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Messages - dnmun

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I have made a point that I do not think that the WAIS will begin a MICI type of collapse until about 2040 (note that SSP5-Baseline projects a GMSTA of about 2C, relative to 1986-2005, by 2040); however, that do not mean that I do not think that we will activate numerous nonlinear positive self-reinforcing feedback mechanisms between now and then, which not only increases the probability of a MICI type of WAIS collapse this century, but also increases the probably that we cross a tipping point for abrupt climate change well before 2040 as cited in the two linked sources and illustrated by the attached image of abrupt regional feedback mechanisms.

Title: "Climate report understates threat"


I would like to note that most of the abrupt regional feedback mechanisms identified in quote above came from CMIP5; however, if CMIP6 has several ESMs with ECS greater than 5C, then CMIP6 will most likely identify many more abrupt feedback mechanisms including several related to ice-climate feedback mechanisms (omitted in CMIP5) even though CMIP6 only considers MISI types of ice sheet collapse mechanisms and omits consideration of MICI type collapse mechanisms.

Furthermore, I note CMIP5 many very well have underestimated the negative feedback from both natural and anthropogenic aerosols, which means that if rainforests (especially the Amazon) degrades rapidly and/or anthropogenic aerosol emissions are rapidly decreased in the coming decades, we are likely to cross many more tipping point thresholds earlier than identified in CMIP5.

While the laws of nature will be followed no matter what, it is the judicial system that determines what is legal fact with regard to human actions (e.g. see the linked article about goverments suing regarding professionally irresponsible behavior and or fraud by the fossil fuel industry); and consensus climate science evaluations play a major role with regard to what judges and juries determine to be legally liable facts about anthropogenic radiative forcing.

Consensus science has helped to establish a legal expectation that staying well below a GMSTA of 2C (relative to pre-industrial) is acceptable; however, James Hansen has stated that establishing an acceptable limit of 350ppm of atmospheric CO₂ concentrations would be advisable.  If consensus science would follow the Precautionary Principle, then it would be easier for youth groups to be successful in their lawsuits; and Greta Thunberg's youth movement might then file multiple lawsuits against governments for failing to adequately safeguard their collective futures (including lawsuits to block irresponsible implementation of geoengineering):

Title: "DC moves closer to climate lawsuit against Exxon"

Extract: "The D.C. government is beefing up its legal team ahead of an anticipated legal challenge against Exxon.

If D.C. moves forward with a lawsuit against Exxon, it will be joining a handful of other states and municipalities looking into how the oil and gas giant may have failed to publicize science it had linking emissions to global warming.

New York sued Exxon in October for allegedly engaging in "a longstanding fraudulent scheme.""

Edit: To be clear, if youth groups were successful in hundreds of lawsuits against hundreds of governments worldwide, then we would likely see these governments enact progressive carbon tax programs around the world.

Edit2, With regards to Hansen's 350ppm acceptable limit for atmospheric CO2 concentrations, the first attached image shows that we past that limit around 1987; and thus I assume that Hansen also meant that atmospheric CH4 concentrations should have an acceptable limit around 1685ppb where they were around 1987 as indicated by the second attached image.

The linked article indicates that the USA and Saudi Arabia recently blocked a U.N. resolution to make the UNEA (U.N. Environment Assembly) the governing body for regulating any future potential implementation of geoengineering.  Apparently, the USA and Saudi Arabia did not want a U.N. body to limit/regulate the impacts of geoengineering on the overall environment and on small countries:

Title: "U.S. Blocks U.N. Resolution on Geoengineering"

The first two (associated) linked sources indicate that due to global warming intense El Nino events will become more frequent (estimated to occur about every 10 years); while the third linked source indicates that there is a good chance that there will be an intense El Nino event in the 2019-2020 season; which would be only four years after the 2015-16 intense El Nino event.  This is a clear indication that the likely range for ECS is higher than AR5 indicates; and this adds to the probability that the WAIS may initiate a MICI type of collapse circa 2040:

Wenju Cai et al. (2018), "Increased variability of eastern Pacific El Nino under greenhouse warming", Nature 564, 201-206,

Extract: "An increase in SST variance implies an increase in the number of 'strong' EP-El Nino events (corresponding to large SST anomalies) and associated extreme weather events."

See also:

Title: "El Nino events to become 'stronger' and more intense, study finds"

"They are stronger and more frequent," Dr Cai said, adding the likelihood of intense El Nino events as measured by sea-surface temperatures will increase from about one every 15 years now to every 10 years on average during this century.

Big El Ninos of recent decades include 1982-83, 1997-98 and 2015-16."

Also, particularly see:

Title: "'Monster' El Nino a chance later this year, pointing to extended dry times"

Extract: "The prospect of a big El Nino later this year was raised at an international conference of climate scientists in Chile earlier this month.

They considered parallel years, such as 2014 when a near-El Nino was reached before conditions revived a year later, creating one of the three most powerful such events in the past half century.

"There is more heat now below the surface waiting to be tapped than there was in early 2015," said Michael McPhaden, a senior scientist with US National Atmospheric and Oceanic Administration who attended the Chilean event.

"If westerly wind bursts of sufficient amplitude, duration and zonal extent develop along the equator in the next couple of months, 2019-20 could be very exciting," he said.

"While it's not a slam dunk that El Nino is going to persist, I think that the odds have certainly increased over one to two months ago," Phil Klotzbach, a research scientist at Colorado State University, said. " We've had a big build up of heat in the eastern and central Pacific."

Cai Wenju, a senior CSIRO scientist who has published widely on the El Nino Southern Oscillation climate pattern, said the chance of El Nino returning is high.

A return of westerlies by about June to halt the easterly tradewinds “could spark the fire and there’s a lot of fuel", Dr Cai said.

“If it’s similar to 2015, the impact this time will be big," he said."

I have previously noted that earlier consensus climate science reports like AR5 have made liberal use of caveats to exclude several right-tailed feedback mechanisms from the confidence ranges that they report for various climate change parameters (see also my comments in at least Replies #707 & #751).  Furthermore, in at least Reply #719 I recommended that consensus science generate families of Maximum-credible Climate-risk Scenarios (MCSs) in order to better assess right-tail climate risks.

In this post I briefly note consensus science only formally cites two limit states (i.e. the aspirational 1.5C GMSTA target and the 'Well below' 2C GMSTA limit by 2100).  To my Civil Engineering way of thinking the 1.5C target can be associated with an 'Operations' limit state where the proper function of our socioeconomic systems begin to fail; while the 'Well below' 2C limit can be associated where significant human life safety becomes threatened.

However, also to my Civil Engineering way of thinking, modern civil society depends on numerous other limit states (in civil engineering designs there are several other limit states such as: 'Progressive Collapse', 'Fatigue' and 'Durability limit states), that it would be good for consensus science to formally specify acceptable limit states for this century such as: a) Sea Level Rise and the associated rate of Sea Level Rise; b) Tropical Pacific SSTA, and c) Cascades of tipping points leading to abrupt changes in climate state.  Also, I note that in limit state design engineers assign partial load factors of safety for each separate forcing according to its uncertainty and partial resistance factors of safety to reflex the fragility of each separate system component according to its uncertainty.  Furthermore, I note that all civil engineering designs to adapt to climate change use the incomplete forcing from consensus science reports like AR5/CMIP5 and use load and resistance safety factors that were empirically established for quasi-static climate change, and that little or no attempts have been made to develop such factors of safety appropriate to maintain civil society under conditions of rapid/dynamic climate change.

Finally, I provide the linked UC Berkeley article and associated images on how the real process of science works; which per the attached images includes community feedback and societal expectations of benefits from scientific work.  In this sense the real consensus climate science process is politicized by community resistance to change and by societal expectation that science bring benefits ('good science') rather than reporting increasing risks/dangers ('bad science'):

Title: "The real process of science"

Extract: "At first this process might seem overwhelming. Even within the scope of a single investigation, science may involve many different people engaged in all sorts of different activities in different orders and at different points in time — it is simply much more dynamic, flexible, unpredictable, and rich than many textbooks represent it as."

The linked open access commentary provides a convenient summary of the nature and likely impacts of Arctic Amplification:

Twila A. Moon et al. (07 March 2019), "The expanding footprint of rapid Arctic change", Earth's Future,

Arctic land ice is melting, sea ice is decreasing, and permafrost is thawing. Changes in these Arctic elements are interconnected, and most interactions accelerate the rate of change. The changes affect infrastructure, economics, and cultures of people inside and outside of the Arctic, including in temperate and tropical regions, through sea level rise, worsening storm and hurricane impacts, and enhanced warming. Coastal communities worldwide are already experiencing more regular flooding, drinking water contamination, and coastal erosion. We describe and summarize the nature of change for Arctic permafrost, land ice, and sea ice, and its influences on lower latitudes, particularly the United States. We emphasize that impacts will worsen in the future unless individuals, businesses, communities, and policy makers proactively engage in mitigation and adaptation activities to reduce the effects of Arctic changes and safeguard people and society.

CMIP6 is already being conducted with at best consideration of MISI types of ice mass loss from both the GIS & AIS, and completely without consideration of MICI types of ice mass losses, therefore, a discussion of the implications of the growing number of consensus climate scientists who are pointing to the findings of Edwards et al. (2019) as justification for ignoring MICI types of ice mass loss in their model projections this century may be academic.  Nevertheless, here I point out that Edwards et al. (2019) used a statistical emulator of ice sheet mass loss over the past 1 million years to indicate that most likely MISI behavior could account for the paleo record; however, this finding is a far different matter than concluding that MICI types of behavior can be discounted in model projections for the rest of this century.

First, as SSP5-Baseline indicates that we may well be at Mid-Pliocene (3.3 Ma–3 Ma) conditions by (or before) 2040, the Edwards et al. (2019) emulation of the past 1Ma are likely not relevant; while Pollard, DeConto & Alley (2018)'s evaluation of MICI under Mid-Pliocene conditions are more relevant.

Second, we are approaching Mid-Pliocene conditions thousands of times faster than occurred during the Mid-Pliocene; which Pollard, DeConto & Alley (2018) took into account by abruptly introducing Mid-Pliocene conditions onto modern AIS conditions in their model.

Third, both Edwards et al (2019) and Pollard, DeConto & Alley (2018) use AIS boundary & starting conditions for the modern AIS that are less aggressive than what is currently observed in 2019 w.r.t. such factors as: a) the large subglacial cavity at the base of the Thwaites Ice Tongue; b) the loss of ice shelf buttressing of the Southwest Tributary Glacier in Pine Island Bay; and c) the amount of ice-climate feedback mechanisms that are already being activated (including MOC slowing, shifting of the ENSO towards more frequent El Nino events & increased advection of warm CDW towards the grounding lines of key AIS marine glaciers).

I understand that CMIP6 is already pushing the computational capacity of the participation ESMs; I think that it is wasteful of research funds to be investigating scenarios with little chance of occurring, and also I note that currently the cost of using Exascale computers is dropping by half about every 3 months.  Therefore, I believe that rather than likely committing a Type 2 error (a false negative, i.e. assuming that MICI ice mass loss will not occur this century when it actually might occur after 2040); it would be better for consensus climate scientists to work harder (possibly by using Exascale computing resources) on including MICI mechanisms in at least some of their scenarios so as to at least evaluate right-tail risks.

Finally, I provide the attached images related to use of the scientific method (without comment), as I believe that the proper use of this method would not result in MICI behavior being discounted in on-going ESM modeling efforts.

Edit: I forgot to mention that the emulator used by Edwards et al. (2019) did not include the impact of the Antarctic ozone holes (as this did not occur in paleo-times); which this ozone hole has accelerated ice mass loss from Antarctica and projections of the impact of continuing GHG emissions on the westerly winds over the Southern Ocean, indicate that as the ozone hole heals the regional impact of increasing GHG atmospheric concentrations will keep these regional westerly winds in an optimal zone for promoting ice mass loss for at least the next few decades.

The linked reference indicates that the warming of the North Pacific subpolar waters in likely the most important feedback for driving enhanced Arctic Amplification with continued global warming, and the attached image demonstrates how the North Pacific subpolar water can be warmed directly by atmospheric telecommunication of energy from the Tropical Pacific.  If show this indicates that the CMIP5 projections likely underestimate ECS, and as ice-climate feedback would likely accelerate warming the Tropical Pacific, it is likely that CMIP6 projections will also underestimate ECS as these models do not consider ice-cliff failures or hydrofracturing:

Summer Praetorius, Maria Rugenstein, Geeta Persad, Ken Caldeira. Global and Arctic climate sensitivity enhanced by changes in North Pacific heat flux. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-05337-8

Abstract: "Arctic amplification is a consequence of surface albedo, cloud, and temperature feedbacks, as well as poleward oceanic and atmospheric heat transport. However, the relative impact of changes in sea surface temperature (SST) patterns and ocean heat flux sourced from different regions on Arctic temperatures are not well constrained. We modify ocean-to-atmosphere heat fluxes in the North Pacific and North Atlantic in a climate model to determine the sensitivity of Arctic temperatures to zonal heterogeneities in northern hemisphere SST patterns. Both positive and negative ocean heat flux perturbations from the North Pacific result in greater global and Arctic surface air temperature anomalies than equivalent magnitude perturbations from the North Atlantic; a response we primarily attribute to greater moisture flux from the subpolar extratropics to Arctic. Enhanced poleward latent heat and moisture transport drive sea-ice retreat and low-cloud formation in the Arctic, amplifying Arctic surface warming through the ice-albedo feedback and infrared warming effect of low clouds. Our results imply that global climate sensitivity may be dependent on patterns of ocean heat flux in the northern hemisphere."

Extract: "Systematic cold biases in North Pacific and North Atlantic SSTs in CMIP5 models48 may thus partly lead to an underestimation of Arctic warming and sea-ice decline in climate projections, with important ramifications for climate and ecological tipping points in the Arctic."

See also:

Title: "Pacific Ocean's effect on Arctic warming"

Extract: "Paleoclimate records show that climate change in the Arctic can be very large and happen very rapidly. During the last deglaciation, as the planet was starting to warm from rising greenhouse gases, there were two episodes of accelerated warming in the Arctic -- with temperatures increasing by 15°C (27°F) in Greenland over the course of decades. Both events were accompanied by rapid warming in the mid-latitude North Pacific and North Atlantic oceans."

While in Reply #353 I provided the first attached image as one simple example of how AR5's ECS risk (probability of occurrence times consequences) could have been better conveyed to decision makers (including the public).  That said, in this post I would like to note that I do not agree with AR5's assessment of the PDF for ECS; nor do I believe that possible high values of ECS represents the only source of under-represented risk of abrupt climate change in the coming decades.

With regards to AR5's assessment of the PDF (probability density function) for ECS I note that:
1. The 1.5C value at the lower end of the likely range, was based on incorrect interpretations of observed data, which has subsequently been proven to be incorrect, so the lower value of the likely range should have been 2C as it was in AR4.

2. AR5 ECS range mixes different means of calculating ECS that result in different definitions of ECS, without any effort to normalize/standardize the values under condition.  AR5's sole bases for including different values of ECS for inclusion in the PDF is whether they fall with the 10% to 90% range of peer-reviewed references published before the cut-off date.  For example, AR5 combines inferred ECS values with true ECS values.

3. AR5 assumes values of ECS that are not 'state-dependent'; which means that AR5 does not consider possible increases in ECS due to either increasing temperature, nor due to ice-climate,  feedback mechanisms (see the second attached image from Hansen and Sato 2012).

With regard to consequences, high values of ECS will most likely cause a collapse of the WAIS (and other key marine glaciers) in the coming decades; which would cause multiple meters of sea level rise, the impacts of which are certainly not included in the first attached image.

Discovery of recent Antarctic ice sheet collapse raises fears of a new global flood

Some 125,000 years ago, during the last brief warm period between ice ages, Earth was awash. Temperatures during this time, called the Eemian, were barely higher than in today’s greenhouse-warmed world. Yet proxy records show sea levels were 6 to 9 meters higher than they are today, drowning huge swaths of what is now dry land.

Scientists have now identified the source of all that water: a collapse of the West Antarctic Ice Sheet. Glaciologists worry about the present-day stability of this formidable ice mass. Its base lies below sea level, at risk of being undermined by warming ocean waters, and glaciers fringing it are retreating fast. The discovery, teased out of a sediment core and reported last week at a meeting of the American Geophysical Union in Washington, D.C., validates those concerns, providing evidence that the ice sheet disappeared in the recent geological past under climate conditions similar to today’s. “We had an absence of evidence,” says Anders Carlson, a glacial geologist at Oregon State University in Corvallis, who led the work. “I think we have evidence of absence now.”

If it holds up, the finding would confirm that “the West Antarctic Ice Sheet might not need a huge nudge to budge,” says Jeremy Shakun, a paleoclimatologist at Boston College. That, in turn, suggests “the big uptick in mass loss observed there in the past decade or two is perhaps the start of that process rather than a short-term blip.” If so, the world may need to prepare for sea level to rise farther and faster than expected: Once the ancient ice sheet collapse got going, some records suggest, ocean waters rose as fast as some 2.5 meters per century.

Thanks for your link to the new evidence about SLR during the Eemian Peak (MIS 5e); however, when I read the associated article it struck me that some people reading the article might believe that SLR during the Eemian might represent an upper-bound limit for the consequences of our current situation.  Furthermore, I am concerned that some readers of my prior posts in this thread may be confused by the dynamic nature of such matters as the 'state-dependence' of climate sensitivity and what it means to 'tip' from one climate state (say our current climate state) into another climate state (say the Early-Pliocene) in the context of oscillating/chaotic Earth Systems, such as indicated by the first 2D image [where panel a shows a normalized climate state (say GMSTA) on the y-axis and a generic climate driver (say GHG) on the x-axis; and panel b showing the time-evolution of the driver for two different scenarios, one leading to a climate state tipping event and one not leading to a climate state tipping event] from Bathiany et al. (2018), and/or the second 3D image (where the z-axis would be other controlling parameters such as the various feedback mechanisms) of abrupt shifts in climate state.

Bathiany, S., Scheffer, M., van Nes, E. H., Williamson, M. S., & Lenton, T. M. (2018). Abrupt Climate Change in an Oscillating World. Scientific Reports, 8(1). doi:10.1038/s41598-018-23377-4,

Caption for the first image: "Figure 1. Stable states and trajectories in the example system (Eq. 1). (a) The equilibria of state x for constant driver D are shown as black lines (continuous: stable; dashed: unstable). The flow towards a stable state is shown as dashed orange arrows; B1 and B2 indicate the bifurcation points. (b) Time evolution of driver D for two pulses, the red one having a longer period than the blue one. The trajectories of the system that result from these forcings are shown as red and blue curves in (a). See Supplementary Information for details on the parameter choices."

Now, to take a larger paleo-overview, I have previous noted (see Replies #252 and #342) that climate sensitivity was higher during the Holsteinian Peak (MIS 11c) than during modern times, during the Holocene Peak and during the Eemian Peak; to the extent that the current ESM projections have not yet been able to match the observed climate sensitivity of the Holsteinian because they intentionally omit numerous possible feedback mechanisms (such as the ice-climate feedback and/or various methane feedback mechanisms).  Note that adding such feedback mechanisms into the ESM models would be the same as moving up the z-axis in the second image, which reduces the size of bifurcation gap between different climate states, thus making it easier for a perturbation (whether a pulse of GHG, or the collapse of the WAIS) to cause a transition into the higher climate state.

Reasons to believe that the MIS 11c is more relevant to our current/modern climate change risks include:

- MIS 11c occurred after a long period of relatively warm climatic conditions such as we have experienced to date during the Holocene.

- MIS 11c had comparable atmospheric greenhouse gas concentrations (considering only the period before the beginning of the Industrial Revolution, i.e. 1800 AD ca.),

- MIS 11c shows the highest-amplitude response to forcing for deglacial warming in the last 5 Myr,

- The period prior to MIS 11c, although cooler than the Holocene, is characterized by overall warm sea-surface temperatures in high latitudes, strong thermohaline circulation, unusual blooms of calcareous plankton in high latitudes, higher sea level than the present, coral reef expansion resulting in enlarged accumulation of neritic carbonates, and overall poor pelagic carbonate preservation and strong dissolution in certain areas. 

- Considering the variability in the astronomically-driven insolation, MIS 11 is the interval in which insolation is highly correlated with predicted near future situation.

Finally, I conclude by re-posting the Coletti et al. (2015) reference that elaborates on the fact that even the most advanced modern analysis of the MIS 11c event cannot yet full account for the exceptionally high Arctic Amplification during this period; which again raises the prospect that a rapid methane emission rate from the possible future collapse of the WAIS pushing warm water into the Arctic Ocean.

Coletti, A. J., DeConto, R. M., Brigham-Grette, J., and Melles, M.: A GCM comparison of Pleistocene super-interglacial periods in relation to Lake El'gygytgyn, NE Arctic Russia, Clim. Past, 11, 979-989, doi:10.5194/cp-11-979-2015, 2015.

Abstract: "Until now, the lack of time-continuous, terrestrial paleoenvironmental data from the Pleistocene Arctic has made model simulations of past interglacials difficult to assess. Here, we compare climate simulations of four warm interglacials at Marine Isotope Stages (MISs) 1 (9 ka), 5e (127 ka), 11c (409 ka) and 31 (1072 ka) with new proxy climate data recovered from Lake El'gygytgyn, NE Russia. Climate reconstructions of the mean temperature of the warmest month (MTWM) indicate conditions up to 0.4, 2.1, 0.5 and 3.1 °C warmer than today during MIS 1, 5e, 11c and 31, respectively. While the climate model captures much of the observed warming during each interglacial, largely in response to boreal summer (JJA) orbital forcing, the extraordinary warmth of MIS 11c compared to the other interglacials in the Lake El'gygytgyn temperature proxy reconstructions remains difficult to explain. To deconvolve the contribution of multiple influences on interglacial warming at Lake El'gygytgyn, we isolated the influence of vegetation, sea ice and circum-Arctic land ice feedbacks on the modeled climate of the Beringian interior. Simulations accounting for climate–vegetation–land-surface feedbacks during all four interglacials show expanding boreal forest cover with increasing summer insolation intensity. A deglaciated Greenland is shown to have a minimal effect on northeast Asian temperature during the warmth of stages 11c and 31 (Melles et al., 2012). A prescribed enhancement of oceanic heat transport into the Arctic Ocean does have some effect on Lake El'gygytgyn's regional climate, but the exceptional warmth of MIS 11c remains enigmatic compared to the modest orbital and greenhouse gas forcing during that interglacial."

Extract: "The timing of significant warming in the circum-Arctic can be linked to major deglaciation events in Antarctica, demonstrating possible interhemispheric linkages between the Arctic and Antarctic climate on glacial–interglacial timescales, which have yet to be explained."


In CMIP5 (& AR5) many models did a poor job of matching the important behavior of the Southern Ocean.  Thus, the first linked reference provides key metrics to better calibrated CMIP6 (& AR6) ESM projections, in order to better account for the Southern Ocean's behavior.  The last two linked references discuss new finds regarding  sea ice and cloud modeling, respectively, that need to be better represented in CMIP6 (& AR5) as compared to CMIP5 (& AR5):

Joellen L. Russell et al. (16 February 2018), "Metrics for the Evaluation of the Southern Ocean in Coupled Climate Models and Earth System Models", JGR Oceans,

Abstract: "The Southern Ocean is central to the global climate and the global carbon cycle, and to the climate's response to increasing levels of atmospheric greenhouse gases, as it ventilates a large fraction of the global ocean volume. Global coupled climate models and earth system models, however, vary widely in their simulations of the Southern Ocean and its role in, and response to, the ongoing anthropogenic trend. Due to the region's complex water‐mass structure and dynamics, Southern Ocean carbon and heat uptake depend on a combination of winds, eddies, mixing, buoyancy fluxes, and topography. Observationally based metrics are critical for discerning processes and mechanisms, and for validating and comparing climate and earth system models. New observations and understanding have allowed for progress in the creation of observationally based data/model metrics for the Southern Ocean. Metrics presented here provide a means to assess multiple simulations relative to the best available observations and observational products. Climate models that perform better according to these metrics also better simulate the uptake of heat and carbon by the Southern Ocean. This report is not strictly an intercomparison, but rather a distillation of key metrics that can reliably quantify the “accuracy” of a simulation against observed, or at least observable, quantities. One overall goal is to recommend standardization of observationally based benchmarks that the modeling community should aspire to meet in order to reduce uncertainties in climate projections, and especially uncertainties related to oceanic heat and carbon uptake."

Extract: "In order to ensure their inclusion in the various model intercomparison projects that are part of the upcoming CMIP6, we encourage all modeling centers to make their simulations available in standard, orthogonal grids (latitude versus longitude versus depth) and to calculate and report quantities with significant covariance (e.g., lateral heat fluxes) for better budget calculations. Toward this goal, the Earth System Model Evaluation Tool (ESMValTool;, Eyring et al., 2016) is an invaluable resource for the climate modeling and assessment community that allows for routine comparison of single or multiple models against observations. Several of us are working on developing packages for the metrics discussed in this study to be included in the ESMValTool, and we strongly encourage other modeling groups to do the same."

See also:

Beaumet, J., Déqué, M., Krinner, G., Agosta, C., and Alias, A.: Effect of uncertainties of Southern Ocean surface temperature and sea-ice change on Antarctic climate projections, The Cryosphere Discuss.,, in review, 2018.

Abstract. In this study, the atmospheric model ARPEGE is used with a stretched grid in order to reach a average horizontal resolution of 35 kilometers over Antarctica. Over the historical period (1981–2010), ARPEGE is forced by the historical sea surface conditions (SSC, i.e. sea surface temperature and sea-ice concentration) from MIROC and NorESM1-M CMIP5 historical runs and by observed SSC (AMIP-experiment). These three simulations are evaluated against ERA-Interim for atmospheric general circulation and against MAR regional climate model and in-situ observations for surface climate. As lower boundary conditions for simulations for the period 2071–2100, we use SSC from coupled climate model CMIP5 simulations of the same models following the RCP8.5 emission scenario. We use these output both directly and with an anomaly method based on quantile mapping. We assess the uncertainties linked to the choice of the coupled model and the impact of the method (direct output and anomalies). For the simulation using SSC from NorESM1-M, we do not find significant changes in climate change signals over Antarctica when using bias-corrected SSC. For the simulation using MIROC-ESM output, an additional increase of +185Gtyr−1 in precipitation and of +0.8K in winter temperatures for the grounded Antarctic ice-sheet was obtained when using bias-corrected SSC.

Hyder, P., Edwards, J. M., Allan, R. P., Hewitt, H. T., Bracegirdle, T. J., Gregory, J. M., … Belcher, S. E. (2018). Critical Southern Ocean climate model biases traced to atmospheric model cloud errors. Nature Communications, 9(1). doi:10.1038/s41467-018-05634-2,

Abstract: "The Southern Ocean is a pivotal component of the global climate system yet it is poorly represented in climate models, with significant biases in upper-ocean temperatures, clouds and winds. Combining Atmospheric and Coupled Model Inter-comparison Project (AMIP5/ CMIP5) simulations, with observations and equilibrium heat budget theory, we show that across the CMIP5 ensemble variations in sea surface temperature biases in the 40–60°S Southern Ocean are primarily caused by AMIP5 atmospheric model net surface flux bias variations, linked to cloud-related short-wave errors. Equilibration of the biases involves local coupled sea surface temperature bias feedbacks onto the surface heat flux components. In combination with wind feedbacks, these biases adversely modify upper-ocean thermal structure. Most AMIP5 atmospheric models that exhibit small net heat flux biases appear to achieve this through compensating errors. We demonstrate that targeted developments to cloud-related parameterisations provide a route to better represent the Southern Ocean in climate models and projections."

The linked reference discusses some of the nuances and complexities associated with projecting abrupt climate change (via tipping points) in an oscillating world.  In this regards, I provide the associated image of different response timeframes for selected key feedback mechanisms, and in this regard I provide the second linked website that discusses climate lag.

Bathiany, S., Scheffer, M., van Nes, E. H., Williamson, M. S., & Lenton, T. M. (2018). Abrupt Climate Change in an Oscillating World. Scientific Reports, 8(1). doi:10.1038/s41598-018-23377-4,

Abstract: "The notion that small changes can have large consequences in the climate or ecosystems has become popular as the concept of tipping points. Typically, tipping points are thought to arise from a loss of stability of an equilibrium when external conditions are slowly varied. However, this appealingly simple view puts us on the wrong foot for understanding a range of abrupt transitions in the climate or ecosystems because complex environmental systems are never in equilibrium. In particular, they are forced by diurnal variations, the seasons, Milankovitch cycles and internal climate oscillations. Here we show how abrupt and sometimes even irreversible change may be evoked by even small shifts in the amplitude or time scale of such environmental oscillations. By using model simulations and reconciling evidence from previous studies we illustrate how these phenomena can be relevant for ecosystems and elements of the climate system including terrestrial ecosystems, Arctic sea ice and monsoons. Although the systems we address are very different and span a broad range of time scales, the phenomena can be understood in a common framework that can help clarify and unify the interpretation of abrupt shifts in the Earth system."

Extract: "One particular challenge in this regard is to investigate the applicability of statistical stability indicators that could provide an early warning of abrupt change. In climate research, this concept has mostly been explored in the static context of classical tipping points. In the case of the systems above, classical indicators like rising variance and autocorrelation are not necessarily the most useful approach. It is therefore important to explore alternative approaches to early warnings of abrupt change. Although conceptual models cannot replace studies based on observations and process-based modelling, they can help raise questions for future research. For example, it may be beneficial to compare abrupt monsoon changes on different time scales and in different regions: Are there common mechanisms behind the abrupt onsets in different monsoon systems on the planet? Are these mechanisms also responsible for abrupt monsoon shifts in palaeorecords? Is the expectation to see early warning signals before the occurrence of a certain shift supported by current process understanding? Will stronger El Niño events have irreversible consequences for tropical forest and savannah ecosystems? Was sea ice involved in a tipping point in the Earth’s history, and what was the role of periodic forcings? To explore such questions, it would be beneficial to further develop models of low to intermediate complexity in addition to existing Earth system models. Such a model hierarchy is most established in the case of sea ice models, but patchy in the case of ecosystems, and lacking in the case of monsoons. A suite of models that are easy to use would also better connect research attempts to understand different monsoon systems.

On top of that, studies on isolated tipping elements may even not be sufficient, as different Earth system components are linked in their stability behaviour and thus do not act in isolation. For example, sea-ice loss and the meridional ocean circulation affect each other, and transitions between vegetation states depend on the global background climate involving the ice sheets and the Atlantic overturning circulation. In light of the large uncertainties, the candidates and suspected mechanisms of tipping points will certainly evolve with new knowledge. As the Earth system is interspersed with feedbacks and natural thresholds, and features oscillations and environmental fluctuations on a vast range of time scales, it seems plausible that non-equilibrium tipping points have already occurred in the past and could occur again in the future."

Title: "Climate Lag"

Extract: "Climate lag is defined as a delay that can occur in a change of some aspect of climate due to the influence of a factor (s) that is slow-acting. An example of climate lag is the full effect of the release of a particular amount of carbon dioxide into the atmosphere. Following its release, some of the gas is absorbed by ocean water to be released into the atmosphere later on as part of the global carbon cycle. Thus, the full effect of carbon dioxide on the warming of the atmosphere will not be apparent until the ocean-bound gas has been released.

Climate lag is an important concept in climate modeling, and in forming policies to deal with climate change. The climate change that is apparent at a certain point in time may not be an accurate indication of the eventual change. Basing an emissions reduction strategy on current data may not completely address the problem."

Edit: I note the bias of the authors in describing the response time of the ice sheets as being on the order of 1,000 to 10,000 years; as they are clearly not considering the risks of ice-cliff failures and hydrofracturing in Antarctica in the coming decades.

The linked reference helps to explain why estimates of climate sensitivity based on observations and traditional global energy budget models, are likely biased towards low estimates.  Hopefully, AR6 will stop comparing apples (inferred climate sensitivity) to oranges (true climate sensitivity) when estimating the likely range for ECS.  If they do, it will almost certainly result in a higher range for the likely value of ECS, than as reported in AR5:

Dong Y, C Proistosescu, KC Armour and DS Battisti (December 2018), "Attributing historical and future evolution of radiative feedbacks to regional warming patterns using a Green’s function approach: The preeminence of the western Pacific", Submitted to the Journal of Climate, Preprint DOI: 10.31223/

Abstract: "Global radiative feedbacks have been found to vary in global climate model (GCM) simulations. Atmospheric GCMs (AGCMs) driven with historical patterns of sea-surface temperatures (SST) and sea-ice concentrations produce radiative feedbacks that trend toward more negative values, implying low climate sensitivity, over recent decades. Freely-evolving coupled GCMs driven by increasing CO2 produce radiative feedbacks that trend toward more positive values, implying increasing climate sensitivity, in the future. While this time-variation in feedbacks has been linked to evolving SST patterns, the role of particular regions has not been quantified. Here, a Green’s function is derived from a suite of simulations within an AGCM (NCAR’s CAM4), allowing an attribution of global feedback changes to surface warming in each region. The results highlight the radiative response to surface warming in ascent regions of the western tropical Pacific as the dominant control on global radiative feedback changes. Historical warming from the 1950s to 2000s preferentially occurred in the western Pacific, yielding a strong global outgoing radiative response at the TOA and producing a strongly negative global feedback. Long-term warming in coupled GCMs occurs preferentially in tropical descent regions and in high latitudes, where surface warming yields small global TOA radiation changes, and thus a less-negative global feedback. These results illuminate the importance of determining mechanisms of warm pool warming for understanding how feedbacks have varied historically and will evolve in the future."

The first image shows atmospheric methane concentrations since 2005 from NOAA's South Pole Station measurements; and it appears clear to me that this plot shows an accelerating trendline.  Also, the second image shows that Antarctic atmospheric methane concentrations are currently well more than twice that of any value in the past 800,000 years.
    (Reply #381)

Please notice that the 2 graphs have concentrations of methane in different units (& from different sources):-
Ist is in nmol mol-1  from surface flasks
2nd is ppb  from air bubbles in ice

Parts per billion, ppb, for gases is generally stated on a molar ratio basis, 2800 ppb is 2800 nmol/mol. The conversion to milligrams per cubic meter requires a standard temperature and pressure. OSHA and EPA use 101.325 kPa, but 75 °F (23.89 °C).

If the WAIS does begin to collapse by 2040, this might induce some countries to implement geoengineering.  However, the linked article indicates that such a unilateral implementation of geoengineering might well lead to war; which, might serve as another positive feedback for more climate change:

Title: "Could geoengineering cause a climate war?"

Extract: "There are fears that one country’s efforts to solve its climate problem could inadvertently mess up the weather elsewhere, creating a new source of political tension. And ultimately, this leads to a worrying question: could we be looking at the dawn of a new kind of war – one fueled by a battle for dominance over our planet’s climate system?"

A lot of climate change contrarians made a big deal that CMIP5 modeling of land-climate feedbacks from nutrient uptake do not consider nutrient competition with microbes and abiotic processes during inactive periods; which reduces the amount of associated N2O emissions (see the first linked reference).  However, such contrarians failed to note that limitations on nitrogen and phosphorus availability will likely severely limit carbon sequestration from plant growth with continued global warming (see the second two references and associated images):

Riley, W. J., Zhu, Q., & Tang, J. Y. (2018). Weaker land–climate feedbacks from nutrient uptake during photosynthesis-inactive periods. Nature Climate Change. doi:10.1038/s41558-018-0325-4,

Abstract: "Terrestrial carbon–climate feedbacks depend on two large and opposing fluxes—soil organic matter decomposition and photosynthesis—that are tightly regulated by nutrients. Earth system models (ESMs) participating in the Coupled Model Intercomparison Project Phase 5 represented nutrient dynamics poorly, rendering predictions of twenty-first century carbon–climate feedbacks highly uncertain. Here, we use a new land model to quantify the effects of observed plant nutrient uptake mechanisms missing in most other ESMs. In particular, we estimate the global role of root nutrient competition with microbes and abiotic processes during periods without photosynthesis. Nitrogen and phosphorus uptake during these periods account for 45 and 43%, respectively, of annual uptake, with large latitudinal variation. Globally, nighttime nutrient uptake dominates this signal. Simulations show that ignoring this plant uptake, as is done when applying an instantaneous relative demand approach, leads to large positive biases in annual nitrogen leaching (96%) and N2O emissions (44%). This N2O emission bias has a GWP equivalent of ~2.4 PgCO2 yr−1, which is substantial compared to the current terrestrial CO2 sink. Such large biases will lead to predictions of overly open terrestrial nutrient cycles and lower carbon sequestration capacity. Both factors imply over-prediction of positive terrestrial feedbacks with climate in current ESMs."

Fu et al (2016), "Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models", Biogeosciences, 13, 5151–5170, doi:10.5194/bg-13-5151-2016

Abstract: " Abstract. We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth system models (ESMs) performed in the framework of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Global NPP and EP are reduced by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, NPP in the 2090s is reduced by 2–16% and EP by 7–18 %. The models with the largest increases in stratification (and largest relative declines in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting overestimation of climate change impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface–ocean warming and freshening, which is accompanied by decreases in surface nutrients, NPP and EP."

Title: "Weaker land–climate feedbacks from nutrient uptake during photosynthesis inactive periods"

Primary production

Extract: " In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide.

Net primary production is the rate at which all the plants in an ecosystem produce net useful chemical energy; it is equal to the difference between the rate at which the plants in an ecosystem produce useful chemical energy (GPP) and the rate at which they use some of that energy during respiration. Some net primary production goes toward growth and reproduction of primary producers, while some is consumed by herbivores."

The total radiative forcings, RFs, from the linked ORNL website article by Blasing, T.J. (that updates such RF values reported in April 2016, see the first attached image/table) are used in the linked Wikipedia article to calculate a CO2e value of 526.6ppm; which assuming the current rate of annual increase in CO2e of about 3.5ppm indicates that late in 2018 CO2e exceeded 534ppm:

Extract: "To calculate the CO2e of the additional radiative forcing calculated from April 2016's updated data: ∑ RF(GHGs) = 3.3793, thus CO2e = 280 e3.3793/5.35 ppmv = 526.6 ppmv."

This relatively high value of 534ppm for CO2e appears to be associated with RF associated with tropospheric ozone and its chemical interaction in the atmosphere with GHGs like methane, as discussed in the following linked references.

Stevenson et al (2013), "Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP),"Atmos. Chem. Phys., 13, 3063–3085, doi:10.5194/acp-13-3063-2013

Abstract. Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410mWm−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17 %. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields) of ±10 %. Applying two different tropopause definitions gives differences in RFs of ±3 %. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12 %), nitrogen oxides (31±9 %), carbon monoxide (15±3 %) and non-methane volatile organic compounds (9±2 %); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42mWm−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mWm−2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport. Climate change has relatively small impacts on global mean tropospheric ozone RF."

See also:

Extract: "Tropospheric O3 is also the source of the hydroxyl radical (OH), which controls the abundance and distribution of many atmospheric constituents (including greenhouse gases such as methane and hydrochlorofluorocarbons). Ozone makes a significant contribution to the radiative balance of the upper troposphere and lower stratosphere, such that changes in the distribution of O3 in these atmospheric regions affect the radiative forcing of climate.

Climate Feedback and Forcing for Tropospheric Ozone

Climate forcing by O3 remains uncertain because O3 change as a function of altitude has been under-measured. In order to better understand the role of tropospheric O3 in climate, accurate temperature measurements are needed along with co-located O3 and CO profiles."

To point out the obvious, the ACCMIP reference shows significant increases in ozone RF by 2030 following a BAU pathway, i.e. "… we calculate future tropospheric ozone RFs (mWm−2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030) …".

Finally, by comparing the major well mixed GHG concentrations from 1979 thru 2017 shown in the second attached image; with the major well mixed GHG concentrations over the past 800,000 years (in Antarctica) shown in the third image; one can readily see that not only CO₂ but also CH4 and N2O are driving us rapidly towards Mid-Pliocene conditions.

The politics / Re: The Trump Presidency (was "Presidential Poll")
« on: September 01, 2018, 07:50:28 AM »
Trade wars, and how they are a tax on consumers, and thus how Trump just gave us a all a nice kick in the balls. Also, where Trump has this idea from. You would be surprised.

Explained clearly by the always amazing John Oliver :

The rest / Re: Mueller Investigation & Cohen Investigation
« on: September 01, 2018, 12:21:26 AM »
But as his tweets get ever more deranged, he is convincing fewer and fewer people, even among the basest of his base:

Only 18% think he should pardon Manifort. That means half of the most basic core of his base doesn't buy it when tRump says that Manifort is a great guy and that his loss in court is a sad thing.

This is how it starts. If they finally find one thing that they don't agree with their fearless leader on, inevitably others will follow...

The rest / Re: Mueller Investigation & Cohen Investigation
« on: August 31, 2018, 11:45:16 PM »
Based on Trump's latest tweets, essentially everyone from the FBI, to the U.S. intelligence community, to the MSM, were all conspiring against Trump even before the 2016 election.  Such insinuations beggar belief.

The rest / Re: Mueller Investigation & Cohen Investigation
« on: August 31, 2018, 11:34:51 PM »
For those who are interested:

Title: "Proof of Collusion: How Trump Betrayed America by Seth Abramson"

Extract: "For the first time, the full, explosive record of the unthinkable: how a U.S. president compromised American foreign policy in exchange for the promise of future business and covert election assistance.

Looking back at this moment in history, historians will ask if Americans knew they were living through the first case of criminal conspiracy between an American presidential candidate turned commander in chief and a geopolitical enemy. The answer might be: it was hard to see the whole picture. The stories coming in from around the globe have often seemed fantastical: clandestine meetings in foreign capitals, secret recordings in a Moscow hotel, Kremlin agents infiltrating the Trump inner circle …

Seth Abramson has tracked every one of these far-flung reports and now in, Proof of Collusion, he finally gives us a record of the unthinkable—a president compromising American foreign policy in exchange for the promise of future business and covert election assistance. The attorney, professor, and former criminal investigator has used his exacting legal mind and forensic acumen to compile, organize, and analyze every piece of the Trump-Russia story. His conclusion is clear: the case for collusion is staring us in the face. Drawing from American and European news outlets, he takes readers through the Trump-Russia scandal chronologically, putting the developments in context and showing how they connect. His extraordinary march through all the public evidence includes:

•   How Trump worked for thirty years to expand his real estate empire into Russia even as he was rescued from bankruptcy by Putin’s oligarchs and Kremlin agents
•   How Russian intelligence gathered compromising material on him over multiple trips
•   How Trump recruited Russian allies and business partners while running for president
•   How he surrounded himself with advisers who engaged in clandestine negotiations with Russia
•   How Trump aides and family members held secret meetings with foreign agents and lied about them

By pulling every last thread of this complicated story together, Abramson argues that—even in the absence of a Congressional investigation or a report from Special Counsel Mueller—the public record already indicates a quid pro quo between Trump and the Kremlin. The most extraordinary part of the case for collusion is that so much of it unfolded in plain sight."

The rest / Re: Mueller Investigation & Cohen Investigation
« on: August 31, 2018, 05:28:56 PM »
The tangled web of deceit and corruption is slowly coming into focus:

Title: "Manafort associate Sam Patten charged in Mueller probe"

Extract: "Sam Patten, a former associate of ex-Trump campaign chairman Paul Manafort, was charged on Friday for failing to register as a foreign agent for his involvement with a Ukrainian political party, Bloomberg reports.

Why it matters: This is yet another person taken down by the far-reaching Mueller investigation. And, as Axios' Mike Allen reported, there is still a lot of evidence the special counsel has — or could have — that we have yet to seen."

Edit, Sam Patten has now flipped:

Title: "Robert Mueller got another cooperator"

Extract: "Sam Patten, an associate of Paul Manafort and Cambridge Analytica, struck a plea deal."

The rest / Re: Mueller Investigation & Cohen Investigation
« on: August 25, 2018, 06:30:43 PM »
Team Trump may collectively be too blind to understand that their arguments would never stand-up in a court of law:

Title: "It Depends on What the Meaning of the Word Obstruction Is"

Extract: "Why Trump doesn’t realize White House Counsel Don McGahn may have already given Robert Mueller everything he needs."

The rest / Re: Mueller Investigation & Cohen Investigation
« on: August 24, 2018, 07:14:07 PM »
Trump continues his efforts to politicize the DOJ, for his own personal benefit:

Title: "Trump Tells Jeff Sessions: Go After My Enemies"

Extract: "The attorney general disagreed with Trump's initial claim that he "never took control" of the DOJ"

The rest / Re: Mueller Investigation & Cohen Investigation
« on: August 24, 2018, 06:36:15 PM »
You can bet that this action is just the tip of the iceberg and that the U.S. District Court for the Southern District of New York (SDNY) investigators will continue prying deeper into the president’s business affairs and associates.  Plus, Trump cannot stop this investigation by just firing Rosenberg and then Mueller:

Title: "Trump Organization CFO Allen Weisselberg gets immunity"

Extract: "Allen Weisselberg, longtime chief financial officer for the Trump organization, has been granted immunity by federal prosecutors for providing information about Michael Cohen and the 2016 payments he made to two women during the 2016 presidential campaign who alleged they had sexual encounters with the president, the Wall Street Journal reports.

A top Washington white collar attorney told Axios that this “could be really big deal but unclear if it’s limited to past Cohen stuff which culminated in his plea or if it’s ongoing. But clearly prosecutors thought he had something of value in return for giving immunity. There had to be some 'showing' by his counsel to get the immunity.”"

The rest / Re: Mueller Investigation & Cohen Investigation
« on: August 24, 2018, 06:27:37 PM »
Dangling the prospect of a pardon in front of Manfort due to 'unfair' government treatment, is obstruction of justice:

Title: "Paul Manafort and Trump’s Pardon Pattern"

Extract: "As he has with Manafort, President Trump has decried the government’s “unfair” treatment of all three men he has pardoned to date. But will the pattern hold with his former campaign manager?"

Edit, see also:

Title: "Giuliani’s comments add confusion about possible Manafort pardon"

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