

It is all very nice that AR5 concluded that anthropogenic climate change is real, but the relatively slow projected responses of the many different Earth Systems in AR5, to me amounts of an extraordinary ordinary claim. Furthermore, it seems to me that as the multiple Earth Systems are better understood a "consilience of inductions" will confirm that minority scientists like James Hansen are more correct (that various Earth Systems will respond more quickly than commonly expected) that the current scientific consensus position.

Due to the complexities of climate change, I do not expect the consensus projections to change for another 10 to 20 years (by which time the advanced ESMs, like the ACME program, should be reasonably well calibrated); but when it does it will likely be too late to stop such sensitive systems as marine ice sheets from tipping into main phase collapse modes; which will have synergistic impacts on other Earth Systems (thus compounding the future climate impacts).

http://www.scientificamerican.com/article/why-climate-skeptics-are-wrong/

Extract: "At some point in the history of all scientific theories, only a minority of scientists – or even just one – supported them, before evidence accumulated to the point of general acceptance.
…
How did this happen?

An answer may be found in what 19th-century philosopher of science William Whewell called a "consilience of inductions."  For a theory to be accepted, Whewell argued, it must be based on more than one induction – or a single generalization drawn from specific facts.  It must have multiple inductions that converge on one another, independently but in conjunction."

[AbruptSLR]

The linked article cites just one example of the intimidation of climate scientists by policymakers; which, despite the national uproar, is still effective at getting most scientist to err-on-the-side-of-least-drama (personally I think that Lamar Smith should be impeached for his actions):

https://www.washingtonpost.com/news/federal-eye/wp/2015/11/24/standoff-over-government-climate-study-provokes-national-uproar-by-scientists/

Extract: "A top House lawmaker’s confrontation with government researchers over a groundbreaking climate change study is provoking a national backlash from scientists, who say his campaign represents the most serious threat Congress has posed to scientific freedom."

See also:

http://www.theguardian.com/science/2015/nov/25/leading-scientists-accuse-house-panel-of-harassing-climate-researchers

[Sigmetnow]

Skeptical Science: Andy Skuse on Kevin Anderson's article.

(I do note that recent years have shown an uncoupling of GDP and emissions, so the article's claimed requirement of a 13% yearly emissions decrease can hardly be deemed a fixed target.)

The Road to Two Degrees, Part Two: Are the experts being candid about our chances?
http://www.skepticalscience.com/Anderson.html

[AbruptSLR]

The linked article points out that policymakers routinely ignore scientific advice about limiting GHG emissions as all that they need to do is to look into mirror in the morning and ask themselves if they feel like making any more effort, anything else is just a flight of fancy.  While this partially helps to explain why many/most climate scientists choose to err on the side of least drama; I suspect that if more scientists were less reticent to inform the world that we are all headed for a Darwin Award, then it would be easier to kick most of the current world leaders to the curb so that a new generation of leaders, with more to lose, could take their places:

http://www.nytimes.com/2015/11/29/science/earth/paris-climate-talks-avoid-scientists-goal-of-carbon-budget.html?partner=rss&emc=rss&smid=tw-nytimes&smtyp=cur&_r=1

Extract: "“The only way you can assess foreign policy is by asking, is what we’re getting better than something else?” Dr. Levi said in an interview. “I don’t see a better deal out there.”"



Edit: For those who did not click on the links provided by Sigmetnow in #1208 about the Kevin Anderson article, I provide the following extracts; which notes that to avoid a 2C world optimistically our remaining CO2 budget is 450 Gt; however, this ignores the risks that climate sensitivity may well be higher than assumed by AR5:

http://www.skepticalscience.com/Anderson.html

Extract: "Therefore, instead of a 1000 Gt CO2 budget, we might only have 450 Gt available for fossil-fuel energy emissions.

Anderson, in a private communication, pointed out that the IPCC shows an optimistic double bias in excluding some carbon-cycle feedbacks in models (because they are currently deemed too uncertain and speculative), whereas they include speculative and untested mitigation technologies.

…

… political expediency is what is driving this. The global "political and economic hegemony" in which growth-based economics is taken as a given and the political status quo is assigned the nature of an ineluctable fact, rather than an obstacle that we must overcome."

Kevin Anderson (2015), "Duality in climate science", Nature Geoscience, Volume: 8, Pages: 898–900, DOI:10.1038/ngeo2559

 http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2559.html

Abstract: "The commentary demonstrates the endemic bias prevalent amongst many of those developing emission scenarios to severely underplay the scale of the 2°C mitigation challenge. In several important respects the modelling community is self-censoring its research to conform to the dominant political and economic paradigm. Moreover, there is a widespread reluctance of many within the climate change community to speak out against unsupported assertions that an evolution of ‘business as usual’ is compatible with the IPCC’s 2°C carbon budgets. With specific reference to energy, this analysis concludes that even a slim chance of “keeping below” a 2°C rise, now demands a revolution in how we both consume and produce energy. Such a rapid and deep transition will have profound implications for the framing of contemporary society and is far removed from the rhetoric of green growth that increasingly dominates the climate change agenda."

See also:
http://kevinanderson.info/blog/duality-in-climate-science/

[Sigmetnow]

The 2C fantasy?

In the run up to the Paris meeting there seem to be a number of people focusing on the idea that the 2°C limit is essentially now a fantasy. There’s a post by Andy Revkin, and there’s a Nature feature called is the 2°C world a fantasy.

My own view is that giving ourselves a good chance of keeping warming below 2°C will be difficult. To have something like a 66% chance of staying below 2oC would require emitting no more than about another 300GtC. At the current rate, this could take less than another 30 years. So, clearly not an easy task. However, that doesn’t mean that it’s impossible, or that there aren’t ways that it could be achieved. So, I find how many seem to frame this issue very frustrating.

https://andthentheresphysics.wordpress.com/2015/11/27/the-2c-fantasy/

[AbruptSLR]

http://www.skepticalscience.com/Anderson.html

Extract: "Therefore, instead of a 1000 Gt CO2 budget, we might only have 450 Gt available for fossil-fuel energy emissions.

Just to avoid confusion between Anderson's 450 Gt CO2 budget and Sigmetnow's 300 GtC budget:

One ton of carbon equals 44/12 = 11/3 = 3.67 tons of carbon dioxide.

So 450/3.67 = 122.6 GtC

Thus, Signmetnow's 30-years to 2C is incorrect, and actually should be:

30(122.6/300) = 12.3 years or by 2028 (assuming that climate sensitivity is not higher than expected by AR5)

Edit: In about the past 1.5 years the mean global temperature has increase by about 0.15C, so if this rate continues then we would be at a 2C rise in about 10 years or by about 2026.

[tombond]

From the trillion tonne website from the Oxford University, the limit is one trillion tonnes of carbon, not CO2.

Their calculation is 404 GtC left to emit and at the current rate we will achieve this by 26th October 2038.

http://www.trillionthtonne.org/

To avoid this we need to reduce emissions by 2.7% per year.

No doubt COP21 delegates will be delighted to learn that the electricity they use in Paris at just 40gms/kWh is nearly CO2 emissions free.

See http://www.rte-france.com/en/eco2mix/chiffres-cles-en

[S.Pansa]

On the other hand, we should not ignore that in reality, our atmosphere contains also non-CO2 GHGs - and quite a few of them.
According to the TS of IPCCs AR5, p. 103 this unconvenient fact reduces the carbon budget from 1.000 PgC to 790. TrillionthTonne estimates that this would require an annual reduction rate of 5,2%.
On the same page the IPCC also points out, that the 790 PgC do not include the permafrost carbon feedback. A recent paper by MacDougall calculates that the permafrost carbon feedback reduces the budget by around 100 PgC. Accounting for that cuts the budget to ~700 PgC (Unfortunately the cumulative carbon budgets in the paper are different from the IPCC ones, so it's difficult to compare them).

As we have, by now, emitted around 600 PgC we have a remaining budget  of ~100 PgC, that is ~370 PgCO2-eq.
Current annual CO2eq emissions are 50PgC (see UNEP emission gap report).

In other words: To stay below 2C, we have 7 1/2 years to reduce our emissions to zero.

[Theta]

On the other hand, we should not ignore that in reality, our atmosphere contains also non-CO2 GHGs - and quite a few of them.
According to the TS of IPCCs AR5, p. 103 this unconvenient fact reduces the carbon budget from 1.000 PgC to 790. TrillionthTonne estimates that this would require an annual reduction rate of 5,2%.
On the same page the IPCC also points out, that the 790 PgC do not include the permafrost carbon feedback. A recent paper by MacDougall calculates that the permafrost carbon feedback reduces the budget by around 100 PgC. Accounting for that cuts the budget to ~700 PgC (Unfortunately the cumulative carbon budgets in the paper are different from the IPCC ones, so it's difficult to compare them).

As we have, by now, emitted around 600 PgC we have a remaining budget  of ~100 PgC, that is ~370 PgCO2-eq.
Current annual CO2eq emissions are 50PgC (see UNEP emission gap report).

In other words: To stay below 2C, we have 7 1/2 years to reduce our emissions to zero.

In that case, humanity needs to expend this first world lifestyle that it lives. There is just no way for us to continue living a life of convenience now that we have delayed action to the extent that we have, so the only solution is rapid degrowth, which is a fantasy in itself because nobody is going to willingly get rid of their first world privileges because we can't really see past the short-term, and even with the short-term scenarios (NTHE for an extremist example), one would mainly associate these with scaremongering. In this case, the path to the future of a better biosphere will probably be bloody either way as intentional degrowth will still yield a large amount of suffering, but this is probably a fallout from what would happen if we let nature take its course, which could be much worse and ensure the extinction of this species which is not very smart.

[jai mitchell]

In other words: To stay below 2C, we have 7 1/2 years to reduce our emissions to zero.

We have gone over this quite a bit in this thread.  Underestimations of feedbacks and the melt rate of the polar ice caps as well as the fact that we are currently at 1.1C above pre-industrial levels indicate that we have already crossed the 2C by 2100 threshold, at current GHG abundances.

[AbruptSLR]

In other words: To stay below 2C, we have 7 1/2 years to reduce our emissions to zero.

We have gone over this quite a bit in this thread.  Underestimations of feedbacks and the melt rate of the polar ice caps as well as the fact that we are currently at 1.1C above pre-industrial levels indicate that we have already crossed the 2C by 2100 threshold, at current GHG abundances.

I concur that many people conveniently forget the influences of such considerations as:

A. Lag time in the system response, including due to the thermal inertia of the ocean, feedback response timing, and phases of multi-decadal cycles like the PDO, etc.

B. Changes in negative forcing associated with aerosols and changes in CO2 absorption by land and ocean sinks.

C. The high degree of uncertainties associated with climate sensitivities is not a source of comfort but rather of alarm.

Edit: Not to mention the effects of increasingly frequent wildfires.

[GeoffBeacon]

ARE CONSERVATIVE SCIENTISTS DOWNPLAYING METHANE UNREASONABLY?

I wrote a piece that I don't quite believe in, Now CO2 is short lived, cows really are bad. However, it does rely on the IPCC claim that BECCS will be taking CO2 out of the atmosphere by the second half of the century.

This comments on the different positions of Ramanathan and Victor, who think that reducing methane emissions is an important action now, against the position of (the more conservative?) Pierrehumbert and Allen who argue that we should worry abut methane emissions  later. (Myles Allen thinks that the potency of methane should be measured over 100 years and contemporary emissions will have dissipated well before the 2°C limit is reached.).

This argument is relevant in judging the importance of reducing meat and dairy consumption. See Chatham House: Reduce meat and dairy to save climate.

I'd be grateful for any help.

[AbruptSLR]

ARE CONSERVATIVE SCIENTISTS DOWNPLAYING METHANE UNREASONABLY?

Geoff,

I do not know whether the following will be use to you or not, but the following linked document provides some comparisons about the different GWP of methane (per AR5 is 34 over 100-years) and carbon dioxide and the practicability of limiting either in different industrial segments.  So the correct scientific answer to your question is that for a given amount of effort that society is will to pay to fight climate change the correct blend of limiting both gases (all GHGs) with the maximum impact for the given amount of effort.  Unfortunately, lobbyists unbalance this optimization exercise, to the extent that in my opinion, policymakers are currently not making sufficient cuts in methane (for optimal impact), not because of scientists but because of politics and crony capitalism.  In other words cutting back on methane emissions today is one of the fastest ways to limit the mount of coming positive feedbacks, so you generally get more bang for the buck by cutting methane sooner (rather than later); however, meat consumption around the world is projected to increase (not decrease), and fracking is continuing despite low fossil fuel prices, so politically is can be hard to actually cut methane emission sources:

http://ecometrica.com/assets/Understanding-the-Changes-to-GWPs.pdf

[AbruptSLR]

For those who did not click on the links provided by Sigmetnow in #1208 about the Kevin Anderson article, I provide the following extracts; which notes that to avoid a 2C world optimistically our remaining CO2 budget is 450 Gt; however, this ignores the risks that climate sensitivity may well be higher than assumed by AR5:

http://www.skepticalscience.com/Anderson.html

Extract: "Therefore, instead of a 1000 Gt CO2 budget, we might only have 450 Gt available for fossil-fuel energy emissions.

Anderson, in a private communication, pointed out that the IPCC shows an optimistic double bias in excluding some carbon-cycle feedbacks in models (because they are currently deemed too uncertain and speculative), whereas they include speculative and untested mitigation technologies.

As S.Pansa pointed out, I should have used the GHG CO2 equivalent emissions of about 53 Gt/year (see the attached plot from the linked article about Anderson's reference) when using Anderson's value of 450 Gt CO2 budget to calculate a remaining time of 8.5 years until a 2C limit is reached.  However, as jai notes, if climate sensitivity (say Arctic albedo or wildfires, etc.) is higher than assumed then this 2C limit could be reached sooner (even assuming that the CoP21 Paris Pact is full implemented).

http://www.washingtonpost.com/sf/national/2015/11/29/carbon/

[GeoffBeacon]

AbruptSLR

Thanks.

However, the linked paper you mention doesn't seem to say anything about the choice between 20year or 100year GWP - or anything in-between. I can see nothing to help distinguish the Ramanathan/Victor position from that of Pierrehumbert/Allen.

In the linked paper I think the increased GWP100 of methane at 34 comes from the paper  Improved Attribution of Climate Forcing to Emissions by Shindell et all (2009). The "with climate-carbon feedback" given probably includes the effect of black carbon (soot) in the atmosphere.  I don't think it includes any feedback effect from the fact that relatively short lived (but powerful) methane has heated the Earth's surface and caused feedbacks like that caused by warming soil, which causes further emissions. (Or of increased forest fires and other feedbacks caused by a warmer Earth.)

I suspect that IPCC AR5 did not model the effects of many feedbacks. See
IPCC carbon budget: Missing feedbacks ignored.

I also feel the linked reference is more about getting level playing fields for business competion than the underlying science .... and should be taken with a pinch of salt by policy makers.

(Sigh) If only policy makers were subtle enough to understand such nuances - important though these issues might be. Then they may be able to ask these questions and get answers.

[AbruptSLR]

However, the linked paper you mention doesn't seem to say anything about the choice between 20year or 100year GWP - or anything in-between.

Geoff,

Per the attached plot (red line) for Shindell 2009, the 20-year GWP for methane is 105, and the plot gives values for other timeframes.

Best,
ASLR

[GeoffBeacon]

ALSR
Thanks

Very useful. I've been wanting a graph like that for years
- and that's not sarcasm!

Geoff

[AbruptSLR]

ALSR
Thanks

Very useful. I've been wanting a graph like that for years
- and that's not sarcasm!

Geoff

Geoff,
Sorry that I can't be of more help but I have a lot of distractions going on now; perhaps the link to Chapter 8 of AR5 co-chaired by Shindell could be of more help to you, particularly the two attached images and Sections: 8.7.2 "Application of Metrics" and 8.7.2.2 "Metrics for Near-Term Climate Forcers".

https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter08_FINAL.pdf


Caption for Second Image: "Figure 8.34 | Net global mean temperature change by source sector after (a) 100 and (b) 20 years (for 1-year pulse emissions). Emission data for 2008 are taken from the EDGAR database. For BC and OC anthropogenic emissions are from Shindell et al. (2012a) and biomass burning emissions are from Lamarque et al. (2010), see Supplementary Material Section 8.SM.17. There are large uncertainties related to the AGTP values and consequentially also to the calculated temperature responses"

Best,
ASLR

[Sigmetnow]

Earthquakes, not climate change, but:  Italy's highest court aquitted six scientists over the dangers they assessed -- but upheld the conviction of a public official who "wrongly reassured the public."

Italian Court Acquits Six Scientists Over Quake Deaths
http://news.discovery.com/earth/weather-extreme-events/italian-court-acquits-six-scientists-over-quake-deaths-151130.htm

[AbruptSLR]

The linked article discusses a practical means to measure local methane emissions:

Magnus Gålfalk, Göran Olofsson, Patrick Crill & David Bastviken (2015), "Making methane visible",
Nature Climate Change, doi:10.1038/nclimate2877


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2877.html

Abstract: "Methane (CH4) is one of the most important greenhouse gases, and an important energy carrier in biogas and natural gas. Its large-scale emission patterns have been unpredictable and the source and sink distributions are poorly constrained. Remote assessment of CH4 with high sensitivity at a m2 spatial resolution would allow detailed mapping of the near-ground distribution and anthropogenic sources in landscapes but has hitherto not been possible. Here we show that CH4 gradients can be imaged on the <m2 scale at ambient levels (~1.8 ppm) and filmed using optimized infrared (IR) hyperspectral imaging. Our approach allows both spectroscopic confirmation and quantification for all pixels in an imaged scene simultaneously. It also has the ability to map fluxes for dynamic scenes. This approach to mapping boundary layer CH4 offers a unique potential way to improve knowledge about greenhouse gases in landscapes and a step towards resolving source–sink attribution and scaling issues."

[AbruptSLR]

The linked Nov 28, 2015-The Economist article entitled "The science of climate change – Supermodels", states: "Satellite-based radar and laser measurements have enabled scientists to peer into clouds; small-scale models designed to capture their behavior have been refined and plugged into global models.  It seems increasingly likely that low cloud cover will diminish as the Earth warms, speeding the process."

http://www.economist.com/news/special-report/21678953-what-known-about-global-warmingand-what-remains-dark-supermodels

See also:
http://www.economist.com/news/special-report/21678951-not-much-has-come-efforts-prevent-climate-change-so-far-mankind-will-have-get

For those who do not know that this The Economist passage means, it means that ECS is likely higher than previously expected and that global warming will likely occur faster than previously (AR5) expected.

[AbruptSLR]

The linked (open access) reference concludes that black carbon emissions from Asia are likely to increase in coming years, thus accelerating Arctic Amplification:

Liu, D., Quennehen, B., Darbyshire, E., Allan, J. D., Williams, P. I., Taylor, J. W., Bauguitte, S. J.-B., Flynn, M. J., Lowe, D., Gallagher, M. W., Bower, K. N., Choularton, T. W., and Coe, H.: The importance of Asia as a source of black carbon to the European Arctic during springtime 2013, Atmos. Chem. Phys., 15, 11537-11555, doi:10.5194/acp-15-11537-2015, 2015

http://www.atmos-chem-phys.net/15/11537/2015/acp-15-11537-2015.html

Abstract: "Black carbon aerosol (BC) deposited to the Arctic sea ice or present in the free troposphere can significantly affect the Earth's radiation budget at high latitudes yet the BC burden in these regions and the regional source contributions are poorly constrained. Aircraft measurements of aerosol composition in the European Arctic were conducted during the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) campaign in March 2013. Pollutant plumes were encountered throughout the lower to upper Arctic troposphere featuring enhancements in CO and aerosol mass loadings, which were chemically speciated into BC and non-refractory sulphate and organic matter. FLEXPART-WRF simulations have been performed to evaluate the likely contribution to the pollutants from regional ground sources. By combining up-to-date anthropogenic and open fire biomass burning (OBB) inventories, we have been able to compare the contributions made to the observed pollution layers from the sources of eastern/northern Asia (AS), Europe (EU) and North America (NA). Over 90 % of the contribution to the BC was shown to arise from non-OBB anthropogenic sources.

AS sources were found to be the major contributor to the BC burden, increasing background BC loadings by a factor of 3–5 to 100.8 ± 48.4 ng sm−3 (in standard air m3 at 273.15 K and 1013.25 mbar) and 55.8 ± 22.4 ng sm−3 in the middle and upper troposphere respectively. AS plumes close to the tropopause (about 7.5–8 km) were also observed, with BC concentrations ranging from 55 to 73 ng sm−3, which will potentially have a significant radiative impact. EU sources influenced the middle troposphere with a BC mean concentration of 70.8 ± 39.1 ng sm−3 but made a minor contribution to the upper troposphere due to the relatively high latitude of the source region. The contribution of NA was shown to be much lower at all altitudes with BC mean concentration of 20 ng sm−3. The BC transported to the Arctic is mixed with a non-BC volume fraction representing between 90–95 % of the mass, and has a relatively uniform core size distribution with mass median diameter 190–210 nm and geometric standard deviation σg = 1.55–1.65 and this varied little across all source regions. It is estimated that 60–95 % of BC is scavenged between emission and receptor based on BC / ΔCO comparisons between source inventories and measurement.

We show that during the springtime of 2013, the anthropogenic pollution particularly from sources in Asia, contributed significantly to BC across the European Arctic free troposphere. In contrast to previous studies, the contribution from open wildfires was minimal. Given that Asian pollution is likely to continue to rise over the coming years, it is likely that the radiative forcing in the Arctic will also continue to increase."

[wili]

Kevin Anderson in Nature recently:

“Instead, my long-standing engagement with many colleagues in science, leaves me in no doubt that although they work diligently, often against a backdrop of organised scepticism, many are ultimately choosing to censor their own research.”

http://www.nature.com/ngeo/journal/v8/n12/full/ngeo2559.html

[AbruptSLR]

Kevin Anderson in Nature recently:

“Instead, my long-standing engagement with many colleagues in science, leaves me in no doubt that although they work diligently, often against a backdrop of organised scepticism, many are ultimately choosing to censor their own research.”

http://www.nature.com/ngeo/journal/v8/n12/full/ngeo2559.html

Per the Keeling curve and all of the attached plots, the actual atmospheric GHG concentrations have always been following the BAU pathway rather than the median of either the SRES or the RCP scenarios.  Is this what scientists call good science or wishful thinking?

[AbruptSLR]

The linked article discusses how the number of cars on the road is projected to double by 2030, and that most of the new cars will be burning fossil fuels.  Unless, China & India plan to cripple their economies, this implies that the transportation sector (including planes and trains) will be increasing net emissions for some time to come:

http://www.nytimes.com/2015/12/08/business/energy-environment/despite-push-for-cleaner-cars-sheer-numbers-could-work-against-climate-benefits.html?_r=0

Extract: "The number of automobiles on the world’s roads is on pace to double — to more than two billion — by the year 2030. And more likely than not, most of those cars will be burning carbon-emitting gasoline or diesel fuels.
That’s because much of the expansion will be propelled by the rise of the consumer class in industrializing parts of the globe, especially in China and India, as hundreds of millions of new drivers discover the glory of the open road."

[Sleepy]

A quote from that article in NYT above, by Mr Jonnaert.

“At the end of the day, when you talk about transport emissions for transport in general, including for freight transport, they increase when the economy is growing,” he said. “So what are we going to say, we’re going to stop the economy to stop emissions?”

That's not the question, even if it's a huge reason to resist mitigation.
This one is closer.

To be, or not to be: that is the question:
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,
Or to take arms against a sea of troubles,
And by opposing end them?

I guess Shakespeare never considered that use?

[jai mitchell]

Kevin Anderson interview on Democracy Now at COP-21

So what we do is we fine-tune our analysis so it fits within a sort of a—the political and economic framing of society, the current political and economic framing. So we don’t really say that—actually, our science now asks fundamental questions about this idea of economic growth in the short term, and we’re very reluctant to say that. In fact, the funding bodies often are reluctant to fund research that raises those questions. So the whole setup, not just the scientists, the research community around it that funds the research, the journalists, events like this, we’re all being—we’re all deliberately being slightly sort of self-delusional.

http://www.democracynow.org/2015/12/8/top_climate_expert_crisis_is_worse?autostart=false

[silkman]

I'd suggest that if Kevin were to delete the word "slightly" he'd be a bit closer to the mark. We'll all be the victims of the tyranny of exponential economic growth - even at a modest 2% per annum!

[AbruptSLR]

The linked reference provides evidence that the reduction of large vertebrates in the tropical rainforest is reduction the dispersion of seeds which is limiting carbon storage in those tropical rainforests.  This positive feedback mechanism is not currently included in any AR5 climate model projections:

Carolina Bello, Mauro Galetti, Marco A. Pizo, Luiz Fernando S. Magnago, Mariana F. Rocha, Renato A. F. Lima, Carlos A. Peres, Otso Ovaskainen and Pedro Jordano (18 Dec 2015), "Defaunation affects carbon storage in tropical forests," Science Advances, Vol. 1, no. 11, e1501105, DOI: 10.1126/sciadv.1501105


http://advances.sciencemag.org/content/1/11/e1501105

Abstract: "Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are threatened by hunting, illegal trade, and habitat loss. We used a large data set on tree species composition and abundance, seed, fruit, and carbon-related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores in 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion of large-seeded trees are extirpated. Although intergovernmental policies to reduce carbon emissions and reforestation programs have been mostly focused on deforestation, our results demonstrate that defaunation, and the loss of key ecological interactions, also poses a serious risk for the maintenance of tropical forest carbon storage."

[AbruptSLR]

A paper in the Proceedings of the National Academy of Sciences entitled: "Cold season emissions dominate the Arctic tundra methane budget" (www.pnas.org/cgi/doi/10.1073/pnas.1516017113), indicates that winter emissions from the Arctic permafrost are much higher than assumed in climate models:

http://phys.org/news/2015-12-methane-emissions-arctic-cold-season.html

Extract: "A team comprising ecologists Walter Oechel (SDSU and Open University) and Donatella Zona (SDSU and the University of Sheffield) and scientists from NASA's Jet Propulsion Laboratory (JPL), Harvard University, the National Oceanic and Atmospheric Administration, and the University of Montana, found that far more methane is escaping from Arctic tundra during the cold months—when the soil surface is frozen (generally from September through May)—as well as from upland tundra, than prevailing assumptions and climate modelers previously believed. In fact, they found that at least half of the annual methane emissions occur in the cold months, and that drier, upland tundra can be a larger emitter of methane than wet tundra. The finding challenges critical assumptions in current global climate models."


Edit: The following caption & associate image comes from the linked supplemental material to the paper: "Fig. S6. Gap filling of the methane fluxes. Gap-filled CH4 fluxes (red) superimposed on the measured fluxes (in gray) for the indicated sites: BES (A), BEO (B),
CMDL (C), ATQ (D), and IVO (E)."

http://www.pnas.org/content/suppl/2015/12/17/1516017113.DCSupplemental/pnas.201516017SI.pdf

[AbruptSLR]

The linked article discusses a PNAS paper citing that thinning Arctic Sea Ice is increasing local precipitation.  If/when that increase precipitation comes in the form of rain, we are all in trouble, as that positive feedback (not currently included in model projections) could cause as much global warming as doubling the atmospheric CO₂ concentration:

http://www.csmonitor.com/Science/2015/1221/Arctic-ice-is-melting.-Rainy-days-ahead

Extract: "Scientists struggling to predict the effects of climate change have suspected that melting sea ice, a problem in its own right, has the additional effect of increasing precipitation. But a wetter world doesn't necessarily mean a better one, and researchers' efforts to more precisely track changes at the top of the world have been stymied by its extreme temperatures and winds.
In a paper published Monday by the National Academy of Sciences, researchers from Dartmouth College and Carleton College became the first team to observationally confirm the relationship between melting seas and higher precipitation in the Arctic, pointing to climate feedback loops that could potentially impact temperatures as much as doubling atmospheric carbon dioxide would. It's a factor that, until now, could not accurately be worked into climate change models.
…
Precipitation changes create feedback loops, either reinforcing or resisting the overall trend of upward temperatures. Arctic regions should hope for snow, which is more reflective than water and can help reflect the sun's energy back into space, cooling down the local climate. Rain, on the other hand, just keeps driving the hotter, wetter trend, disrupting the Earth's energy equilibrium.
Either way, it's a significant impact: possibly as big as doubling the atmosphere's carbon dioxide. And while snow alone can't undo the global trend, it could counteract local impacts and "slow things down," Kopec says.
Researchers haven't yet determined which kind of precipitation is dominating the trend, but that's next on Kopec's to-do list; he plans to take a closer look at seasonal trends to determine which feedback loops are gaining ground. And then there's the challenge of figuring out what Arctic trends mean for those of us below the Arctic Circle. "

[AbruptSLR]

While the linked article about evidence that lakes are warming fast focuses on fish and algae; I am concerned that warmer lakes will also likely mean more methane emissions from both lakes & man made reservoirs:

https://www.washingtonpost.com/national/health-science/our-lakes-are-warming-too-and-thats-bad-for-humans-and-fish/2015/12/20/0de0e830-a5a3-11e5-ad3f-991ce3374e23_story.html

[Neven]

Researchers haven't yet determined which kind of precipitation is dominating the trend, but that's next on Kopec's to-do list; he plans to take a closer look at seasonal trends to determine which feedback loops are gaining ground. And then there's the challenge of figuring out what Arctic trends mean for those of us below the Arctic Circle."

He will probably run into this paper as described in this blog post: A wetter and warmer Arctic

[AbruptSLR]

Researchers haven't yet determined which kind of precipitation is dominating the trend, but that's next on Kopec's to-do list; he plans to take a closer look at seasonal trends to determine which feedback loops are gaining ground. And then there's the challenge of figuring out what Arctic trends mean for those of us below the Arctic Circle."

He will probably run into this paper as described in this blog post: A wetter and warmer Arctic

Neven,

Thanks for the link.  My concern is that currently most of the increase precipitation is occurring as snow that is insulating both the permafrost and the sea ice; which could prove to be a masking factor if more and more frequently (with continued warming) this precipitation occurs as rain; which might then unmask this current negative feedback and reveal it as a positive feedback, potentially in the near future.

Best,
ASLR

[AbruptSLR]

The linked reference projects a massive die-off of coniferous trees in the US Southwest sometime this century (and this positive feedback is not included in AR5 projections):

N. G. McDowell, A. P. Williams, C. Xu, W. T. Pockman, L. T. Dickman, S. Sevanto, R. Pangle, J. Limousin, J. Plaut, D. S. Mackay, J. Ogee, J. C. Domec, C. D. Allen, R. A. Fisher, X. Jiang, J. D. Muss, D. D. Breshears, S. A. Rauscher & C. Koven (2015), "Multi-scale predictions of massive conifer mortality due to chronic temperature rise", Nature Climate Change, doi:10.1038/nclimate2873


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2873.html

Abstract: "Global temperature rise and extremes accompanying drought threaten forests and their associated climatic feedbacks. Our ability to accurately simulate drought-induced forest impacts remains highly uncertain in part owing to our failure to integrate physiological measurements, regional-scale models, and dynamic global vegetation models (DGVMs). Here we show consistent predictions of widespread mortality of needleleaf evergreen trees (NET) within Southwest USA by 2100 using state-of-the-art models evaluated against empirical data sets. Experimentally, dominant Southwest USA NET species died when they fell below predawn water potential (Ψpd) thresholds (April–August mean) beyond which photosynthesis, hydraulic and stomatal conductance, and carbohydrate availability approached zero. The evaluated regional models accurately predicted NET Ψpd, and 91% of predictions (10 out of 11) exceeded mortality thresholds within the twenty-first century due to temperature rise. The independent DGVMs predicted ≥50% loss of Northern Hemisphere NET by 2100, consistent with the NET findings for Southwest USA. Notably, the global models underestimated future mortality within Southwest USA, highlighting that predictions of future mortality within global models may be underestimates. Taken together, the validated regional predictions and the global simulations predict widespread conifer loss in coming decades under projected global warming."


See also:
https://www.washingtonpost.com/news/energy-environment/wp/2015/12/21/scientists-say-climate-change-could-cause-a-massive-tree-die-off-in-the-southwest/

Extract: "In a troubling new study just out in Nature Climate Change, a group of researchers says that a warming climate could trigger a “massive” dieoff of coniferous trees, such as junipers and piñon pines, in the U.S. southwest sometime this century."

[Neven]

Researchers haven't yet determined which kind of precipitation is dominating the trend, but that's next on Kopec's to-do list; he plans to take a closer look at seasonal trends to determine which feedback loops are gaining ground. And then there's the challenge of figuring out what Arctic trends mean for those of us below the Arctic Circle."

He will probably run into this paper as described in this blog post: A wetter and warmer Arctic

Neven,

Thanks for the link.  My concern is that currently most of the increase precipitation is occurring as snow that is insulating both the permafrost and the sea ice; which could prove to be a masking factor if more and more frequently (with continued warming) this precipitation occurs as rain; which might then unmask this current negative feedback and reveal it as a positive feedback, potentially in the near future.

Best,
ASLR

Ah yes, I forgot that precipitation also includes snow. Silly me.

[AbruptSLR]

The linked reference indicates that ECS has a 95%CL range of from 3C to 6.3C, with a best estimate of 4C:

Climate sensitivity by Roy Thompson published by Earth and Environmental Science Transactions of the Royal Society of Edinburgh, DOI: 10.1017/S1755691015000213

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10061758&fileId=S1755691015000213

Abstract: "Earth has been habitable through most of its history, but the anthropogenically mediated greenhouse effect, if sufficiently strong, can threaten Earth's long-standing equability. This paper's main aim is to determine the strength of the anthropogenic greenhouse effect (the climate sensitivity) from observational data and basic physics alone, without recourse to the parameterisations of earth-system models and their inevitable uncertainties. A key finding is that the sensitivity can be constrained by harmonising historical records of land and ocean temperatures with observations of potential climate-change drivers in a non-steady state, energy-balance equation via a least-squares optimisation. The global temperature increase, for a CO2 doubling, is found to lie (95 % confidence limits) between 3.0^oC and 6.3^oC, with a best estimate of +4^oC. Under a business-as-usual scenario, which assumes that there will be no significant change in people's attitudes and priorities, Earth's surface temperature is forecast to rise by 7.9^oC over the land, and by 3.6^oC over the oceans, by the year 2100. Global temperature rise has slowed in the last decade, leading some to question climate predictions of substantial 21st-Century warming. A formal runs test, however, shows that the recent slowdown is part of the normal behaviour of the climate system."

[Shared Humanity]

It's game  over if this is the case.

[AbruptSLR]

It's game  over if this is the case.

I think that people need to start opening their eyes.  As this is only ECS, it is possible that if traditionally slow response positive feedback mechanisms become fast response (as we are exceeding any radiative forcing for hundreds of millions of years) we could be in for even more consequences.

[Sleepy]

Wise words.
People need to look at everything. Not just what they want to see.

Video with Roy Thompson.

[AbruptSLR]

With a hat tip to salbers (see post in the Permafrost folder), I provide the following linked open access reference, which helps to further quantify the risk of significant methane emissions from the East Siberian Arctic Shelf, ESAS, this century:

Natalia Shakhova, Igor Semiletov, Valentin Sergienko, Leopold Lobkovsky, Vladimir Yusupov, Anatoly Salyuk, Alexander Salomatin, Denis Chernykh, Denis Kosmach, Gleb Panteleev, Dmitry Nicolsky, Vladimir Samarkin, Samantha Joye, Alexander Charkin, Oleg Dudarev, Alexander Meluzov, Orjan Gustafsson (7 September 2015), "The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice", Philosophical Transactions A, DOI: 10.1098/rsta.2014.0451

http://rsta.royalsocietypublishing.org/content/373/2052/20140451

Abstract: "Sustained release of methane (CH4) to the atmosphere from thawing Arctic permafrost may be a positive and significant feedback to climate warming. Atmospheric venting of CH4 from the East Siberian Arctic Shelf (ESAS) was recently reported to be on par with flux from the Arctic tundra; however, the future scale of these releases remains unclear. Here, based on results of our latest observations, we show that CH4 emissions from this shelf are likely to be determined by the state of subsea permafrost degradation. We observed CH4 emissions from two previously understudied areas of the ESAS: the outer shelf, where subsea permafrost is predicted to be discontinuous or mostly degraded due to long submergence by seawater, and the near shore area, where deep/open taliks presumably form due to combined heating effects of seawater, river run-off, geothermal flux and pre-existing thermokarst. CH4 emissions from these areas emerge from largely thawed sediments via strong flare-like ebullition, producing fluxes that are orders of magnitude greater than fluxes observed in background areas underlain by largely frozen sediments. We suggest that progression of subsea permafrost thawing and decrease in ice extent could result in a significant increase in CH4 emissions from the ESAS."

[AbruptSLR]

The linked open access reference studied atmospheric methane and ethane concentrations from 1999 thru 2014 (see associated image).  The authors found that since 2007 atmospheric methane concentrations have been increase at a rate of over 6 ppb, with the sources primarily coming from tropical wetlands and secondarily from anthropogenic sources.  This indicates that we are current following a BAU pathway for these two greenhouse gases:

Hausmann, P., Sussmann, R., and Smale, D.: Contribution of oil and natural gas production to renewed increase of atmospheric methane (2007–2014): top-down estimate from ethane and methane column observations, Atmos. Chem. Phys. Discuss., 15, 35991-36028, doi:10.5194/acpd-15-35991-2015, 2015.

http://www.atmos-chem-phys-discuss.net/15/35991/2015/acpd-15-35991-2015.html

Abstract. Harmonized time series of column-averaged mole fractions of atmospheric methane and ethane over the period 1999–2014 are derived from solar Fourier transform infrared (FTIR) measurements at the Zugspitze summit (47° N, 2964 m a.s.l.) and at Lauder (45° S, 370 m a.s.l.). Long-term trend analysis reveals a consistent renewed methane increase since 2007 of 6.2 [5.6, 6.9] ppb yr−1 at the Zugspitze and 6.0 [5.3, 6.7] ppb yr−1 at Lauder (95 % confidence intervals). Several recent studies provide pieces of evidence that the renewed methane increase is most likely driven by two main factors: (i) increased methane emissions from tropical wetlands, followed by (ii) increased thermogenic methane emissions due to growing oil and natural gas production. Here, we quantify the magnitude of the second class of sources, using long-term measurements of atmospheric ethane as tracer for thermogenic methane emissions. In 2007, after years of weak decline, the Zugspitze ethane time series shows the sudden onset of a significant positive trend (2.3 [1.8, 2.8] × 10-2 ppb yr−1 for 2007–2014), while a negative trend persists at Lauder after 2007 (−0.4 [−0.6, −0.1] × 10-2 ppb yr−1). Zugspitze methane and ethane time series are significantly correlated for the period 2007–2014 and can be assigned to thermogenic methane emissions with an ethane-to-methane ratio of 10–21 %. We present optimized emission scenarios for 2007–2014 derived from an atmospheric two-box model. From our trend observations we infer a total ethane emission increase over the period 2007–2014 from oil and natural gas sources of 1–11 Tg yr−1 along with an overall methane emission increase of 24–45 Tg yr−1. Based on these results, the oil and natural gas emission contribution C to the renewed methane increase is deduced using three different emission scenarios with dedicated ranges of methane-to-ethane ratios (MER). Reference scenario 1 assumes an oil and gas emission combination with MER = 3.3–7.6, which results in a minimum contribution C > 28 % (given as lower bound of 99 % confidence interval). For the limiting cases of pure oil-related emissions with MER = 1.7–3.3 (scenario 2) and pure natural gas sources with MER = 7.6–12.1 (scenario 3) the results are C > 13 % and C > 53 %, respectively. Our results suggest that long-term observations of column-averaged ethane provide a valuable constraint on the source attribution of methane emission changes and provide basic knowledge for developing effective climate change mitigation strategies.

[AbruptSLR]

The linked reference indicates that the Amazon is more sensitive to climate change (not counting wildfires and logging) than traditional models have assumed:


Naomi M. Levine, Ke Zhang, Marcos Longo, Alessandro Baccini, Oliver L. Phillips, Simon L. Lewis, Esteban Alvarez-Dávila, Ana Cristina Segalin de Andrade, Roel J. W. Brienen, Terry L. Erwin, Ted R. Feldpausch, Abel Lorenzo Monteagudo Mendoza, Percy Nuñez Vargas, Adriana Prieto, Javier Eduardo Silva-Espejo, Yadvinder Malhi, and Paul R. Moorcroft (2015), "Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change", PNAS, doi: 10.1073/pnas.1511344112


http://www.pnas.org/content/early/2015/12/23/1511344112


Significance
Understanding how changes in climate will affect terrestrial ecosystems is particularly important in tropical forest regions, which store large amounts of carbon and exert important feedbacks onto regional and global climates. By combining multiple types of observations with a state-of-the-art terrestrial ecosystem model, we demonstrate that the sensitivity of tropical forests to changes in climate is dependent on the length of the dry season and soil type, but also, importantly, on the dynamics of individual-level competition within plant canopies. These interactions result in ecosystems that are more sensitive to changes in climate than has been predicted by traditional models but that transition from one ecosystem type to another in a continuous, non–tipping-point manner.

Abstract
Amazon forests, which store ∼50% of tropical forest carbon and play a vital role in global water, energy, and carbon cycling, are predicted to experience both longer and more intense dry seasons by the end of the 21st century. However, the climate sensitivity of this ecosystem remains uncertain: several studies have predicted large-scale die-back of the Amazon, whereas several more recent studies predict that the biome will remain largely intact. Combining remote-sensing and ground-based observations with a size- and age-structured terrestrial ecosystem model, we explore the sensitivity and ecological resilience of these forests to changes in climate. We demonstrate that water stress operating at the scale of individual plants, combined with spatial variation in soil texture, explains observed patterns of variation in ecosystem biomass, composition, and dynamics across the region, and strongly influences the ecosystem’s resilience to changes in dry season length. Specifically, our analysis suggests that in contrast to existing predictions of either stability or catastrophic biomass loss, the Amazon forest’s response to a drying regional climate is likely to be an immediate, graded, heterogeneous transition from high-biomass moist forests to transitional dry forests and woody savannah-like states. Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions.

[AbruptSLR]

The linked reference tinkers with the efficacies of various feedbacks in AR5 climate models to essentially conclude that AR5 when too far (w.r.t. erring on the side of least drama) when it cited that ECS could be as low as 1.5C.  Otherwise, this recalculation exercise still shows a wide possible range of TCR and ECS values as indicated in the attached tables from the supplementary material.  This uncertainty still allows people like Gavin Schmidt to continue leaning towards erring on the side of least drama (with regard to TCR & ECS values); however, as most of their observed (satellite era) data was taken during the faux hiatus, I suspect that if they were to re-run their exercise after the next two decades they would likely lean towards higher TCR & ECS values than they are currently willing to acknowledge:

Kate Marvel, Gavin A. Schmidt, Ron L. Miller & Larissa S. Nazarenko (2015) "Implications for climate sensitivity from the response to individual forcings", Nature Climate Change, doi:10.1038/nclimate2888


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2888.html
http://www.nature.com/nclimate/journal/vaop/ncurrent/extref/nclimate2888-s1.pdf

Abstract: "Climate sensitivity to doubled CO2 is a widely used metric for the large-scale response to external forcing. Climate models predict a wide range for two commonly used definitions: the transient climate response (TCR: the warming after 70 years of CO2 concentrations that rise at 1% per year), and the equilibrium climate sensitivity (ECS: the equilibrium temperature change following a doubling of CO2 concentrations). Many observational data sets have been used to constrain these values, including temperature trends over the recent past, inferences from palaeoclimate and process-based constraints from the modern satellite era. However, as the IPCC recently reported, different classes of observational constraints produce somewhat incongruent ranges. Here we show that climate sensitivity estimates derived from recent observations must account for the efficacy of each forcing active during the historical period. When we use single-forcing experiments to estimate these efficacies and calculate climate sensitivity from the observed twentieth-century warming, our estimates of both TCR and ECS are revised upwards compared to previous studies, improving the consistency with independent constraints."