Conservative Scientists & its Consequences

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The linked (open access) reference cites the importance of both poleward jet shifting and of high-latitude cloud ice microphysical processes, on model projections of cloud feedback.  Given uncertainties in the multiple models examined it appears difficult to say from these findings whether the net change in cloud feedback is positive or negative compared to prior assumptions.  Nevertheless, the research does support the findings of Sherwood (2014), which suggested that ECS was likely higher than previously assumed:

Casey J. Wall and Dennis L. Hartmann (Dec 30, 2015), "On the influence of poleward jet shift on shortwave cloud feedback in global climate models", JAMES, DOI: 10.1002/2015MS000520


http://onlinelibrary.wiley.com/doi/10.1002/2015MS000520/full

Abstract: "Experiments designed to separate the effect of atmospheric warming from the effect of shifts of the eddy-driven jet on shortwave (SW) cloud feedback are performed with three global climate models (GCMs). In each model a warming simulation produces a robust SW cloud feedback dipole, with a negative (positive) feedback in the high-latitudes (subtropics). The cloud brightening in high-latitudes that characterizes warming simulations is not produced by jet shifts alone in any of the models, but is highly sensitive to perturbations of freezing temperature seen by the cloud microphysics scheme, indicating that thermodynamic mechanisms involving the phase of cloud condensate dominate the SW feedback at high-latitudes. In one of the models a poleward jet shift causes significant cloud dimming throughout the midlatitudes, but in two models it does not. Differences in cloud response to jet shifts in two of the models are attributed to differences in the shallow convection parameterizations."

Extract: "Warming simulations in GCMs, including the aquaplanet models used in this study and fully coupled CMIP5 models, show a robust SW cloud feedback dipole in the Southern Hemisphere extratropics, with a negative feedback in the high-latitudes and a positive feedback in the subtropics. The results of this study suggest that the negative SW cloud feedback at high-latitudes is driven by changes in cloud ice microphysical processes, rather than jet shifts, confirming the findings of previous studies [Kay et al., 2014; Ceppi et al., 2015; GP14]. In the subtropics, however, the role of poleward jet shift/Hadley cell expansion in driving the positive SW cloud feedback varies greatly between models, and in the two models tested in this study, the difference results largely from inter-model differences in the shallow convection parameterization.
Further evaluation of cloud microphysics in GCMs may significantly reduce uncertainty in high-latitude SW cloud feedback. Cloud microphysics are represented by paramaterizations that differ largely between GCMs [Tsushima et al., 2006]. For example, McCoy et al. [2015] found that the average temperature at which CMIP5 models produce clouds with equally mixed liquid and ice (the “glaciation temperature”) over the Southern Ocean varies by over 40K between models. In this study it is demonstrated that the glaciation temperature (which is perturbed by way of perturbing the freezing temperature) in both AM2 and CAM5 is highly correlated with the latitude and strength of the negative SW cloud feedback at mid- to high-latitudes, such that lower glaciation temperature corresponds to a poleward shift and strengthening of the negative SW feedback at mid- to high-latitudes. We therefore hypothesize that narrowing both the bias and inter-model spread in glaciation temperature will constrain the strength and latitude of the negative SW cloud feedback at high-latitudes in GCMs.
Additionally, further evaluation of inter-model differences in shallow convection schemes is likely to reduce inter-model spread in SW cloud feedback in the midlatitudes. It has previously been demonstrated that convective mixing between the boundary layer and the free troposphere in the tropics can explain a large amount of variance in climate sensitivity and cloud feedback between GCMs [Sherwood et al., 2014]. Here we further demonstrate that shallow convection can play a role in inter-model differences in SW cloud feedback in the extratropics."

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The linked (open access) reference emphasizes the importance of boundary layer schemes in representing subtropical marine low-level clouds in climate models.  While the author does not clearly state that his finding indicate higher values of ECS; nevertheless, his findings do support the approach used by Sherwood (2014) who did find evidence that ECS is likely higher than previously assumed:

R. A. J. Neggers (Dec 30 2015), "Attributing the behavior of low-level clouds in large-scale models to subgrid-scale parameterizations", JAMES, DOI: 10.1002/2015MS000503


http://onlinelibrary.wiley.com/doi/10.1002/2015MS000503/full

Abstract: "This study explores ways of establishing the characteristic behavior of boundary layer schemes in representing subtropical marine low-level clouds in climate models. To this purpose, parameterization schemes are studied in both isolated and interactive mode with the larger-scale circulation. Results of the EUCLIPSE/GASS intercomparison study for Single-Column Models (SCM) on low-level cloud transitions are compared to General Circulation Model (GCM) results from the CFMIP-2 project at selected grid points in the subtropical eastern Pacific. Low cloud characteristics are plotted as a function of key state variables for which Large-Eddy Simulation results suggest a distinct and reasonably tight relation. These include the Cloud Top Entrainment Instability (CTEI) parameter and the total cloud cover. SCM and GCM results are thus compared and their resemblance is quantified using simple metrics. Good agreement is reported, to such a degree that SCM results are found to be uniquely representative of their GCM, and vice versa. This suggests that the system of parameterized fast boundary layer physics dominates the model state at any given time, even when interactive with the larger-scale flow. This behavior can loosely be interpreted as a unique “fingerprint” of a boundary layer scheme, recognizable in both SCM and GCM simulations. The result justifies and advocates the use of SCM simulation for improving weather and climate models, including the attribution of typical responses of low clouds to climate change in a GCM to specific parameterizations."

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The linked research indicates that the Indonesian Throughflow (ITF) increases during La Nina phases and decreases during El Nino phases; which, helps to clarify climate behavior during the faux hiatus:

Qin-Yan Liu, Ming Feng, Dongxiao Wang & Susan Wijffels (Dec 28 2015), "Interannual variability of the Indonesian Throughflow transport: A revisit based on 30 year expendable bathythermograph data", Journal of Geophysical Research Oceans, DOI: 10.1002/2015JC011351

http://onlinelibrary.wiley.com/doi/10.1002/2015JC011351/full

Abstract: "Based on 30 year repeated expendable bathythermograph (XBT) deployments between Fremantle, Western Australia, and the Sunda Strait, Indonesia, from 1984 to 2013, interannual variability of geostrophic transport of the Indonesian Throughflow (ITF) and its relationships with El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are investigated. The IOD induced coastal Kelvin waves propagate along the Sumatra-Java coast of Indonesia, and ENSO induced coastal Kelvin waves propagate along the northwest coast of Australia, both influencing interannual variations of the ITF transport. The ITF geostrophic transport is stronger during La Niña phase and weaker during El Niño phase, with the Niño3.4 index leading the ITF variability by 7 months. The Indian Ocean wind variability associated with the IOD to a certain extent offset the Pacific ENSO influences on the ITF geostrophic transport during the developing and mature phases of El Niño and La Niña, due to the covarying IOD variability with ENSO. The ITF geostrophic transport experiences a strengthening trend of about 1 Sv every 10 years over the study period, which is mostly due to a response to the strengthening of the trade winds in the Pacific during the climate change hiatus period. Decadal variations of the temperature-salinity relationships need to be considered when estimating the geostrophic transport of the ITF using XBT data."

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While the linked (open access) reference has many appropriate qualifying statements and disclaimers, it notes that the AR5 paleo estimates of ECS were linear approximations that change when non-linear issues are considered.  In particular the find for the specific ECS, S[CO2,LI], during the Pleistocence (ie the most recent 2 million years) that:
"During Pleistocene intermediate glaciated climates and interglacial periods, S[CO2,LI] is on average ~ 45 % larger than during Pleistocene full glacial conditions."

Therefore, researchers such as James Hansen who relied on paleo findings that during recent full glacial periods ECS was about 3.0C, did not know that during interglacial periods this value would be 45% larger, or 4.35C.

Köhler, P., de Boer, B., von der Heydt, A. S., Stap, L. B., and van de Wal, R. S. W. (2015), "On the state dependency of the equilibrium climate sensitivity during the last 5 million years", Clim. Past, 11, 1801-1823, doi:10.5194/cp-11-1801-2015.


http://www.clim-past.net/11/1801/2015/cp-11-1801-2015.html
http://www.clim-past.net/11/1801/2015/cp-11-1801-2015.pdf


Abstract. It is still an open question how equilibrium warming in response to increasing radiative forcing – the specific equilibrium climate sensitivity S – depends on background climate. We here present palaeodata-based evidence on the state dependency of S, by using CO2 proxy data together with a 3-D ice-sheet-model-based reconstruction of land ice albedo over the last 5 million years (Myr). We find that the land ice albedo forcing depends non-linearly on the background climate, while any non-linearity of CO2 radiative forcing depends on the CO2 data set used. This non-linearity has not, so far, been accounted for in similar approaches due to previously more simplistic approximations, in which land ice albedo radiative forcing was a linear function of sea level change. The latitudinal dependency of ice-sheet area changes is important for the non-linearity between land ice albedo and sea level. In our set-up, in which the radiative forcing of CO2 and of the land ice albedo (LI) is combined, we find a state dependence in the calculated specific equilibrium climate sensitivity, S[CO2,LI], for most of the Pleistocene (last 2.1 Myr). During Pleistocene intermediate glaciated climates and interglacial periods, S[CO2,LI] is on average ~ 45 % larger than during Pleistocene full glacial conditions. In the Pliocene part of our analysis (2.6–5 Myr BP) the CO2 data uncertainties prevent a well-supported calculation for S[CO2,LI], but our analysis suggests that during times without a large land ice area in the Northern Hemisphere (e.g. before 2.82 Myr BP), the specific equilibrium climate sensitivity, S[CO2,LI], was smaller than during interglacials of the Pleistocene. We thus find support for a previously proposed state change in the climate system with the widespread appearance of northern hemispheric ice sheets. This study points for the first time to a so far overlooked non-linearity in the land ice albedo radiative forcing, which is important for similar palaeodata-based approaches to calculate climate sensitivity. However, the implications of this study for a suggested warming under CO2 doubling are not yet entirely clear since the details of necessary corrections for other slow feedbacks are not fully known and the uncertainties that exist in the ice-sheet simulations and global temperature reconstructions are large.

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I provide the following selected quotes from the Kohler et al (2015) paper; which emphasize that the AR5 projections do not include many potentially important feedback mechanisms (note that just because AR5 assumes that slow feedbacks will only effect the distant future does not mean that this is true at our current high rates of forcing):

Extracts: "…. important feedbacks of the climate system are not incorporated into all models. For example, when coupling a climate model interactively to a model of stratospheric chemistry, including ozone, the calculated transient warming on a 100-year timescale differs by 20% from results without such an interactive coupling (Nowack et al., 2015).

…

A major restriction of any geological-data-based estimate of climate sensitivity is that there was no period in Earth’s history during which the atmospheric CO2 concentration and global temperature changed as rapidly as today. Therefore, in all these data-based approaches (including our study here), ECS defined as global equilibrium temperature rise in response to a doubling of atmospheric CO2 can only be roughly estimated.

…

Slow feedbacks are of interest in a more distant future (Zeebe, 2013) but are not yet considered in climate simulations using fully coupled climate models underlying the fifth assessment report of the IPCC (Stocker et al., 2013)."

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This post is a follow-up to my Reply #1249, where Gavin Schmidt acknowledges that the previously assumed values for TCR & ECS were too low.  All that I will say is that as head for Goddard, Schmidt is fundamentally tied to the IPCC process, and for him to be acknowledging that TCR & ECS have been to low in the AR process, strongly indicates that AR6 projections will used higher values than AR5.  Until that time I imagine that denialists and most policymakers (and many people on this forum) will keep referring to the out dated AR5 results as if they are gospel:


http://www.accuweather.com/en/weather-blogs/climatechange/earths-climate-sensitivity-to/54522483

Extract: "According to the NASA GISS researchers, the predictions for TCR and ECS have been lower than they should be, which means that Earth's climate sensitivity to atmospheric CO2 has been underestimated.
"If you've got a systematic underestimate of what the greenhouse gas-driven change would be, then you're systematically underestimating what's going to happen in the future when greenhouse gases are by far the dominant climate driver," Schmidt said. (via NASA)."

Edit: Just so that I do not over emphasize the change that Schmidt is acknowledging, as the extract below indicates, it is no where in the area of change indicated by Sherwood (2014), but if Schmidt makes enough baby steps, maybe he will eventually catch-up to where Sherwood was in 2014:

http://phys.org/news/2015-12-earth-history-key-global-temperatures.html

Extract: "Because earlier studies do not account for what amounts to a net cooling effect for parts of the northern hemisphere, predictions for TCR and ECS have been lower than they should be. This means that Earth's climate sensitivity to carbon dioxide—or atmospheric carbon dioxide's capacity to affect temperature change—has been underestimated, according to the study. The result dovetails with a GISS study published last year that puts the TCR value at 3.0°F (1.7° C); the Intergovernmental Panel on Climate Change, which draws its TCR estimate from earlier research, places the estimate at 1.8°F (1.0°C)."

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To provide some perspective on the fact that Marvel et al (2015) [including Gavin Schmidt] is playing catch-up with more reasonable scientists like Drew Shindell, I provide a link to Shindell's guest post on Real Climate in 2014 with the associated plot of TCR range:

http://www.realclimate.org/index.php/archives/2014/04/shindell-on-constraining-the-transient-climate-response/

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The linked reference confirms that the source of the relatively large spread for ECS in climate models is cloud feedback.  Furthermore, this reference sights short-coming in the current methodology for determining ECS and develops a new approach that both highlights several underappreciated cloud feedback mechanisms and which defines feedbacks based on fixed relative humidity instead of specific humidity, thereby reducing the covariances in the spread of ECS values.  Hopefully, the new approach, with reduced uncertainty, will be adopted by future climate models so that we can achieve a clearer understanding of the risks that society is subjected to with continued anthropogenic global warming:

Caldwell, P.M., M.D. Zelinka, K.E. Taylor, and K. Marvel (2015), "Quantifying the sources of inter-model spread in equilibrium climate sensitivity", J. Climate, doi:10.1175/JCLI-D-15-0352.1.


http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0352.1


Abstract: "This study clarifies the causes of inter-model differences in the global-average temperature response to doubled CO2, commonly known as equilibrium climate sensitivity (ECS). We begin by noting several issues with the standard approach for decomposing ECS into a sum of forcing and feedback terms. This leads us to derive an alternative method based on linearizing the effect of the net feedback. Consistent with previous studies, the new method identifies shortwave cloud feedback as the dominant source of inter-model spread in ECS. Our new approach also reveals that covariances between cloud feedback and forcing, between lapse rate and longwave cloud feedbacks, and between albedo and shortwave cloud feedbacks play an important and previously underappreciated role in determining model differences in ECS. Defining feedbacks based on fixed relative rather than specific humidity (as suggested by Held and Shell 2012) reduces the covariances between processes and leads to more straightforward interpretations of results."

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The linked reference uses palaeodata to support the concept the wildfires in boreal forests are likely to increase more than expected with continued global warming; which of course is a positive feedback mechanism:

Ryan Kelly, Hélène Genet, A. David McGuire & Feng Sheng Hu (2016), "Palaeodata-informed modelling of large carbon losses from recent burning of boreal forests", Nature Climate Change, Volume: 6, Pages: 79–82, doi:10.1038/nclimate2832


http://www.nature.com/nclimate/journal/v6/n1/full/nclimate2832.html

Abstract: "Wildfires play a key role in the boreal forest carbon cycle, and models suggest that accelerated burning will increase boreal C emissions in the coming century. However, these predictions may be compromised because brief observational records provide limited constraints to model initial conditions. We confronted this limitation by using palaeoenvironmental data to drive simulations of long-term C dynamics in the Alaskan boreal forest. Results show that fire was the dominant control on C cycling over the past millennium, with changes in fire frequency accounting for 84% of C stock variability. A recent rise in fire frequency inferred from the palaeorecord led to simulated C losses of 1.4 kg C m−2 (12% of ecosystem C stocks) from 1950 to 2006. In stark contrast, a small net C sink of 0.3 kg C m−2 occurred if the past fire regime was assumed to be similar to the modern regime, as is common in models of C dynamics. Although boreal fire regimes are heterogeneous, recent trends and future projections point to increasing fire activity in response to climate warming throughout the biome. Thus, predictions that terrestrial C sinks of northern high latitudes will mitigate rising atmospheric CO2 may be over-optimistic."

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While I have posted about the linked reference previously, I would like to remind readers of this important paper that indicates that double-ITCZ bias constrains ECS to its high end (around 4.0C):

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


http://onlinelibrary.wiley.com/doi/10.1002/2015GL064119/abstract


Abstract: "Despite decades of climate research and model development, two outstanding problems still plague the latest global climate models (GCMs): the double-Intertropical Convergence Zone (ITCZ) bias and the 2 5°C spread of equilibrium climate sensitivity (ECS). Here we show that the double-ITCZ bias and ECS in 44 GCMs from Coupled Model Intercomparison Project Phases 3/5 are negatively correlated. The models with weak (strong) double-ITCZ biases have high (low)-ECS values of ~4.1(2.2)°C. This indicates that the double-ITCZ bias is a new emergent constraint for ECS based on which ECS might be in the higher end of its range (~4.0°C) and most models might have underestimated ECS. In addition, we argue that the double-ITCZ bias can physically affect both cloud and water vapor feedbacks (thus ECS) and is a more easily measured emergent constraint for ECS than previous ones. It can be used as a performance metric for evaluating and comparing different GCMs."

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While I am often cautious of papers with Mauritsen & Stevens as co-authors (as they ESLD), nevertheless, the following reference identifies that climate models must couple cloud activity together with atmospheric circulation models in order to characterize the positive feedback between these two mechanisms (remember that I believe that the ENSO cycle itself is a positive feedback on climate change).  I would have hoped that any researcher worth his salt would have recognized this years ago (as Sherwood did); but maybe now the foot-draggers are starting to catch-up with reality:


Gaby Rädel, Thorsten Mauritsen, Bjorn Stevens, Dietmar Dommenget, Daniela Matei, Katinka Bellomo & Amy Clement. (2016), "Amplification of El Niño by cloud longwave coupling to atmospheric circulation", Nature Geoscience, DOI: 10.1038/ngeo2630

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2630.html


Abstract: "The El Niño/Southern Oscillation (ENSO) is the dominant mode of inter-annual variability, with major impacts on social and ecological systems through its influence on extreme weather, droughts and floods. The ability to forecast El Niño, as well as anticipate how it may change with warming, requires an understanding of the underlying physical mechanisms that drive it. Among these, the role of atmospheric processes remains poorly understood. Here we present numerical experiments with an Earth system model, with and without coupling of cloud radiative effects to the circulation, suggesting that clouds enhance ENSO variability by a factor of two or more. Clouds induce heating in the mid and upper troposphere associated with enhanced high-level cloudiness over the El Niño region, and low-level clouds cool the lower troposphere in the surrounding regions. Together, these effects enhance the coupling of the atmospheric circulation to El Niño surface temperature anomalies, and thus strengthen the positive Bjerknes feedback mechanism between west Pacific zonal wind stress and sea surface temperature gradients. Behaviour consistent with the proposed mechanism is robustly represented in other global climate models and in satellite observations. The mechanism suggests that the response of ENSO amplitude to climate change will in part be determined by a balance between increasing cloud longwave feedback and a possible reduction in the area covered by upper-level clouds."

See also:
http://phys.org/news/2016-01-clouds-impact-el-nino-thought.html

Extract: "A small team of researchers from the U.S., Australia and Germany has found evidence that suggests cloud formation may have a much bigger impact on weather patterns associated with El Niño events than has been thought. In their paper published in the journal Nature Geoscience, the team describes they differences they found when they input cloud data into computer models that simulated weather patterns associated with El Niño' events and why they now believe that all such models should include such data going forward."

Edit: Also see:
http://www.nytimes.com/2016/01/05/science/study-shows-larger-effect-of-clouds-on-el-nino.html?_r=0

Extract: "Dr. Mauritsen and his colleagues compared climate model simulations that accounted for the role of clouds with models that did not.

They found that if clouds are not factored in, the strength of an El Niño event is underestimated by about two-thirds."

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The linked research confirms that northern lakes will release more methane (with continued global warming) than previously assumed, which will serve as a stronger positive feedback than current climate models consider:

Martin Wik, Ruth K. Varner, Katey Walter Anthony, Sally MacIntyre and David Bastviken (2016), "Climate-sensitive northern lakes and ponds are critical components of methane release", Nature Geoscience, doi:10.1038/ngeo2578

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2578.html

Abstract: "Lakes and ponds represent one of the largest natural sources of the greenhouse gas methane. By surface area, almost half of these waters are located in the boreal region and northwards. A synthesis of measurements of methane emissions from 733 lakes and ponds north of ~50° N, combined with new inventories of inland waters, reveals that emissions from these high latitudes amount to around 16.5 Tg CH4 yr−1 (12.4 Tg CH4-C yr−1). This estimate — from lakes and ponds alone — is equivalent to roughly two-thirds of the inverse model calculation of all natural methane sources in the region. Thermokarst water bodies have received attention for their high emission rates, but we find that post-glacial lakes are a larger regional source due to their larger areal extent. Water body depth, sediment type and ecoclimatic region are also important in explaining variation in methane fluxes. Depending on whether warming and permafrost thaw cause expansion or contraction of lake and pond areal coverage, we estimate that annual water body emissions will increase by 20–54% before the end of the century if ice-free seasons are extended by 20 days. We conclude that lakes and ponds are a dominant methane source at high northern latitudes."

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The linked research finds that at the end of the last ice age as Antarctic sea ice melted, massive amounts of carbon dioxide that had been trapped in the ocean were released into the atmosphere.  This indicates that the current growth in Antarctic sea ice extent could be a masking factor, and that in the future (with continued global warming) when the Antarctic sea ice extent decreases, carbon dioxide trapped in the Southern Ocean could be released in greater quantities than previously assumed (which would be a positive feedback):

Jenny Roberts, Julia Gottschalk, Luke C. Skinner, Victoria L. Peck, Sev Kender, Henry Elderfield, Claire Waelbroeck, Natalia Vázquez Riveiros, and David A. Hodell (2016), "Evolution of South Atlantic density and chemical stratification across the last deglaciation", Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.1511252113

http://www.pnas.org/content/early/2016/01/02/1511252113

Significance: "PNAS reports the significance of this research as follows: The cause of the rise in atmospheric pCO2 over the last deglaciation has been a puzzle since its discovery in the early 1980s. It is widely believed to be related to changes in carbon storage in the deep ocean, but the exact mechanisms responsible for releasing CO2 from the deep-ocean reservoir, including the role of ocean density stratification, remains an open question. Here we reconstruct changes in the intermediate-deep density gradient in the South Atlantic across the last deglaciation and find evidence of an early deglacial chemical destratification and a late deglacial density destratification These results suggest that other mechanisms, besides deep-ocean density destratification, were responsible for the ocean–atmosphere transfer of carbon over the deglacial period."
Abstract: "Explanations of the glacial–interglacial variations in atmospheric pCO2 invoke a significant role for the deep ocean in the storage of CO2. Deep-ocean density stratification has been proposed as a mechanism to promote the storage of CO2 in the deep ocean during glacial times. A wealth of proxy data supports the presence of a “chemical divide” between intermediate and deep water in the glacial Atlantic Ocean, which indirectly points to an increase in deep-ocean density stratification. However, direct observational evidence of changes in the primary controls of ocean density stratification, i.e., temperature and salinity, remain scarce. Here, we use Mg/Ca-derived seawater temperature and salinity estimates determined from temperature-corrected δ18O measurements on the benthic foraminifer Uvigerina spp. from deep and intermediate water-depth marine sediment cores to reconstruct the changes in density of sub-Antarctic South Atlantic water masses over the last deglaciation (i.e., 22–2 ka before present). We find that a major breakdown in the physical density stratification significantly lags the breakdown of the deep-intermediate chemical divide, as indicated by the chemical tracers of benthic foraminifer δ13C and foraminifer/coral 14C. Our results indicate that chemical destratification likely resulted in the first rise in atmospheric pCO2, whereas the density destratification of the deep South Atlantic lags the second rise in atmospheric pCO2 during the late deglacial period. Our findings emphasize that the physical and chemical destratification of the ocean are not as tightly coupled as generally assumed."

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I am cautious of the Pollyannaish tone of the linked paper that focuses on the approximately linear nature of regional TCRE (RTCRE); while down playing the more non-linear response in the Arctic Ocean area.  Furthermore, I suspect that more of the author's calibrations used data taken during the faux hiatus and thus may well be biased towards more linear behavior:

Martin Leduc, H. Damon Matthews & Ramón de Elía (2016), "Regional estimates of the transient climate response to cumulative CO2 emissions", Nature Climate Change, doi:10.1038/nclimate2913

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2913.html

Abstract: "The Transient Climate Response to cumulative carbon Emissions (TCRE) measures the response of global temperatures to cumulative CO2 emissions. Although the TCRE is a global quantity, climate impacts manifest predominantly in response to local climate changes. Here we quantify the link between CO2 emissions and regional temperature change, showing that regional temperatures also respond approximately linearly to cumulative CO2 emissions. Using an ensemble of twelve Earth system models, we present a novel application of pattern scaling to define the regional pattern of temperature change per emission of CO2. Ensemble mean regional TCRE values range from less than 1 °C per TtC for some ocean regions, to more than 5 °C per TtC in the Arctic, with a pattern of higher values over land and at high northern latitudes. We find also that high-latitude ocean regions deviate more strongly from linearity as compared to land and lower-latitude oceans. This suggests that ice-albedo and ocean circulation feedbacks are important contributors to the overall negative deviation from linearity of the global temperature response to high levels of cumulative emissions. The strong linearity of the regional climate response over most land regions provides a robust way to quantitatively link anthropogenic CO2 emissions to local-scale climate impacts."

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The linked SciAm article discusses a new ice sheet monitoring initiative called IMBIE to use a new generation of satellite data to more continuously monitor ice mass balance, in order to improve the accuracy of the currently highly uncertain projections in this area of research:

http://www.scientificamerican.com/article/ice-sheets-hold-the-secrets-of-sea-level-rise/

Extract: "“There are processes we know about that happen in the ice sheet—we can see them on land, and from sky and space—that can cause them to destabilize really quickly,” said Andrew Shepherd, a professor of earth observation at the University of Leeds.
The initiative, called IMBIE (ice mass balance inter-comparison exercise), is meant to address one of the fundamental unknowns about climate change: By how much will sea levels rise in the next century, and what is the probability of disastrous sea-level rise?

…

Since 2012, about 100 new studies have been published about Greenland and Antarctic ice sheets. That prompted the polar scientists to launch IMBIE last month in order to update their study every year. Their record would stretch over 40 years, as opposed to 19 in the previous study.
“Now, we have 15 satellite missions; we can go backward in time, making use of earlier satellite missions; and we know there are new missions on the horizon to give us better data,” Shepherd said.
The European Space Agency this year will launch Sentinel-3, which will measure topography over ice sheets and sea ice; NASA and the German Research Center for Geosciences will launch the GRACE follow-on in 2017, which will measure the weight of the polar ice sheets and track changes in mass; NASA will launch ICESat-2 in 2017 to measure the change in shape of an ice sheet; and NASA and the Indian Space Research Organization will launch the NISAR mission in 2020 to measure the speed of ice flow.
NASA’s focus is to go beyond just collecting data to bringing together scientists across fields of research to better understand the processes behind ice sheet destabilization, said Thomas Wagner, a program scientist at NASA.
“One of the things we need to do is change the way we view the ice in Antarctica,” Wagner said. “It is not that we are assembling information to predict how the ice will change; rather, the changes we are observing in the ice tell us about a lot of other things.”
NASA is also promoting CubeSats, which are miniature cuboid satellites—about the size of a loaf of bread—built using off-the-shelf components and launched, often for free, into low Earth orbit. For instance, the RainCube CubeSat, to be built next year, would measure rainfall from space.
“These satellites are in development right now,” Wagner said.
The ultimate goal of the scientists is to improve climate models and the certainty of sea-level rise projections.

Edit: While the SciAm article focuses on sea level rise projections, I remind readers that Hansen et al (2015) project that extensive ice mass loss from ice sheet would also increase the planetary energy imbalance, which would at least temporarily increase the effective climate sensitivity (until the rate of ice mass loss drops back to relatively low levels).

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The linked reference discusses the negative feedback associated with the acclimation of plants to climate change.  This research notes that this negative feedback becomes weaker with time and is concentrated on tropical rainforests.  While this is good news, I note that most ESMs do not include the effects of wildfires on plants, and that the trend towards increasing frequency & magnitude of El Ninos will put more stress on tropical rainforests than most ESMs currently project.  Thus the good news of plant acclimation should be viewed with caution, as with it may be correct at the current time, this negative feedback may likely weaken (or turn positive) faster than the authors estimate:

Nicholas G. Smith, Sergey L. Malyshev, Elena Shevliakova, Jens Kattge & Jeffrey S. Dukes (2015), "Foliar temperature acclimation reduces simulated carbon sensitivity to climate", Nature Climate Change, doi:10.1038/nclimate2878


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2878.html


Abstract: "Plant photosynthesis and respiration are the largest carbon fluxes between the terrestrial biosphere and the atmosphere, and their parameterizations represent large sources of uncertainty in projections of land carbon uptake in Earth system models (ESMs). The incorporation of temperature acclimation of photosynthesis and foliar respiration, commonly observed processes, into ESMs has been proposed as a way to reduce this uncertainty. Here we show that, across 15 flux tower sites spanning multiple biomes at various locations worldwide (10° S–67° N), acclimation parameterizations improve a model’s ability to reproduce observed net ecosystem exchange of CO2. This improvement is most notable in tropical biomes, where photosynthetic acclimation increased model performance by 36%. The consequences of acclimation for simulated terrestrial carbon uptake depend on the process, region and time period evaluated. Globally, including acclimation has a net effect of increasing carbon assimilation and storage, an effect that diminishes with time, but persists well into the future. Our results suggest that land models omitting foliar temperature acclimation are likely to overestimate the temperature sensitivity of terrestrial carbon exchange, thus biasing projections of future carbon storage and estimates of policy indicators such as the transient climate response to cumulative carbon emissions."

[AbruptSLR]

I have linked to and commented about Marvel et al (2015) in Replies #1249, 1255 & 1256.  At the following link Gavin Schmidt (an influential co-author as Marvel's boss) discusses this paper as well.  In my opinion Schmidt (and Kate Marvel) make(s) valuable contributions (see the attached image) to the field but that he is institutionalized (as head of Goddard) and slow to accept findings such as Sherwood (2014) and others showing still higher values of ECS (not to mention higher values of ESS):

http://www.realclimate.org/index.php/archives/2016/01/marvel-et-al-2015-part-1-reconciling-estimates-of-climate-sensitivity/

Extract: "The recent paper by Kate Marvel and others (including me) in Nature Climate Change looks at the different forcings and their climate responses over the historical period in more detail than any previous modeling study. The point of the paper was to apply those results to improve calculations of climate sensitivity from the historical record and see if they can be reconciled with other estimates. But there are some broader issues as well – how scientific anomalies are dealt with and how simulation can be used to improve inferences about the real world. It also shines a spotlight on a particular feature of the IPCC process…"

[AbruptSLR]

It is a little sad that even "edgy" articles like the linked Climate Central article (see also the attached associated image) on how the PDO cycle has caused a surge in global warming, can still get the surge wrong for 2015 by saying that it was 1C above pre-industrial when it is almost certainly more than 1.1C about pre-industrial.  Science has a very sedate tradition and is not well suited for reporting on dynamically changing situations:

http://www.climatecentral.org/news/earth-experiences-global-warming-spurt-19877

Extract: "The effects of the PDO on global warming can be likened to a staircase, with warming leveling off for periods, typically of more than a decade, and then bursting upward.
“It seems to me quite likely that we have taken the next step up to a new level,” said Kevin Trenberth, a scientist with the National Center for Atmospheric Research.
The 2014 flip from the cool PDO phase to the warm phase, which vaguely resembles a long and drawn out El Niño event, contributed to record-breaking surface temperatures across the planet in 2014.
The record warmth set in 2014 was surpassed again in 2015, when global temperatures surged to 1°C (1.8°F) above pre-industrial averages, worsening flooding, heatwaves and storms.
…
“Last time we went from a negative to a positive was in the mid-‘70s,” said Gerald Meehl, a National Center for Atmospheric Research scientist. “Then we had larger rates of global warming from the ‘70s to the late ‘90s, compared to the previous 30 years.”
“It’s not just an upward sloping line,” Meehl said. “Sometimes it’s steeper, sometimes it’s slower.”
The effects of the warm phase of the PDO and the current El Niño may be cumulative in terms of warming the planet. It also seems likely that changes in the ocean cycles are linked, with changes between El Niño and La Niña driving changes in the PDO cycle.
Or, perhaps the PDO doesn’t exist at all, other than as a tidy pile of data points, and it’s simply a manifestation of changes in the shorter-running cycle between El Niño and La Niña.
“There’s some debate about whether there is a low frequency oscillation — is there a distinct interdecadal oscillation?” said Penn State meteorology professor Michael Mann. “Or is what we call a low frequency oscillation just a change over time in the frequency and magnitude of individual El Niño and La Niña events?”
Regardless, “it seems pretty clear that we’ve transitioned from a time period where there was a prevalence for La Niña conditions,” Mann said. “Over the past several years we’ve been in the multi-year El Niño state, and it has culminated with an extremely large El Niño event.”
The future of PDO phases will not slow down or speed up the overall long-term rate of global warming. That will continue to rise with pollution levels. But scientists are expecting more intense heat during the months ahead, which should bring with it more wild weather.
“There are a lot of things in place that have locked us on course to have a really warm start to 2016,” said National Oceanic and Atmospheric Administration scientist Nate Mantua. “I have a hard time seeing how we’re not going to be looking at either record level or near-record level global mean surface temperatures for at least the first half of 2016.”"

[AbruptSLR]

Part 2 of RealClimate's coverage of the Marvel et al (2015) paper.  Unfortunately, this write-up highlights how effectively denialist's like WUWT sidetrack mainstream climate scientists from moving ahead.  This is unfortunate because it means that AR6 will likely err of the side of least drama (ESLD) just to minimize sidetracking by denialist, while failing to adequately make the world safer from likely climate change:

http://www.realclimate.org/index.php/archives/2016/01/marvel-et-al-2015-part-2-media-responses/#more-18953

[AbruptSLR]

The US DOE is inviting (pre-applications due Jan 19, 2016, see link below) applications for research funds (typically single-investigator projects) to contribute to the ACME development.  Hopefully, Pollard, Rignot, Hansen, and other deserving researchers get part of the $6 million being offered:

http://science.energy.gov/~/media/grants/pdf/foas/2016/SC_FOA_0001482.pdf

Extract: "Research Grant Awards (typically single-investigator projects) are expected to be made for a period of two or three years at a funding level appropriate for the proposed scope, without-year support contingent on the availability of funds and satisfactory progress. Total funding up to
$6,000,000 annually is expected to be available to support this FOA subject to appropriation of funds by the Congress."

See the following link for other ACME news:
http://climatemodeling.science.energy.gov/news

[wili]

Another reason some scientists may be 'conservative': https://www.skepticalscience.com/why-is-largest-earth-science-conference-agu15-sponsored-by-exxon.html

Why is the largest Earth science conference still sponsored by Exxon?

So they are faced with the 'carrot'  of pleasing the likes of Exxon so it will keep sponsoring their largest conference, and the 'stick' of rabid denialist smears and threats.

They are being psychologically 'played' in very powerful ways, and under those pressures, it is surprising that so many continue to do the work they do, and it would be completely unsurprising if some of them were...hesitant to push the more drastic implications of their findings.

[AbruptSLR]

The linked reference discusses how dwarf-shrubs, or graminoids, promote the release of ancient carbon from northern peatlands due to primary microbial activity associate with the shrub's root system. As northern peatlands hold 1/3rd of Earth's soil carbon stock and this microbial activity accelerates ancient carbon release from peat by 40%, this new finding is of significant importance as current global carbon cycle models do not yet acknowledge this key mechanism:

Tom N. Walker, Mark H. Garnett, Susan E. Ward, Simon Oakley, Richard D. Bardgett and Nicholas J. Ostle (2016), "Vascular plants promote ancient peatland carbon loss with climate warming", Global Change Biology, DOI: 10.1111/gcb.13213

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13213/abstract

Abstract: "Northern peatlands have accumulated one third of the Earth's soil carbon stock since the last Ice Age. Rapid warming across northern biomes threatens to accelerate rates of peatland ecosystem respiration. Despite compensatory increases in net primary production, greater ecosystem respiration could signal the release of ancient, century- to millennia-old carbon from the peatland organic matter stock. Warming has already been shown to promote ancient peatland carbon release, but, despite the key role of vegetation in carbon dynamics, little is known about how plants influence the source of peatland ecosystem respiration. Here, we address this issue using in situ 14C measurements of ecosystem respiration on an established peatland warming and vegetation manipulation experiment. Results show that warming of approximately 1 °C promotes respiration of ancient peatland carbon (up to 2100 years old) when dwarf-shrubs or graminoids are present, an effect not observed when only bryophytes are present. We demonstrate that warming likely promotes ancient peatland carbon release via its control over organic inputs from vascular plants. Our findings suggest that dwarf-shrubs and graminoids prime microbial decomposition of previously ‘locked-up’ organic matter from potentially deep in the peat profile, facilitating liberation of ancient carbon as CO2. Furthermore, such plant-induced peat respiration could contribute up to 40% of ecosystem CO2 emissions. If consistent across other sub-arctic and arctic ecosystems, this represents a considerable fraction of ecosystem respiration that is currently not acknowledged by global carbon cycle models. Ultimately, greater contribution of ancient carbon to ecosystem respiration may signal the loss of a previously stable peatland carbon pool, creating potential feedbacks to future climate change."

[AbruptSLR]

The linked reference indicates that the shrub-line in South-Central Alaska is advancing northward at a rate matching the climate change velocity.  If this holds true for other parts of the tundra, then taken together with the microbial activity cited in my immediate prior post, and the albedo change associated with shrubs in the tundra; this is not good news:

Roman J. Dial, T Scott Smeltz, Patrick F. Sullivan, Christina L. Rinas, Katriina Timm, Jason E. Geck, S Carl Tobin, Trevor S. Golden & Edward C. Berg (2016), "Shrub-line but not treeline advance matches climate velocity in montane ecosystems of south-central Alaska", Global Change Biology, DOI: 10.1111/gcb.13207

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13207/abstract

Abstract: "Tall shrubs and trees are advancing into many tundra and wetland ecosystems but at a rate that often falls short of that predicted due to climate change. For forest, tall shrub, and tundra ecosystems in two pristine mountain ranges of Alaska we apply a Bayesian, error-propagated calculation of expected elevational rise (climate velocity), observed rise (biotic velocity), and their difference (biotic inertia). We show a sensitive dependence of climate velocity on lapse rate and derive biotic velocity as a rigid elevational shift. Ecosystem presence identified from recent and historic orthophotos ~50 years apart was regressed on elevation. Biotic velocity was estimated as the difference between critical point elevations of recent and historic logistic fits divided by time between imagery. For both mountain ranges the 95% highest posterior density of climate velocity enclosed the posterior distributions of all biotic velocities. In the Kenai Mountains mean tall shrub and climate velocities were both 2.8 m y−1. In the better sampled Chugach Mountains mean tundra retreat was 1.2 m y−1 and climate velocity 1.3 m y−1. In each mountain range the posterior mode of tall woody vegetation velocity (the complement of tundra) matched climate velocity better than either forest or tall shrub alone, suggesting competitive compensation can be important. Forest velocity was consistently low at 0.1 – 1.1 m y−1 indicating treeline is advancing slowly. We hypothesize that the high biotic inertia of forest ecosystems in south-central Alaska may be due to competition with tall shrubs and/or more complex climate controls on the elevational limits of trees than tall shrubs. Among tall shrubs, those that disperse farthest had lowest inertia. Finally, the rapid upward advance of woody vegetation may be contributing to regional declines in Dall's sheep (Ovis dalli), a poorly-dispersing alpine specialist herbivore with substantial biotic inertia due to dispersal reluctance."

[AbruptSLR]

The linked Eos article provides links to the NCAR Community Climate System Model (CCSM4), and simulations prepared for the 5th Assessment Report of the Intergovernmental Panel on Climate Change; and is provided over the Internet to help communities to plan for and adapt to climate change (this assumes that there will be climate consequences that need to be adapted to).  My major concern is that AR5 projections seriously underestimate the true climate change risks and that adaptive measures planned for such projections may well be overwhelmed by the actual climate consequences.  It would be nice to believe that in less than five years, after the current ACME program is complete, that a comparable website would be established for the ACME projections, so that the general public can plan more accordingly:


Wilhelmi, O., J. Boehnert, and K. Sampson (2016), Visualizing the climate’s future, Eos, 97, doi:10.1029/2016EO042207

https://eos.org/project-updates/visualizing-the-climates-future

Extract: "As communities plan for and adapt to climate change, demand for usable climate information is growing. To do their jobs and protect their communities and themselves, policy makers, planners, businesses, and citizens need to know how factors like temperature and precipitation will change in the decades ahead."

See also:
http://gisclimatechange.ucar.edu/
http://gisclimatechange.ucar.edu/inspector

[AbruptSLR]

The linked reference provides satellite evidence that the actually size of the negative feedback associated with global terrestrial CO2 fertilization is less than half of that currently assumed by most ESM projections.

W. Kolby Smith, Sasha C. Reed, Cory C. Cleveland, Ashley P. Ballantyne, William R. L. Anderegg, William R. Wieder, Yi Y. Liu & Steven W. Running (2015), "Large divergence of satellite and Earth system model estimates of global terrestrial CO2 fertilization", Nature Climate Change, doi:10.1038/nclimate2879

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2879.html

Abstract: "Atmospheric mass balance analyses suggest that terrestrial carbon (C) storage is increasing, partially abating the atmospheric [CO2] growth rate, although the continued strength of this important ecosystem service remains uncertain. Some evidence suggests that these increases will persist owing to positive responses of vegetation growth (net primary productivity; NPP) to rising atmospheric [CO2] (that is, ‘CO2 fertilization’). Here, we present a new satellite-derived global terrestrial NPP data set, which shows a significant increase in NPP from 1982 to 2011. However, comparison against Earth system model (ESM) NPP estimates reveals a significant divergence, with satellite-derived increases (2.8 ± 1.50%) less than half of ESM-derived increases (7.6  ±  1.67%) over the 30-year period. By isolating the CO2 fertilization effect in each NPP time series and comparing it against a synthesis of available free-air CO2 enrichment data, we provide evidence that much of the discrepancy may be due to an over-sensitivity of ESMs to atmospheric [CO2], potentially reflecting an under-representation of climatic feedbacks and/or a lack of representation of nutrient constraints. Our understanding of CO2 fertilization effects on NPP needs rapid improvement to enable more accurate projections of future C cycle–climate feedbacks; we contend that better integration of modelling, satellite and experimental approaches offers a promising way forward."

See also:

http://phys.org/news/2015-12-satellite-global-growth-co2-emissions.html

Extract: ""Current Earth system models assume that global plant growth will provide the tremendous benefit of offsetting a significant portion of humanity's CO2 emissions, thus buying us much needed time to curb emissions," says Smith. "Unfortunately, our observation-based estimates of global vegetation growth indicate that plant growth may not buy us as much time as expected, [so] action to curb emissions is all the more urgent."

The authors identify two important factors that could be driving the divergence between satellite-based results and model-based results: availability of water and availability of nutrients. Satellite data indicate that warmer climate conditions resulting from rising atmospheric CO2 may be increasing plant water stress, counteracting any positive effect of CO2. Additionally, limited availability of nitrogen and phosphorus in the environment could also limit the ability of plants to soak up additional CO2"

 

[AbruptSLR]

While Marvel et al (2015) found that the most likely value for TCR is 1.7C, the following research cites a most likely value for TCR of 1.9C (with a 95% CL interval of 1.2C to 2.7C).  It looks like Marvel and Schmidt may well be erring on the side of least drama (see Replies #1249, 1255, 1256, and 1266):

Storelvmo, Trude; Leirvik, Thomas; Phillips, Petter; Lohmann, Ulrike; Wild, Martin (2015), "Disentangling Aerosol Cooling and Greenhouse Warming to Reveal Earth's Climate Sensitivity", GU General Assembly 2015, held 12-17 April, 2015 in Vienna, Austria. id.4326, Bibliographic Code: 2015EGUGA..17.4326S

Abstract: "Earth's climate sensitivity has been the subject of heated debate for decades, and recently spurred renewed interest after the latest IPCC assessment report suggested a downward adjustment of the most likely range of climate sensitivities. Here, we present a study based on the time period 1964 to 2010, which is unique in that it does not rely on global climate models (GCMs) in any way. The study uses surface observations of temperature and incoming solar radiation from approximately 1300 surface sites, along with observations of the equivalent CO2 concentration (CO2,eq) in the atmosphere, to produce a new best estimate for the transient climate sensitivity of 1.9K (95% confidence interval 1.2K - 2.7K). This is higher than other recent observation-based estimates, and is better aligned with the estimate of 1.8K and range (1.1K - 2.5K) derived from the latest generation of GCMs. The new estimate is produced by incorporating the observations in an energy balance framework, and by applying statistical methods that are standard in the field of Econometrics, but less common in climate studies. The study further suggests that about a third of the continental warming due to increasing CO2,eq was masked by aerosol cooling during the time period studied."

[Sigmetnow]

New Evidence Suggests Human Beings Are a Geological Force of Nature

For years, the term “Anthropocene” has been used to informally describe the human era on Earth. But new evidence suggests there’s nothing informal about it. We’re a true force of nature — and there’s good reason to believe we’ve sparked a new and unprecedented geological epoch.

A team of international geoscientists say the time has come for us to formally recognize the Anthropocene as a new epoch, one as significant as previous geological eras like the Holocene and Pleistocene. According to the new study, which appears in the latest issue of Science, it began sometime around the midpoint of the 20th century, and is fueled by a number of unquestionably human influences — including elevated greenhouse gas levels and the global proliferation of invasive species, along with the spread of materials such as aluminium, concrete, fly ash, and even fallout from nuclear testing.

http://gizmodo.com/new-evidence-suggests-human-beings-are-a-geological-for-1751429480

[AbruptSLR]

From July 13 to 17 2015 a workshop was held on: "Workshop on Uncertainty Quantification in Climate Modeling and Projection".  The workshop was focused on educating developing countries on the risks associated with climate change uncertainties that they are exposed to (see the links below).  Most of the general public in developed countries and most of the policymakers in developing countries are not well informed of the potentially high consequences associated with our current high levels of uncertainty about climate change and climate sensitivity:

http://indico.ictp.it/event/a14268/

Extract: :The prediction of future climate changes is one of the most complex problems undertaken by the scientific community. Although scientists have been striving to better understand the physical basis of the climate system behavior and to improve climate models, the overall uncertainty in projecting future climate has not been reduced (e.g., from the IPCC 2007 to 2013). With the rapid increase of complexity in Earth system models, reducing uncertainties and increasing reliability of climate projections becomes an extremely challenging task. Since uncertainties always exist in climate models, interpreting model simulations and quantifying uncertainty is key to understanding and modeling atmospheric, land, ocean, and socio-economic phenomena and processes. Meanwhile, climate change adaption and impact communities rely on climate models to provide climate change information. Such information, if not accurate, should be provided with well-quantified uncertainty.
Uncertainty Quantification (UQ) is a fundamental challenge in numerical simulations of Earth’s weather and climate. It entails much more than attaching defensible error bars to predictions. In recent years, formal methods of verification, validation, and UQ employed in other simulation problems have been applied to climate simulations. The topics to be discussed in this workshop will include many aspects of UQ in climate modeling, such as identifying sources of uncertainty, describing uncertainty associated with input parameters, evaluating model uncertainty through validation against observations, model comparison between numerical and/or analytical solutions, and upscaling/downscaling, as well as quantifying uncertainty through both forward modeling (sensitivity analyses) and inverse modeling (optimization/calibration) in all components of climate and integrated Earth system models at various spatial and temporal scales. The workshop is also aimed at providing both theoretical lectures and hands-on sessions on the theory and application of the various UQ methods and approaches, such as sensitivity analysis, construction of surrogate models and response surfaces, input parameter calibration studies, forward propagation of uncertainties, and assessment of model discrepancies and structural uncertainties. Supervised by the directors and lecturers, participants will be encouraged to design, complete and report on short research projects during the event."

See also (with an open access pdf):

Qian, Y., C. Jackson, F. Giorgi, B. Booth, Q. Duan, C. Forest, D. Higdon, Z. Hou,
and G. Huerta, 2016: Uncertainty Quantification in Climate Modeling and
Projection. Bull. Amer. Meteor. Soc., doi: 10.1175/BAMS-D-15-00297.1

http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-15-00297.1

[AbruptSLR]

The linked reference discusses a decadally-delayed response of the ENSO to the AMO variability.  Note that the AMO is currently entering a cooling phase and that per this research this implies that about 30-years from now (circa 2045) the ENSO will be entering a warming phase, perhaps stronger than our current phase of positive PDO behavior, which is not considered in the current AR5 forecasts:

Davide Zanchettin, Oliver Bothe, Hans F. Graf, Nour-Eddine Omrani, Angelo Rubino & Johann H. Jungclaus (2016), "A decadally-delayed response of the tropical Pacific to Atlantic multidecadal variability", Geophysical Research Letters, DOI: 10.1002/2015GL067284

http://onlinelibrary.wiley.com/doi/10.1002/2015GL067284/abstract

Abstract: "North Atlantic sea-surface temperature anomalies are known to affect tropical Pacific climate variability and El Niño-Southern Oscillation (ENSO) through thermocline adjustment in the equatorial Pacific Ocean. Here, coupled climate simulations featuring repeated idealized cycles of the Atlantic Multidecadal Oscillation (AMO) generated by nudging its tropical branch demonstrate that the tropical Pacific response to the AMO also entails a substantial decadally-delayed component. The simulations robustly show multidecadal fluctuations in central equatorial Pacific sea-surface temperatures lagging the AMO by about three decades and a sub-decadal cold-to-warm transition of the tropical Pacific mean state during the AMO's cooling phase. The interplay between out-of-phase responses of seawater temperature and salinity in the western Pacific and associated density anomalies in local thermocline waters emerge as crucial factors of remotely-driven multidecadal variations of the equatorial Pacific climate. The delayed AMO influences on tropical Pacific dynamics could help understanding past and future ENSO variability."

[AbruptSLR]

The linked articles highlight the fact that climate change projections are limited not only by limited scientific understanding, but also significantly by computer speed:

http://www.extremetech.com/extreme/220819-ncar-to-get-new-sgi-supercomputer-to-sharpen-climate-change-projections

Extract: "Climate science will soon get a big boost from a new supercomputer. The National Center for Atmospheric Research (NCAR) will be working with the venerable SGI on a new system to develop more advanced climate and weather models. NCAR’s new supercomputer will be the SGI ICE XA, named “Cheyenne.” It will replace the current “Yellowstone” IBM supercomputer (pictured above), deliver 2.5 times the computing power, and will help provide more accurate — and therefore actionable — projections about the impact of climate change for specific regions 10 years into the future, SGI said in a statement.
The SGI ICE XA is expected to deliver 5.34 petaflops, or perform 5.34 quadrillion calculations per second. It consists of a modular design with over 7,000 future-generation Intel Xeon processors of an unspecified nature, with SGI E-cell water cooling, an enhanced hypercube interconnect courtesy of Mellanox EDR InfiniBand, and 20 petabytes of storage from Data Direct Networks (DDN). “NCAR requires an increasingly more advanced system. For example, doubling the resolution of a weather system requires a tenfold increase of compute power,” said Al Kellie, director of CISL at NCAR, in the same statement."


See also:
http://www2.ucar.edu/atmosnews/news/18751/ncar-announces-powerful-new-supercomputer-scientific-discovery

[AbruptSLR]

The linked reference indicates that clouds over the Greenland Ice Sheet enhance meltwater runoff by about one-third relative to clear skies; and indicates that current climate models do not adequately account for this behavior, which will increase sea level rise projections (when accounted for).

K. Van Tricht, S. Lhermitte, J. T. M. Lenaerts, I. V. Gorodetskaya, T. S. L’Ecuyer, B. Noël, M. R. van den Broeke, D. D. Turner & N. P. M. van Lipzig  (2016), "Clouds enhance Greenland ice sheet meltwater runoff", Nature Communications, Volume: 7, Article number: 10266, doi:10.1038/ncomms10266


http://www.nature.com/ncomms/2016/160112/ncomms10266/full/ncomms10266.html

Abstract: "The Greenland ice sheet has become one of the main contributors to global sea level rise, predominantly through increased meltwater runoff. The main drivers of Greenland ice sheet runoff, however, remain poorly understood. Here we show that clouds enhance meltwater runoff by about one-third relative to clear skies, using a unique combination of active satellite observations, climate model data and snow model simulations. This impact results from a cloud radiative effect of 29.5 (±5.2) W m−2. Contrary to conventional wisdom, however, the Greenland ice sheet responds to this energy through a new pathway by which clouds reduce meltwater refreezing as opposed to increasing surface melt directly, thereby accelerating bare-ice exposure and enhancing meltwater runoff. The high sensitivity of the Greenland ice sheet to both ice-only and liquid-bearing clouds highlights the need for accurate cloud representations in climate models, to better predict future contributions of the Greenland ice sheet to global sea level rise."

See also:
http://phys.org/news/2016-01-greenland-ice-sheet-cloudy.html

Extract: "The Greenland Ice Sheet is the second largest ice sheet in the world and it's melting rapidly, likely driving almost a third of global sea level rise.  A new study shows clouds are playing a larger role in that process than scientists previously believed.

…

When it comes to heat, clouds essentially behave in two ways: They either cool the Earth's surface by reflecting sunlight back into space, or, like a thick blanket, they trap heat at the surface—the greenhouse effect of clouds. On Greenland, which is covered in bright, light-reflecting snow, clouds primarily act to trap heat."

[sidd]

The pendulum just got a ratchet. The melt refroze in the past, keeping mass waste total zero. Now it runs away to the ocean, nonero mass waste. And it is now dominant.

Something else that worries me is that water saturated firn is quite different than dry firn. I fear avalanche, especially considering  ice lenses detected below saturated firn.

I wonder if this will be a factor in saddle collapse at 67N

I think this should be in the Greenland threads.

sidd

[AbruptSLR]

I think this should be in the Greenland threads.

sidd

sidd,

Feel free to repost any posts that I make as this topic could just as well go into the Sea Level Rise thread, or to the discussion about Hansen et al 2015.  With climate change being a "wicked problem" there are so many cross-connections that it is hard to see the forest from the trees and vice versa.

ASLR

[AbruptSLR]

The linked website indicates that from Dec 2016 until Dec 2017, Scripps (lead by Julie McClean) will investigate Ocean and Sea-Ice Processes for the ACME program.  Therefore, I believe that it is reasonable to assume that preliminary findings from Phase 1 of the ACME program will not be publically available before 2018.

https://scripps.ucsd.edu/research/proposals/accelerated-climate-modeling-energy-acme-ocean-and-sea-ice-processes

Extract: "For cryosphere, the team will examine the near-term risks of initiating the dynamic instability and onset of the collapse of the Antarctic Ice Sheet due to rapid melting by warming waters adjacent to the ice sheet grounding lines.
 
The experiment would be the first fully coupled global simulation to include dynamic ice shelf–ocean interactions for addressing the potential instability associated with grounding line dynamics in marine ice sheets around Antarctica."

[AbruptSLR]

The linked (open access) reference quantifies the influence of tides on water mass mixing and sea ice loss in the Arctic Ocean and find that tides account for about 15% of the measured ice mass loss.  As this consideration was not included in the AR5 projections; hopefully future ESM projections in AR6 will account for this mechanism:

Maria V. Luneva, Yevgeny Aksenov, James D. Harle & Jason T. Holt (October 2015),  "The effects of tides on the water mass mixing and sea ice in the Arctic Ocean", Journal of Geophysical Research Oceans, Volume 120, Issue 10, Pages 6669–6699, DOI: 10.1002/2014JC010310

http://onlinelibrary.wiley.com/doi/10.1002/2014JC010310/abstract

Abstract: "In this study, we use a novel pan-Arctic sea ice-ocean coupled model to examine the effects of tides on sea ice and the mixing of water masses. Two 30 year simulations were performed: one with explicitly resolved tides and the other without any tidal dynamics. We find that the tides are responsible for a ∼15% reduction in the volume of sea ice during the last decade and a redistribution of salinity, with surface salinity in the case with tides being on average ∼1.0–1.8 practical salinity units (PSU) higher than without tides. The ice volume trend in the two simulations also differs: −2.09 × 103 km3/decade without tides and −2.49 × 103 km3/decade with tides, the latter being closer to the trend of −2.58 × 103 km3/decade in the PIOMAS model, which assimilates SST and ice concentration. The three following mechanisms of tidal interaction appear to be significant: (a) strong shear stresses generated by the baroclinic clockwise rotating component of tidal currents in the interior waters; (b) thicker subsurface ice-ocean and bottom boundary layers; and (c) intensification of quasi-steady vertical motions of isopycnals (by ∼50%) through enhanced bottom Ekman pumping and stretching of relative vorticity over rough bottom topography. The combination of these effects leads to entrainment of warm Atlantic Waters into the colder and fresher surface waters, supporting the melting of the overlying ice."


Strelich, L. (2016), Arctic tides drive water mixing and sea ice loss, Eos, 97, doi:10.1029/2016EO043461. Published on 14 January 2016

https://eos.org/research-spotlights/arctic-tides-drive-water-mixing-and-sea-ice-loss

Extract: "Scientists are grappling with the implications of the steady disappearance of sea ice, but the effects are difficult to simulate in global climate models. Ice loss is tied to a range of interdependent processes, including ocean circulation, temperature, weather, and the Earth’s albedo—its ability to reflect solar energy back into space. But to understand these broad consequences of ice loss and how it will impact the global climate, scientists must first pin down the small-scale and high-frequency mechanisms that drive ice loss.
Researchers from the United Kingdom’s National Oceanography Centre focused on the role of tides in order to examine the relationship between sea ice loss and climate variability. Luneva et al. modeled Arctic tidal dynamics over a span of 30 years, with data from 1978 to 2009, and found that the movement of tidal currents accounted for approximately 15% of sea ice loss in the last decade.
The models also pinpoint some of the mechanisms that make tides so influential. Friction—where water meets the seabed and the rough underside of the ice—is the driving force behind vertical mixing that brings the warm, salty waters of the Atlantic Ocean to the surface, where it warms the colder, fresher waters of the Arctic and accelerates melting.
Tides wield a lot of power over salinity and temperature, two traits that are critical to the mechanics of ocean circulation. The authors demonstrated that modeling tidal dynamics can be a boon to climate projections and contribute to a more complete picture of Earth’s climate systems."

[wili]

Apologies if this has already been linked--more from Kevin Anderson on the way that many scientists are self-censoring to downplay risks, on Democracy Now from back in December after the COP21 talks:

[AbruptSLR]

Apologies if this has already been linked--more from Kevin Anderson on the way that many scientists are self-censoring to downplay risks, on Democracy Now from back in December after the COP21 talks:

Thanks for the link; however, it made me cringe to hear him say that scientists understand very well what the remaining Carbon Budget is to remain below a 2C increase.  In actuality, in a few years to no more than twenty years, it will likely become very clear that the TCR used in AR5 to calculate their published Carbon Budget, was way too low (and that they should have used an effective ECS valuing using more activated [non-liner] positive feedback systems), and consequently their published Carbon Budget is way too high.

[wili]

Yeah, even those pointing out how optimistic everyone else is tend to be pretty optimistic themselves.

[Pmt111500]

Apologies if this has already been linked--more from Kevin Anderson on the way that many scientists are self-censoring to downplay risks, on Democracy Now from back in December after the COP21 talks:

Thanks for the link; however, it made me cringe to hear him say that scientists understand very well what the remaining Carbon Budget is to remain below a 2C increase.  In actuality, in a few years to no more than twenty years, it will likely become very clear that the TCR used in AR5 to calculate their published Carbon Budget, was way too low (and that they should have used an effective ECS valuing using more activated [non-liner] positive feedback systems), and consequently their published Carbon Budget is way too high.

ECS should be the only way to go until BAU supporters prove beyond doubt that CCS-methods can be applied in large scale. But that is only my opinion and only when I'm pessimistic of humans and the future adaptative capability of nature. I've never quite understood why they attempt to calculate TCR, since that depends so much on the human response. It's not like they develop a Hari Sheldon type psychohistory in near future to calculate that, to add the most obvious scifi-reference.

[AbruptSLR]

The linked reference indicates that the AR5 climate models under estimated the strength of the AMO under continued global warming by not adequately accounting for the activity of the tropical arm of the AMO.  This adds further support to the position that the AR5 model projections underestimate climate sensitivity (to both low cloud and dust feedbacks):

Tianle Yuan, Lazaros Oreopoulos, Mark Zelinka, Hongbin Yu, Joel Norris, Mian Chin, Steven Platnick and Kerry Meyer (2016), "Positive low cloud and dust feedbacks amplify tropical North Atlantic multidecadal oscillation", Geophysical Research Letters, DOI: 10.1002/2016GL067679

http://onlinelibrary.wiley.com/doi/10.1002/2016GL067679/abstract

Abstract: "The Atlantic Multidecadal Oscillation (AMO) is characterized by a horseshoe pattern of sea surface temperature (SST) anomalies and has a wide range of climatic impacts. While the tropical arm of AMO is responsible for many of these impacts, it is either too weak or completely absent in many climate model simulations. Here we show, using both observational and model evidence, that the radiative effect of positive low cloud and dust feedbacks is strong enough to generate the tropical arm of AMO, with the low cloud feedback more dominant. The feedbacks can be understood in a consistent dynamical framework: weakened tropical trade wind speed in response to a warm middle latitude SST anomaly reduces dust loading and low cloud fraction over the tropical Atlantic, which warms the tropical North Atlantic SST. Together they contribute to appearance of the tropical arm of AMO. Most current climate models miss both the critical wind speed response and two positive feedbacks though realistic simulations of them may be essential for many climatic studies related to the AMO."

[AbruptSLR]

The linked article indicates that more global warming has been sequestered into the deep ocean than previously recognized.  While some would say that this is good news, these finding can also be taken to mean that climate sensitivity is higher than previously recognized:

Peter J. Gleckler, Paul J. Durack, Ronald J. Stouffer, Gregory C. Johnson & Chris E. Forest (2016), "Industrial-era global ocean heat uptake doubles in recent decades", Nature Climate Change, doi:10.1038/nclimate2915


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2915.html

Abstract: "Formal detection and attribution studies have used observations and climate models to identify an anthropogenic warming signature in the upper (0–700 m) ocean. Recently, as a result of the so-called surface warming hiatus, there has been considerable interest in global ocean heat content (OHC) changes in the deeper ocean, including natural and anthropogenically forced changes identified in observational, modelling and data re-analysis studies. Here, we examine OHC changes in the context of the Earth’s global energy budget since early in the industrial era (circa 1865–2015) for a range of depths. We rely on OHC change estimates from a diverse collection of measurement systems including data from the nineteenth-century Challenger expedition, a multi-decadal record of ship-based in situ mostly upper-ocean measurements, the more recent near-global Argo floats profiling to intermediate (2,000 m) depths, and full-depth repeated transoceanic sections5. We show that the multi-model mean constructed from the current generation of historically forced climate models is consistent with the OHC changes from this diverse collection of observational systems. Our model-based analysis suggests that nearly half of the industrial-era increases in global OHC have occurred in recent decades, with over a third of the accumulated heat occurring below 700 m and steadily rising."


Also see:
https://www.washingtonpost.com/news/energy-environment/wp/2016/01/18/this-is-where-90-percent-of-global-warming-is-going/

[AbruptSLR]

While I have commented about the linked reference with paleo-findings previously, I would like to reiterate that:
(a) The finding of variable time lags for complex nonlinear feedback mechanisms implies that we cannot have strong confidence in the AR5 model projections that were heavily calibrated to relatively recent observations where the time lags likely masked possibly strong positive feedback mechanisms that might already be engaged but that we would not know it, and
(b) The finding that the paleo record contained evidence of multiple marked positive feedback mechanisms.

Egbert H. van Nes, Marten Scheffer, Victor Brovkin, Timothy M. Lenton, Hao Ye, Ethan Deyle and George Sugihara (2015), "Causal feedbacks in climate change", Nature Climate Change, doi:10.1038/nclimate2568

http://www.nature.com/nclimate/journal/v5/n5/full/nclimate2568.html


Abstract: "The statistical association between temperature and greenhouse gases over glacial cycles is well documented, but causality behind this correlation remains difficult to extract directly from the data. A time lag of CO2 behind Antarctic temperature—originally thought to hint at a driving role for temperature—is absent at the last deglaciation, but recently confirmed at the last ice age inception and the end of the earlier termination II . We show that such variable time lags are typical for complex nonlinear systems such as the climate, prohibiting straightforward use of correlation lags to infer causation. However, an insight from dynamical systems theory now allows us to circumvent the classical challenges of unravelling causation from multivariate time series. We build on this insight to demonstrate directly from ice-core data that, over glacial–interglacial timescales, climate dynamics are largely driven by internal Earth system mechanisms, including a marked positive feedback effect from temperature variability on greenhouse-gas concentrations."

[AbruptSLR]

The linked article indicates that more global warming has been sequestered into the deep ocean than previously recognized.  While some would say that this is good news, these finding can also be taken to mean that climate sensitivity is higher than previously recognized:

Peter J. Gleckler, Paul J. Durack, Ronald J. Stouffer, Gregory C. Johnson & Chris E. Forest (2016), "Industrial-era global ocean heat uptake doubles in recent decades", Nature Climate Change, doi:10.1038/nclimate2915

Related to the Gleckler reference, the linked Forbes article, & associated image, discuss possible implications of the changes in the ocean that occurred during the faux hiatus period:

http://www.forbes.com/sites/ericmack/2016/01/18/todays-oceans-are-different-than-they-were-twenty-years-ago/#2715e4857a0b33c6d1bc14fb


Caption: "Pacific and Atlantic meridional sections showing upper-ocean warming for the most recent complete decade. Red colors indicate a warming (positive) anomaly and blue colors indicate a cooling (negative) anomaly. (Source: Timo Bremer/LLNL)"

[AbruptSLR]

The linked open access reference addresses the limits of linear climate models (w.r.t. accessing climate sensitivity) and states: "... state- and forcing-dependency of feedbacks are probably not appreciated enough, and not considered appropriately in many studies."  I could not agree more with this position, and I find it astonishing that most mainstream climate scientists defend the findings of the linear climate models used in AR5:


Reto Knutti, Maria A. A. Rugenstein (2015), "Feedbacks, climate sensitivity and the limits of linear models", Philosophical Transactions of the Royal Society A, DOI: 10.1098/rsta.2015.0146

http://rsta.royalsocietypublishing.org/content/373/2054/20150146

Abstract: "The term ‘feedback’ is used ubiquitously in climate research, but implies varied meanings in different contexts. From a specific process that locally affects a quantity, to a formal framework that attempts to determine a global response to a forcing, researchers use this term to separate, simplify and quantify parts of the complex Earth system. We combine new model results with a historical and educational perspective to organize existing ideas around feedbacks and linear models. Our results suggest that the state- and forcing-dependency of feedbacks are probably not appreciated enough, and not considered appropriately in many studies. A non-constant feedback parameter likely explains some of the differences in estimates of equilibrium climate sensitivity from different methods and types of data. Clarifying the value and applicability of the linear forcing feedback framework and a better quantification of feedbacks on various timescales and spatial scales remains a high priority in order to better understand past and predict future changes in the climate system."

Extract: "…it becomes clear that ECS and TCR are rather limited characterizations of a much larger and interactive system. Other feedbacks such as vegetation, chemistry or land ice are now included in some climate models as their relevance is better understood.

...

… some but not all recent studies on the twentieth-century warming find rather low ECS values (median at or less than 2°C). Climate models show a large spread in ECS, with the spread half as big as the actual value. The highest uncertainty can be attributed to the cloud feedbacks (traceable to certain cloud types and regions), and the lapse rate feedback. But all comprehensive climate models indicate sensitivities above 2°C, and those that simulate the present-day climate best even point to a best estimate of ECS in the range of 3–4.5°C."

Edit: Here is one figure and associated caption from the reference:

Caption: "Timescales of climate relevant processes. Light grey bars indicate processes that act on timescales that a GCM can resolve, but are usually assumed to be (partly) inactive or non-existent. Dashed lines indicate timescales where specific feedbacks are weaker or only operate under certain circumstances. The arrow for clouds, lapse rate, water vapour and albedo indicates that those feedbacks operate on short timescales, but, because the surface warming takes centuries or more to equilibrate, these feedbacks continue to change and affect the overall response of the systems up to millennia. This can apply similarly to other feedbacks that respond quickly but continue to change over long timescales in response to other feedbacks. The coloured ellipses each cover different methods used to estimate climate sensitivity. The vertical ordering of the feedbacks is arbitrary. Models of intermediate complexity (EMICs) can bridge the gap between GCMs and palaeo proxies, for example by including carbon cycles, weathering and ice sheets. Usually, there are trade-offs between simulating very long timescales and the level of detail of short timescale processes."

[sidd]

The van Nes paper (doi:10.1038/nclimate2568) and the references to Sugihara therein are worth study. I am applying the Sugihara application of Taken's theorem in other fields, and it is a powerful weapon indeed. 

[AbruptSLR]

The linked article indicates that more global warming has been sequestered into the deep ocean than previously recognized.  While some would say that this is good news, these finding can also be taken to mean that climate sensitivity is higher than previously recognized:

Peter J. Gleckler, Paul J. Durack, Ronald J. Stouffer, Gregory C. Johnson & Chris E. Forest (2016), "Industrial-era global ocean heat uptake doubles in recent decades", Nature Climate Change, doi:10.1038/nclimate2915

Related to the Gleckler reference, the linked Forbes article, & associated image, discuss possible implications of the changes in the ocean that occurred during the faux hiatus period:

Per Trenberth, the Gleckler et al 2016 paper errs on the side of least drama w.r.t. how much heat the deep ocean has been absorbing, and he says that is about 25% higher than Gleckler et al cite:

https://news.vice.com/article/heres-the-most-detailed-picture-yet-of-how-much-the-worlds-oceans-are-warming

Extract: "Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research, said he was "unimpressed with the paper," adding that he plans to publish a paper demonstrating that the rate of ocean warming in the past 40 years was about 25 percent more than found in current Nature Climate Change study and that more of it is being stored in the deeper ocean than estimated.
"The general story is that this paper has got is reasonable, except it's not the final answer," he said."

[sidd]

Trenberth may be right. I have a feeling that the deep ocean responds faster than we suppose, and perhaps faster than we can suppose.

[AbruptSLR]

The linked reference assumes different degrees of nonlinearity for climate feedback mechanisms and concludes that such nonlinearity for positive feedback represents a Black Swan risk that linear climate models cannot recognize:

Jonah Bloch-Johnson, Raymond T. Pierrehumbert & Dorian S. Abbot (24 June 2015), "Feedback temperature dependence determines the risk of high warming", Geophysical Research Letters, DOI: 10.1002/2015GL064240

http://onlinelibrary.wiley.com/doi/10.1002/2015GL064240/full

Abstract: "The long-term warming from an anthropogenic increase in atmospheric CO2 is often assumed to be proportional to the forcing associated with that increase. This paper examines this linear approximation using a zero-dimensional energy balance model with a temperature-dependent feedback, with parameter values drawn from physical arguments and general circulation models. For a positive feedback temperature dependence, warming increases Earth's sensitivity, while greater sensitivity makes Earth warm more. These effects can feed on each other, greatly amplifying warming. As a result, for reasonable values of feedback temperature dependence and preindustrial feedback, Earth can jump to a warmer state under only one or two CO2 doublings. The linear approximation breaks down in the long tail of high climate sensitivity commonly seen in observational studies. Understanding feedback temperature dependence is therefore essential for inferring the risk of high warming from modern observations. Studies that assume linearity likely underestimate the risk of high warming."

[AbruptSLR]

The linked open access reference (doi:10.1038/srep15510) discusses one way to characterize nonlinearity in the observed climate record:


http://www.nature.com/articles/srep15510

[AbruptSLR]

As I have my doubts as to how much of the ACME finding will be published in peer-reviewed journals early enough to be included in AR6, I provide the following link to the "Decadal and Regional Climate Prediction Using Earth System Models (EaSM)" project which should provide significantly more powerful projections than those for existing models:

https://www2.cesm.ucar.edu/projects/easm

Extract for EaSM Phase I:
"• Climate-to-Humans: A Study of Urbanized Coastal Environments, their Economics and Vulnerability to Climate Change | PI Julio Bacmeister
•Simulations of Anthropogenic Climate Change Using a Multi-scale Modeling Framework | PI Andrew Gettelman (end)
•Decadal Predictability of Extreme Events: Impact of a Model Error Representation and Numerical Resolution | PI Judith Berner (end)
•CRI-EaSM Multiscale Modeling of Aerosol Indirect Effects on Decadal Timescales | PI Sungsu Park
•Quantifying the Uncertainties of Aerosol Indirect Effects and Impacts on Decadal-scale Climate Variability in NCAR CAM5 and CESM1 | PI Sungsu Park
•An Informed Guide to Climate Data Sets with Relevance to Earth System Model Evaluation | PI Clara Deser
•Ecosystem Impacts of Variability and Extreme Events in the Arctic | PI Marika Holland
•MOBY: Modeling Ocean Variability and Biogeochemical Cycles | PI William Large
•Improved regional and decadal predictions of the carbon cycle | PI Keith Lindsay
•Topographic control of the Gulf Stream | PI Gokhan Danabasoglu
•Assessing and Improving the Scale Dependence of Ecosystem Processes in Earth System Models | PI Gordon Bonan
•Improved Cold Region Hydrology Process Representation as a Cornerstone of Arctic Biogeochemical Modeling | PI David Lawrence"