Conservative Scientists & its Consequences

[AbruptSLR]

The attached image of the NASA-NOAA 2015 Surface Temperature Anomaly map highlights the rapid warming that took place last year in Siberia.  That reminded me of the following post that I recently made in the "Permafrost" folder:

The linked open access reference indicates that degradation of continuous areas of permafrost (such as in Siberia) currently results in increased local evaporation which in turn promotes local summertime rainfall that promotes snow cover loss, resulting in a current positive feedback for accelerated climate change (global warming).  However, the paper also notes that in the distant future when the permafrost is largely degraded, this pattern should result in less rainfall and a general drying out of the Arctic regions:

Trent Ford & Oliver W. Frauenfeld (January 2016), Surface-Atmosphere Moisture Interactions in the Frozen Ground Regions of Eurasia", Scientific Reports, Vol 6, No 19163, doi: 10.1038/srep19163

http://www.nature.com/articles/srep19163

See also:
http://www.newswise.com/articles/future-of-arctic-may-depend-on-permafrost

That in-turn reminded me of the following Melles et al (2012) reference, indicating that Siberia has exhibited high Arctic Amplification for millions of years; which made me wonder whether a large part of the reason for the high Siberian Amplification (or Alaskan Amplification by extension) is due to the local rainfall feedback mechanism identified by Ford et al (2016):


Martin Melles, Julie Brigham-Grette, Pavel S. Minyuk, Norbert R. Nowaczyk, Volker Wennrich, Robert M. DeConto, Patricia M. Anderson, Andrei A. Andreev, Anthony Coletti, Timothy L. Cook, Eeva Haltia-Hovi, Maaret Kukkonen, Anatoli V. Lozhkin, Peter Rosén, Pavel Tarasov, Hendrik Vogel & Bernd Wagner (20 July 2012), "2.8 Million Years of Arctic Climate Change from Lake El’gygytgyn, NE Russia", Science, Vol. 337 no. 6092 pp. 315-320, DOI: 10.1126/science.1222135


https://www.geo.umass.edu/climate/papers2/Melles_Science2012.pdf

ABSTRACT
"The reliability of Arctic climate predictions is currently hampered by insufficient knowledge of natural climate variability in the past. A sediment core from Lake El’gygytgyn in northeastern (NE) Russia provides a continuous, high-resolution record from the Arctic, spanning the past 2.8 million years. This core reveals numerous “super interglacials” during the Quaternary; for marine benthic isotope stages (MIS) 11c and 31, maximum summer temperatures and annual precipitation values are ~4° to 5°C and ~300 millimeters higher than those of MIS 1 and 5e. Climate simulations show that these extreme warm conditions are difficult to explain with greenhouse gas and astronomical forcing alone, implying the importance of amplifying feedbacks and far field influences. The timing of Arctic warming relative to West Antarctic Ice Sheet retreats implies strong interhemispheric climate connectivity."

See also:
http://www.clim-past.net/special_issue48.html

[Theta]

New research indicates that a 2 degree rise in temperature would result in a massive jump in temperature by 2030.

The research states that worldwide temperature extremes could be 6 degrees

Under a business as usual scenario, the world is not expected to see global average temperatures rise by 2 degrees Celsius compared to preindustrial times until the 2040s. However, new research shows that this may not be the case, and temperatures may rise far more quickly than expected.
In this latest study, the researchers found worldwide warming extremes over land generally exceeded the rise in the commonly seen scenario. In fact, it exceeded it in some instances by as much as 6 degrees Celsius.

http://www.scienceworldreport.com/articles/36219/20160121/2-degree-rise-temperature-cause-massive-increase-temperatures-worldwide.htm

[AbruptSLR]

For those wanting a direct link to the reference that Theta cites, it is provided below and it focuses on regional impacts:

Sonia I. Seneviratne, Markus G. Donat, Andy J. Pitman, Reto Knutti & Robert L. Wilby (2016), "Allowable CO2 emissions based on regional and impact-related climate targets", Nature, doi:10.1038/nature16542


http://www.nature.com/nature/journal/vaop/ncurrent/full/nature16542.html


Abstract: "Global temperature targets, such as the widely accepted limit of an increase above pre-industrial temperatures of two degrees Celsius, may fail to communicate the urgency of reducing carbon dioxide (CO2) emissions. The translation of CO2 emissions into regional- and impact-related climate targets could be more powerful because such targets are more directly aligned with individual national interests. We illustrate this approach using regional changes in extreme temperatures and precipitation. These scale robustly with global temperature across scenarios, and thus with cumulative CO2 emissions. This is particularly relevant for changes in regional extreme temperatures on land, which are much greater than changes in the associated global mean."

[AbruptSLR]

As I think that the Egbert H. van Nes et al (2015) reference cited in Reply #1291 is important, I provide the following linked article that discusses this paper and provides a video summarizing the implications:

http://phys.org/news/2015-03-evidence-positive-feedback-climate.html

Extract: "... researchers can now confirm directly from ice-core data that the global temperature has a profound effect on atmospheric greenhouse gas concentrations. This means that as the Earth's temperature rises, the positive feedback in the system results in additional warming."

[AbruptSLR]

The linked reference indicates by combining of A-train satellite observations and modelling should allow for the determination of short-term cloud feedback:

Qing Yue, Brian H. Kahn, Eric J. Fetzer, Mathias Schreier, Sun Wong, Xianglei Huang & Xiuhong Chen (2016), "Observation-based Longwave Cloud Radiative Kernels Derived from the A-Train", Journal of Climate, doi: http://dx.doi.org/10.1175/JCLI-D-15-0257.1


http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0257.1

Abstract: "We present a new method to derive both the broadband and spectral longwave observation-based cloud radiative kernels (CRKs) using cloud radiative forcing (CRF) and cloud fraction (CF) for different cloud types using multi-sensor A-Train observations and MERRA collocated on the pixel scale. Both observation-based CRKs and model-based CRKs derived from the Fu-Liou radiative transfer model are shown. Good agreement between observation- and model-derived CRKs is found for optically thick clouds. For optically thin clouds, the observation-based CRKs show a larger radiative sensitivity at TOA to cloud cover change than model-derived CRKs. Four types of possible uncertainties in the observed CRKs are investigated: 1) uncertainties in Moderate Resolution Imaging Spectroradiometer cloud properties; 2) the contributions of clear-sky changes to the CRF; 3) the assumptions regarding clear-sky thresholds in the observations; and 4) the assumption of a single-layer cloud. The observation-based CRKs show the TOA radiative sensitivity of cloud types to unit cloud fraction change as observed by A-Train. Therefore, a combination of observation-based CRKs with cloud changes observed by these instruments over time will provide an estimate of the short-term cloud feedback by maintaining consistency between CRKs and cloud responses to climate variability."

[sidd]

I thank AbruptSLR for reiterating the pointer to van Nes  doi:10.1038/NCLIMATE2568
the paper is important for the results, but also for the extension of the demonstration in
Sugihara(2012)

van Nes led me back to Takens(1981) of which I was dimly aware back then, being but a humble phycisist, but not a mathematician then (or now.)  But I did and do have mathematician friends and we have ventured to apply some of this.

I list some of my breadcrumbs along the trail after reading Egbert:

Takens(1981) "Detecting strange attractors in turbulence" available after a cursory search.
Sugihara (1994) Phil. Trans. Roy. Soc. A, 1994, pp 497-495
Sugihara(2012) doi:10.1126/science.1227079

Have fun, I am. The technique is not so hard to use. I have some code i can share.

sidd

[AbruptSLR]

I thank AbruptSLR for reiterating the pointer to van Nes  doi:10.1038/NCLIMATE2568
the paper is important for the results, but also for the extension of the demonstration in
Sugihara(2012)

van Nes led me back to Takens(1981) of which I was dimly aware back then, being but a humble phycisist, but not a mathematician then (or now.)  But I did and do have mathematician friends and we have ventured to apply some of this.

I list some of my breadcrumbs along the trail after reading Egbert:

Takens(1981) "Detecting strange attractors in turbulence" available after a cursory search.
Sugihara (1994) Phil. Trans. Roy. Soc. A, 1994, pp 497-495
Sugihara(2012) doi:10.1126/science.1227079

Have fun, I am. The technique is not so hard to use. I have some code i can share.

sidd

sidd,

Thanks for your contributions to this important topic.  Also, in my opinion strange attractor manifolds cannot only be used to provide paleo-evidence of relatively high values of past ECS, but also, as illustrated in the attached image, such strange attractors like the ENSO cycle can accelerate a global warming trend by ratcheting up such quasi-static [episodic] equilibrium Earth System states as: (a) accelerated degradation of tropical rainforests via drought/flood cycles; (b) accelerated advection of atmospheric water vapor [which is GHG] from southern latitudes (such as the Mediterranean Sea) to the Arctic; and (c) accelerated collapse of the WAIS, which per Hansen et al 2015 will result in a several decade long increase in the planetary imbalance.

Best,
ASLR

[AbruptSLR]

The linked research indicates that anthropogenic GHG has weakened the Walker Cell over the past 100-years, and that continued anthropogenic GHG emissions will:
(a) Shift the center of the Walker Cell eastward, which is indicative of an increased frequency of El Nino events;
(b) Decrease rainfall in Indonesia, which will increase wildfires and peat-fires; and
(c) Amplify warming near the tropical equator in the future

All of these are positive feedback effects that are not included in AR5 projections:

Katinka Bellomo & Amy C. Clement (21 September 2015), "Evidence for weakening of the Walker circulation from cloud observations", Geophysical Research Letters, DOI: 10.1002/2015GL065463


http://onlinelibrary.wiley.com/doi/10.1002/2015GL065463/abstract

Abstract: "Climate models simulate a weakening of the Walker circulation in response to increased greenhouse gases, but it has not been possible to detect this weakening with observations because there are not direct measurements of atmospheric circulation strength. Indirect measurements, such as equatorial gradients in sea level pressure (SLP), exhibit trends of inconsistent sign. In this study we estimate the change in midtropospheric velocity (ω500) from observed change in cloud cover, which we argue is more closely tied to the overturning circulation than indirect measurements of SLP at the surface. Our estimates suggest a weakening and eastward shift of the Walker circulation over the last century. Because changes in cloud cover in Atmospheric Model Intercomparison Project simulations forced with increased sea surface temperature are remarkably similar in pattern, sign, and magnitude, we assert that the observed changes in cloud cover and the associated weakening of Walker circulation are at least in part externally forced."

See also:
http://phys.org/news/2015-11-cloud-tropical-pacific-reveals-future.html
Extract: "A new analysis using changes in cloud cover over the tropical Indo-Pacific Ocean showed that a weakening of a major atmospheric circulation system over the last century is due, in part, to increased greenhouse gas emissions. The findings from researchers at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science provide new evidence that climate change in the tropical Pacific will result in changes in rainfall patterns in the region and amplify warming near the equator in the future.
…
Their findings revealed a weakening and eastward shift of the Walker circulation over the last century due to greenhouse gas emissions.
…
The study suggests that rainfall will decrease over Indonesia and in the western Pacific and increase over the central Pacific Ocean."

[AbruptSLR]

The linked (open access) reference discusses methodology that might be able to access the risk of abrupt Arctic Sea Ice loss, given sufficient short-term data:


Bathiany, S., van der Bolt, B., Williamson, M. S., Lenton, T. M., Scheffer, M., van Nes, E., and Notz, D. (2016), "Trends in sea-ice variability on the way to an ice-free Arctic", The Cryosphere Discuss., doi:10.5194/tc-2015-209.

http://www.the-cryosphere-discuss.net/tc-2015-209/tc-2015-209.pdf

Abstract: " It has been widely debated whether Arctic sea-ice loss can reach a tipping point, beyond which a large sea-ice area disappears abruptly. An important argument for this scenario is the destabilising role of the ice-albedo feedback. The theory of dynamical systems predicts a "slowing down" when a system destabilises towards a tipping point. In simple stochastic systems this can result in increasing variance and autocorrelation, potentially yielding an early warning of an abrupt change. Here we aim to establish whether the loss of Arctic sea ice would follow these conceptual predictions, and which trends in sea ice variability can be expected from pre-industrial conditions toward an Arctic that is ice-free during the whole year.

To this end, we apply a model hierarchy consisting of two box models and one comprehensive Earth system model. We find a consistent and robust decrease of the ice volume's annual relaxation time before summer ice is lost because thinner ice can adjust more quickly to perturbations. Thereafter, the relaxation time increases, mainly because the system becomes dominated by the ocean water's large heat capacity when the ice-free season becomes longer. Both trends carry over to the autocorrelation of sea ice thickness in time series. Also accounting for the geometric effect of increasing open-water formation efficiency for thinning ice, we obtain an increasing variability in sea-ice area fraction, but a decreasing variability in sea-ice thickness.

These changes are robust to the nature and origin of climate variability in the models and hardly depend on the balance of feed backs. Therefore, characteristic trends can be expected in the future. As these trends are not specific to the existence of abrupt ice loss, the prospects for early warnings seem very limited. This result also has implications for statistical indicators in other systems whose effective "mass" changes over time, affecting the trend of their relaxation time. However, the robust relation between state and variability would allow an estimate of sea-ice variability from only short observations. This could help one to estimate the likelihood and persistence of extreme events in the future."

[AbruptSLR]

The linked (open access) reference uses mitigation delay sensitivity (MDS) to explain why delays in reducing GHG emissions, activates long-term Earth system changes a much faster rates (e.g. 7 to 25 times faster for increases in peak long-term temperature) than what we are currently observing:

Patrik L Pfister and Thomas F Stocker (21 January 2016), "Earth system commitments due to delayed mitigation", Environ. Res. Lett. 11 (2016) 014010, doi:10.1088/1748-9326/11/1/014010


http://iopscience.iop.org/article/10.1088/1748-9326/11/1/014010/pdf

Abstract: "As long as global CO2 emissions continue to increase annually, long-term committed Earth system changes grow much faster than current observations. A novel metric linking this future growth to policy decisions today is the mitigation delay sensitivity (MDS), but MDS estimates for Earth system variables other than peak temperature (ΔTmax) are missing. Using an Earth System Model of Intermediate Complexity, we show that the current emission increase rate causes a ΔTmax increase roughly 3–7.5 times as fast as observed warming, and a millenial steric sea level rise (SSLR) 7–25 times as fast as observed SSLR, depending on the achievable rate of emission reductions after the peak of emissions. These ranges are only slightly affected by the uncertainty range in equilibrium climate sensitivity, which is included in the above values. The extent of ocean acidification at the end of the century is also strongly dependent on the starting time and rate of emission reductions. The preservable surface ocean area with sufficient aragonite supersaturation for coral reef growth is diminished globally at an MDS of roughly 25%–80% per decade. A near-complete loss of this area becomes unavoidable if mitigation is delayed for a few years to decades. Also with respect to aragonite, 12%–18% of the Southern Ocean surface become undersaturated per decade, if emission reductions are delayed beyond 2015–2040.Weconclude that the consequences of delaying global emission reductions are much better captured if the MDS of relevant Earth system variables is communicated in addition to current trends and total projected future changes."

[AbruptSLR]

The linked reference could not make it more clear that paleo-evidence from inter-glacial periods indicates that ECS is meaningfully higher than 3C and that climate models are commonly under predicting the magnitude of coming climate change.

Dana L. Royer (2016), "Climate Sensitivity in the Geologic Past", Annual Review of Earth and Planetary Sciences, Vol. 44


http://www.annualreviews.org/doi/abs/10.1146/annurev-earth-100815-024150?src=recsys


Abstract: "The response of temperature to CO2 change (climate sensitivity) in the geologic past may help inform future climate predictions. Proxies for CO2 and temperature generally imply high climate sensitivities: ≥3 K per CO2 doubling during ice-free times (“fast-feedback” sensitivity) and ≥6 K during times with land ice (Earth-system sensitivity). Climate models commonly under predict the magnitude of climate change and have fast-feedback sensitivities close to 3 K. A better characterization of feedbacks in warm worlds boosts climate sensitivity to values more in line with proxies and produce climate simulations that better fit geologic evidence. As CO2 builds in our atmosphere, we should expect both slow (e.g., land ice) and fast (e.g., vegetation, clouds) feedbacks to elevate the long-term temperature response over that predicted from the canonical fast-feedback value of 3 K. Because temperatures will not decline for centuries to millennia, climate sensitivities that integrate slower processes do have relevance for current climate policy."

Edit: These finding concur with those of Köhler et al (2015) cited in Reply #1253; which indicates that inter-glacial values for specific ECS was about 45% higher than during glacial periods.  See also Reply #1254.

[AbruptSLR]

The linked reference presents ultra-high-resolution paleo-data from a Santa Barbara Basin seafloor core, indicating that 631.5ka an abrupt 4-5C sea surface warming occurred in about a 50-year period.  This abrupt warming was geochemically linked to repeated discharges of methane into the atmosphere from methane hydrate disassociation with both ocean warming and low sea level (as this was a glacial period).  While there are clear differences between the MIS 16-15 boundary conditions and those today; nevertheless, the finding that the introduction of warm ocean water into shallow seas areas (like continental shelves around the world and most notably in the East Siberian Arctic Shelf, ESAS) can lead to repeated large discharges of methane into the atmosphere certainly sound similar to the "Clathrate Gun" theory.  This is additionally disturbing as scientists are finding that the deep ocean heat content is increasing much faster than they previously assumed:

Walter E. Dean, James P. Kennett, Richard J. Behl, Craig Nicholson, Christopher C. Sorlien (2015), "Abrupt termination of Marine Isotope Stage 16 (Termination VII) at 631.5 ka in Santa Barbara Basin, California", Paleoceanography, 30 (10): 1373 DOI: 10.1002/2014PA002756

http://onlinelibrary.wiley.com/doi/10.1002/2014PA002756/abstract

Abstract: "The Marine Isotope Stage 16–15 boundary (Termination VII) is the first deglacial warming step of the late Quaternary following the mid-Pleistocene transition (MPT), when 41 kyr climatic cycles shifted to strong 100 kyr cycles. The detailed structure of this important climatic event has remained unknown until now. Core MV0508-19JPC from Santa Barbara Basin, California, contains a decadal-scale climatic and geochemical sediment record of 4000 years duration that includes the early part of this deglacial episode. This record reveals that the climatic shift during the early deglacial occurred rapidly (<700 years), in a progression of three abrupt warming steps. The onset of Marine Isotope Stage (MIS) 15 was remarkably abrupt with 4–5°C sea surface warming in ~50 years. The deglacial sequence contains the well-dated Lava Creek tephra (631.3 ± 4 ka) from Yellowstone Caldera used to date the onset of Termination VII at 631.5 ka. The late MIS 16 and early MIS 15 interval exhibits multiple decadal-scale negative excursions in δ13C of planktic foraminifera, likely the result of repeated discharges of methane from methane hydrates associated with both ocean warming and low sea level. A warm interstadial that interrupts late MIS 16 is marked by elevated concentrations of redox-sensitive elements indicating sulfidic, oxygen-deficient bottom and pore-waters, and elevated concentrations of total organic carbon and Cd, reflecting increased surface productivity. Unlike younger sediments on the California margin, these indicators of increased productivity and low dissolved oxygen do not consistently correspond with each other or with preserved laminations, possibly reflecting instability of a still evolving ocean-atmosphere system following the MPT."


See also:
http://www.sciencedaily.com/releases/2015/12/151202155724.htm

Extract: "… a core from the ocean floor in the Santa Barbara Basin provides a remarkable ultra-high-resolution record of Earth's paleoclimate history during a brief, dynamic time hundreds of thousands of years ago.
New research from UC Santa Barbara geologist James Kennett and colleagues examines a shift from a glacial to an interglacial climate that began about 630,000 years ago. Their research demonstrates that, although this transition developed over seven centuries, the initial shift required only 50 years. Called a deglacial episode because of its association with the melting of large Northern Hemisphere ice sheets, this interval illustrates the extreme sensitivity to change of Earth's climate system.  The findings appear in the journal Paleoceanography.
"One of the most astonishing things about our results is the abruptness of the warming in sea surface temperatures," explained co-author Kennett, a professor emeritus in UCSB's Department of Earth Science. "Of the 45 degree Fahrenheit total, a shift of about 40 degrees occurred almost immediately right at the beginning."

…

Kennett noted that this remarkable record of paleoclimate changes also raises an important question: What process can possibly push Earth's climate so fast from a glacial to an interglacial state? The researchers may have discovered the answer based on the core's geochemical record: The warming associated with the major climatic shift was accompanied by simultaneous releases of methane -- a potent greenhouse gas.
"This particular episode of climate change is closely associated with instability that caused the release of methane from gas hydrates at the ocean floor," Kennett said. "These frozen forms of methane melt when temperatures rise or pressure decreases. Changes in sea level affect the stability of gas hydrates and water temperature even more so.
"The clear synchronism of this rapid warming and the onset of the destabilization of gas hydrates is important," Kennett concluded. "It suggests that methane hydrate instability and the warming are somehow linked, which is an interesting and potentially important observation. The beauty of these paleoclimate records from the Santa Barbara Basin is that you can actually determine these relationships at high fidelity.""

Edit: For reference I provide the attached plot from Hansen & Sato (2011) showing the relative temperatures 631.5ka ago.

[Sigmetnow]

Why Scientists Need to Give Up on the Passive Voice

Among other things, the passive voice may make it more difficult to celebrate particular scientific accomplishments. When scientists fight for the passive voice, they’re not fighting for their right to write poorly. They think science should speak for itself. But in a time when climate change deniers blind themselves to hard data and vaccine conspiracy theorists blithely cover their ears to public health risks, it has never been more clear that science doesn’t speak for itself.

http://www.slate.com/blogs/future_tense/2015/04/01/scientists_should_stop_writing_in_the_passive_voice.html

[wili]

This covers ground already gone over here, but it's good to see more of this brought to light in the msm: http://www.abc.net.au/news/2016-01-29/glikson-the-dilemma-of-a-climate-scientist/7123246

Global heating and the dilemma of climate scientists

In private conversations, many climate scientists express far greater concern at the progression of global warming and its consequences than they do in public

"Climate scientists have been so distracted and intimidated by the relentless campaign against them that they tend to avoid any statements that might get them labelled 'alarmists', retreating into a world of charts and data."

...

So why don't many scientists talk more directly to the public?

There is more than one answer to this question.

For one, they do.

A number of prominent climate scientists, mostly representing the scientific consensus on climate change documented by the IPCC, have tried their best to convey the message in public forums. These scientists are mostly shunned by the conservative media which commonly offers platforms for those who do not accept the scientific evidence and the basic laws of nature.


...A sizable group of climate scientists tends to regard the IPCC-based climate consensus as too optimistic.

However, mostly these scientists tend to be shunned by the media...

...There is a heavy price to be paid for those who alert the public to dangers against collective optimism since, even though the alarm is based on hard evidence, such people are denounced as alarmists, scaremongers, including such accusations as "pagan emptiness".

In a rare twist of the facts, climate scientists are referred to as 'warmists', even though what they do is the opposite, warning the world against GHG-triggered global warming.

Scientists have lost employment in government and other institutions. Scientists have been abused and threatened, and continue to face potential Royal Commissions and Congressional inquiries, constituting McCarthy-type witch hunts by those who deny the science.

Perhaps worst are the personal effects on, and responses, by people immediately associated with scientists, including friends and family.

Many, already aware of the progression and dangers posed by global warming, and who experience climate change fatigue, are reluctant to follow the gory details. Going downtown, caught by traffic jams, walking through the malls, watching school children apparently unaware of the risk to their future, reflecting on the criminal consequences of saturating the atmosphere with carbon and on the lies propagated by those who do not accept the scientific method - climate scientists despair from expressing the unthinkable.

[AbruptSLR]

The linked reference reassesses ECS from CMIP3 &5 and find an ensemble-mean of 3.9C, and I note that CMIP3&5 likely err on the side of least drama as they ignore several important non-linear slow feedbacks that could be accelerated by global warming:

Chengxing Zhai, Jonathan H. Jiang, Hui Su (2015), "Long-term cloud change imprinted in seasonal cloud variation: More evidence of high climate sensitivity", Geophysical Research Letters, DOI: 10.1002/2015GL065911

http://onlinelibrary.wiley.com/doi/10.1002/2015GL065911/full

Abstract: "The large spread of model equilibrium climate sensitivity (ECS) is mainly caused by the differences in the simulated marine boundary layer cloud (MBLC) radiative feedback. We examine the variations of MBLC fraction in response to the changes of sea surface temperature (SST) at seasonal and centennial time scales for 27 climate models that participated in the Coupled Model Intercomparison Project phase 3 and phase 5. We find that the intermodel spread in the seasonal variation of MBLC fraction with SST is strongly correlated with the intermodel spread in the centennial MBLC fraction change per degree of SST warming and that both are well correlated with ECS. Seven models that are consistent with the observed seasonal variation of MBLC fraction with SST at a rate −1.28 ± 0.56%/K all have ECS higher than the multimodel mean of 3.3 K yielding an ensemble-mean ECS of 3.9 K and a standard deviation of 0.45 K."

[Shared Humanity]

Great...3C to 5C it is then. We are so very screwed.

[AbruptSLR]

The linked reference develops a very simple linear model for approximating future GMST, and concludes that: "… the greatest threat to the stability of the global climate is the inability of humankind to respond in time."

Rypdal, K. (2016), "Global warming projections derived from an observation-based minimal model", Earth Syst. Dynam., 7, 51-70, doi:10.5194/esd-7-51-2016.

http://www.earth-syst-dynam.net/7/51/2016/

Abstract: "A simple conceptual model for the global mean surface temperature (GMST) response to CO2 emissions is presented and analysed. It consists of linear long-memory models for the GMST anomaly response ΔT to radiative forcing and the atmospheric CO2-concentration response ΔC to emission rate. The responses are connected by the standard logarithmic relation between CO2 concentration and its radiative forcing. The model depends on two sensitivity parameters, αT and αC, and two "inertia parameters," the memory exponents βT and βC. Based on observation data, and constrained by results from the Climate Model Intercomparison Project Phase 5 (CMIP5), the likely values and range of these parameters are estimated, and projections of future warming for the parameters in this range are computed for various idealised, but instructive, emission scenarios. It is concluded that delays in the initiation of an effective global emission reduction regime is the single most important factor that influences the magnitude of global warming over the next 2 centuries. The most important aspect of this study is the simplicity and transparency of the conceptual model, which makes it a useful tool for communicating the issue to non-climatologists, students, policy makers, and the general public."

[AbruptSLR]

Great...3C to 5C it is then. We are so very screwed.

Maybe you should write the summary for AR6.

[Shared Humanity]

Great...3C to 5C it is then. We are so very screwed.

Maybe you should write the summary for AR6.

I thought I already did.

[AbruptSLR]

I thought I already did.

Don't forget that in the linked reference Thompson indicates that ECS has a 95%CL range of from 3C to 6.3C, with a best estimate of 4C, and Sherwood (2014) has a higher value still:

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

Edit: I should also summarize that:
(1) Tian (2015) indicates that the double-ITCZ bias constrains ECS to its high end (around 4.0C):

Tian, B. (2015), "Spread of model climate sensitivity linked to double-Intertropical Convergence Zone bias", Geophys. Res. Lett., 42, doi:10.1002/2015GL064119.


http://onlinelibrary.wiley.com/doi/10.1002/2015GL064119/abstract
(2) Sherwood et al (2014), which found that ECS cannot be less than 3C, and is likely currently in the 4.1C range.  Also, everyone should remember that the effective ECS is not a constant, and models project that following a BAU pathway will result in the effective ECS increasing this century:


Sherwood, S.C., Bony, S. and Dufresne, J.-L., (2014) "Spread in model climate sensitivity traced to atmospheric convective mixing", Nature; Volume: 505, pp 37–42, doi:10.1038/nature12829

http://www.nature.com/nature/journal/v505/n7481/full/nature12829.html

[AbruptSLR]

he linked reference indicates that research that points at the low end of AR5's ECS like range (1.5 to 4.5C); are likely in error because they do not adequately consider decadal feedback.  The reference indicates that the best way to address this matter is by diagnosing the role played by effective radiative forcing (ERF) within climate models:

Piers M. Forster (Volume publication date June 2016), "Inference of Climate Sensitivity from Analysis of Earth's Energy Budget", Annual Review of Earth and Planetary Sciences, Vol. 44


http://www.annualreviews.org/doi/abs/10.1146/annurev-earth-060614-105156

Abstract: "Recent attempts to diagnose Equilibrium Climate Sensitivity (ECS) from changes in Earth’s energy budget point towards values at the low-end of the Intergovernmental Panel on Climate Change Fifth Assessment Report’s (AR5) likely range (1.5 to 4.5 K). These studies employ observations but still require an element of modeling to infer ECS. Their diagnosed effective ECS over the historic period of around 2 K holds up to scrutiny but there is tentative evidence that this underestimates the true ECS from a doubling of carbon dioxide. Different choices of energy imbalance data explain most of the difference between published best estimates while effective radiative forcing (ERF) dominates the overall uncertainty. For decadal analyses the largest source of uncertainty comes from a poor understanding of the relationship between ECS and decadal feedback. Considerable progress could be made by diagnosing ERF in models."

Edit: If it is not clear what decadal feedbacks are, they are associated with such phenomena as the PDO/IPO, AMO, etc.  As we have just left a period of negative PDO and are now in a period of positive PDO, we can expect El Ninos to keep driving up estimates of the ECS based on the satellite record.

[AbruptSLR]

The linked reference makes a concerted effort to identify the sources of uncertainty for ECS associated with cloud feedback using the next-generation Geophysical Fluid Dynamics Laboratory global climate model.  The authors conclude that such enhanced versions of the models used in the AR5 projections are not suitable for adequately reducing this uncertainty.

Ming Zhao, J.-C. Golaz, I. M. Held, V. Ramaswamy, S.-J. Lin, Y. Ming, P. Ginoux, B. Wyman, L. J. Donner, D. Paynter, and H. Guo, 2016: Uncertainty in Model Climate Sensitivity Traced to Representations of Cumulus Precipitation Microphysics. J. Climate, 29, 543–560. doi: http://dx.doi.org/10.1175/JCLI-D-15-0191.1


http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0191.1

Abstract: "Uncertainty in equilibrium climate sensitivity impedes accurate climate projections. While the intermodel spread is known to arise primarily from differences in cloud feedback, the exact processes responsible for the spread remain unclear. To help identify some key sources of uncertainty, the authors use a developmental version of the next-generation Geophysical Fluid Dynamics Laboratory global climate model (GCM) to construct a tightly controlled set of GCMs where only the formulation of convective precipitation is changed. The different models provide simulation of present-day climatology of comparable quality compared to the model ensemble from phase 5 of CMIP (CMIP5). The authors demonstrate that model estimates of climate sensitivity can be strongly affected by the manner through which cumulus cloud condensate is converted into precipitation in a model’s convection parameterization, processes that are only crudely accounted for in GCMs. In particular, two commonly used methods for converting cumulus condensate into precipitation can lead to drastically different climate sensitivity, as estimated here with an atmosphere–land model by increasing sea surface temperatures uniformly and examining the response in the top-of-atmosphere energy balance. The effect can be quantified through a bulk convective detrainment efficiency, which measures the ability of cumulus convection to generate condensate per unit precipitation. The model differences, dominated by shortwave feedbacks, come from broad regimes ranging from large-scale ascent to subsidence regions. Given current uncertainties in representing convective precipitation microphysics and the current inability to find a clear observational constraint that favors one version of the authors’ model over the others, the implications of this ability to engineer climate sensitivity need to be considered when estimating the uncertainty in climate projections."

[AbruptSLR]

The linked reference studies that past 250-years-worth of forest management in Europe, and found that it contributed to increased radiative forcing (over that period), rather than decreasing radiative forcing as had been previously assumed.  This indicates that either some forest management practices should be revised, or that the radiative forcing scenarios used in climate models should be revised, and also that the RCP scenarios used in the AR5 projections probably err on the side of increasing risk of future climate change damage:

Kim Naudts, Yiying Chen, Matthew J. McGrath, James Ryder, Aude Valade, Juliane Otto & Sebastiaan Luyssaert (05 Feb 2016), "Europe’s forest management did not mitigate climate warming", Science, Vol. 351, Issue 6273, pp. 597-600, DOI: 10.1126/science.aad7270

http://science.sciencemag.org/content/351/6273/597

Extract: "Afforestation and forest management are considered to be key instruments in mitigating climate change. Here we show that since 1750, in spite of considerable afforestation, wood extraction has led to Europe’s forests accumulating a carbon debt of 3.1 petagrams of carbon. We found that afforestation is responsible for an increase of 0.12 watts per square meter in the radiative imbalance at the top of the atmosphere, whereas an increase of 0.12 kelvin in summertime atmospheric boundary layer temperature was mainly caused by species conversion. Thus, two and a half centuries of forest management in Europe have not cooled the climate. The political imperative to mitigate climate change through afforestation and forest management therefore risks failure, unless it is recognized that not all forestry contributes to climate change mitigation."

[sidd]

It may well be that we have another hard choice to make. Afforestation may decrease albedo in certain regions, but enhance bioresilience.

[AbruptSLR]

It may well be that we have another hard choice to make. Afforestation may decrease albedo in certain regions, but enhance bioresilience.

There are certainly a lot of hard choices to be made with regard to climate change, but as the saying goes:  “If not us, who? If not now, when?”

[AbruptSLR]

The linked reference uses an Earth System state dependent coupled climate model (more advanced than AR5 projections) to project that on a decadal-scale the North Atlantic sea ice loss rate will slow due to the slow-down in the AMOC; while by the end of the century Arctic sea ice extent should decrease due to global warming.  I separately note that:
(a) The projected slow-down of the AMOC will result in less heat being sequestered in the deep ocean which will cause the effective ECS to increase;
(b) The increased winter time ice cover (in both the NH & SH) will result in reduced heat loss to outer space which will result in an increase in surface heat building up in the tropical zone;
(c) The increase in SH ice cover will cause snow to fall more on the sea ice thus promoting surface ice mass loss in Antarctica, which will accelerate SLR for the coming decades:

Stephen G. Yeager, Alicia R. Karspeck & Gokhan Danabasoglu (2016), "Predicted slowdown in the rate of Atlantic sea ice loss", Geophysical Research Letters, DOI: 10.1002/2015GL065364

http://onlinelibrary.wiley.com/doi/10.1002/2015GL065364/abstract

Abstract: "Coupled climate models initialized from historical climate states and subject to anthropogenic forcings can produce skillful decadal predictions of sea surface temperature change in the subpolar North Atlantic. The skill derives largely from initialization, which improves the representation of slow changes in ocean circulation and associated poleward heat transport. We show that skillful predictions of decadal trends in Arctic winter sea ice extent are also possible, particularly in the Atlantic sector. External radiative forcing contributes to the skill of retrospective decadal sea ice predictions, but the spatial and temporal accuracy is greatly enhanced by the more realistic representation of ocean heat transport anomalies afforded by initialization. Recent forecasts indicate that a spin-down of the thermohaline circulation that began near the turn of the century will continue, and this will result in near-neutral decadal trends in Atlantic winter sea ice extent in the coming years, with decadal growth in select regions."

See also:
Strelich, L. (2016), "Atlantic sea ice could grow in the next decade", Eos, 97, doi:10.1029/2016EO044955

https://eos.org/research-spotlights/atlantic-sea-ice-could-grow-in-the-next-decade

Extract: " The researchers analyzed simulations from the Community Earth System Model, modeling both atmosphere and ocean circulation. They found that decadal-scale trends in Arctic winter sea ice extent are largely explained by changes in ocean circulation rather than by large-scale external factors like anthropogenic warming.
The team emphasized the influence of the thermohaline circulation (THC), a global current that carries heat around the planet and that experts believe has been slowing down in the Atlantic since about 2000. Although anthropogenic warming may produce a long-term global temperature rise, the THC slowdown contributes to short-term cooling in the subpolar Atlantic and, consequently, a decline in the ice melt rate. The researchers make the connection between these circulation changes and satellite observations taken between 2005 and 2015 that show a positive trend in winter ice cover. In other words, slowing circulation hinders heat transport to the North Atlantic, allowing surface waters to stay cool and sea ice to expand.
Ultimately, the rise of global temperatures will generate a loss of sea ice cover over the coming century. This study is a stepping-stone toward the ultimate goal of decadal climate prediction, which is vital to understanding and anticipating the short-term trends and changes that communities will be tackling in the near future."

Edit: I note that Hansen et al (2015) forecast just such a slow-down in the AMOC due to sheet ice meltwater, and they forecast that this will increase storm severity in the coming decades.

[AbruptSLR]

The linked article discusses some of the mysteries around the causes of the expansion of the tropics; which I suspect is also linked to Sherwood's issue of deep atmospheric convection in the tropics, the PDO, the ENSO and all of the impacts on the ECS.  Scientists are having a hard time communicating the implications of this behavior and consequently tend to ESLD in their publications:

Olive Heffernan (04 February 2016), "The mystery of the expanding tropics", Nature, Volume: 530, Pages: 20–22, doi:10.1038/530020a

http://www.nature.com/news/the-mystery-of-the-expanding-tropics-1.19271

Extract: "As Earth's dry zones shift rapidly polewards, researchers are scrambling to figure out the cause — and consequences.
…

In their study, Lu and his colleagues found that climate models generally forecast that the outer edge of the Hadley cell will shift because of global warming. But the models predict a much slower rate of tropical expansion than has been seen so far — which has led researchers to suspect that something else is going on.
A common view, and one held by Lucas, is that natural climatic variability is playing some part. That variability could take the form of large-scale climatic cycles such as the Pacific Decadal Oscillation, in which temperatures in the Pacific Ocean swing between hot and cold across timescales of 15–20 years or more. “Or it could be in the form of much more random, chaotic noise,” says Lucas, who thinks that large cycles and noise together account for 50% or more of the expansion.

…
Another answer might involve different forces in the Northern and Southern hemispheres. South of the Equator, tropical expansion has been strongest in the summer, and that leads some researchers to suspect that it is related to the pattern of ozone loss in the southern stratosphere. Pollutants chew up ozone molecules above Antarctica in the spring, which triggers circulation changes throughout other parts of the Southern Hemisphere during summer. The correlation with tropical expansion suggests that the two phenomena could be connected. What's more, climate models that factor in ozone loss are able to account for much more of the tropical expansion between 1980 and 2000, when the Antarctic ozone hole was growing bigger nearly every year says Waugh.
In the Northern Hemisphere, a different explanation is called for because, in general, the Arctic does not suffer the same sort of ozone loss as the Antarctic. Research led by climate scientist Bob Allen at the University of California, Riverside, suggests that the culprits in the north might be black soot and tropospheric ozone — which are both generated by burning fossil fuels. Allen and his team ran simulations with a climate model that featured detailed atmospheric physics, and their analysis showed that black soot and tropospheric ozone have heated the atmosphere in the Northern Hemisphere and driven tropical expansion more than carbon dioxide and other greenhouse gases, particularly in summer.
Not everyone is comfortable with the idea that entirely separate factors could drive tropical expansion to such a large extent on either side of the Equator. Fu, for one, thinks it's unlikely given the similar patterns in the north and south. “If ozone depletion was dominating the expansion in the Southern Hemisphere in the past 30 years, would you see such symmetry? I'm not convinced,” says Fu.
The proliferation of hypotheses shows how much researchers are struggling to explain what's happening. “I think we're piecing this together slowly,” says Lucas. “We don't have a full explanation yet and I don't think there's going to be one single explanation. It's going to be a little bit of this and a little bit of that.”"

[AbruptSLR]

The linked, open access, reference indicates that if the AR5 global mean surface temperature, GMST, projections had not adopted procedures (w.r.t. carbon cycles) that err on the side of least drama, they would have projected higher values of GMST, with wider ranges of uncertainty, as illustrated by the attached plot with the caption cited below:

Bodman, R. W., Rayner, P. J. and Jones, R. N. (2016), "How do carbon cycle uncertainties affect IPCC temperature projections?",  Atmosph. Sci. Lett., doi: 10.1002/asl.648

http://onlinelibrary.wiley.com/doi/10.1002/asl.648/abstract

Abstract: "Carbon cycle uncertainties associated with the Intergovernmental Panel on Climate Change temperature-change projections were treated differently between the Fourth and Fifth Assessment Reports as the latter focused on concentration- rather than emission-driven experiments. Carbon cycle feedbacks then relate to the emissions consistent with a particular concentration. A valuable alternative is to include all uncertainties in a single step from emissions to temperatures. We use a simple climate model with an observationally constrained parameter distribution to explore the carbon cycle and temperature-change projections, simulating the emission-driven Representative Concentration Pathways. The resulting range of uncertainty is a somewhat wider and asymmetric likely range (biased high)."

Caption: "Plume plots for ΔGMT change projections 2000–2100, ∘C relative to 1986–2005. MAGICC results with carbon cycle temperature feedbacks on (CC-on) and switched off (CC-off) (a) RCP2.6, (b) RCP4.5, (c) RCP6.0 and (d) RCP8.5. Shaded regions indicate the 67% confidence interval for CC-on (green) and CC-off (blue), with median results as solid green and dashed blue lines, respectively."

[AbruptSLR]

The linked reference indicates that as small ponds are difficult to map, their GHG emissions have been excluded to date from GHG budget estimates.  However, the reference finds that such small ponds make a larger than proportional share of GHG emissions compared to other still bodies of water.  Thus climate scientists should stop erring on the side of least drama and start including these emissions in their GHG emission estimates:

Meredith A. Holgerson & Peter A. Raymond (2016), "Large contribution to inland water CO2 and CH4 emissions from very small ponds", Nature Geoscience, doi:10.1038/ngeo2654

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2654.html

Abstract: "Inland waters are an important component of the global carbon cycle. Although they contribute to greenhouse gas emissions, estimates of carbon processing in these waters are uncertain. The global extent of very small ponds, with surface areas of less than 0.001 km2, is particularly difficult to map, resulting in their exclusion from greenhouse gas budget estimates. Here we combine estimates of the lake and pond global size distribution, gas exchange rates, and measurements of carbon dioxide and methane concentrations from 427 lakes and ponds ranging in surface area from 2.5 m2 to 674 km2. We estimate that non-running inland waters release 0.583 Pg C yr−1. Very small ponds comprise 8.6% of lakes and ponds by area globally, but account for 15.1% of CO2 emissions and 40.6% of diffusive CH4 emissions. In terms of CO2 equivalence, the ratio of CO2 to CH4 flux increases with surface area, from about 1.5 in very small ponds to about 19 in large lakes. The high fluxes from very small ponds probably result from shallow waters, high sediment and edge to water volume ratios, and frequent mixing. These attributes increase CO2 and CH4 supersaturation in the water and limit efficient methane oxidation. We conclude that very small ponds represent an important inland water carbon flux."

[AbruptSLR]

AR5 recognized very low values for ECS based largely on (biased) articles that focused on simplified interpretation of the recent observed record, which included a period of increased terrestrial carbon uptake by vegetation (what I consider to be a masking factor).  The research indicates how dynamic (nonlinear) such carbon cycle feedbacks can be by re-examining the 1959-2013 record.  While acknowledging that these dynamic effects have reduced atmosphere CO₂ concentrations over the study period, the paper recommends that the identified nonlinear relationships are too important to be ignored (as they largely were in the AR5 projections), and should be included in future climate model (ESM) projections, such as those to be included in AR6:

Xuanze Zhang, Peter J. Rayner, Ying Ping Wang, Jeremy D. Silver, Xingjie Lu, Bernard Pak & Xiaogu Zheng (2016), "Linear and nonlinear effects of dominant drivers on the trends in global and regional land carbon uptake: 1959 to 2013", Geophysical Research Letters, DOI: 10.1002/2015GL067162


http://onlinelibrary.wiley.com/doi/10.1002/2015GL067162/abstract

Abstract: "Changes in atmospheric CO2 levels, surface temperature or precipitation have been identified to have significantly contributed to the estimated increase in the terrestrial carbon-uptake rate over the last few decades, however those analyses did not consider the interactions. Using the Australian community land surface model (CABLE), we performed factorial experiments to quantify the importance of external drivers (climate drivers and atmospheric CO2) and their interactions on annual terrestrial carbon uptake (FL), excluding land-use change and fires, from 1959 to 2013. Our model simulations show a trend of 0.025 ±0.015 Pg C yr-2 (or ~1.5% yr-1) in global FL for 1959-2013, which is largely attributed to the positive influences of the increased atmospheric CO2 (0.050± 0.001 Pg C yr-2) and negative influences of changes in climate (-0.026 ± 0.014 Pg C yr-2). Globally contribution of the nonlinear effects of dominant drivers to the simulated trend in FL is small (<10%), but can be significant regionally (>35%), particularly in the boreal forests and semi-arid regions. The interactions between temperature and CO2 or temperature and precipitation can dominate the simulated trend in parts of Europe, south-eastern North America, southern China and some semi-arid regions. This modelling result suggests that the effects of nonlinear interactions of drivers on the trend of land carbon uptake should be considered in future studies."

[Sigmetnow]

What’s Missing at the U.N. Climate Panel’s Meeting on Climate Change Communication
By Andrew C. Revkin

Despite substantial introspection and external analysis since 2007, the United Nations climate panel has seemed persistently locked in an antiquated view of how to improve its communication efforts, largely oblivious to the “new communication climate” out there.

Thankfully, on Tuesday and Wednesday, the climate panel is holding its first “expert meeting” on climate communication, in Oslo (there’s a long list of earlier special sessions on a variety of scientific issues).

Here’s the goal:

The main objective of the meeting is to increase the efficiency and impact of communications of I.P.C.C. findings across the world.

This workshop is long overdue, and a hopeful sign that panel leaders (and, just as importantly, the nations that created the I.P.C.C. in 1988, pay for its operations and look forward to its sixth set of reports later this decade) recognize there’s work to be done.

http://dotearth.blogs.nytimes.com/2016/02/08/whats-missing-at-the-u-n-climate-panels-meeting-on-climate-change-communication/

[AbruptSLR]

Valerie Masson-Delmotte will be the Co-chair for WGI of AR6, and the following link provides a Carbon Brief (CB) interview with her.  While it is possible that I miss understand the following extract, but on face value it looks like she believes that ECS is higher than 2.5C:

http://www.carbonbrief.org/the-carbon-brief-interview-valerie-masson-delmotte

Extract:
"CB: Is 2C likely to be too low as well, or is it just the very lower boundary that you think is emerging as too low?
VMD: I cannot say with the precision of half a degree. And I think so far, from what I have seen, there has not been any comprehensive study that would allow to produce an informed number. I have a feeling that probably values between around 2.5C or more may be more realistic. And that’s also based on revised information for changes in tropical sea surface temperatures in the past that are critical to constrain the low end values as well."

[AbruptSLR]

The linked reference recommends a major revision on how climate models address carbon cycle sensitivity.  Denialist may use this uncertainty to support BAU activity; however, I suspect that if/when AR6 climate models make the recommended changes that the values of the effective ECS will increase from those used in AR5.

A. Anthony Bloom, Jean-François Exbrayat, Ivar R. van der Velde, Liang Feng, and Mathew Williams (February 2, 2016), "The decadal state of the terrestrial carbon cycle: Global retrievals of terrestrial carbon allocation, pools, and residence times", PNAS, vol. 113, no. 5, pp 1285–1290, doi: 10.1073/pnas.1515160113


www.pnas.org/cgi/doi/10.1073/pnas.1515160113
http://www.pnas.org/content/113/5/1285.full.pdf
http://www.pnas.org/content/suppl/2016/01/13/1515160113.DCSupplemental

Abstract: "The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle and its processes is, therefore, necessary to better understand its current state and predict its future state.  We combine a diagnostic ecosystem carbon model with satellite observations of leaf area and biomass (where and when available) and soil carbon data to retrieve the first global estimates, to our knowledge, of carbon cycle state and process variables at a 1° × 1° resolution; retrieved variables are independent from the plant functional type and steady-state paradigms. Our results reveal global emergent relationships in the spatial distribution of key carbon cycle states and processes. Live biomass and dead organic carbon residence times exhibit contrasting spatial features (r = 0.3). Allocation to structural carbon is highest in the wet tropics (85–88%) in contrast to higher latitudes (73–82%), where allocation shifts toward photosynthetic carbon.  Carbon use efficiency is lowest (0.42–0.44) in the wet tropics.  We find an emergent global correlation between retrievals of leaf mass per leaf area and leaf lifespan (r = 0.64–0.80) that matches independent trait studies. We show that conventional land cover types cannot adequately describe the spatial variability of key carbon states and processes (multiple correlation median = 0.41). This mismatch has strong implications for the prediction of terrestrial carbon dynamics, which are currently based on globally applied parameters linked to land cover or plant functional types."

[AbruptSLR]

The linked reference uses satellite data to help to partially explain why atmospheric methane concentrations have been higher than expected using national inventory estimates over the past decade.  The reference attributes 30 to 60% of the unexpected high methane concentrations to emissions from the US.  Given that the GWP10 for methane is 130, this is back news for the accuracy of short-term global warming projections:

A. J. Turner, D. J. Jacob, J. Benmergui, S. C. Wofsy, J. D. Maasakkers, A. Butz, O. Hasekamp, S. C. Biraud & E. Dlugokencky (2016), "A large increase in US methane emissions over the past decade inferred from satellite data and surface observations", Geophysical Research Letters, DOI: 10.1002/2016GL067987

http://onlinelibrary.wiley.com/doi/10.1002/2016GL067987/full

Abstract: "The global burden of atmospheric methane has been increasing over the past decade but the causes are not well understood. National inventory estimates from the US Environmental Protection Agency (EPA) indicate no significant trend in US anthropogenic methane emissions from 2002 to present. Here we use satellite retrievals and surface observations of atmospheric methane to suggest that US methane emissions have increased by more than 30% over the 2002–2014 period. The trend is largest in the central part of the country but we cannot readily attribute it to any specific source type. This large increase in US methane emissions could account for 30–60% of the global growth of atmospheric methane seen in the past decade."

[AbruptSLR]

I believe that this qualifies as an anthropogenic positive feedback, and once the US Forest Service passes its financial tipping point, wildfires will become more widespread, which will cause more financial distress:

http://www.theguardian.com/world/2016/feb/08/us-forest-service-stretched-after-wildfires-record-year-climate-change

Extract: "The US Forest Service has warned it is at the “tipping point” of a crisis in dealing with escalating wildfires and diseases that are ravaging America’s increasingly fragile forest ecosystems."

[Sigmetnow]

The Weather Social
A group of meteorologists and social scientists have started a discussion of how to communicate impending weather hazards to the public and government.
Their bios:  http://thewxsocial.com/our-bios/

The Weather Social website:    http://thewxsocial.com/     
Twitter:  @thewxsocial

THINK SOCIAL
“Sacrificing technical completeness to justify user understanding isn’t the worst possible solution. People and time outweigh the science.”
-Josh

“The intersection of social science and very high impact weather events is the current number one challenge for operational meteorology.”
-Gary

“The way we communicate with the public, whether during a time of severe weather or during just a casual day, will greatly impact the trust the public will have in you when it comes to a life or death situations.”
-Jon

By: Gary Szatkowski

Who thinks this is strictly a physical science problem? Hopefully, you did not raise your hand.


I started chatting on Twitter about a potential East Coast snowstorm on Sunday, January 17th. The National Weather Service (NWS) office in Mount Holly, NJ issued its first briefing package for the potential upcoming event on Monday, January 18th. Five more briefing packages would be issued before the first snow started to fall on Friday afternoon, January 22nd. Well before the first flake of snow fell, NWS offices all across the affected area issued Blizzard Watches and Winter Storm Watches, and then upgraded them to Blizzard Warnings and Winter Storm Warnings.   Media and other parts of the weather enterprise reacted similarly, talking about the impacts of the storm multiple days in advance of the first snow.

And despite all that advance notice and all that advance information, two tractor trailers jackknifed on the Pennsylvania Turnpike around 800 PM Friday evening, only several hours after the storm had begun.  The accident occurred in one of the most remote and hilly stretches of the PA Turnpike, with roughly 40 miles between exits.   Stranded motorists spent over 24 hours on the PA Turnpike, with wind chills in the single digits and near-blizzard conditions.
...

http://thewxsocial.com/2016/02/09/whats-wrong-with-this-picture-a-lot/

[AbruptSLR]

The Weather Social
A group of meteorologists and social scientists have started a discussion of how to communicate impending weather hazards to the public and government.

But what will that be communicating, AR5 projections, or perhaps the Paris Pact projections, both of which err on the side of least drama?  This type of thinking that such thinking represents settled science is rather dangerous, as indicated by the following article that suggests that more and more nations will cut their funding for climate change science drastically now that the Paris Pact has been signed and there is nothing left to talk about:


http://www.csmonitor.com/Science/2016/0209/Is-Australia-s-retreat-from-climate-change-research-start-of-a-global-trend

Extract: "While the international scientific community has reacted with almost universal dismay to the announcement by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), a fundamental question remains: does this represent the start of a broader shift, or is Australia an outlier?

“I believe this is the start of a global trend,” says David Carlson, director of the World Climate Research Program (WCRP), Geneva, in a telephone interview with The Christian Science Monitor.

“Because of Paris [United Nations Conference on Climate Change, 2015], people will begin to relax their guard. The worry is that Australia is just the first.”

The WCRP is a part of the United Nations and, as such, rarely comments on the activities of particular countries. But this situation is very unusual, an “extraordinary event," says Mr. Carlson.

“My steering committee really lit up about this on Friday. We know so many of the [affected] scientists personally.”"

My general belief is that meteorologists on average are skeptical of climate change, and that anything thing that they are communicating to the public will leave the public exposed to substantial climate change risk.

[Sigmetnow]

ASLR,
This group of meteorologists and social scientists concerns itself with the difficulties of communicating warnings about
adverse weather -- not necessarily climate -- but I posted it because I thought it was a fitting corollary to the difficulties of communicating climate change impacts.

Another article from their website describes this interaction about terminology:

Hurricane Patricia was the strongest hurricane “ever recorded” in the Western Hemisphere. Linguists and meteorologists would agree that leaving out the word “recorded” conveys a meaning that simply cannot be proven.

On Friday, meteorologists decided to publicly debate this fact on the open forum of social media while a violent hurricane wreaked havoc on impoverished communities of Coastal Mexico.

In one of the more diplomatic conversations of the day, one meteorologist tweeted, “My thought is we can’t say what happened before we have records. Might, might not. Inaccurate to suggest we know.”

Another replied, “I understand, but I am camped out in social science land right now. Either message can convey the huge threat.”

These are both sound arguments. But, let me quote something I’ve already written: “On Friday, meteorologists decided to publicly debate this fact in the open forum of social media while a violent hurricane wreaked havoc on impoverished communities of Coastal Mexico.”

Do emergency medical technicians or surgeons argue over petty terminology when it is crunch time? Why do meteorologists?

I will attempt to answer that. Meteorologists have been laughed at and scorned too many times. Consider November 2014 when New York Governor Andrew Cuomo addressed a significant lake effect snow event by criticizing the National Weather Service, apparently ignorant of the fact that forecasters warned of a potentially historic snowfall, days in advance. In August, forecasters took flak when Tropical Storm Erika fizzled because several residents of the Southeastern United States began preparing for impact. However, responsible forecasts never suggested anything contrary to what happened. Government measures were cautionary and proactive—the appropriate response when uncertainty looms."

http://thewxsocial.com/2015/10/23/never-say-ever/

Meteorologists have long been said to have "cried, 'Wolf'" after storms have underperformed -- and alternatively to have "failed at their job" when storms turn out to be stronger than forecast (or when government needs someone to blame for its inadequate response to a well-warned storm emergency).  Meteorologists have been burned often enough that they may have particular insight into the problem of communicating environmental risks, just like "conservative scientists" and their consequences. 

[AbruptSLR]

The linked (open access) reference discusses how nonlinearity can be accounted for to improve the value of paleodata, and focuses on ENSO case studies:

Emile-Geay, J. and Tingley, M.: Inferring climate variability from nonlinear proxies: application to palaeo-ENSO studies, Clim. Past, 12, 31-50, doi:10.5194/cp-12-31-2016, 2016.

http://www.clim-past.net/12/31/2016/cp-12-31-2016.html
http://www.clim-past.net/12/31/2016/cp-12-31-2016.pdf

Abstract: "Inferring climate from palaeodata frequently assumes a direct, linear relationship between the two, which is seldom met in practice. Here we simulate an idealized proxy characterized by a nonlinear, thresholded relationship with surface temperature, and we demonstrate the pitfalls of ignoring nonlinearities in the proxy–climate relationship. We explore three approaches to using this idealized proxy to infer past climate: (i) methods commonly used in the palaeoclimate literature, without consideration of nonlinearities; (ii) the same methods, after empirically transforming the data to normality to account for nonlinearities; and (iii) using a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting nonlinearity often exaggerates changes in climate variability between different time intervals and leads to reconstructions with poorly quantified uncertainties. In contrast, explicit recognition of the nonlinear relationship, using either a mechanistic model or an empirical transform, yields significantly better estimates of past climate variations, with more accurate uncertainty quantification. We apply these insights to two palaeoclimate settings. Accounting for nonlinearities in the classical sedimentary record from Laguna Pallcacocha leads to quantitative departures from the results of the original study, and it markedly affects the detection of variance changes over time. A comparison with the Lake Challa record, also a nonlinear proxy for El Niño–Southern Oscillation, illustrates how inter-proxy comparisons may be altered when accounting for nonlinearity. The results hold implications for how univariate, nonlinear recorders of normally distributed climate variables are interpreted, compared to other proxy records, and incorporated into multiproxy reconstructions."

[AbruptSLR]

While I have discussed the linked reference previously, I am doing so again to both emphasize the TCRE is dependent on the rate of GHG emissions and to provide the two images that quantify this trajectory sensitivity:

J. P. Krasting, J. P. Dunne, E. Shevliakova, R. J. Stouffer. Trajectory sensitivity of the transient climate response to cumulative carbon emission. Journal: Geophysical Research Letters. DOI: 10.1002/2013GL059141.

http://onlinelibrary.wiley.com/doi/10.1002/2013GL059141/abstract

See also:
http://www.gfdl.noaa.gov/index/news-app/story.96/title.trajectory-sensitivity-of-the-transient-climate-response-to-cumulative-carbon-emission

Extract: " The insensitivity of the global climate response once emissions cease in simplified coupled climate models has been used to argue for lack of committed warming based on past carbon emissions. Additional studies have also demonstrated that the cessation of carbon emissions results in a stabilization or decrease of global mean surface air temperature. Such studies generally assume either a 1%/year increase or an instantaneous doubling/quadrupling of atmospheric CO2.
For this study, the ESM2G coupled climate-carbon cycle model was used to evaluate Transient Climate Response to cumulative carbon Emissions (TCRE) by forcing the model with 7 constant carbon emission rates (2, 3, 5, 10, 15, 20 and 25 GtC/yr), including low emission rates that have been largely unexplored in previous studies. The range of TCRE resulting from these varying emission pathways is 0.76 to 1.04 ºC/TtC.
TCRE has a complex relationship with emission rates; TCRE is largest for both very low (2 GtC/yr) and very high (25 GtC/yr) emissions and smallest for present-day emissions (5-10 GtC/yr). We demonstrate that natural climate variability hinders precise estimates of TCRE for periods shorter than 50 years for emission rates near or smaller than present day values. If carbon emissions were to suddenly cease, the prior emissions pathways would affect the future climate responses.
This study confirms the robustness of the proportionality between surface air warming and ongoing cumulative carbon emissions. This study, however, demonstrates a larger response dependence on carbon emissions pathway when forced by constant "low" carbon emissions that take many centuries to double atmospheric CO2. This trajectory dependence is related, in part, to oceanic heat and carbon uptake. These processes are dependent on ocean mixing and the equilibrium climate sensitivity, which vary from model to model. The results from these experiments also indicate that the mechanisms that give rise to the proportionality depend of the emissions pathway and possibly depend on processes other than oceanic heat and carbon uptake, as demonstrated here by the varying terrestrial response to different carbon emission rates.
TCRE is appealing to both the scientific and policy communities since it provides a single metric that integrates both climate and carbon cycle sensitivities. Based on the results of this study, the additional uncertainty related to emissions trajectory should be taken into account when interpreting TCRE in policy-making timescales (i.e. multi-decadal and longer). TCRE, however, has the potential to be a useful metric in bench-marking coupled climate-carbon-cycle models."

[Theta]

Unexpected Consequences of biodiversity loss

http://www.commondreams.org/views/2016/02/10/biodiversity-loss-and-doomsday-clock-invisible-disaster-almost-no-one-talking-about

[AbruptSLR]

The linked (open access) reference studied data from 1951 to 2010 & finds that there was reduced albedo in the US Great Plains due to a trend of fewer days of snowfall.  This represents a positive feedback for global warming:

Fassnacht, S. R., Cherry, M. L., Venable, N. B. H., and Saavedra, F.: Snow and albedo climate change impacts across the United States Northern Great Plains, The Cryosphere, 10, 329-339, doi:10.5194/tc-10-329-2016, 2016.

http://www.the-cryosphere.net/10/329/2016/
http://www.the-cryosphere.net/10/329/2016/tc-10-329-2016.pdf

Abstract: "In areas with a seasonal snowpack, a warmer climate could cause less snowfall, a shallower snowpack, and a change in the timing of snowmelt, all which could reduce the winter albedo and yield an increase in net short-wave radiation. Trends in temperature, precipitation (total and as snow), days with precipitation and snow, and winter albedo were investigated over the 60-year period from 1951 to 2010 for 20 meteorological stations across the Northern Great Plains. This is an area where snow accumulation is shallow but persistent for most of the winter (November to March). The most consistent trends were minimum temperature and days with precipitation, both of which increased at a majority of the stations. Among the stations included, a decrease in the modelled winter albedo was more prevalent than an increase. There was substantial spatial variability in the climate trends. For most variables, the period of record used influenced the magnitude and sign of the significant trends."

[wili]

Apologies if this has already been posted somewhere. Here Kevin Anderson of the Tyndall Centre on CC Research discusses the "endemic bias prevalent amongst many of those building emission scenarios to underplay the scale of the 2°C challenge."

http://www.lse.ac.uk/newsAndMedia/videoAndAudio/channels/publicLecturesAndEvents/player.aspx?id=3363

[AbruptSLR]

The linked (open access) reference discusses uncertainty in warming threshold limits (1.5C, 2C or 3C) to climate sensitivity & climate feedbacks.  The attached image relates the equivalent CO₂ concentration (I believe corrected for the negative forcing associated with aerosols) and ECS for warming thresholds of 1.5C, 2C and 3C.  This indicates that if ECS is actually close to 4.0C, then we are essentially already at the tipping point to reach 2C warming (presumably with a 10-year lapse time from the present or 2026):


Zhou Tianjun, Xiaolong Chen, 2015: Uncertainty in the 2C Warming Threshold Related to Climate Sensitivity and Climate Feedback. J. Meteor. Res., 29(6), 884-895, doi: 10.1007/s13351- 015-5036-4

http://link.springer.com/article/10.1007%2Fs13351-015-5036-4
http://www.lasg.ac.cn/staff/ztj/group/files/201612292920438.pdf

Abstract: "Climate sensitivity is an important index that measures the relationship between the increase in greenhouse gases and the magnitude of global warming. Uncertainties in climate change projection and climate modeling are mostly related to the climate sensitivity. The climate sensitivities of coupled climate models determine the magnitudes of the projected global warming. In this paper, the authors thoroughly review the literature on climate sensitivity, and discuss issues related to climate feedback processes and the methods used in estimating the equilibrium climate sensitivity and transient climate response (TCR), including the TCR to cumulative CO2 emissions. After presenting a summary of the sources that affect the uncertainty of climate sensitivity, the impact of climate sensitivity on climate change projection is discussed by addressing the uncertainties in 2°C warming. Challenges that call for further investigation in the research community, in particular the Chinese community, are discussed."

Edit: Note that the dotted example of 450ppm CO2-e to reach the 2C threshold assumes an ECS value of 2.88C in accord with AR5.  However, subsequent research has demonstrated that the 2.88C value for ECS is too low.

Edit2:  I note that CO2-e is currently around 490 ppm; while the impact of aerosol negative forcing is discussed in:

Hua Zhang, Shuyun Zhao, Zhili Wang, Xiaoye Zhang & Lianchun Song (25 January 2016), "The updated effective radiative forcing of major anthropogenic aerosols and their effects on global climate at present and in the future", International Journal of Climatology, DOI: 10.1002/joc.4613

http://onlinelibrary.wiley.com/doi/10.1002/joc.4613/abstract

Edit3: On the other hand (& if one really loves their children) then it many be more reasonable to assume that by 2040 the effective ECS will be around 4.5C, which the attached figure would then indicate that the CO2-e (less the aerosol negative forcing impact) would be around 450ppm for a threshold of 3C.  So if one assumes that by May 2016 the Mauna Loa CO2 concentration will be round 406ppm and if one assumes that this will increase at a rate of 3ppm/year then we will be at a CO2 concentration of 450ppm by about 2031 so with a 10-year lapse time we could be at a 3C threshold by 2041 plus of minus.

[AbruptSLR]

Edit3: On the other hand (& if one really loves their children) then it many be more reasonable to assume that by 2040 the effective ECS will be around 4.5C, which the attached figure would then indicate that the CO2-e (less the aerosol negative forcing impact) would be around 450ppm for a threshold of 3C.  So if one assumes that by May 2016 the Mauna Loa CO2 concentration will be round 406ppm and if one assumes that this will increase at a rate of 3ppm/year then we will be at a CO2 concentration of 450ppm by about 2031 so with a 10-year lapse time we could be at a 3C threshold by 2041 plus of minus.

If you are asking yourself whether it is physically possible for the Earth to warm at a rate of about 0.1C per year for the next 25 years (2016 to 2041) then note in the attached Nick Stokes plot from August 2015 thru January 2016, GMST increased by over 0.2C in 1/2-years due partially to the current Super El Nino.  Furthermore, if you follow the El Nino thread you will see that there is a strong possibility that a strong MJO event will trigger a strong Westerly Wind Burst near the Eq Pacific International Dateline starting Feb 17 2016, which will likely result in a weak El Nino event occurring for the last half of 2016 thru the first half of 2017.  Furthermore, if this MJO driven trend continues then the Eastern Equatorial Pacific could remain anomalously warm for the next 25-years (or more); which could both result in an effective ECS of about 4.5C and a global mean surface temperature, GMST, increase rate of about 0.1C per year over the next 25 years.

Edit: For the Nick Stokes plot see:
http://moyhu.blogspot.com/2016/02/january-templs-surface-temperature-down.html

[AbruptSLR]

For those who wonder how an ECS of 4.0 could increase to an effective ECS of 4.5 by 2041 (and who do not read the El Nino 2015-16 thread), I offer the attached images and following linked pdf to indicate that:

1.  The Land CO₂ sink is much more variable than the Ocean CO₂ sink.
2.  The ENSO has a pronounced influence on the Land CO₂ sink particularly with regard to tropical rainforests.
3. Climate change is threatening the carbon cycle in tropical rainforests with a possible tipping point.
4. Albedo changes associated with snow coverage reductions in both North America and Siberia.

http://biogeomod.net/talks/P_Cox_4_10_2011.pdf

[sidd]

Thanx for the Cox reference. The steady reduction in land and ocean CO2 sinks is disquieting. The huge dip in the early nineties upon the fall of soviet block tells us how powerful politics can be ... all we gotta do is shut down the coal burners to see even bigger effects. Glad to see that Cox is actually optimistic regarding amazon dieback. The precipitous fall in soil carbon sink in Lenton probably results from permafrost degradation ?

[AbruptSLR]

The linked EOS article discusses how large climate models are currently calibrated against modern observed data using a system called a "climate model test bed".  Such a process is critical, particularly as more nonlinearity is introduced into models such as ACME, and the "climate model test bed" for ACME will be ready for use by the end of 2016.

It is truly unfortunate that since the end of 1998 a negative phase of the PDO has encouraged modelers to calibrate their largely linear climate models to a climate phase that introduced more radiative forcing energy into the ocean than is typical.  It is even more unfortunate that paleo-data indicates that the Eastern Pacific could enter a condition where its average surface temperature is well above what has been experienced during the Holocene, and we are only beginning to collect data since 2015 that match this type of condition (note the current positive phase of the PDO should last until at least 2035).  Thus it is not likely that the ACME program will be properly calibrated until well after 2035.

https://eos.org/project-updates/better-tools-to-build-better-climate-models

Extract: "To determine the accuracy of predictions, results are validated by comparing them to present-day observations.  As new data are fed to the model and scientific understanding of climate systems evolves, new information gets built into the model, and the testing and validation continue.
One of the most resource-intensive aspects of climate modeling is the creation of a system for calibrating climate models, where model simulations are used to validate model output against observational data sets that span the globe. We call this system a “climate model test bed.” Such test bed environments typically evaluate each component of the model in isolation, using a skeleton framework that makes the module behave as if it were functioning within the larger program.

…

The prototype test bed team is now under the banner of the newly formed Accelerated Climate Modeling for Energy (ACME) project, under the auspices of the U.S. Department of Energy’s Office of Science. Under ACME, the team will continue its efforts to deliver an advanced model development, testing, and execution workflow and data infrastructure production test bed for DOE climate and energy research needs. We anticipate rolling out the test bed by end of 2016 for ACME use."

[AbruptSLR]

Thanx for the Cox reference. The steady reduction in land and ocean CO2 sinks is disquieting. The huge dip in the early nineties upon the fall of soviet block tells us how powerful politics can be ... all we gotta do is shut down the coal burners to see even bigger effects. Glad to see that Cox is actually optimistic regarding amazon dieback. The precipitous fall in soil carbon sink in Lenton probably results from permafrost degradation ?

sidd,

The topic of soil carbon contributions to future atmospheric GHG concentrations has been, and is continuing to be, strongly debated, and the Cox/Lenton data may be towards the upper end of expected contribution.  As the following random listing of references indicate, this is a complex topic including not only permafrost contributions, but also peat, forest litter, and methane/carbon dioxide mix.  These few article indicate that topics that must be quantified include: fires (both boreal & tropical), microbe activity, burrowing rodents, insects, droughts/floods, farming practice, changes in local precipitation (rain vs snow), polar amplification, etc. etc.

Charles D. Kovena, David M. Lawrence and William J. Rileya (2015), "Permafrost carbon−climate feedback is sensitive to deep soil carbon decomposability but not deep soil nitrogen dynamics", Proceedings of the National Academy of Sciences (PNAS), doi: 10.1073/pnas.1415123112

http://www.pnas.org/content/112/12/3752.abstract

The linked article (and associated image & extract) indicates that GHG emissions from farming rose 13% after 1990.  With a growing world population and a growing global middle class, this trend will be difficult to reverse anytime soon:

http://www.climatecentral.org/news/farming-now-worse-for-climate-than-deforestation-18629

Merritt R. Turetsky, Brian Benscoter, Susan Page, Guillermo Rein, Guido R. van der Werf & Adam Watts, (2015), "Global vulnerability of peatlands to fire and carbon loss", Nature Geoscience, Volume: 8, Pages: 11–14, doi:10.1038/ngeo2325

http://www.nature.com/ngeo/journal/v8/n1/full/ngeo2325.html

Nigel Golden, Susan Natali and Nikita Zimov, (2014), "Consequences of artic ground squirrels on soil carbon loss from Siberian tundra", Fall AGU Conference

https://agu.confex.com/agu/fm14/meetingapp.cgi#Paper/20090

Benjamin N. Sulman, Richard P. Phillips, A. Christopher Oishi, Elena Shevliakova, and Stephen W. Pacala, (2014), "Microbe-driven turnover offsets mineral-mediated storage of soil carbon under elevated CO₂", Nature Climate Change, DOI: 10.1038/nclimate2436

http://www.nature.com/nclimate/journal/v4/n12/full/nclimate2436.html
See also:

http://blogs.princeton.edu/research/2014/12/22/dirty-pool-soils-large-carbon-stores-could-be-freed-by-increased-co2-plant-growth-nature-climate-change/

Caption: "Researchers based at Princeton University report that an increase in human-made carbon dioxide in the atmosphere could initiate a chain reaction between plants and microorganisms that would unsettle one of the largest carbon reservoirs on the planet — soil. The researchers developed the first computer model to show at a global scale the complex interaction between carbon, plants and soil. The model projected changes (above) in global soil carbon as a result of root-soil interactions, with blue indicating a greater loss of soil carbon to the atmosphere. (Image by Benjamin Sulman, Princeton Environmental Institute).

Zhaosheng Fan, Jason C. Neff, Mark P. Waldrop, Ashley P. Ballantyne, Merritt R. Turetsky, (2014), "Transport of oxygen in soil pore-water systems: implications for modeling emissions of carbon dioxide and methane from peatlands", Biogeochemistry, doi:10.1007/s1053-014-0012-0.

http://link.springer.com/article/10.1007%2Fs10533-014-0012-0#page-1

Berenguer, E., Ferreira, J., Gardner, T. A., Aragão, L. E. O. C., De Camargo, P. B., Cerri, C. E., Durigan, M., Oliveira, R. C. D., Vieira, I. C. G. and Barlow, J. (2014), A large-scale field assessment of carbon stocks in human-modified tropical forests. Global Change Biology. doi: 10.1111/gcb.12627

http://onlinelibrary.wiley.com/doi/10.1111/gcb.12627/full

Marín-Spiotta, E., N.T. Chaopricha, A.F. Plante, A.F. Diefendorf, C.W. Müller, S. Grandy, and J.A. Mason. Long-term stabilization of deep soil carbon by fire and burial during early Holocene climate change. Nature Geoscience

http://www.nature.com/ngeo/journal/vaop/ncurrent/pdf/ngeo2169.pdf



Nishina, K., Ito, A., Beerling, D. J., Cadule, P., Ciais, P., Clark, D. B., Falloon, P., Friend, A. D., Kahana, R., Kato, E., Keribin, R., Lucht, W., Lomas, M., Rademacher, T. T., Pavlick, R., Schaphoff, S., Vuichard, N., Warszawaski, L., and Yokohata, T.: Global soil organic carbon stock projection uncertainties relevant to sensitivity of global mean temperature and precipitation changes, Earth Syst. Dynam. Discuss., 4, 1035-1064, doi:10.5194/esdd-4-1035-2013, 2013

http://www.earth-syst-dynam-discuss.net/4/1035/2013/esdd-4-1035-2013.html


Warming accelerates decomposition of decades-old carbon in forest soils;
by: Francesca M. Hopkins, Margaret S. Torn, and Susan E. Trumbore; PNAS June 11, 2012; doi: 10.1073/pnas.1120603109

http://www.pnas.org/content/early/2012/06/07/1120603109.abstract


Best,
ASLR

[AbruptSLR]

The linked references provides both model paleo-data regarding the PETM, that indicate a substantial positive feedback from carbon release from soils and conclude that: "…. soils might serve as a large source for atmospheric CO2 during warming events."

Jennifer M. Cotton, Nathan D. Sheldon, Michael T. Hren and Timothy M. Gallagher (Online April 2015), "Positive feedback drives carbon release from soils to atmosphere during Paleocene/Eocene warming", AJS, vol. 315, no. 4 337-361, doi: 10.2475/04.2015.03

http://www.ajsonline.org/content/315/4/337.abstract

Abstract: "The Paleocene-Eocene Thermal Maximum (PETM) is the most rapid climatic warming event in the Cenozoic and informs us how the Earth system responds to large-scale changes to the carbon cycle. Warming was triggered by a massive release of 13C depleted carbon to the atmosphere, evidenced by negative carbon isotope excursions (CIE) in nearly every carbon pool on Earth. Differences in these CIEs can give insight into the response of different ecosystems to perturbations in the carbon cycle. Here we present records of δ13Ccc of pedogenic carbonates and δ13Corg from preserved soil organic matter in corresponding paleosols to understand changes to soil carbon during the PETM. CIEs during the event are larger in pedogenic carbonates than preserved organic matter for corresponding paleosols at three sites across two continents. The difference in the CIEs within soil carbon pools can be explained by increased respiration and carbon turnover rates of near-surface labile soil carbon. Increased rates of labile carbon cycling combined with decreases in the amount of preserved organic carbon in soils during the PETM suggests a decrease in the size of the soil carbon pool, resulting in a potential increase in atmospheric pCO2 and a positive feedback with warming. The PETM is a model for how the earth system responds to warming, and this mechanism would suggest that soils might serve as a large source for atmospheric CO2 during warming events."