Conservative Scientists & its Consequences

[AbruptSLR]

The linked reference concludes that w.r.t. stratospheric ozone recovery (SOR) that: "We find that although SOR would cause significant surface warming (global mean: 0.2 K) in a climate free of clouds and sea ice, it causes surface cooling (~0.06 K) in the real climate."  While some might find this reassuring; I wonder whether SOR will contribute to global warming if the sea ice cover diminishes sufficiently and if global warming changes the assumed cloud cover pattern:

Yan Xia, Yongyun Hu and Yi Huang (2016), "Strong modification of stratospheric ozone forcing by cloud and sea-ice adjustments", Atmos. Chem. Phys., 16, 7559–7567, doi: 10.5194/acp-16-7559-2016

http://www.atmos-chem-phys.net/16/7559/2016/acp-16-7559-2016.pdf

Abstract: "We investigate the climatic impact of stratospheric ozone recovery (SOR), with a focus on the surface temperature change in atmosphere–slab ocean coupled climate simulations. We find that although SOR would cause significant surface warming (global mean: 0.2 K) in a climate free of clouds and sea ice, it causes surface cooling (~0.06 K) in the real climate. The results here are especially interesting in that the stratosphere-adjusted radiative forcing is positive in both cases. Radiation diagnosis shows that the surface cooling is mainly due to a strong radiative effect resulting from significant reduction of global high clouds and, to a lesser extent, from an increase in high-latitude sea ice. Our simulation experiments suggest that clouds and sea ice are sensitive to stratospheric ozone perturbation, which constitutes a significant radiative adjustment that influences the sign and magnitude of the global surface temperature change."

[AbruptSLR]

The linked reference identifies the occurrence of atmospheric rivers extending from the Maritime Continent to the Bering Strait as one factor contributing to Arctic Amplification.  Hopefully, CMIP6 will use such findings to better calibrate their model runs so that AR6 will account for (rather than ignore) this positive feedback mechanism:

Cory Baggett, Sukyoung Lee & Steven Feldstein (12 August 2016), "An investigation of the presence of atmospheric rivers over the North Pacific during planetary-scale wave life cycles and their role in Arctic warming", Journal of the Atmospheric Sciences, DOI: http://dx.doi.org/10.1175/JAS-D-16-0033.1

http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-16-0033.1

Abstract: "Heretofore, the Tropically Excited Arctic warMing mechanism (TEAM) put forward that localized tropical convection amplifies planetary-scale waves which transport sensible and latent heat into the Arctic – leading to an enhancement of downward infrared radiation and Arctic surface warming. In this study, an investigation is made into the previously unexplored contribution of the synoptic-scale waves and their attendant atmospheric rivers to the TEAM mechanism.
Reanalysis data is used to conduct a suite of observational analyses, trajectory calculations, and idealized model simulations. It is shown that localized tropical convection over the Maritime Continent precedes the peak of the planetary-scale wave life cycle by ~10 to 14 days. The Rossby wave source induced by the tropical convection excites a Rossby wave train over the North Pacific that amplifies the climatological December-March stationary waves. These amplified planetary-scale waves are baroclinic and transport sensible and latent heat poleward. During the planetary-scale wave life cycle, synoptic-scale waves are diverted northward over the central North Pacific. The warm conveyor belts associated with the synoptic-scale waves channel moisture from the subtropics into atmospheric rivers which ascend as they move poleward and penetrate into the Arctic near the Bering Strait. At this time, the synoptic-scale waves undergo cyclonic Rossby wave breaking which further amplifies the planetary-scale waves. The planetary-scale wave life cycle ceases as ridging over Alaska retrogrades westward. The ridging blocks additional moisture transport into the Arctic. However, sensible and latent heat remain elevated over the Arctic which enhances downward infrared radiation and maintains warm surface temperatures."

[AbruptSLR]

The linked authors have played significant roles in helping to establish 3.2C as the canonical value of ECS in both AR5 and CMIP5.  Therefore, attention should be paid when they acknowledge that the scientific community currently use an ad-hoc ‘ensemble of opportunity’ approach to determining the canonical range of 2 to 4.5C for ECS; and that: "Climate models cannot sensibly be considered independent estimates of reality…".  The authors then recommend Bayesian procedures for enhanced learning from different sets of observed climate change data, say from paleodata where dust masked the impact of positive feedbacks and from modern observations where aerosols masked the impact of positive feedbacks.  I strongly suspect that if such Bayesian procedures are adopted for both CMIP6 and/or AR6 that we will see the canonical range for ECS translate towards higher values:

Annan, J. and Hargreaves, J.: On the meaning of independence in climate science, Earth Syst. Dynam. Discuss., doi:10.5194/esd-2016-34, in review, 2016.

http://www.earth-syst-dynam-discuss.net/esd-2016-34/
&
http://www.earth-syst-dynam-discuss.net/esd-2016-34/esd-2016-34.pdf

Abstract. The concept of independence has been frequently raised in climate science, but has rarely been defined and discussed in a theoretically robust and quantifiable manner. Improved understanding of this topic is critical to better understanding of climate change. In this paper, we introduce a unifying approach based on the statistical definition of independence, and illustrate with simple examples how it can be applied to practical questions.

Extract: "But should the consensus between models really lead to confidence in these results? If we were to re-run the same scenario with the same model 30 times, we would get the same answer 30 times, whether it be a good or bad model. This repetition of results would not tell us how good the model is, and the behaviour of the real climate system would inevitably lie outside this (empty) range of results. Different model development teams share code, and even when code is rewritten from scratch, algorithms and methods are often copied, and many fundamental theories are common across all models (Knutti et al., 2013).  So how much confidence can we draw from the fact that multiple models provide consistent answers? How likely is it that all models are biased in the same ways, and thus too similar for their spread of results to be useful? These questions have proved difficult to answer, and indeed there appears little consensus as to how we can even address them. Further questions arise from the increasingly common situation where a single modelling centre contributes multiple model simulations to the CMIP archive, some of which only differ in terms of the settings of uncertain parameters, or even just the initial state of the atmosphere/ocean system. A common heuristic when performing multi-model analyses based on a generation of the CMIP ensemble is to use a single simulation from each modelling centre, but it is not clear where to draw the line when different centres may share a common core or sub-models. Is there a better way to select models, and should we use a weighted ensemble —in which case, further questions arise as to how the weights should be defined, in terms of either model performance relative to observations of the real climate, or else in terms of their relationship to other models?

Another important question that has been posed in recent years, is whether the scientific community could design or select ensemble members in a more rational and scientifically defensible way than the current ad-hoc ‘ensemble of opportunity’. It may be possible to address this issue in terms of statistical sampling and experimental design, but appropriate methods and even language do not yet appear to be well developed in this area.

…

We have discussed and presented a coherent statistical framework for understanding independence, and explained how this applies in two distinct applications. Climate models cannot sensibly be considered independent estimates of reality, but fortunately this strong assumption is not required in order to make use of them. A more plausible, though still optimistic, assumption, might be to interpret the ensemble as merely constituting independent samples of a distribution which represents our collective understanding of the climate system. This assumption is challenged by the near-replication of some climate models within the ensemble, and therefore re-weighting or sub-sampling the ensemble could improve its usefulness. We have shown how the statistical definition of (conditional) independence can apply and how it helps in defining independence in a quantifiable manner.  The definition we have presented is certainly not the only possible one and we expect that others may be able to suggest improvements within this framework.

When considering the use of observational evidence in constraining climate system behaviour (including the specific example of the equilibrium climate sensitivity), observational uncertainties themselves can generally be regarded as independent.  However, the independence of the resulting likelihood functions is not so immediately clear, as it typically also rests on a number of modelling assumptions and uncertainties. Here we have shown how the question of independence can be readily interpreted and understood in terms of the conditional prediction of observations. These ideas may be useful in the design and analysis of ensemble experiments underpinning the analysis of observational constraints.

While our analyses may not provide complete solutions to the questions raised, we have shown how the statistical framework can be usefully applied. Further, we see little prospect for progress to be made unless it is underpinned by a rigorous mathematical framework. Therefore, we hope that other researchers will be able to make use of these ideas in their future work."

[AbruptSLR]

The linked reference provides new observational evidence for a positive cloud feedback that amplifies the AMO, and increases SSTA associated with the AMO over the tropics:

Katinka Bellomo, Amy C. Clement, Lisa N. Murphy, Lorenzo M. Polvani & Mark A. Cane (18 August 2016), "New Observational Evidence for a Positive Cloud Feedback that Amplifies the Atlantic Multidecadal Oscillation", Geophysical Research Letters, DOI: 10.1002/2016GL069961


http://onlinelibrary.wiley.com/doi/10.1002/2016GL069961/abstract

Abstract: "The Atlantic Multidecadal Oscillation (AMO) affects climate variability in the North Atlantic basin and adjacent continents with potential societal impacts. Previous studies based on model simulations and short-term satellite retrievals hypothesized an important role for cloud radiative forcing in modulating the persistence of the AMO in the tropics, but this mechanism remains to be tested with long-term observational records. Here we analyze datasets that span multiple decades and present new observational evidence for a positive feedback between total cloud amount, sea-surface temperature (SST), and atmospheric circulation that can strengthen the persistence and amplitude of the tropical branch of the AMO. In addition, we estimate cloud amount feedback from observations and quantify its impact on SST with idealized modeling experiments. From these experiments we conclude that cloud feedbacks can account for 10% to 31% of the observed SST anomalies associated with the AMO over the tropics."

[AbruptSLR]

The linked reference provides paleo-evidence that methane emissions from seafloor seeps in the Fram Strait increased during warm periods during the last 35,000 years:

Kamila Sztybor & Tine L. Rasmussen (19 August 2016), "Diagenetic disturbances of marine sedimentary records from methane-influenced environments in the Fram Strait as indications of variation in seep intensity during the last 35 000 years", Boreas, DOI: 10.1111/bor.12202


http://onlinelibrary.wiley.com/doi/10.1111/bor.12202/abstract

Abstract: "The effect of seeping of methane on marine sediment records has been studied in four gravity cores from Vestnesa Ridge, Svalbard margin. The area shows acoustic signs in the form of flares indicating active methane gas seepage. For a better understanding of the timing and variability of the flux of methane in the past and the effects on potential proxies, a detailed study of the diagenetic processes that may affect the composition and structure of both sediments and foraminiferal shells is needed. Here we discuss deep-sea records from methane-influenced environments in three cores from an active and very heterogeneous seep-area (pockmark) and one core from outside the pockmark for background. The results include the distribution and stable isotopes of authigenic carbonates and of benthic and planktonic foraminifera, magnetic susceptibility, AMS-14C dates, sedimentary data and biostratigraphy. Extremely low δ13C values recorded in both benthic and planktonic foraminifera during the Bølling-Allerød interstadials indicate possible increased methane flux beginning at late Heinrich event H1. The recorded low values are mainly a result of diagenetic overprint by methane-derived authigenic carbonates. The δ18O signals of authigenic carbonates are close to those of foraminiferal calcite and thus the δ18O records remain a valid stratigraphical tool in methane seep sites, except in the case of severely encrusted samples. In addition, the records from the active pockmark show nearly constant values of low magnetic susceptibility in contrast to higher and more variable magnetic susceptibility values from the control station and other published records from normal sediments west of Svalbard. This phenomenon is probably caused by dissolution of magnetic minerals in the reducing environmental conditions of methane seep sediments, associated with anaerobic oxidation of methane and formation of paramagnetic minerals (pyrite). This process enables magnetic susceptibility to be used as a common diagnostic tool for identifying methane-related palaeo-reductive environments."

[AbruptSLR]

The linked National Geographic (which is owned by Rupert Murdoch) article is entitled: "Ocean Slime Spreading Quickly Across the Earth".  Such trends were not suspected as recently as a year or two ago, but I guess that such news is so disturbing (certainly it is to me) that even Rupert Murdoch cannot suppress it:

http://news.nationalgeographic.com/2016/08/toxic-algae/

Extract: "Toxic algae blooms, perhaps accelerated by ocean warming and other climate shifts, are spreading, poisoning marine life and people."

[Sigmetnow]

The linked National Geographic (which is owned by Rupert Murdoch) article is entitled: "Ocean Slime Spreading Quickly Across the Earth".  Such trends were not suspected as recently as a year or two ago, but I guess that such news is so disturbing (certainly it is to me) that even Rupert Murdoch cannot suppress it:
...

James Murdoch is chief executive of the National Geographic Society, and a "very different proposition to his father."  It's heartening to see his independence.
https://www.theguardian.com/media/media-blog/2015/sep/13/james-murdoch-fox-national-geographic

[Theta]

The linked National Geographic (which is owned by Rupert Murdoch) article is entitled: "Ocean Slime Spreading Quickly Across the Earth".  Such trends were not suspected as recently as a year or two ago, but I guess that such news is so disturbing (certainly it is to me) that even Rupert Murdoch cannot suppress it:

http://news.nationalgeographic.com/2016/08/toxic-algae/

Extract: "Toxic algae blooms, perhaps accelerated by ocean warming and other climate shifts, are spreading, poisoning marine life and people."

Wasn't Guy McPherson featured on National Geographic with Bill Nye? If they're willing to show the man who predicts the death of everything and everyone within months then it's not too surprising that they would have an article about algae blooms.

[Bruce Steele]

Craig Welch, the author of the "slime" article in the National Geographic came out on my boat and did a story on me a couple years ago while he was working at the Seattle Times.

http://www.google.com/search?q=Seattle+times+Craig+welch+Bruce+Steele&ie=UTF-8&oe=UTF-8&hl=en&client=safari

The domoic acid closures last year along the west coast were very hard on both the dungeness and rock crab fisheries last year. Closures of anchovy and sardines for domoic acid have been an annual occurrence for parts of Calif. for several years. There is going to be more vigilance on several more species this year and lobster might also have problems with closures. Seasons for dungeness and lobster are designed around biological factors like molt and breeding season so closures iduring fishing season cut deeply into fishing incomes.
  I presented a short primer on ocean acidification to the Calif Fish and Wildlife Commission several years ago but last month was the first time that the commission formally asked for input from scientists on the issue. Although I am a fisherman and not a scientist I gave a presentation along with a couple scientists at the Commissions last meeting. It is amazing how long it takes for climate change ( or acidification ) to percolate up to managers of our resources.
 There has been science implicating domoic acid and increased toxicity of algae blooms to acidification for ten years . Co2 fertilization increases algae growth which turns toxic as the blooms exceed nutrient
availability. A paper " Effects of changing pCO2 and phosphate availability on Domoic acid production and physiology of marine harmful bloom diatoms" by Jun Sun ( 2011 ) and coauthored by Dave Hutchins can fill in the details . We are talking toxicity increases by factors of 40x under some conditions.     

[Bruce Steele]

I thought more info on Domoic acid might be in order. In humans it can cause short term memory loss and case reports from an outbreak in British Columbia resulted in 3 deaths and short term memory loss that lasted five years + in the most affected cases. I can't find the source but one case, a university professor ,could still teach but couldn't remember where he parked his car.
 There is lab work on rats that also shows potential heart damage. Anecdotally I and at least six of my close fishermen friends deal with bouts of atrial arrhythmia , mine started when I was 30. My wife had a pretty scary case of PSP ( paralytic shellfish poisoning ) from a batch of littleneck clams. PSP is a different disease also caused by toxic algae blooms. Diving commercially is living dangerously and doing it with a heart condition eventually lead me to retire but 40 years ( 30 with a-fib attacks ) is probably all the human body should ever be exposed to anyhow. Commercial urchin divers run about a 1in 300 chance of dying on job every year they dive. Eating shellfish is very safe compared to those odds.

  http://ic.ucsc.edu/~kudela/OS130/Readings/DA_review.pdf

The domoic acid troubles are likely IMO to increase over time and anyone thinking survival food should get a better idea about how to reduce their chances of poisoning themselves should hard times come.
Starving isn't however a better option. Cats are very subject to PSP so in a very tight spot .

[AbruptSLR]

The linked reference indicates that the record ice melting in Greenland in 2015 was the result of Arctic Amplification:

M. Tedesco, T. Mote, X. Fettweis, E. Hanna, J. Jeyaratnam, J. F. Booth, R. Datta & K. Briggs (2016), “Arctic cut-off high drives the poleward shift of a new Greenland melting record”, Nature Communications 7, Article number: 11723, doi:10.1038/ncomms11723


http://www.nature.com/ncomms/2016/160609/ncomms11723/full/ncomms11723.html


Abstract: “Large-scale atmospheric circulation controls the mass and energy balance of the Greenland ice sheet through its impact on radiative budget, runoff and accumulation. Here, using reanalysis data and the outputs of a regional climate model, we show that the persistence of an exceptional atmospheric ridge, centred over the Arctic Ocean, was responsible for a poleward shift of runoff, albedo and surface temperature records over the Greenland during the summer of 2015. New records of monthly mean zonal winds at 500 hPa and of the maximum latitude of ridge peaks of the 5,700±50 m isohypse over the Arctic were associated with the formation and persistency of a cutoff high. The unprecedented (1948–2015) and sustained atmospheric conditions promoted enhanced runoff, increased the surface temperatures and decreased the albedo in northern Greenland, while inhibiting melting in the south, where new melting records were set over the past decade.”

[AbruptSLR]

The linked reference provides field evidence that aquatic plants in arctic tundra wetlands is a major source of methane emissions, and will likely serve as a positive feedback mechanism with continued global warming (the AR5 & CMIP5 projections do not account for this source of methane):

C G Andresen, M J Lara, C E Tweedie & V L Lougheed (19 August 2016) "Rising Plant-mediated Methane Emissions from Arctic Wetlands", Global Change Biology, DOI: 10.1111/gcb.13469

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13469/abstract

Abstract: "Plant-mediated CH4 flux is an important pathway for land-atmosphere CH4 emissions but the magnitude, timing, and environmental controls, spanning scales of space and time, remain poorly understood in arctic tundra wetlands, particularly under the long term effects of climate change. CH4 fluxes were measured in situ during peak growing season for the dominant aquatic emergent plants in the Alaskan arctic coastal plain, Carex aquatilis and Arctophila fulva, to assess the magnitude and species-specific controls on CH4 flux. Plant biomass was a strong predictor of A. fulva CH4 flux while water depth and thaw depth were co-predictors for C. aquatilis CH4 flux. We used plant and environmental data from 1971-72 from the historic International Biological Program (IBP) research site near Barrow, Alaska, which we resampled in 2010-13, to quantify changes in plant biomass and thaw depth, and used these to estimate species-specific decadal-scale changes in CH4 fluxes. A ~60% increase in CH4 flux was estimated from the observed plant biomass and thaw depth increases in tundra ponds over the past 40 years. Despite covering only ~5% of the landscape, we estimate that aquatic C. aquatilis and A. fulva account for two-thirds of the total regional CH4 flux of the Barrow Peninsula. The regionally observed increases in plant biomass and active layer thickening over the past 40 years not only have major implications for energy and water balance, but have significantly altered land-atmosphere CH4 emissions for this region, potentially acting as a positive feedback to climate warming."

[AbruptSLR]

The two linked articles discuss the increasing risks associated with scientific reticence, w.r.t. climate change:

"Dangerous Scientific Reticence" by James Hansen (2016)

http://csas.ei.columbia.edu/2016/03/24/dangerous-scientific-reticence/

&

"Beware the "fat tail": Climate risk and scientific reticence" by David Spratt (2016)

http://www.climatecodered.org/2016/03/climate-risk-and-scientific-reticence.html

[AbruptSLR]

In the linked research: "Severe testing is applied to observed global and regional surface and satellite temperatures and modelled surface temperatures to determine whether these interactions are independent, as in the traditional signal-to-noise model, or whether they interact, resulting in steplike warming."  The reference concludes that indeed steplike warming occurs due to "… a store-and-release mechanism from the ocean to the atmosphere…" like the classical Lorenzian attractor case of ENSO decadal cycles.  Such steplike behavior raises the issue of what I call "Ratcheting Quasi-static Equilibrium States" that can accelerate non-linear Earth Systems response beyond the linear Earth Systems response assumed by AR5/CMIP5 researchers (see the first attachment).  As the authors point-out such AR5/CMIP5 researcher likely missed this behavior because: "This may be due in part to science asking the wrong questions."; and they advise that such AR5/CMIP5 researchers should change how they view the output from their models.  For example, the second attached image (see panel "e" of that Figure 6) from the reference shows global warming increasing much faster for a steplike response if ECS is 4.5 than for a the traditional AR5/CMIP5 interpretation; which means that ESLD researchers are exposing society to far more risk of the consequences of high ECS values than AR5/CMIP5 are leading us to believe:

Jones, R. N. and Ricketts, J. H.: Reconciling the signal and noise of atmospheric warming on decadal timescales, Earth Syst. Dynam. Discuss., doi:10.5194/esd-2016-35, in review, 2016.

http://www.earth-syst-dynam-discuss.net/esd-2016-35/
&
http://www.earth-syst-dynam-discuss.net/esd-2016-35/esd-2016-35.pdf

Abstract: "Interactions between externally-forced and internally-generated climate variations on decadal timescales is a major determinant of changing climate risk. Severe testing is applied to observed global and regional surface and satellite temperatures and modelled surface temperatures to determine whether these interactions are independent, as in the traditional signal-to-noise model, or whether they interact, resulting in steplike warming. The multi-step bivariate test is used to detect step changes in temperature data. The resulting data are then subject to six tests designed to show strong differences between the two statistical hypotheses, hstep and htrend: (1) Since the mid-20th century, most of the observed warming has taken place in four events: in 1979/80 and 1997/98 at the global scale, 1988/89 in the northern hemisphere and 1968/70 in the southern hemisphere. Temperature is more steplike than trend-like on a regional basis. Satellite temperature is more steplike than surface temperature. Warming from internal trends is less than 40 % of the total for four of five global records tested (1880–2013/14). (2) Correlations between step-change frequency in models and observations (1880–2005), are 0.32 (CMIP3) and 0.34 (CMIP5). For the period 1950–2005, grouping selected events (1963/64, 1968–70, 1976/77, 1979/80, 1987/88 and 1996–98), correlation increases to 0.78. (3) Steps and shifts (steps minus internal trends) from a 107-member climate model ensemble 2006–2095 explain total warming and equilibrium climate sensitivity better than internal trends. (4) In three regions tested, the change between stationary and non-stationary temperatures is steplike and attributable to external forcing. (5) Steplike changes are also present in tide gauge observations, rainfall, ocean heat content, forest fire danger index and related variables. (6) Across a selection of tests, a simple stepladder model better represents the internal structures of warming than a simple trend – strong evidence that the climate system is exhibiting complex system behaviour on decadal timescales. This model indicates that in situ warming of the atmosphere does not occur; instead, a store-and-release mechanism from the ocean to the atmosphere is proposed. It is physically plausible and theoretically sound. The presence of steplike – rather than gradual – warming is important information for characterising and managing future climate risk."


Extract: "This finding does not invalidate the huge literature that assesses long-term (>50 years) climate change as a relatively linear process, and the warming response as being broadly additive with respect to forcing (e.g., Lucarini et al., 2010; Marvel et al., 2015). However, on decadal scales, this is not the case – warming appears to be largely governed by a storage and release process, where heat is stored in the ocean and released in bursts projecting onto modes of climate variability as suggested by Corti et al. (1999). We discuss this further in another paper (Jones and Ricketts, 2016).

This has serious implications for how climate change is understood and applied in a whole range of decision-making contexts.  The characterisation of changing climate risk as a smooth process will leave climate risk as being seriously underdetermined, affecting how adaptation is perceived, planned and undertaken (Jones et al., 2013).

The interaction of change and variability is typical of a complex, rather than mechanistic, system. The possibility of Lorenzian attractors in the ocean-atmosphere acting on decadal time scales was raised by Palmer (1993) and, despite later discussions about the potential for nonlinear responses on those timescales (e.g., Lucarini and Ragone, 2011;Tsonis and Swanson, 2012), very little progress has been made in translating this into applied research that can portray a better understanding of changing climate risk. This may be due in part to science asking the wrong questions.

The signal to noise model of a gradually changing mean surrounded by random climate variability poorly represents warming on decadal timescales. The separation of signal and noise into ‘good’ and ‘bad, likewise, is poor framing for the purposes of understanding and managing risk in fundamentally nonlinear systems (Koutsoyiannis, 2010; Jones, 2015b). However, as we show, the presence of such changes within climate models shows their current potential for investigating nonlinearly changing climate risks. Investigating step changes in temperature and related variables does not indicate a need to fundamentally change how climate modelling is carried out. It does, however, indicate a need to change how the results are analysed."


Furthermore, the linked SkS article indicates that traditional (AR5/CMIP5) climate sciences would benefit from adopting a true Bayesian methodology where they let theory (like chaos theory with strange attractors) guide their observations otherwise as Darwin stated they "… might as well go into a gravel pit and count the pebbles and describe the colors. How odd it is that anyone should not see that observation must be for or against some view if it is to be of any service".

https://www.skepticalscience.com/naive-empiricism.html

Extract: "… University of California professor of biology and philosophy Francisco Ayala writes in Darwin and the scientific method:

“Let theory guide your observations.” Indeed, Darwin had no use for the empiricist claim that a scientist should not have a preconception or hypothesis that would guide his work. Otherwise, as he wrote, one “might as well go into a gravel pit and count the pebbles and describe the colors. How odd it is that anyone should not see that observation must be for or against some view if it is to be of any service”"

[AbruptSLR]

As a follow-on to my last post Reply #1513), the linked article describes how a series of "working papers" about the implications of stepped climate changes will be released in 2016:

https://2risk.wordpress.com/2016/07/31/step-change-hypothesis-and-working-paper/

Extract: "The problem with publishing these days is that it is difficult to get such things into the literature. Publishing is geared towards making limited advances in 3,000 words. Arguing against a long-held paradigm is not part of the deal.
For that reason, we have decided to release all of the past three years work as working papers, while the later papers are reformatted and submitted to journals."

For example one "working paper" is as follows:

Roger Neville Jones & James Henry Ricketts (2016), "Atmospheric warming 1997–2014: hiatus, pause or regime?"

https://www.researchgate.net/publication/305989994_Atmospheric_warming_1997-2014_hiatus_pause_or_regime

Abstract: "For the past decade, climate research has responded to challenges that atmospheric warming either slowed or stopped in 1998. Of the responses, the hypothesis least examined is whether climate change and variability are interacting to produce step-like regime changes. Step-change analysis identifies a step of 0.32±0.01°C in five records of global mean surface temperature (GMST) in 1997, followed by a trend to 2014 ranging between 0.06°C decade 1 and 0.11°C decade 1. Thirty-nine of 45 zonal, hemispheric and global records register a step change over the period 1996–98. The difference between one trend and the next across a step change provides a minimum estimate of the shift. Globally, the average shift in 1997 is 0.16±0.01°C, around 50% of the average step. For the northern hemisphere mid-latitudes, steps/shifts measure 0.43°C/0.44°C, indicating no trend. Of the 107 members of a multi-model ensemble (MME) from the CMIP5 RCP4.5 archive, 58 register a step change in 1996–98, averaging 0.41°C (0.22°C to 0.73°C). The following step averaging 0.31°C (0.16°C to 0.52°C) occurs after a period of 7 to 26 years. The 1996–98 step is uncorrelated with model equilibrium climate sensitivity (ECS) but the following step change is highly correlated (0.58). Step-change analysis in both observations and models suggests that rapid changes punctuate more stable regimes forming a step-ladder like progression. If the current spike in temperature from the 2014–16 El Niño event represents the early stages of a step change similar to 1997–98, the world may be entering a regime of new and heightened climate risk."

[AbruptSLR]

While I am too cheap to get past the pay wall, the following linked 2014 pdf is clearly an earlier draft of the final paper, that uses chaos theory (Ruelle's response theory) & linear theory to study the response of Climate Systems (CS) and the associated climate sensitivity to decadal scale step-like variations.  The reference indicates that the linear theory could be upgraded to include non-linear cases (as is the real Earth Systems case) with further study.  I suspect that such research will support higher values of climate sensitivity than traditionally assumed (in this regards I note that the researchers use an ECS value of 8.1C to prove the stability of their methodology):

Ragone, F., Lucarini, V. & Lunkeit, F. (2016), "A new framework for climate sensitivity and prediction: a modelling perspective", Clim Dyn, 46: 1459. doi:10.1007/s00382-015-2657-3

http://link.springer.com/article/10.1007/s00382-015-2657-3

Abstract: "The sensitivity of climate models to increasing CO2 concentration and the climate response at decadal time-scales are still major factors of uncertainty for the assessment of the long and short term effects of anthropogenic climate change. While the relative slow progress on these issues is partly due to the inherent inaccuracies of numerical climate models, this also hints at the need for stronger theoretical foundations to the problem of studying climate sensitivity and performing climate change predictions with numerical models. Here we demonstrate that it is possible to use Ruelle’s response theory to predict the impact of an arbitrary CO2 forcing scenario on the global surface temperature of a general circulation model. Response theory puts the concept of climate sensitivity on firm theoretical grounds, and addresses rigorously the problem of predictability at different time-scales. Conceptually, these results show that performing climate change experiments with general circulation models is a well defined problem from a physical and mathematical point of view. Practically, these results show that considering one single CO2 forcing scenario is enough to construct operators able to predict the response of climatic observables to any other CO2 forcing scenario, without the need to perform additional numerical simulations. We also introduce a general relationship between climate sensitivity and climate response at different time scales, thus providing an explicit definition of the inertia of the system at different time scales. This technique allows also for studying systematically, for a large variety of forcing scenarios, the time horizon at which the climate change signal (in an ensemble sense) becomes statistically significant. While what we report here refers to the linear response, the general theory allows for treating nonlinear effects as well. These results pave the way for redesigning and interpreting climate change experiments from a radically new perspective."


 Francesco Ragone, Valerio Lucarini & Frank Lunkeit (2014), "A new framework for climate sensitivity and prediction"

https://www.researchgate.net/profile/Valerio_Lucarini/publication/260945847_A_new_framework_for_climate_sensitivity_and_prediction/links/0a85e53301d283571d000000.pdf

Extract: "The importance of addressing the properties of the climate system (CS) on various temporal horizons is also emphasized by the presence of substantial uncertainties in the predictive skills of the models at decadal time scale. The need of substantial advances in the scientific ideas at the basis of climate modelling strategies is more and more clear in the climate community. An illuminating perspective on mathematical frameworks suited for a theory of climate sensitivity has been recently presented. Here, we follow a complementary approach.
In the past, several attempts have been aimed at constructing some sort of response operator for the CS. Early attempts tried to address empirically the problem of the cold start of climate simulations. More recently, the fluctuation-dissipation theorem (FDT) has inspired various authors to reconstructing the climatic response to perturbations from some statistical properties of the unperturbed system, typically using severely simplified, quasi-Gaussian approximations, or constructing blended response algorithms16. A basic obstacle is that, as already anticipated by Lorenz, forced and free fluctuations are not equivalent. Ruelle introduced general methods for studying how nonequilibrium systems respond to external perturbations. Ruelle’s response theory (RRT) clarifies that Lorenz’s intuition applies to general nonequilibrium systems, so that applying FDT can lead in principle to large errors. Nonetheless, it is indeed possible to compute deviations from a nonequilibrium steady state (NESS) due to weak forcings through response formulas formally similar to those of the equilibrium case."

[AbruptSLR]

To continue my recent series of posts about climate sensitivity and chaos theory with strange/lorenz attractors; the linked (open access) research indicates that the traditional model approach consistently underestimates values of climate sensitivity based on experiments (& paleo data) with dynamic changes in atmospheric CO2 concentrations:

Anna S. von der Heydt, Peter Ashwin (Submitted on 12 Apr 2016), "State-dependence of climate sensitivity: attractor constraints and palaeoclimate regimes",    arXiv:1604.03311


http://arxiv.org/abs/1604.03311
&
http://arxiv.org/pdf/1604.03311v1.pdf

Abstract: "Equilibrium climate sensitivity is a frequently used measure to predict long-term climate change. However, both climate models and observational data suggest a rather large uncertainty on climate sensitivity (CS). The reasons for this include: the climate has a strong internal variability on many time scales, it is subject to a non-stationary forcing and it is, on many timescales, out of equilibrium with the changes in the radiative forcing. Palaeo records of past climate variations give insight into how the climate system responds to various forcings although care must be taken of the slow feedback processes before comparing palaeo CS estimates with model estimates. In addition, the fast feedback processes can change their relative strength and time scales over time. Consequently, another reason for the large uncertainty on palaeo climate sensitivity may be the fact that it is strongly state-dependent. Using a conceptual climate model, we explore how CS can be estimated from unperturbed and perturbed model time series. Even in this rather simple model we find a wide range of estimates of the distribution of CS, depending on climate state and variability within the unperturbed attractor. For climate states perturbed by instantaneous doubling of CO2, the sensitivity estimates agree with those for the unperturbed model after transient decay back the attractor. In this sense, climate sensitivity can be seen as a distribution that is a local property of the climate attractor. We also follow the classical climate model approach to sensitivity, where CO2 is prescribed and non-dynamic, leading to CS values consistently smaller than those derived from the experiments with dynamic CO2. This suggests that climate sensitivity estimates from climate models may depend significantly on future dynamics, and not just the level of CO2."

Extract: “... the presence of variability on the attractor on a number of timescales means there are clear and non-trivial distributions of sensitivities, even for unperturbed climates. The distribution of sensitivities depends strongly on the background state as well as on the timescale considered. This suggests that it could be useful to think of the unperturbed climate sensitivity as a local property of the “climate attractor”. For a perturbed system (we have considered instantaneously doubled CO2) this is still useful once an initial transient has decayed. This transient will depend in particular on ocean heat uptake, though also on carbon cycle and biosphere processes that act on time scales roughly equivalent with the forcing time scale. If the climate system has more than one attractor, the perturbed system may clearly evolve to a completely different set of states than the original attractor – a situation that did not occur in the climate model used here. In less extreme cases, there may still be very long transients for some perturbations associated parts of the climate system that are associated with slow feedbacks.

Such perturbations (illustrated in Fig. 1b,d) are not normally applied in climate models used for climate predictions [IPCC, 2013], where climate sensitivity is derived from model simulations considering prescribed, non-dynamic atmospheric CO2. In our conceptual model, we have derived climate sensitivities from both types of perturbations and find that the classical climate model approach (section 2.2, Fig. 4f) leads to significantly lower values of the climate sensitivity than the perturbations away from the attractor with dynamic CO2 (section 2.3, Fig. 11a). This emphasises the importance of including dynamic carbon cycle processes into climate prediction models. Moreover, it supports the idea that the real observed climate response may indeed be larger than the model predicted one, because those models never will include all feedback processes in the climate system. “

[AbruptSLR]

The linked reference discusses paleo information (from the past 21,000 years) about CO₂ emissions from permafrost thawing that has not yet been included in CMIP5 projections, and this reference concludes: "In simulations of future warming we find that the permafrost carbon feedback increases global mean temperature by 10–40% relative to simulations without this feedback, with the magnitude of the increase dependent on the evolution of anthropogenic carbon emissions."

K. A. Crichton, N. Bouttes, D. M. Roche, J. Chappellaz & G. Krinner (2016), "Permafrost carbon as a missing link to explain CO 2 changes during the last deglaciation", Nature Geoscience, doi:10.1038/ngeo2793

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2793.html

Abstract: "The atmospheric concentration of CO2 increased from 190 to 280 ppm between the last glacial maximum 21,000 years ago and the pre-industrial era. This CO2 rise and its timing have been linked to changes in the Earth’s orbit, ice sheet configuration and volume, and ocean carbon storage. The ice-core record of δ13CO2  in the atmosphere can help to constrain the source of carbon, but previous modelling studies have failed to capture the evolution of δ13CO2 over this period. Here we show that simulations of the last deglaciation that include a permafrost carbon component can reproduce the ice core records between 21,000 and 10,000 years ago. We suggest that thawing permafrost, due to increasing summer insolation in the northern hemisphere, is the main source of CO2 rise between 17,500 and 15,000 years ago, a period sometimes referred to as the Mystery Interval. Together with a fresh water release into the North Atlantic, much of the CO2 variability associated with the Bølling-Allerod/Younger Dryas period ~15,000 to ~12,000 years ago can also be explained. In simulations of future warming we find that the permafrost carbon feedback increases global mean temperature by 10–40% relative to simulations without this feedback, with the magnitude of the increase dependent on the evolution of anthropogenic carbon emissions."

[AbruptSLR]

The linked article discusses evidence of a possible "early onset of industrial-era warming", which may mean that we have erred on the side of least drama about where to draw our baseline from which we measure the 2C limit:

Authors: Nerilie J. Abram, Helen V. McGregor, Jessica E. Tierney, Michael N. Evans, Nicholas P. McKay, Darrell S. Kaufman and the PAGES 2k Consortium (Published online 24 August 2016), "Early onset of industrial‐era warming across the oceans and continents", Nature, Vol. 536, pp. 411-415, doi: 10.1038/nature19082

http://www.nature.com/nature/journal/v536/n7617/full/nature19082.html

Abstract: "The evolution of industrial-era warming across the continents and oceans provides a context for future climate change and is important for determining climate sensitivity and the processes that control regional warming. Here we use post-AD 1500 palaeoclimate records to show that sustained industrial-era warming of the tropical oceans first developed during the mid-nineteenth century and was nearly synchronous with Northern Hemisphere continental warming. The early onset of sustained, significant warming in palaeoclimate records and model simulations suggests that greenhouse forcing of industrial-era warming commenced as early as the mid-nineteenth century and included an enhanced equatorial ocean response mechanism. The development of Southern Hemisphere warming is delayed in reconstructions, but this apparent delay is not reproduced in climate simulations. Our findings imply that instrumental records are too short to comprehensively assess anthropogenic climate change and that, in some regions, about 180 years of industrial-era warming has already caused surface temperatures to emerge above pre-industrial values, even when taking natural variability into account."

See also:
http://www.climatecentral.org/news/human-driven-warming-may-reach-back-nearly-200-years-20631

[Sigmetnow]

"The 35 scientists on the WGA – who voted 30 to three in favour of formally designating the Anthropocene, with two abstentions – will now spend the next two to three years determining which signals are the strongest and sharpest. Crucially, they must also decide a location which will define the start of the Anthropocene. Geological divisions are not defined by dates but by a specific boundary between layers of rock or, in the case of the Holocene, a boundary between two ice layers in a core taken from Greenland and now stored in Denmark."

The Anthropocene epoch: scientists declare dawn of human-influenced age

Humanity’s impact on the Earth is now so profound that a new geological epoch – the Anthropocene – needs to be declared, according to an official expert group who presented the recommendation to the International Geological Congress in Cape Town on Monday.

The new epoch should begin about 1950, the experts said, and was likely to be defined by the radioactive elements dispersed across the planet by nuclear bomb tests, although an array of other signals, including plastic pollution, soot from power stations, concrete, and even the bones left by the global proliferation of the domestic chicken were now under consideration.

https://www.theguardian.com/environment/2016/aug/29/declare-anthropocene-epoch-experts-urge-geological-congress-human-impact-earth

[AbruptSLR]

The linked reference documents just how quickly our wilderness areas are declining; which will make it harder to stay below the 2C target than previously assumed:

James E.M. Watson, Danielle F. Shanahan, Moreno Di Marco, James Allan, William F. Laurance, Eric W. Sanderson, Brendan Mackey & Oscar Venter (2016), "Catastrophic Declines in Wilderness Areas Undermine Global Environment Targets", Current Biology, DOI: http://dx.doi.org/10.1016/j.cub.2016.08.049


http://www.cell.com/current-biology/fulltext/S0960-9822(16)30993-9

See also:
https://www.theguardian.com/environment/2016/sep/08/humans-have-destroyed-a-tenth-of-earths-wilderness-in-25-years-study

Extract: "Humans have destroyed a tenth of Earth’s remaining wilderness in the last 25 years and there may be none left within a century if trends continue, according to an authoritative new study.

Researchers found a vast area the size of two Alaskas – 3.3m square kilometres – had been tarnished by human activities between 1993 and today, which experts said was a “shockingly bad” and “profoundly large number”."

[AbruptSLR]

van Ruijven knows as much about this topic as anyone else on the planet and he believes that in the past few years emission scenario assessments have focused on low emission scenarios (including extensive use of geoengineering) at the expense of assessments of medium level emission scenarios.  This research gap could leave us somewhat blinded to coming impacts if/when the global community fails to achieve the postulated low emission scenarios (I note that the world is still following the 90% CL RCP 8.5 emission pathway):

van Ruijven, B.J. (2016), "Mind the gap – the case for medium level emission scenarios", Climatic Change, 138: 361. doi:10.1007/s10584-016-1744-8


http://rd.springer.com/article/10.1007%2Fs10584-016-1744-8?wt_mc=Affiliate.CommissionJunction.3.EPR1089.DeepLink


Abstract: "In this essay I argue that the research on emission scenarios over the past few years has focused on low emission scenarios while producing few medium level emission scenarios. As a consequence, there is a gap in the literature on emission scenarios which prohibits answering several basic questions. This relative lack of medium emission scenarios is problematic for three reasons. First, scientific integrity, as the research community should produce scenarios along the full range of future options. Second, there is currently a very limited number of scenarios that describe real-world conditions of imperfect climate policy combined with technology restrictions. Finally, I observe a growing mismatch between the mitigation research focus on low emission scenarios and research to impacts and adaptation on medium and high emission scenarios. If this trend continues, it will be difficult to draw overarching conclusions from mitigation and impacts research in IPCCs 6th Assessment Report. Therefore, this essay ends with several recommendations for the mitigation research community to stimulate production and publication of medium level emission scenarios."

[AbruptSLR]

The following article by Carbon Brief confirms that the research presented in: "Early onset of industrial-era warming across the oceans and continents", Nature. DOI: 10:1038/nature19082; indicates that climate sensitivity is likely higher than scientists previously thought:

https://www.carbonbrief.org/scientists-clarify-starting-point-for-human-caused-climate-change

Extract: "Knowing how quickly the Earth responded to greenhouse gases at the start of the industrial era tells scientists a lot about the sensitivity of the climate system.

Pinning a number on how much global temperature rises in response to a doubling of carbon dioxide – known as the climate sensitivity – is a big question in climate science as it helps more accurately predict how much warming we’ll see in future.

But while today’s study suggests the world’s oceans are more sensitive than previously thought, there is an element of good news to take from that, say the authors. If we can reduce greenhouse gas emissions, there might just be some regions where we could see quick paybacks, proffers Abram."

[AbruptSLR]

The linked reference indicates that CMIP5 models might incorrectly estimate future mid-latitude cloud feedbacks in regions where appreciable changes in both vertical velocity and enhancement of the boundary layer inversion strength (EIS) are projected.

Kevin M. Grise & Brian Medeiros (2016), "Understanding the varied influence of mid-latitude jet position on clouds and cloud-radiative effects in observations and global climate models", Journal of Climate, DOI: http://dx.doi.org/10.1175/JCLI-D-16-0295.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0295.1

Abstract: "This study examines the dynamical mechanisms responsible for changes in mid-latitude clouds and cloud-radiative effects (CRE) that occur in conjunction with meridional shifts in the jet streams over the North Atlantic, North Pacific, and Southern Oceans. When the mid-latitude jet shifts poleward, extratropical cyclones and their associated upward vertical velocity anomalies closely follow. As a result, a poleward jet shift contributes to a poleward shift in high-topped storm track clouds and their associated longwave CRE. However, when the jet shifts poleward, downward vertical velocity anomalies increase equatorward of the jet, contributing to an enhancement of the boundary layer inversion strength (EIS) and an increase in low cloud amount there. Because shortwave CRE depends on the reflection of solar radiation by clouds in all layers, the shortwave cooling effects of mid-latitude clouds increase with both upward vertical velocity anomalies and positive EIS anomalies. Over mid-latitude oceans where a poleward jet shift contributes to positive EIS anomalies but downward vertical velocity anomalies, the two effects cancel, and net observed changes in shortwave CRE are small.

Global climate models generally capture the observed anomalies associated with mid-latitude jet shifts. However, there is large inter-model spread in the shortwave CRE anomalies, with a subset of models showing a large shortwave cloud-radiative warming over mid-latitude oceans with a poleward jet shift. In these models, mid-latitude shortwave CRE is sensitive to vertical velocity perturbations, but the observed sensitivity to EIS perturbations is underestimated. Consequently, these models might incorrectly estimate future mid-latitude cloud feedbacks in regions where appreciable changes in both vertical velocity and EIS are projected."

[AbruptSLR]

The linked open access reference finds considerable evidence that the ability of the Earth Systems to absorb CO₂ from the atmosphere will weaken with continued warming and concludes: "Failure to accurately account for carbon cycle feedbacks which increase the need for such negative emissions may strongly and adversely affect the feasibility of achieving these targets."  This indicates that it will likely be more difficult to limit global warming than previously assumed:

C D Jones, P Ciais, S J Davis, P Friedlingstein, T Gasser, G P Peters, J Rogelj, D P van Vuuren, J G Canadell, A Cowie (2016), "Simulating the Earth system response to negative emissions", Environmental Research Letters, doi:10.1088/1748-9326/11/9/095012


http://iopscience.iop.org/article/10.1088/1748-9326/11/9/095012/meta

Abstract: "Natural carbon sinks currently absorb approximately half of the anthropogenic CO2 emitted by fossil fuel burning, cement production and land-use change. However, this airborne fraction may change in the future depending on the emissions scenario. An important issue in developing carbon budgets to achieve climate stabilisation targets is the behaviour of natural carbon sinks, particularly under low emissions mitigation scenarios as required to meet the goals of the Paris Agreement. A key requirement for low carbon pathways is to quantify the effectiveness of negative emissions technologies which will be strongly affected by carbon cycle feedbacks. Here we find that Earth system models suggest significant weakening, even potential reversal, of the ocean and land sinks under future low emission scenarios. For the RCP2.6 concentration pathway, models project land and ocean sinks to weaken to 0.8 ± 0.9 and 1.1 ± 0.3 GtC yr−1 respectively for the second half of the 21st century and to −0.4 ± 0.4 and 0.1 ± 0.2 GtC yr−1 respectively for the second half of the 23rd century. Weakening of natural carbon sinks will hinder the effectiveness of negative emissions technologies and therefore increase their required deployment to achieve a given climate stabilisation target. We introduce a new metric, the perturbation airborne fraction, to measure and assess the effectiveness of negative emissions."

[AbruptSLR]

The linked open access reference introduces methodology for determining a point of no return to dangerous anthropogenic interference, DAI.  The attached imagine presents a summary of such an assessment for the very optimistic RCP 4.5 scenario (assuming that we are currently only 1.0C above pre-industrial, which is not very likely to be true):

van Zalinge, B. C., Feng, Q. Y., and Dijkstra, H. A.: On determining the Point of no Return in Climate Change, Earth Syst. Dynam. Discuss., doi:10.5194/esd-2016-40, in review, 2016.

http://www.earth-syst-dynam-discuss.net/esd-2016-40/
http://www.earth-syst-dynam-discuss.net/esd-2016-40/esd-2016-40.pdf

Abstract. Earth's Global Mean Surface Temperature (GMST) has increased by about 1.0 °C over the period 1880–2015. One of the main causes is thought to be the increase in atmospheric greenhouse gases (GHGs). If GHG emissions are not substantially decreased, several studies indicate there will be a dangerous anthropogenic interference (DAI) with climate by the end of this century. However, there is no good quantitative measure to determine when it is "too late" to start reducing GHGs in order to avoid DAI. In this study, we develop a method for determining a so-called Point of No Return (PNR) for several GHG emission scenarios. The method is based on a combination of stochastic viability theory and uses linear response theory to estimate the probability density function of the GMST. The innovative element in this approach is the applicability to high-dimensional climate models as is demonstrated by results obtained with the PLASIM climate model.

[AbruptSLR]

The linked reference provides satellite evidence that the CMIP5 projections substantially underestimate the positive feedback from precipitating clouds.  This is more evidence that consensus science has underestimated climate sensitivity:

J.-L. F. Li, Wei-Liang Lee, Yi-Hui Wang, Mark Richardson, Jia-Yuh Yu, E. Suhas, Eric Fetzer, Min-Hui Lo & Qing Yue (2016), "Assessing the Radiative Impacts of Precipitating Clouds on Winter Surface Air Temperatures and Land Surface Properties in GCMs Using Observations", JGR: Atmospheres, DOI: 10.1002/2016JD025175


http://onlinelibrary.wiley.com/doi/10.1002/2016JD025175/abstract


Abstract: "Using CloudSat-CALIPSO ice water, cloud fraction and radiation; CERES radiation and long-term station-measured surface air temperature (SAT), we identified a substantial underestimation of the total ice water path, total cloud fraction, land surface radiative flux, land surface temperature (LST) and SAT during Northern Hemisphere winter in CMIP5 models. We perform sensitivity experiments with the NCAR Community Earth System Model version 1 (CESM1) in fully coupled modes to identify processes driving these biases. We found that biases in land surface properties are associated with the exclusion of downwelling long-wave heating from precipitating ice during Northern Hemisphere winter. The land surface temperature biases introduced by the exclusion of precipitating ice radiative effects in CESM1 and CMIP5 both spatially correlate with winter biases over Eurasia and North America. The underestimated precipitating ice radiative effect leads to colder LST, associated surface energy-budget adjustments and cooler SAT. This bias also shifts regional soil moisture state from liquid to frozen, increases snow cover and depresses evapotranspiration (ET) and total leaf area index (TLAI) in Northern Hemisphere winter. The inclusion of the precipitating ice radiative effects largely reduces the model biases of surface radiative fluxes (more than 15 W m-2), SAT (up to 2-4 K), snow cover and ET (25-30%), compared with those without snow-radiative effects."

[AbruptSLR]

The linked video provides some idea that the most challenging risk to face with regards to climate would be to exceed the tipping points for abrupt positive feedback mechanisms such as Hansen et al 2016's ice-climate feedback (nevertheless I believe that the video errs on the side of least drama):

http://www.bing.com/videos/search?q=Abrupt+Climate+Change+Scenario+2016&view=detail&mid=16E8976274BCFF11A6B416E8976274BCFF11A6B4&FORM=VIRE

[AbruptSLR]

The linked (open access) reference examines: "Mechanisms of seasonal Arctic sea ice evolution and Artic amplification".  It finds that there are different mechanisms that apply to different Artic areas at different times of the year.  Nevertheless, it does find a net positive feedback associated with recent changes in sea ice area/extent that is largely related to:
"Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice."
This net positive feedback mechanism is not adequately represented in the AR5 findings:

Kim, K.-Y., Hamlington, B. D., Na, H., and Kim, J.: Mechanism of seasonal Arctic sea ice evolution and Arctic amplification, The Cryosphere, 10, 2191-2202, doi:10.5194/tc-10-2191-2016, 2016.

http://www.the-cryosphere.net/10/2191/2016/

Abstract. Sea ice loss is proposed as a primary reason for the Arctic amplification, although the physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-Interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice loss in the Arctic Ocean and the Arctic amplification. While sea ice loss is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains thin in winter only in the Barents–Kara seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice reduction warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be free of ice. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents–Kara seas and Laptev, East Siberian, Chukchi, and Beaufort seas.

Extract: "The physical process of sea ice loss and increased air temperature appears to have been accelerating. According to a simple exponential fitting to the PC time series of the warming mode, the strength of this positive feedback process increases by ~8% every year. At this rate, SAT (850 hPa temperature) may increase by ~10K (~3 K) over the Barents and Kara seas with respect to the 1979 winter mean value as sea ice completely disappears (see also IPCC, 2013)."

[SteveMDFP]

While I am too cheap to get past the pay wall, the following linked 2014 pdf is clearly an earlier draft of the final paper....

Ragone, F., Lucarini, V. & Lunkeit, F. (2016), "A new framework for climate sensitivity and prediction: a modelling perspective", Clim Dyn, 46: 1459. doi:10.1007/s00382-015-2657-3

http://link.springer.com/article/10.1007/s00382-015-2657-3

sci-hub.cc (and other sci-hub mirrors) permits access to many pay-walled articles

In this case,
http://sci-hub.cc/10.1007/s00382-015-2657-3

[AbruptSLR]

The following is a repost of jai mitchell's Reply #320 in the Carbon Cycle thread, as this information clearly belongs in both of these threads:

"RadioCarbon Dating of soil-sequestered carbon indicates that carbon uptake to soil (in some cases) is 1/6th as rapid as many models hold - This reduces the likely century-scale carbon sequestration to soil by as much as 1/2 through 2100.

https://www.washingtonpost.com/news/energy-environment/wp/2016/09/22/the-earth-is-soaking-up-less-carbon-than-we-thought-which-means-global-warming-may-go-faster/

The Earth is soaking up less carbon than we thought — which could make it warm up even faster



In any case, the results suggest the process can take a lot longer than scientists previously assume — up to thousands of years, instead of just tens or hundreds. This means that previous research may have significantly overestimated how much carbon the world’s soil can store away throughout the rest of the century. In fact, the new study suggests that, worldwide, soil’s carbon sequestration potential this century may only be half what we thought it was.




Study here (science)

http://science.sciencemag.org/content/353/6306/1419

Radiocarbon constraints imply reduced carbon uptake by soils during the 21st century
Yujie He

Abstract

Soil is the largest terrestrial carbon reservoir and may influence the sign and magnitude of carbon cycle–climate feedbacks. Many Earth system models (ESMs) estimate a significant soil carbon sink by 2100, yet the underlying carbon dynamics determining this response have not been systematically tested against observations. We used 14C data from 157 globally distributed soil profiles sampled to 1-meter depth to show that ESMs underestimated the mean age of soil carbon by a factor of more than six (430 ± 50 years versus 3100 ± 1800 years). Consequently, ESMs overestimated the carbon sequestration potential of soils by a factor of nearly two (40 ± 27%). These inconsistencies suggest that ESMs must better represent carbon stabilization processes and the turnover time of slow and passive reservoirs when simulating future atmospheric carbon dioxide dynamics."

[AbruptSLR]

The linked RealClimate article by Gavin Schmidt is entitled: "Why correlations of CO2 and Temperature over ice age cycles don’t define climate sensitivity"; and in this article he asserts his opinion that the paleo-proxy recording supports a Charney climate sensitivity value of between 2.5 and 3C.  While Gavin Schmidt as the Director of the NASA Goddard Institute for Space Studies (GISS) is entitled to his opinion, that does not mean that he his opinion is correct, for reasons including the following:

1. He does not appear to account for the significant masking influence of paleo-dust.

2. He does not appear to correct for the "strange attractor" influence explicitly described by chaos theory when interpreting a paleo-record that is clearly chaotic.

3. Climate change models clearly demonstrate that Charney sensitivity is a function of the rate of change in radiative forcing; & Gavin makes no corrections for this consideration.

4. Most people are truly only interested in the effective climate sensitivity, and thus do not want to be told about purely academic discussions of Charney sensitivity; when slow-response feedbacks can be accelerated, and when feedbacks such as Hansen's ice-climate feedback need to be considered. Edit: Also, the effective climate sensitivity must also account for the net reduction in the effective GHG absorption by both the land and the ocean.

http://www.realclimate.org/index.php/archives/2016/09/why-correlations-of-co2-and-temperature-over-ice-age-cycles-dont-define-climate-sensitivity/?wpmp_tp=1


Extract: "Instead, to constrain the Charney sensitivity from the ice age cycle you need to specifically extract out those long term changes (in ice sheets, vegetation, sea level etc.) and then estimate the total radiative forcing including these changes as forcing, not responses. In most assessments of this, you end up with 2.5ºC to 3ºC in response to 2xCO2."

[AbruptSLR]

While it is impossible to predict the future, the linked reference discusses the possibility of substantial increases in global temperature (based on paleo-data) if we continue to sustain atmospheric GHG at their current levels. In the subsequent linked Gizmodo article Schmidt indicates that at current GHG levels we are currently only committed to an additional 0.5 to 1C increase (i.e. if we were to somehow miraculously dropped to net zero emissions today).  I believe that one important point of the linked Snyder (2016) reference is that global warming has been occurring since at least 1750 so for the early portion of anthropogenic emissions we should use ESS values instead of ECS or TCR values for climate sensitivity:

Carolyn W. Snyder (2016), "Evolution of global temperature over the past two million years",
Nature, doi:10.1038/nature19798

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature19798.html

Abstract: "Reconstructions of Earth’s past climate strongly influence our understanding of the dynamics and sensitivity of the climate system. Yet global temperature has been reconstructed for only a few isolated windows of time, and continuous reconstructions across glacial cycles remain elusive. Here I present a spatially weighted proxy reconstruction of global temperature over the past 2 million years estimated from a multi-proxy database of over 20,000 sea surface temperature point reconstructions. Global temperature gradually cooled until roughly 1.2 million years ago and cooling then stalled until the present. The cooling trend probably stalled before the beginning of the mid-Pleistocene transition, and pre-dated the increase in the maximum size of ice sheets around 0.9 million years ago. Thus, global cooling may have been a pre-condition for, but probably is not the sole causal mechanism of, the shift to quasi-100,000-year glacial cycles at the mid-Pleistocene transition. Over the past 800,000 years, polar amplification (the amplification of temperature change at the poles relative to global temperature change) has been stable over time, and global temperature and atmospheric greenhouse gas concentrations have been closely coupled across glacial cycles. A comparison of the new temperature reconstruction with radiative forcing from greenhouse gases estimates an Earth system sensitivity of 9 degrees Celsius (range 7 to 13 degrees Celsius, 95 per cent credible interval) change in global average surface temperature per doubling of atmospheric carbon dioxide over millennium timescales. This result suggests that stabilization at today’s greenhouse gas levels may already commit Earth to an eventual total warming of 5 degrees Celsius (range 3 to 7 degrees Celsius, 95 per cent credible interval) over the next few millennia as ice sheets, vegetation and atmospheric dust continue to respond to global warming."

See also:
http://gizmodo.com/dont-worry-the-earth-is-not-locked-into-ten-degrees-of-1787058579

Extract: "Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, told Gizmodo. “The actual committed warming is only 0.5 to perhaps 1 [degree Celsius]—and nothing in the study changes that.”

[AbruptSLR]

The linked reference discusses "decadal variations and trends of the global ocean carbon sink", and concludes that over the study period the ocean absorbed less carbon dioxide than assumed by the IPCC's carbon budget, due to a long-term trend for the ocean to absorb less carbon dioxide:

Peter Landschützer, Nicolas Gruber & Dorothee C. E. Bakker (20 September 2016), "Decadal variations and trends of the global ocean carbon sink", Global Biogeochemical Cycles, DOI: 10.1002/2015GB005359

http://onlinelibrary.wiley.com/doi/10.1002/2015GB005359/full

Abstract: "We investigate the variations of the ocean CO2 sink during the past three decades using global surface ocean maps of the partial pressure of CO2 reconstructed from observations contained in the Surface Ocean CO2 Atlas Version 2. To create these maps, we used the neural network-based data-interpolation method of [Landschützer2014], but extended the work in time from 1998 through 2011 to the period from 1982 through 2011. Our results suggest strong decadal variations in the global ocean carbon sink around a long-term increase that corresponds roughly to that expected from the rise in atmospheric CO2. The sink is estimated to have weakened during the 1990s toward a minimum uptake of only -0.8 ± 0.5 Pg C yr − 1 in 2000, and thereafter to have strengthened considerably to rates of more than -2.0 ± 0.5 Pg C yr − 1. These decadal variations originate mostly from the extratropical oceans while the tropical regions contribute primarily to interannual variations. Changes in sea-surface temperature affecting the solubility of CO2 explain part of these variations, particularly at subtropical latitudes. But most of the higher latitude changes are attributed to modifications in the surface concentration of dissolved inorganic carbon and alkalinity, induced by decadal variations in atmospheric forcing, with patterns that are reminiscent of those of the Northern and Southern Annular Modes. These decadal variations lead to a substantially smaller cumulative anthropogenic CO2 uptake of the ocean over the 1982 through 2011 period (reduction of 7.5 ± 5.5 Pg C) relative to that derived by the Global Carbon Budget."

[AbruptSLR]

In Reply #1532, I provide a link to Synder (2016), which includes the statement: "Earth system sensitivity of 9 degrees Celsius (range 7 to 13 degrees Celsius, 95 per cent credible interval) change in global average surface temperature per doubling of atmospheric carbon dioxide over millennium timescales".  The following first linked Foster Lab article and the associated second linked Martínez-Botí et. al. (2015) reference indicate (see attached image) that such a paleo ESS value is not relevant to future ESS values and suggests that based on Pliocene ESS values of 2.2 to 5.2C (with a mean of 3.7C), may be more appropriate for future conditions.

That said, the third linked Shaffer et. al. (2016) reference discusses paleodata that indicates that climate sensitivity increased from 3.3 - 5.6 (mean of 4.45k) at the beginning of the PETM up to 3.7 - 6.5 K (mean of 5.1K) near the peak of the PETM.  Thus who is to say that the Pliocene is the best guide for future values of ESS, when we may well be headed to conditions near the peak of the PETM:

http://www.thefosterlab.org/blog/2016/9/27/future-relevant-earth-system-sensitivity

Extract: "Synder calculated that ESS was around 9 oC per CO2 doubling over the last 800 thousand years.  As discussed here, this is not a relevant measure of how our future climate system will behave because the high ESS during the cold Pleistocene was driven in part by the changes in surface albedo caused by the waxing and waning of the continental ice sheets of North America and Europe – ice sheets that are no longer present on the Earth so are not able to act as a feedback in the future.  ESS for the future is therefore much lower than what Synder calculates.  In a paper last year we @thefosterlab used new Pliocene CO2 data from the boron isotope proxy to show that a future relevant ESS is more likely in the range 2.2 to 5.2 oC per CO2 doubling (which is in good agreement with modelling studies; Lunt et al. 2010).  This suggests that estimates of equilibrium climate sensitivity from the IPCC (1.5 to 4.5 oC per CO2 doubling) do adequately describe the long-term (1000 year) response of the future climate system to CO2 change because the northern hemisphere ice sheets are currently at close to their minimum extent."


M. A. Martínez-Botí, G. L. Foster, T. B. Chalk, E. J. Rohling, P. F. Sexton, D. J. Lunt, R. D. Pancost, M. P. S. Badger & D. N. Schmidt (05 February 2015), "Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records", Nature, Volume: 518, Pages: 49–54, doi:10.1038/nature14145


http://www.nature.com/nature/journal/v518/n7537/abs/nature14145.html

Abstract: "Theory and climate modelling suggest that the sensitivity of Earth’s climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth’s climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice–albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2."


Gary Shaffer, Matthew Huber, Roberto Rondanelli & Jens Olaf Pepke Pedersen (23 June 2016), "Deep-time evidence for climate sensitivity increase with warming", Geophysical Research Letters, DOI: 10.1002/2016GL069243


http://onlinelibrary.wiley.com/doi/10.1002/2016GL069243/full

Abstract: "Future global warming from anthropogenic greenhouse gas emissions will depend on climate feedbacks, the effect of which is expressed by climate sensitivity, the warming for a doubling of atmospheric CO2 content. It is not clear how feedbacks, sensitivity, and temperature will evolve in our warming world, but past warming events may provide insight. Here we employ paleoreconstructions and new climate-carbon model simulations in a novel framework to explore a wide scenario range for the Paleocene-Eocene Thermal Maximum (PETM) carbon release and global warming event 55.8 Ma ago, a possible future warming analogue. We obtain constrained estimates of CO2 and climate sensitivity before and during the PETM and of the PETM carbon input amount and nature. Sensitivity increased from 3.3–5.6 to 3.7–6.5 K (Kelvin) into the PETM. When taken together with Last Glacial Maximum and modern estimates, this result indicates climate sensitivity increase with global warming."

[AbruptSLR]

While I have been aware of GHG (primarily methane) emissions from man-made reservoirs for some time now; the linked article indicates that policy makers have largely ignored this GHG emission source from their carbon budget estimates to date (while they make-up about 1.3% of the global emissions total).  This is yet another example of scientists not making policy makers publically aware of climate change risks:

https://www.washingtonpost.com/news/energy-environment/wp/2016/09/28/scientists-just-found-yet-another-way-that-humans-are-creating-greenhouse-gases/?utm_term=.0427eac13612

Extract: "The new paper, slated to be published next week in BioScience, confirms a  significant volume of greenhouse gas emissions coming from a little-considered place: Man-made reservoirs, held behind some 1 million dams around the world and created for the purposes of electricity generation, irrigation, and other human needs. In the study, 10 authors from U.S., Canadian, Chinese, Brazilian, and Dutch universities and institutions have synthesized a considerable body of prior research on the subject to conclude that these reservoirs may be emitting just shy of a gigaton, or billion tons, of annual carbon dioxide equivalents. That would mean they contributed 1.3 percent of the global total.
Moreover, the emissions are largely in the form of methane, a greenhouse gas with a relatively short life in the atmosphere but a very strong short-term warming effect."
…
The new research concludes that methane accounted for 79 percent of carbon dioxide equivalent emissions from reservoirs, while the other two greenhouse gases, carbon dioxide and nitrous oxide, accounted for 17 percent and 4 percent.
…
In fact, Harrison said that based on the new study, it appears that reservoir emissions and rice paddy emissions are of about the same magnitude on a global scale — but rice paddy emissions have been taken into account for some time. Reservoir emissions often have not."

[AbruptSLR]

The linked article indicates that most current climate models focus on ECS related mechanisms and are not adequately calibrated for ESS related feedback mechanisms; "… many of which may prove to be important for predicting the climate trajectory in the shorter term."

Latif, M., M. Claussen, M. Schulz, and T. Brücher (2016), Comprehensive Earth system models of the last glacial cycle, Eos, 97, doi:10.1029/2016EO059587

https://eos.org/project-updates/comprehensive-earth-system-models-of-the-last-glacial-cycle?utm_source=eos&utm_medium=email&utm_campaign=EosBuzz093016

Extract: "Much of modern climate science fails to consider millennium-scale processes, many of which may prove to be important for predicting the climate trajectory in the shorter term.
…
The paleoclimate modeling initiative PalMod aims at filling gaps in knowledge about climate processes and climate modeling. The program, supported by the German Federal Ministry of Education and Research, is specifically designed to better understand climate system dynamics and their variability on timescales up to the multimillennial. The target is to simulate a full glacial cycle with comprehensive Earth system models (ESMs) incorporating a detailed description of interactions between the physical and biogeochemical components of the Earth system.
…
We aim to identify and quantify the relative contributions of the fundamental processes that determined the Earth’s climate trajectory and variability during the last glacial cycle, spanning approximately the past 126,000 years. We are also working to simulate the climate with comprehensive ESMs from the peak of the last interglacial up to the present, including the changes in the spectrum of variability. A third goal of the program is to assess possible future climate trajectories beyond this century and into the next millennia with sophisticated ESMs tested in such a way.
…
So far, most model studies have attempted to estimate equilibrium climate sensitivity—the globally averaged equilibrium surface air temperature change in response to a doubling of the preindustrial CO2 concentration. However, the response of the very slow components of the Earth system, including ice sheets and weathering, is not yet represented in the models. Thus, the question of the “true” climate system sensitivity, or Earth system sensitivity, remains unanswered."

See also:
https://www.palmod.de/

[jai mitchell]

Study of permafrost regions show that an increased emission profile is warranted due to the increased soil permeability to water after thaw.  The reduction of surface water greatly increases the heat absorption rate of the soil, further increasing decomposition and emissions.

http://phys.org/news/2016-09-biologist-comments-startling-climate.html

As this permafrost melts, it sets off a biochemical chain reaction in the soil that could dramatically increase the emission of greenhouse gases into the atmosphere, accelerating further climate change. San Diego State University biologist Donatella Zona wrote about this issue in a commentary article this week in the journal Nature.

Read more at: http://phys.org/news/2016-09-biologist-comments-startling-climate.html#jCp

much less what a 30 year ahead of schedule sea ice minimum will incur. . .

[AbruptSLR]

The linked article indicates that the World Meteorological Organization is warning that Arctic Amplification is occurring faster than previously expected.  While the attached image issued by Gavin Schmidt confirms that we are currently at risk of being near the 95% CL for the CMIP3 + the aggressive scenario SRES A1B by the end of 2016; which if true indicates that we are likely on the extreme side of the extreme radiative forcing scenario expected just a few years ago:

http://www.voanews.com/a/world-meteorological-organiztion-melting-sea-ice-accelerated-global-warming/3528929.html

Extract: "The World Meteorological Organization warned recently that Arctic sea ice was melting faster than expected, indicating dramatic changes in the climate system. The agency called for establishment of an Arctic observatory to help cope with the potentially dangerous changes.
The WMO considers changes in the Arctic akin to a "canary in a coal mine" in terms of signaling an impending disaster. The agency noted that global temperatures were continuing to rise as a result of climate change, with 2016 predicted to be the hottest year since record-keeping began 150 years ago."

[AbruptSLR]

The linked article is entitled: "Climate change has doubled western US forest fires".  As this is not considered in the AR5 this increase in GHG emissions will accelerate global warming above the AR5 projections:

http://phys.org/news/2016-10-climate-western-forest.html

Extract: "A new study says that human-induced climate change has doubled the area affected by forest fires in the U.S. West over the last 30 years. According to the study, since 1984 heightened temperatures and resulting aridity have caused fires to spread across an additional 16,000 square miles than they otherwise would have—an area larger than the states of Massachusetts and Connecticut combined. The authors warn that further warming will increase fire exponentially in coming decades. The study appears today in the journal Proceedings of the National Academy of Sciences. "

[AbruptSLR]

The linked reference provides evidence that consensus climate models (like CMIP5) typically overestimate the negative feedback from clouds; which indicates that ECS is likely higher than AR5 indicates:

A. Bodas-Salcedo, T. Andrews, A. V. Karmalkar & M. A. Ringer (11 October 2016), "Cloud liquid water path and radiative feedbacks over the Southern Ocean", Geophysical Research Letters, DOI: 10.1002/2016GL070770

http://onlinelibrary.wiley.com/doi/10.1002/2016GL070770/abstract

Abstract: "Climate models show a robust shortwave negative feedback in the midlatitude oceans in climate change simulations. This feedback is commonly attributed to an increase in cloud optical depth due to ice to liquid phase change as the climate warms. Here we use a cyclone compositing technique to show that the models' cloud liquid water path (LWP) response is strongly dependent on cloud regime. The radiative and LWP responses are not as tightly coupled as a zonal-mean analysis would suggest, implying that the physical mechanisms that control the overall LWP response are not necessarily responsible for the radiative response. The area of the cyclone dominated by low-level stratiform and shallow convective clouds plays dominant role in the radiative response. Since these are mostly supercooled liquid clouds, the strength of a negative cloud-phase feedback in the real world should be smaller than the one predicted by current models."

[AbruptSLR]

The linked article is entitled: "Science, cities and innovation in the human age".   The article indicates that "… the pace of science may be unable to keep up with today’s rapidly-changing world."

https://www.theguardian.com/global/2016/oct/16/science-cities-and-innovation-in-the-human-age

Extract: "Over the next week, leaders from around the world will take part in a historic summit on the future of cities. But this landmark event highlights how the pace of science may be unable to keep up with today’s rapidly-changing world."

[AbruptSLR]

The findings of the linked reference (based on both paleodata and modeled projections) highlight the risk that with continued global warming this century the tropical rainforests could collapse; which, would increase realized temperatures above those projected this century by AR5:

Isabel P. Montañez, Jennifer C. McElwain, Christopher J. Poulsen Joseph D. White, William A. DiMichele, Jonathan P. Wilson, Galen Griggs & Michael T. Hren (2016), "Climate, pCO2 and terrestrial carbon cycle linkages during late Palaeozoic glacial–interglacial cycles, Nature Geoscience", nature.com/articles/doi:10.1038/ngeo2822


http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2822.html

Abstract: "Earth’s last icehouse, 300 million years ago, is considered the longest-lived and most acute of the past half-billion years, characterized by expansive continental ice sheets and possibly tropical low-elevation glaciation. This atypical climate has long been attributed to anomalous radiative forcing promoted by a 3% lower incident solar luminosity and sustained low atmospheric pCO2 (≤300 ppm)5. Climate models, however, indicate a CO2 sensitivity of ice-sheet distribution and sea-level response that questions this long-standing climate paradigm by revealing major discrepancy between hypothesized ice distribution, pCO2, and geologic records of glacioeustasy. Here we present a high-resolution record of atmospheric pCO2 for 16 million years of the late Palaeozoic, developed using soil carbonate-based and fossil leaf-based proxies, that resolves the climate conundrum. Palaeo-fluctuations on the 10⁵-yr scale occur within the CO2 range predicted for anthropogenic change and co-vary with substantial change in sea level and ice volume. We further document coincidence between pCO2 changes and repeated restructuring of Euramerican tropical forests that, in conjunction with modelled vegetation shifts, indicate a more dynamic carbon sequestration history than previously considered and a major role for terrestrial vegetation–CO2 feedbacks in driving eccentricity-scale climate cycles of the late Palaeozoic icehouse."


http://phys.org/news/2016-10-ancient-co2-future-climate.html

Extract: "The last time Earth experienced both ice sheets and carbon dioxide levels within the range predicted for this century was a period of major sea level rise, melting ice sheets and upheaval of tropical forests."

[Lennart van der Linde]

...Palaeo-fluctuations on the 105-yr scale...

This is 10 to the 5th power, so "on the 100,000-yr scale".

Thanks for the reference! I'll check the paper for more info.

[AbruptSLR]

The linked article is entitled: "How overfishing and shark-finning could increase the pace of climate change".  This projected increase in CO₂ emissions from the ocean due to overfishing is not included in either the AR5, nor the CMIP5, projections.

https://theconversation.com/how-overfishing-and-shark-finning-could-increase-the-pace-of-climate-change-67664

Extract: "Since most commercially caught fish are predators, fishing and shark finning are resulting in a rapidly decreasing number of predators in the marine ecosystem. Our research suggests that this removal of predators is likely to lead to a increase in ocean ecosystems’ CO2 production, and ultimately that fishing and shark finning are contributing to climate change.
The reason for this increase in carbon dioxide production is based on a simple and well-founded ecological principle taught to biology students in schools, that energy and biomass are not efficiently transferred through the food chain. Typically, a predator population will only gain 10% of the biomass of the prey it consumes.

Predators have the potential to reduce the biomass of prey species such as small fish and zooplankton (small animals in the water column). Removing the predators, therefore, can result in a large increase in these low level populations – in fact, due to inefficient energy transfer, this increase could be up to 90% more in terms of biomass than the weight of the predators removed. This results in more respiration occurring, and therefore more carbon dioxide production."

Edit: See the associated graphic.

[Bruce Steele]

ASLR, I have read the above linked article and I am having some serious doubts about the validity of the premise. I don't believe top down control of the ocean ecosystem via predators can change the CO2 content of the biomass. CO2 is absorbed by physical processes , atmosphere to ocean when gas partial pressure differences support such transfer . Plants then have the ability to convert that CO2 into organic matter that can then be transferred up the food chain. Some phytoplankton  can also convert CO2 into calcium carbonate . Maybe someone can correct me but the biomass of all tropic levels above plants and the potential net biomass of the food system is dependent upon nutrient availability , the sun and CO2 . If predators consume too many prey species that can result in less conversion of energy up the food chain but the CO2 converted into organic matter or calcium carbonate will still be remineralized at some point by bacteria anyway. Some small portion of that absorbed CO2 will sink and contribute to the sediment carbon sink . Although the amount of carbon that annually moves into the sediment is small in comparison to the atmospheric, or inorganic deep ocean reservoir , the phytoplankton responsible for that transfer contributes to a carbon sink that can last millions of years.
How predators that eat prey species somehow positively contributes to this sink by reducing prey species is beyond me.
 I don't want to get into an argument about overfishing and the prior debunking of Worm et al 2003 that is contained in sources of the paper linked above but Worms work is majorly flawed. I don't think overfishing is a good thing , but somehow linking it into carbon sinks is unsupported  by the evidence
presented in the article...conjecture at best but hardly sound science based on verifiable evidence.

[AbruptSLR]

The linked reference and associated linked article indicate that transitory cloud cover (see the attached image) contributed to the faux hiatus (between 1998 & 2013), which contributed (together with heat absorption by the ocean) to masking the true climate sensitivity, which is likely closer to that proposed by Steven Sherwood (i.e. closer to 4.5C).  This indicates that current AR5 & CMIP5 projections ESLD:

Chen Zhou, Mark D. Zelinka & Stephen A. Klein (2016), "Impact of decadal cloud variations on the Earth’s energy budget", Nature Geoscience, doi:10.1038/ngeo2828

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2828.html

Abstract: "Feedbacks of clouds on climate change strongly influence the magnitude of global warming. Cloud feedbacks, in turn, depend on the spatial patterns of surface warming, which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback. Here we present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. We find that cloud anomalies associated with these patterns significantly modify the Earth’s energy budget. Specifically, the decadal cloud feedback between the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. These results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and offer a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low."


See also the associated linked article entitled: "Clouds dampened warming since 1980s, study shows"

https://www.carbonbrief.org/clouds-dampened-warming-since1980s

Extract: "A new study helps unravel one of the biggest uncertainties for scientists making climate change projections – how clouds will be affected as the Earth’s warms up.
Clouds can have both a warming and cooling effect on the Earth. They insulate the Earth’s surface like a blanket, while simultaneously cooling it by reflecting away energy from the sun.
Overall, scientists expect that changes to clouds will amplify human-caused warming in the long-term. But a new study, published in Nature Geoscience, shows that they can have an important short-term cooling impact.
…
The findings explain why estimates based on past warming have been lower than those obtained by other methods, says Prof Steven Sherwood, director of the Climate Change Research Centre at the University of New South Wales, who wasn’t involved in the study. He tells Carbon Brief:
“The real significance of these results is that they make it much more likely that estimates of climate sensitivity based on historical warming have been biased low compared to reality.”
The study also suggests that low-level cloud changes in the tropics had a role in the slower pace of warming at Earth’s surface in the 2000s, compared to previous decades – the so-called “hiatus“.
That’s not to say it caused the slowdown, notes Zhou – that’s likely to be a combination of several factors, such as fluctuations in the Pacific Ocean, human-caused aerosol emissions and volcanic eruptions – but it may have enhanced its impact:
“The cloud changes we’ve diagnosed have been driven by the observed pattern of warming; they are responding to it, and in so doing, are modifying the planet’s energy budget in such a way as to reinforce the hiatus.”
So even though clouds are expected to amplify warming from greenhouse gases, they can “temporarily impede” warming too, concludes Zhou."

See also:
http://arstechnica.com/science/2016/10/clouds-may-actually-have-slowed-recent-warming-but-that-wont-last/

Extract: "“To me, the upshot of this work (as well as some previous work that this builds on) is that ‘climate sensitivity’ is not a single number, but can depend on other factors,” Texas A&M’s Andrew Dessler told Ars. “If one looks at the late 20th century, one might infer that a warming climate increased low clouds—a negative cloud feedback. But that's just a temporary conclusion. Ultimately, those places must warm and the low clouds will burn off, eventually generating a positive cloud feedback and a bigger climate sensitivity.”"

Edit, see also:

https://phys.org/news/2016-10-cloudy-feedback-global.html


Extract: “Lawrence Livermore National Laboratory researchers have identified a mechanism that causes low clouds - and their influence on Earth's energy balance - to respond differently to global warming depending on their spatial pattern.

The results imply that studies relying solely on recent observed trends are likely to underestimate how much Earth will warm due to increased carbon dioxide. The research appears in the Oct. 31 edition of the journal, Nature Geosciences.”

[AbruptSLR]

I don't want to get into an argument about overfishing and the prior debunking of Worm et al 2003 that is contained in sources of the paper linked above but Worms work is majorly flawed. I don't think overfishing is a good thing , but somehow linking it into carbon sinks is unsupported  by the evidence presented in the article...conjecture at best but hardly sound science based on verifiable evidence.

Thanks for the input, as I am not an expert on this topic, I will adopt a wait and see attitude.

Best,
ASLR

[AbruptSLR]

The linked reference indicates that the soil currently absorbs carbon dioxide but with continued global warming it will so emit meaningful amounts of carbon dioxide.  This was not considered in AR5:

http://www.nature.com/articles/srep35798

See also:
http://www.upi.com/Science_News/2016/11/03/Soil-could-become-significant-CO2-contributor-in-near-future-Study/8031478197167/?spt=hs&or=sn

[AbruptSLR]

The linked article is entitled: "Sea surface warming and cloud feedbacks" and it provides additional information related to my Reply #1546 about Zhou et. al. (2016):

https://andthentheresphysics.wordpress.com/

Extract: "The figure below shows the basic result from a set of model run. The left-hand panel shows the net feedback response, while the right-hand panel shows the cloud feedback only. Essentially if you run a model with prescribed sea surface temperatures you get much more negative cloud feedbacks than the mean from long-term warming runs with either uniform, or patterned, sea surface temperatures. The suggestion is that over time we would expect the feedback response to tend back towards the mean, but we just happened to have experienced a period during which it was more negative than the mean."