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Author Topic: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS  (Read 202427 times)

AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #100 on: January 22, 2014, 11:58:57 PM »
The following reference (with a linked free access pdf), implies that the most likely value for climate sensitivity is greater than 4 degrees C:

Tett, Simon F. B., Daniel J. Rowlands, Michael J. Mineter, Coralia Cartis, 2013: Can Top-of-Atmosphere Radiation Measurements Constrain Climate Predictions? Part II: Climate Sensitivity. J. Climate, 26, 9367–9383; doi: http://dx.doi.org/10.1175/JCLI-D-12-00596.1

http://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-12-00596.1

Abstract: "A large number of perturbed-physics simulations of version 3 of the Hadley Centre Atmosphere Model (HadAM3) were compared with the Clouds and the Earth's Radiant Energy System (CERES) estimates of outgoing longwave radiation (OLR) and reflected shortwave radiation (RSR) as well as OLR and RSR from the earlier Earth Radiation Budget Experiment (ERBE) estimates. The model configurations were produced from several independent optimization experiments in which four parameters were adjusted. Model–observation uncertainty was estimated by combining uncertainty arising from satellite measurements, observational radiation imbalance, total solar irradiance, radiative forcing, natural aerosol, internal climate variability, and sea surface temperature and that arising from parameters that were not varied. Using an emulator built from 14 001 “slab” model evaluations carried out using the climateprediction.net ensemble, the climate sensitivity for each configuration was estimated. Combining different prior probabilities for model configurations with the likelihood for each configuration and taking account of uncertainty in the emulated climate sensitivity gives, for the HadAM3 model, a 2.5%–97.5% range for climate sensitivity of 2.7–4.2 K if the CERES observations are correct. If the ERBE observations are correct, then they suggest a larger range, for HadAM3, of 2.8–5.6 K. Amplifying the CERES observational covariance estimate by a factor of 20 brings CERES and ERBE estimates into agreement. In this case the climate sensitivity range is 2.7–5.4 K. The results rule out, at the 2.5% level for HadAM3 and several different prior assumptions, climate sensitivities greater than 5.6 K."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #101 on: January 23, 2014, 12:39:06 AM »
The following linked free access paper by Hansen, Sato and Ruedy Jan. 21, 2014, states that an El Nino event is likely in either 2014 or 2015; which would likely result in the warmest year on record (note that NOAA has 2013 as the fourth warmest year on record):

 James Hansen, Makiko Sato and Reto Ruedy; "Global Temperature Update Through 2013"; 21 January 2014

http://www.columbia.edu/~jeh1/mailings/2014/20140121_Temperature2013.pdf

 "Summary. Global surface temperature in 2013 was +0.6°C (~1.1°F) warmer than the 1951-1980 base period average, thus the seventh warmest year in the GISS analysis. The rate of global warming is slower in the past decade than in the prior three decades. Slower growth of net climate forcings and cooling in the tropical Pacific Ocean both contribute to the slower warming rate, with the latter probably the more important effect. The tropical Pacific cooling is probably unforced variability, at least in large part. The trend toward an increased frequency of extreme hot summer anomalies over land areas has continued despite the Pacific Ocean cooling. The “bell curves” for observed temperature anomalies show that, because of larger unforced variability in winter, it is more difficult in winter than in summer to recognize the effect of global warming on the occurrence of extreme warm or cold seasons. It appears that there is substantial likelihood of an El Niño beginning in 2014, and as a result a probable record global temperature in 2014 or 2015."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #102 on: January 24, 2014, 05:26:39 PM »
Not that this is breaking news, but according to the following link the IPCC will shortly admit that mean global temperature increase will likely significantly exceed 2 degrees C this century; however, with the passage of time, I believe that they will progressively admit temperature increases of 3, then 4, then 5 (or more) degrees C, this century:

http://theweek.com/article/index/255504/why-climate-change-is-inevitable
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #103 on: January 27, 2014, 12:30:52 AM »
The following two references indicate that with increasing global temperature the world's rainforest will fail to absorb carbon dioxide about twice as fast as previously modeled (possibly because the earlier models did not fully account for the disruptive nature droughts on rainforests).  Clearly, this will result in a positive feedback mechanism resulting in a higher equilibrium climate sensitivity value than previously modeled, indicating that mean global temperatures will increase faster and that consequently sea level rise will occur faster than previously modeled by sea level rise experts:

University of Exeter. "Sensitivity of carbon cycle to tropical temperature variations has doubled." ScienceDaily. ScienceDaily, 26 January 2014. www.sciencedaily.com/releases/2014/01/140126134647.htm

Xuhui Wang, Shilong Piao, Philippe Ciais, Pierre Friedlingstein, Ranga B. Myneni, Peter Cox, Martin Heimann, John Miller, Shushi Peng, Tao Wang, Hui Yang, Anping Chen. A two-fold increase of carbon cycle sensitivity to tropical temperature variations. Nature, 2014; DOI: 10.1038/nature12915

See also the discussion at:  http://www.independent.co.uk/news/science/climate-change-rainforest-absorption-of-co2-becoming-erratic-9086304.html

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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #104 on: January 27, 2014, 10:09:31 AM »
While some researchers have thought that aerosols (air pollution) reduce global warming, the following more recent research indicates that the actual case is much more complex than that:

Climate Effects of Aerosol-Cloud Interactions by Daniel Rosenfeld, Steven Sherwood, Robert Wood and Leo Donner published in Science 24 January 2014: Vol. 343 no. 6169 pp. 379-380. DOI: 10.1126/science.1247490.

Abstract: "Aerosols counteract part of the warming effects of greenhouse gases, mostly by increasing the amount of sunlight reflected back to space. However, the ways in which aerosols affect climate through their interaction with clouds are complex and incompletely captured by climate models. As a result, the radiative forcing (that is, the perturbation to Earth's energy budget) caused by human activities is highly uncertain, making it difficult to predict the extent of global warming (1, 2). Recent advances have led to a more detailed understanding of aerosol-cloud interactions and their effects on climate, but further progress is hampered by limited observational capabilities and coarse-resolution climate models."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #105 on: January 27, 2014, 07:51:53 PM »
Skeptical Science has an interesting article at the following link about methane leaks from US oil & gas field; implying that within the USA that natural gas still has a smaller carbon footprint than does coal; however, I am concerned that the rest of the world will likely not control/monitor such leaks as well globally, and also as the atmospheric concentration of methane increases, so will the Global Warming Potential, GWP, not only for newly leaked methane, but for all of the methane in the atmosphere at any given future time:

http://www.skepticalscience.com/frackingrevisited.html
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #106 on: January 29, 2014, 01:51:05 AM »
The following reference indicates that black carbon emissions in portions of China and India are two to three times more concentrated than previously expected (which implies that the RCP scenarios are two low wrt black carbon emissions):

Rong Wang, Shu Tao, Yves Balkanski, Philippe Ciais, Olivier Boucher, Junfeng Liu, Shilong Piao, Huizhong Shen, Maria Raffaella Vuolo, Myrto Valari, Han Chen, Yuanchen Chen, Anne Cozic, Ye Huang, Bengang Li, Wei Li, Guofeng Shen, Bin Wang, and Yanyan Zhang, (2014), "Exposure to ambient black carbon derived from a unique inventory and high-resolution model", PNAS, doi: 10.1073/pnas.1318763111.
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #107 on: January 29, 2014, 04:32:17 PM »
The linked information from the Australian Bureau of Meteorology (BoM) confirms what has already been stated here, that El Nino conditions could begin as early as this later this summer (austral winter) 2014:

http://www.bom.gov.au/climate/enso/
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wili

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #108 on: January 29, 2014, 07:11:38 PM »
Thanks for all these posts and links, ASLR. I hope you don't mind if I steal them and sprinkle them around on other threads and forums.

Meanwhile, did you see this latest from SkS?:

http://www.skepticalscience.com/warming-oceans-rising-sea-level-energy-imbalance-consistent.html

Warming oceans consistent with rising sea level & global energy imbalance

Quote
Key Points:

   >> The ocean is quickly accumulating heat and is doing so at an increased rate at depth during the so-called “hiatus” – a period over the last 16 years during which average global surface temperatures have risen at a slower rate than previous years.

   >> This continued accumulation of heat is apparent in ocean temperature observations, as well as reanalysis and modeling experiments, and is now supported by up-to-date assessments of Earth's energy imbalance.

   >> Another key piece of evidence is rising global sea level. The expansion of the oceans (as they warm) has contributed to 35–40% of sea level rise over the last two decades - providing independent corroboration of the increase in ocean temperatures.

« Last Edit: January 29, 2014, 09:10:30 PM by wili »
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #109 on: January 29, 2014, 09:48:51 PM »
wili,

Feel free to re-post any information from my posts, wherever, and in whatever form, you like.

Regarding the SkS article on ocean heat content; it is certainly frightening to think that all of the heat increase in the ocean has occurred in the Southern Hemisphere, and that for decades after the end of the current El Nino hiatus period, this ocean heat content will continue to migrate toward the Southern Ocean where it will be available to drive ice mass loss from the southern continent.

Best,
ASLR
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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wili

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #110 on: January 30, 2014, 06:26:32 AM »
Thanks, and much appreciation and respect for all you do here!
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #111 on: January 31, 2014, 01:48:00 AM »
The attached image shows that while the coal consumption in the USA is down and falling, the global consumption of coal is up, and growing:
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #112 on: January 31, 2014, 01:52:51 AM »
According to the linked article, drug traffic operations are damaging rainforests; which, will mean less CO2 absorption and faster global warming than previously estimated:

http://www.google.com/hostednews/afp/article/ALeqM5hOQocMllqGygBxQx_IOELiJ_sjEA?docId=934ee32f-5fc0-4e68-843e-6ddd799b98e9&hl=en
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #113 on: January 31, 2014, 08:26:36 PM »
The linked reference indicates that many scientists are still not certain as to why atmospheric methane concentrations are rising again, and the article discusses various possible sources including coal mining and biological sources (in any event in my opinion uncertainty is not an excuse for inaction):

Euan G. Nisbet, Edward J. Dlugokencky, Philippe Bousquet, "ATMOSPHERIC SCIENCE: Methane on the Rise—Again", Science 31 January 2014: Vol. 343 no. 6170 pp. 493-495, DOI: 10.1126/science.1247828.

http://www.sciencemag.org/content/343/6170/493.short
http://www.climatecentral.org/news/sources-of-methane-emissions-still-uncertain-study-17010
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #114 on: January 31, 2014, 11:40:17 PM »
As a follow-up to my last post in this thread, the linked article indicates that funding for monitoring greenhouse gas emissions is being reduced.  This budget reduction poses a particular problem for determining the current sources of methane emissions in to the atmosphere (which is presently not understood adequately):

http://www.livescience.com/42986-methane-greenhouse-gas-monitoring-threatened.html
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #115 on: February 01, 2014, 12:31:07 AM »
The linked free access article indicates that the projected declines in anthropogenic aerosols, will impact the Southern Hemisphere like an increase in GHGs:

Leon D Rotstayn, (2013) "Projected effects of declining anthropogenic aerosols on the southern annular mode", Environ. Res. Lett. 8 044028; doi:10.1088/1748-9326/8/4/044028

http://iopscience.iop.org/1748-9326/8/4/044028/article

Abstract: "Declining emissions of anthropogenic aerosols have been shown to contribute to global warming in climate projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5). This study considers the response of the southern annular mode (SAM) in austral summer to declining aerosols in simulations forced by Representative Concentration Pathway 4.5 (RCP4.5) using CSIRO-Mk3.6, a CMIP5-generation model. A ten-member ensemble forced by RCP4.5 for the period 2006–2100 is compared with another experiment, which is identical except that emissions of anthropogenic aerosols are held fixed at their 2005 values.
With fixed aerosol emissions, the model simulates a negative (but statistically insignificant) ensemble-mean SAM trend in austral summer, suggesting that the effects of recovering stratospheric ozone slightly outweigh the effects of increasing long-lived greenhouse gases (GHGs). In contrast, the standard RCP4.5 experiment (including additional warming due to declining aerosols) simulates a positive ensemble-mean SAM trend, and the difference between the two trends is significant at 5%. The response of Southern Hemisphere zonal-mean atmospheric circulation and temperature to declining aerosols resembles the response to increasing GHGs; this suggests that the positive SAM trend due to declining aerosols may be driven by mechanisms that are similar to those that cause the positive SAM trend in response to increasing GHGs."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #116 on: February 03, 2014, 04:17:02 AM »
The linked article indicates that temperature feedbacks are the dominate source of Arctic amplification, and that albedo effects are secondary, thus warming continues even without SIE being a minimum:

Felix Pithan & Thorsten Mauritsen , (2014), "Arctic amplification dominated by temperature feedbacks in contemporary climate models", Nature Geoscience, doi:10.1038/ngeo2071

http://www.nature.com/ngeo/journal/vaop/ncurrent/pdf/ngeo2071.pdf

Abstract: "Climate change is amplified in the Arctic region. Arctic amplification has been found in past warm and glacial periods, as well as in historical observations and climate model experiments. Feedback effects associated with temperature, water vapor and clouds have been suggested to contribute to amplified warming in the Arctic, but the surface albedo feedback—the increase in surface absorption of solar radiation when snow and ice retreat—is often cited as the main contributor. However, Arctic amplification is also found in models without changes in snow and ice cover. Here we analyze climate model simulations from the Coupled Model Intercomparison Project Phase 5 archive to quantify the contributions of the various feedbacks. We find that in the simulations, the largest contribution to Arctic amplification comes from a temperature feedbacks: as the surface warms, more energy is radiated back to space in low latitudes, compared with the Arctic. This effect can be attributed to both the different vertical structure of the warming in high and low latitudes, and a smaller increase in emitted blackbody radiation per unit warming at colder temperatures. We find that the surface albedo feedback is the second main contributor to Arctic amplification and that other contributions are substantially smaller or even oppose Arctic amplification."
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wili

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #117 on: February 03, 2014, 05:00:36 AM »
"as the surface warms, more energy is radiated back to space in low latitudes, compared with the Arctic. This effect can be attributed to both the different vertical structure of the warming in high and low latitudes, and a smaller increase in emitted blackbody radiation per unit warming at colder temperatures."

This is very interesting to me (and I would hope to others--I may steal from you here again!).

Is the "vertical structure" bit talking about lapse rate? I hadn't thought about the significance of the temperature difference in this context before. But when you consider that every degree of difference creates a difference in radiation to the fourth power...it is obvious that this could be quite significant.

Thanks, once again.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

sidd

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #118 on: February 03, 2014, 05:15:40 AM »
unfortunately the models underestimate. given the Box results on greenland albedo, i do not trust the models, especially in polar regions

on another note, and sorry to interrupt this thread:

Mr. AbruptSLR, which was the thread where you commented on shorting opportunities ? I have a titbit or two to add along those lines

sidd

AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #119 on: February 03, 2014, 12:36:14 PM »
sidd,

I concur that the current GCMs underestimate the importance of Arctic/Greenland albedo; but at the moment it seems likely that atmospheric effects dominate Arctic amplification.

Regarding my comments on shorting opportunities, I believed that I commented on it in the Policy and Solutions folder several months ago, and as I cannot remember which particular thread in that folder that I made the comment in, you might want to post information at the following link:

http://forum.arctic-sea-ice.net/index.php/topic,741.0.html

I believe that my old comment was something to the affect that while Black Swan events (such as abrupt SLR) are unforeseeable; what is unforeseeable for the turkey is not unforeseeable for the butcher.  Furthermore, I believe that I commented that decision makers may believe that geoengineering will be demanded by the public if they allow extreme climate events to get worse, and that this would represent a shorting opportunity for those planning on implementing geoengineering (whether it solves the problem or not).
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #120 on: February 03, 2014, 04:01:15 PM »
sidd,

I made another post in the Policy and solutions folder about "shorting opportunities", if you care to add to that thread.

Also, I thought that I should mention that not only do I agree with you that current GCMs do not adequately account for future changes in Arctic albedo (include the growth of shrubs in the tundra); but that also currently do not adequately account for methane emission from present and future permafrost degradation, when they are estimating the magnitude of Artic (Polar) amplification.

Nevertheless, many people do not realize that in the past the Arctic atmosphere was very dry, and that with global warming, it is becoming more humid (and that water vapor is a GHG); and thus on a percentage basis a unit increase in humidity in the Arctic (Poles) is much more important (much great amplification) than a unit increase in humidity near the equator/tropics.

Best,
ASLR
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #121 on: February 03, 2014, 05:02:55 PM »
While the atmospheric conditions in the Arctic and the Antarctic are different, still the following article (see link below to a free access pdf) indicates how important it is to correctly model atmospheric moisture and associated cloud cover, when trying to project surface temperatures in the Antarctic (note that their improved model projects higher surface temperatures than previously projected).  As the Southern Ocean warms, and puts more moisture into the Southern Hemisphere atmosphere, not only will future precipitation (first snow and then rain) increase, but so will Polar Amplification:

J. M. van Wessem, C. H. Reijmer, J. T. M. Lenaerts, W. J. van de Berg, M. R. van den Broeke, and E. van Meijgaard, (2014), "Updated cloud physics in a regional atmospheric climate model improves the modelled surface energy balance of Antarctica", The Cryosphere, 8, 125–135, 2014, www.the-cryosphere.net/8/125/2014/, doi:10.5194/tc-8-125-2014

http://www.the-cryosphere.net/8/125/2014/tc-8-125-2014.pdf

"Abstract. In this study the effects of changes in the physics package of the regional atmospheric climate model RACMO2 on the modelled surface energy balance, near surface temperature and wind speed of Antarctica are presented.  The physics package update primarily consists of an improved turbulent and radiative flux scheme and a revised cloud scheme that includes a parameterisation for ice cloud super-saturation. The ice cloud super-saturation has led to more moisture being transported onto the continent, resulting in more and optically thicker clouds and more downward long-wave radiation. Overall, the updated model better represents the surface energy balance, based on a comparison with > 750 months of data from nine automatic weather stations located in East Antarctica. Especially the representation of the turbulent sensible heat flux and net long-wave radiative flux has improved with a decrease in biases of up to 40%. As a result, modelled surface temperatures have increased and the bias, when compared to 10m snow temperatures from 64 ice-core observations, has decreased from −2.3K to −1.3 K.  The weaker surface temperature inversion consequently improves the representation of the sensible heat flux, whereas wind speed biases remain unchanged. However, significant model biases remain, partly because RACMO2 at a resolution of 27 km is unable to resolve steep topography."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #122 on: February 06, 2014, 10:59:04 PM »
According to the following reference hiatus periods associated with a negative PDO period typically last for about 15 years.  Therefore, as the accompanying NOAA chart indicates that the current negative period for the PDO starting in about 1999, on average, we can expect the current hiatus period to end by the end of 2014, or the beginning of 2015; which is very much in line with current projections for an El Nino event to occur during the next austral summer:

Meehl, Gerald A., Aixue Hu, Julie M. Arblaster, John Fasullo, Kevin E. Trenberth, 2013: Externally Forced and Internally Generated Decadal Climate Variability Associated with the Interdecadal Pacific Oscillation. J. Climate, 26, 7298–7310. doi: http://dx.doi.org/10.1175/JCLI-D-12-00548.1
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #123 on: February 09, 2014, 03:41:32 AM »
The linked reference (with a free access pdf) indicates that the albedo of both melting snow and ice are affected times more adversely than non-melting snow and ice by black carbon.  Therefore, as the polar areas continue warm-up the positive feedback from black carbon will likely increase:

Marks, A. A. and King, M. D.: The effect of snow/sea ice type on the response of albedo and light penetration depth (e-folding depth) to increasing black carbon, The Cryosphere Discuss., 8, 1023-1056, doi:10.5194/tcd-8-1023-2014, 2014.

http://www.the-cryosphere-discuss.net/8/1023/2014/tcd-8-1023-2014.html

"Abstract. The optical properties of snow/sea ice vary with age and by the processes they were formed, giving characteristic types of snow and sea ice. The response of albedo and light penetration depth (e-folding depth) to increasing mass-ratio of black carbon is shown to depend on the snow and sea ice type and the thickness of the snow or sea ice. The response of albedo and e-folding depth of three different types of snow (cold polar snow, windpacked snow and melting snow) and three sea ice (multi-year ice, first-year ice and melting sea ice) to increasing black carbon is calculated using a coupled atmosphere–snow/sea ice radiative-transfer model (TUV-snow), over the optical wavelengths of 300–700 nm. The snow and sea ice types are defined by a scattering-cross section, density and asymmetry parameter. The relative change in albedo of a melting snowpack is a factor of four more responsive to additions of black carbon compared to cold polar snow over a black carbon increase from 1 to 50 ng g−1. While the relative change in albedo of a melting sea ice is a factor of two more responsive to additions of black carbon compared to multi-year ice for the same black carbon mass-ratio increase. The response of e-folding depth is effectively not dependent on snow/sea ice type. The albedo of sea ice is more responsive to increased mass-ratios of black carbon than snow."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #124 on: February 09, 2014, 08:07:27 PM »
The linked reference is important because it clarifies that changes wind-driven ocean circulation patterns are the main reason for the Pacific Ocean contribution to the ongoing warming hiatus period.  This work indicates that the current generation of GCMs only capture about half of the influence of this recent change in wind-driven ocean circulation.  Also, when combined with the influence of recent increases in aerosol air-pollution in Asia and Africa; this implies that the current generation of GCM projections are probably using climate sensitivities that are too low, even for RCP 8.5 (which we are currently exceeding).  This supports the position that I have taken that the current GCM projections of global warming are too low, which raises the probability of abrupt climate change (including the risk of ASLR this century):

Matthew H. England, Shayne McGregor, Paul Spence, Gerald A. Meehl, Axel Timmermann, Wenju Cai, Alex Sen Gupta, Michael J. McPhaden, Ariaan Purich & Agus Santoso, (2014)
"Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus", Nature Climate Change, doi:10.1038/nclimate2106, published online: 09 February 2014

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2106.html

Abstract: "Despite ongoing increases in atmospheric greenhouse gases, the Earth’s global average surface air temperature has remained more or less steady since 2001. A variety of mechanisms have been proposed to account for this slowdown in surface warming. A key component of the global hiatus that has been identified is cool eastern Pacific sea surface temperature, but it is unclear how the ocean has remained relatively cool there in spite of ongoing increases in radiative forcing. Here we show that a pronounced strengthening in Pacific trade winds over the past two decades—unprecedented in observations/reanalysis data and not captured by climate models—is sufficient to account for the cooling of the tropical Pacific and a substantial slowdown in surface-warming through increased subsurface ocean heat uptake. The extra uptake has come about through increased subduction in the Pacific shallow overturning cells, enhancing heat convergence in the equatorial thermocline. At the same time, the accelerated trade winds have increased equatorial upwelling in the central and eastern Pacific, lowering sea surface temperature there, which drives further cooling in other regions. The net effect of these anomalous winds is a cooling in the 2012 global average surface air temperature of 0.1–0.2 °C, which can account for much of the hiatus in surface warming observed since 2001. This hiatus could persist for much of the present decade if the trade wind trends continue, however rapid warming is expected to resume once the anomalous wind trends abate."

Further discussion can be found at:
http://www.newscientist.com/article/dn25015-climate-slowdown-just-wait-until-the-wind-changes.html#.UvfJBqPTnIU
Selected extracts from the New Scientist article:
"Powerful winds in the Pacific are largely responsible for the recent slowdown in global warming. The intense winds have encouraged heat to sink into the oceans. But as soon as the winds die down, the heat will escape again.
Over the past 20 years, the trade winds that gust westwards across the Pacific have soared to unprecedented strengths. The strongest winds are now twice as powerful." …
"So why are the winds so strong? One reason may be a repeating pattern in the weather called the Interdecadal Pacific Oscillation (IPO). In its current state, the IPO should produce stronger winds and cool surface waters, says England. "But the models capture less than half the magnitude at best," he says." …
"Earlier studies had suggested an alternative explanation for the slowdown: maybe Earth has been absorbing less heat, because the sun was slightly dimmer, or pollution was reflecting more heat out into space.
If these factors are also in play, that could ultimately be bad news. That's because the slowdown should actually have been bigger with so many cooling processes at work, says England.
"People keep talking about the hiatus but we should be talking about why the world hasn't cooled over the last decade," he says. "If you add all those factors up you would have expected to see somewhat of a cooling. Maybe our models should be predicting more sensitivity to greenhouse gas warming.""
Side Note according to Wikipedia: "The Pacific Decadal Oscillation (PDO) is the leading EOF of monthly sea surface temperature anomalies (SSTA) over the North Pacific (poleward of 20° N) after the global mean SSTA has been removed, the PDO index is the standardized principal component time series." While: "The interdecadal Pacific oscillation (IPO or ID) displays similar sea-surface temperature (SST) and sea-level pressure (SLP) patterns, with a cycle of 15–30 years, but affects both the north and south Pacific."  Using either EOF (empirical orthogonal function), we could leave the current pattern as soon as less than one to more than five years from now.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #125 on: February 09, 2014, 09:17:09 PM »
Not to beat a dead horse, but according to the attached image from NOAA (updated Feb 8, 2014) the chances are increasing for a mild El Nino by late summer of 2014, and possibly a Super El Nino by the austral summer of 2014-2015. 

When you look at the fractured nature of both the Pine Island Ice Shelf, and the Thwaites Eastern Ice Shelf, shown in the "PIG has calved" thread (here: http://forum.arctic-sea-ice.net/index.php/topic,429.0.html); one has to wonder how much calving will occur in just these two ice shelves if a Super El Nino (like in 1998) were to move the Amundsen Bellingshausen Sea Low, ABSL, so as to drive more warm CDW into the ASE.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #126 on: February 10, 2014, 05:11:28 AM »
"possibly a Super El Nino by the austral summer of 2014-2015"

Could you link to exactly where it says or implies that so I can use it on another blog?
Are you just extending where you think the graph is going in this case?
« Last Edit: February 10, 2014, 09:19:08 AM by wili »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #127 on: February 10, 2014, 11:19:55 AM »
wili,

Peer reviewable forecasts of ENSO currently do not extend beyond 9 months, as discussed in the free pdf at the following link:

http://news.imau.nl/wp-content/uploads/2013/09/naw5-2013-14-3-195.pdf

Therefore, officially I am merely extending where I think that the graph will go.  Also, for updated graphs see the following links:

http://www.cpc.ncep.noaa.gov/products/CFSv2/CFSv2seasonal.shtml
http://www.cpc.ncep.noaa.gov/products/CFSv2/imagesInd3/nino34Sea.gif

That said, Will P.M. de Ruijter of the Institute for Marine and Atmospheric Research Utrecht (and the co-author of the first linked pdf on ENSO prediction periods) at the following link:

http://news.imau.nl/?p=1056

Makes the following quote:
"Based on anomalously low sea surface temperatures in the southwestern Indian Ocean north of Madagascar (see http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.shtml), I predict the evolution of a big El Niño in the Pacific that will peak around January 2015. We have an ongoing fight to get our analysis published."

Thus if Will P.M. de Ruijter unpublished research is correct then we may have a Super El Nino in the austral summer of 2014-2015.

Best,
ASLR
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #128 on: February 10, 2014, 02:32:09 PM »
wili,

For what it is worth, the attached PDO Feb 8 2014 forecast from NOAA is trending up, and could become positive by January 2015:

Note: I figured-out how to make larger images, so see the third image for a better view.
« Last Edit: February 10, 2014, 05:45:35 PM by AbruptSLR »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #129 on: February 10, 2014, 04:27:08 PM »
wili,

As I do not have much time, but I was unhappy with the size of the images in my last post, I provide the attached abbreviated pdf of a PowerPoint from the Climate Prediction Center, NCEP/NOAA, for Feb 7, 2014.  In the second slide note the statement: "PDO has been in prevalent negative phase since 1999." And as the negative phase of a PDO cycle normally lasts 15-years, this would imply that on average the PDO may become positive by the austral summer of 2014-2015.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #130 on: February 10, 2014, 05:31:21 PM »
The attached two images come from the linked article from The Guardian.  These figures offer insight as to when the current warming hiatus (and associated El Nino hiatus) may end:

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/feb/10/unprecedented-trade-winds-global-warming-oceans

First image caption: "Top frame: Global surface temperature anomalies. Bottom frame: Pacific wind stress anomalies. From England et al. (2014)."

Second image caption: "Annual (grey bars) and a five-year running mean (black solid line) global surface temperature measurements. Climate model projections are shown in red. The blue and green show results from an ocean and a coupled climate model adjusted by the trade-wind-induced surface cooling. From England et al. (2014)."

The following related linked article also offers good insight:
http://www.theguardian.com/environment/2014/feb/09/global-warming-pause-trade-winds-pacific-ocean-study
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #131 on: February 10, 2014, 05:57:59 PM »
Thanks for the links, graphs, and insights, ASLR. Very helpful, as usual.

From the Guardian article: "...it was unclear what has caused the increase in Pacific trade winds, although warming in the Indian Ocean has been cited as a potential trigger."

So is it possible that this is a kind of (temporary) negative feedback: the more that GW heats the Indian Ocean, the faster the trade winds are driven, and the more GW heat is pumped down into the oceans?

If so, what might interrupt that dynamic?
« Last Edit: February 10, 2014, 06:10:32 PM by wili »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #132 on: February 10, 2014, 10:52:38 PM »
wili,

One more figure from the English et al 2014 paper, is attached with the following caption:

"This is a schematic of the trends in temperature and ocean-atmosphere circulation in the Pacific over the past two decades. Color shading shows observed temperature trends (C per decade) during 1992-2011 at the sea surface (Northern Hemisphere only), zonally averaged in the latitude-depth sense (as per Supplementary Fig. 6) and along the equatorial Pacific in the longitude-depth plane (averaged between 5N S). Peak warming in the western Pacific thermocline is 2.0C per decade in the reanalysis data and 2.2C per decade in the model. The mean and anomalous circulation in the Pacific Ocean is shown by bold and thin arrows, respectively, indicating an overall acceleration of the Pacific Ocean shallow overturning cells, the equatorial surface currents and the Equatorial Undercurrent (EUC). The accelerated atmospheric circulation in the Pacific is indicated by the dashed arrows; including the Walker cell (black dashed) and the Hadley cell (red dashed; Northern Hemisphere only). Anomalously high SLP in the North Pacific is indicated by the symbol "H." An equivalent accelerated Hadley cell in the Southern Hemisphere is omitted for clarity. Credit: From Nature Climate Change."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #133 on: February 11, 2014, 02:09:39 AM »
The attached figure is from Real Climate (after Cowtan & Way 2013) showing the change in measured increase in mea global surface temperature, before and after the Cowtan & Way correction.  The caption of this figure is: "The corrected data (bold lines) are shown in the graph compared to the uncorrected ones (thin lines). The temperatures of the last three years have become a little warmer, the year 1998 a little cooler".

[Cowtan, K. & Way, R.G., (2013), "Coverage bias in the HadCRUT4 temperature series and its impact on recent temperature trends", Quarterly Journal of the Royal Meteorological Society, DOI: 10.1002/qj.2297.]

Real Climate indicates that this Cowtan & Way correction brings the measured mean global surface temperature record into agreement with the AR5/IPCC projections.

http://www.realclimate.org/index.php/archives/2013/11/global-warming-since-1997-underestimated-by-half/

While English et al 2014 state that:
“… the net effect of these anomalous winds is a cooling in the 2012 global average surface air temperature of 0.1–0.2°C."

However, as the AR5/IPCC projections included only about ½ the anomalous winds cited by English et al 2014; this implies that the world's climate sensitivity is actually higher than that used in the AR5/IPCC models.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #134 on: February 12, 2014, 07:30:14 PM »
wili,

Hans at the ASI blog cited the following reference that has extended the forecast period for El Nino events up to one year and that give a 76% chance of an El Nino happening in 2014:

Josef Ludescher, Avi Gozolchiani, Mikhail I. Bogachev, Armin Bunde, Shlomo Havlin, and Hans Joachim Schellnhuber, (2014), "Very early warning of next El Niño", PNAS, 111 (6) 2064-2066, doi: 10.1073/pnas.1323058111


http://www.pnas.org/content/early/2014/02/07/1323058111


Abstract: "The most important driver of climate variability is the El Niño Southern Oscillation, which can trigger disasters in various parts of the globe. Despite its importance, conventional forecasting is still limited to 6 mo ahead. Recently, we developed an approach based on network analysis, which allows projection of an El Niño event about 1 y ahead. Here we show that our method correctly predicted the absence of El Niño events in 2012 and 2013 and now announce that our approach indicated (in September 2013 already) the return of El Niño in late 2014 with a 3-in-4 likelihood. We also discuss the relevance of the next El Niño to the question of global warming and the present hiatus in the global mean surface temperature."


See also discuss on this topic at:

http://www.bloomberg.com/news/2014-02-10/if-ocean-heat-pump-switches-on-expect-to-feel-it.html

and at:

http://www.reportingclimatescience.com/news-stories/article/three-in-four-chance-of-2014-el-nino-says-research.html

« Last Edit: February 12, 2014, 07:35:15 PM by AbruptSLR »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #135 on: February 13, 2014, 10:17:31 PM »
The following article says that a soon to be published peer-reviewed paper says that currently use of natural gas is worse than the use of diesel, due to leaks.

http://www.nytimes.com/2014/02/14/us/study-finds-methane-leaks-negate-climate-benefits-of-natural-gas.html?_r=0
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #136 on: February 14, 2014, 12:20:44 PM »
The reference (and an image) for the paper (about Methane Leaks) that I cited in my last post is provided below.  The paper implies that methane in the atmosphere over North America is 50% higher than the EPA currently officially acknowledges:


A. R. Brandt, G. A. Heath, E. A. Kort, F. O'Sullivan, G. Pétron, S. M. Jordaan, P. Tans, J. Wilcox, A. M. Gopstein, D. Arent, S. Wofsy, N. J. Brown, R. Bradley, G. D. Stucky, D. Eardley, and R. Harriss, (2014), "Methane Leaks from North American Natural Gas Systems", Science 14 February 2014: 343 (6172), 733-735. [DOI:10.1126/science.1247045].


http://www.sciencemag.org/content/343/6172/733.summary


Abstract: "Natural gas (NG) is a potential “bridge fuel” during transition to a decarbonized energy system: It emits less carbon dioxide during combustion than other fossil fuels and can be used in many industries. However, because of the high global warming potential of methane (CH4, the major component of NG), climate benefits from NG use depend on system leakage rates. Some recent estimates of leakage have challenged the benefits of switching from coal to NG, a large near-term greenhouse gas (GHG) reduction opportunity. Also, global atmospheric CH4 concentrations are on the rise, with the causes still poorly understood."
« Last Edit: February 14, 2014, 12:28:40 PM by AbruptSLR »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #137 on: February 14, 2014, 04:07:45 PM »
In 2011 Anderson 2011 of the Norwegian Space Centre cited a possible positive feedback mechanism for ratcheting a regional climatic system upward from one quasi-static equilibrium state to another, as shown in the accompanying image (see image caption below).  Anderson's hypothesis is that Summer minimum can be projected as a fraction of the preceding Winter Sea Ice Extent using the fraction shown in the image, where for 2011 the fraction is 0.68 and the Winter Sea Ice Extent in 2011 is 13.1 million sq. kilometers (i.e. 13.1 - (0.68)(13.1) = 4.1, see the image).

Image Caption: The Fraction of Winter Ice Extent that Melts by the Following September, i.e.: (Aw-As)/Aw, from 1979 to 2010 [where Aw = Maximum Winter Arctic Ice Extent and As = Minimum Summer Ice Extent] (from Anderson 2011 of the Norwegian Space Centre).

I cite this old hypothesis because: (a) it looks like 2014 may have a very low maximum SIE; and (b) the prior discussion in this thread about the "warming hiatus" and the IPO oscillations; makes quasi-static equilibrium states for Arctic SIE sound like a reasonable hypothesis.  Obviously, this hypothesis indicates that a low Winter SIE maximum will result in a low Summer SIE minimum, resulting in lower albedo and more Arctic amplification.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #138 on: February 15, 2014, 10:57:48 AM »
The second to last sentence of the linked abstract is of some concern to increasing methane concentration in the atmosphere, i.e.:  "Sustained submergence into the future should increase gas venting rate roughly exponentially as sediments continue to warm."

J. M. Frederick, and B. A. Buffett, (2014), "Taliks in relict submarine permafrost and methane hydrate deposits: Pathways for gas escape under present and future conditions", Journal of Geophysical Research: Earth Surface, DOI: 10.1002/2013JF002987

http://onlinelibrary.wiley.com/doi/10.1002/2013JF002987/abstract

Abstract: "We investigate the response of relict Arctic submarine permafrost and gas hydrate deposits to warming and make predictions of methane gas flux to the water column using a 2-D multiphase fluid flow model. Exposure of the Arctic shelf during the last glacial cycle formed a thick layer of permafrost, protecting hydrate deposits below. However, talik formation below paleo-river channels creates permeable pathways for gas migration from depth. An estimate of the maximum gas flux at the present time for conditions at the East Siberian Arctic Seas is 0.2047 kg yr−1 m−2, which produces a methane concentration of 142 nM in the overlying water column, consistent with several field observations. For conditions at the North American Beaufort Sea, the maximum gas flux at the present time is 0.1885 kg yr−1 m−2, which produces a methane concentration of 78 nM in the overlying water column. Shallow sediments are charged with residual methane gas after venting events. Sustained submergence into the future should increase gas venting rate roughly exponentially as sediments continue to warm. Studying permafrost-associated gas hydrate reservoirs will allow us to better understand the Arctic's contribution to the global methane budget and global warming."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #139 on: February 15, 2014, 07:59:59 PM »
In regard to the recent posts that I have made about the risk of a big El Nino event in 2014-2015, I find the accompanying image post by BornFromTheVoid in the Consequence folder, disturbing, see:
http://forum.arctic-sea-ice.net/index.php/topic,730.0.html

The image not only shows that the eastern Pacific surface water temperature has warmed significantly between Feb 9 and Feb 14 2014; but also that the high atmospheric pressure system in the Southern Pacific is weakening, which might possibly portend a reduction in the Pacific Tradewind speeds.  Obviously, a five day pattern is not conclusive of any long term trends for an El Nino event starting in 2014; but if the trend indicate by BornFromTheVoids image continues for another week, or two, it may be strong evidence of a Big El Nino event in the 2014-2015 timeframe.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #140 on: February 16, 2014, 08:00:57 PM »
I would like to give BornFromTheVoid credit again for posting (in the Consequence folder) the attached graph of the PDO index from Jan2007 to Jan 2014.  The positive PDO index of +0.3 in January 2014 is the first positive value since May 2010 and one of the relatively few positive PDO index values since 1999; which possibly could be the beginning of a long-term positive phase of the PDO cycle, and if so this would imply more El Nino events for the next 15-years (on average):
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #141 on: February 18, 2014, 10:39:30 PM »
The following reference states that the reduction in Arctic albedo is larger than previously expected resulting in more rapid "slow-response" climate sensitivity:

Kristina Pistone, Ian Eisenman and V. Ramanathan, (2014), "Observational determination of albedo decrease caused by vanishing Arctic sea ice", PNAS, doi: 10.1073/pnas.1318201111


http://www.pnas.org/content/early/2014/02/13/1318201111.abstract


Abstract: "The decline of Arctic sea ice has been documented in over 30 y of satellite passive microwave observations. The resulting darkening of the Arctic and its amplification of global warming was hypothesized almost 50 y ago but has yet to be verified with direct observations. This study uses satellite radiation budget measurements along with satellite microwave sea ice data to document the Arctic-wide decrease in planetary albedo and its amplifying effect on the warming. The analysis reveals a striking relationship between planetary albedo and sea ice cover, quantities inferred from two independent satellite instruments. We find that the Arctic planetary albedo has decreased from 0.52 to 0.48 between 1979 and 2011, corresponding to an additional 6.4 ± 0.9 W/m2 of solar energy input into the Arctic Ocean region since 1979. Averaged over the globe, this albedo decrease corresponds to a forcing that is 25% as large as that due to the change in CO2 during this period, considerably larger than expectations from models and other less direct recent estimates. Changes in cloudiness appear to play a negligible role in observed Arctic darkening, thus reducing the possibility of Arctic cloud albedo feedbacks mitigating future Arctic warming."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #142 on: February 21, 2014, 04:30:58 PM »
The trend of reduced average Northern Hemisphere land snow cover is one of several factors contributing to the previously cited trend of reducing Arctic albedo (which is considered a slow response positive feedback).  However, the accompanying graph from Mariclimategraphs (see link below), shows that the situation is actually worse than the trend of reduced average NH land snow cover might indicate, as the trend for winter snow cover has actually been increasing resulting in more insulation of the underlying land during a period of relatively low sunlight (so the high winter albedo from the high snow cover has little impact on radiative forcing).  This winter insulation means that the underlying land is relatively warm at the end of winter, contributing to rapid snow melt in the spring and summer months, thus contributing to the indicated trend for very low NH land snow cover during the summer months, why the associated low albedo of the land contributes significantly to radiative forcing from this positive feedback.

https://sites.google.com/site/marclimategraphs/

As NH atmospheric humidity continues to increase in the future with increasing GHG concentrations and with decreasing Arctic sea ice extent (allowing more evaporation); this trend of increasing winter NH land snow cover and decreasing summer NH land snow cover, show continue (or accelerate).  Furthermore, increased winter snow fall also insulates the Arctic sea ice, meaning that it is thinner and melts more easily in the spring/summer (which is another related positive feedback mechanism).
« Last Edit: February 21, 2014, 04:49:39 PM by AbruptSLR »
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #143 on: February 22, 2014, 05:16:22 PM »
For those who do not often visit other folders in this Forum; I have recent made a number of posts in the "Consequences" folder in the El Nino thread (see: http://forum.arctic-sea-ice.net/index.php/topic,730.msg20743.html#msg20743) about the possibility of a Super El Nino in 2014 .  My posts in the "Consequences" folder are base on information from the following link (Jeff Masters' website) which provides an excellent explanation of why an El Nino (possibly a Super El Nino) may be coming in 2014:


http://www.wunderground.com/blog/JeffMasters/article.html?entrynum=2635


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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #144 on: February 23, 2014, 11:42:50 PM »
The linked reference calculates that: "In two simulations with more realistic volcanic influences following the 1991 Pinatubo eruption, differences between simulated and observed tropospheric temperature trends over the period 1998 to 2012 are up to 15% smaller, with large uncertainties in the magnitude of the effect."  This implies without a comparable level of volcanic activity in the future, that global warming will increase at a rate faster than previously estimated (of course should volcanic activity increase due to mass redistribution associated with rapid SLR, then this would be a negative feedback):


Benjamin D. Santer, Céline Bonfils, Jeffrey F. Painter, Mark D. Zelinka, Carl Mears, Susan Solomon, Gavin A. Schmidt, John C. Fyfe, Jason N. S. Cole, Larissa Nazarenko, Karl E. Taylor & Frank J. Wentz, (2014), "Volcanic contribution to decadal changes in tropospheric temperature", Nature Geoscience, doi:10.1038/ngeo2098


http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2098.html


Abstract: "Despite continued growth in atmospheric levels of greenhouse gases, global mean surface and tropospheric temperatures have shown slower warming since 1998 than previously. Possible explanations for the slow-down include internal climate variability, external cooling influences and observational errors. Several recent modelling studies have examined the contribution of early twenty-first-century volcanic eruptions to the muted surface warming. Here we present a detailed analysis of the impact of recent volcanic forcing on tropospheric temperature, based on observations as well as climate model simulations. We identify statistically significant correlations between observations of stratospheric aerosol optical depth and satellite-based estimates of both tropospheric temperature and short-wave fluxes at the top of the atmosphere. We show that climate model simulations without the effects of early twenty-first-century volcanic eruptions overestimate the tropospheric warming observed since 1998. In two simulations with more realistic volcanic influences following the 1991 Pinatubo eruption, differences between simulated and observed tropospheric temperature trends over the period 1998 to 2012 are up to 15% smaller, with large uncertainties in the magnitude of the effect. To reduce these uncertainties, better observations of eruption-specific properties of volcanic aerosols are needed, as well as improved representation of these eruption-specific properties in climate model simulations."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #145 on: February 25, 2014, 12:37:16 AM »
The linked referenced research is potentially very bad news as this indicates that the permafrost may produce large amounts of methane as it decomposes (potentially acting as a very strong positive feedback):


Rhiannon Mondav, Ben J. Woodcroft, Eun-Hae Kim, Carmody K. McCalley, Suzanne B. Hodgkins, Patrick M. Crill, Jeffrey Chanton, Gregory B. Hurst, Nathan C. VerBerkmoes, Scott R. Saleska, Philip Hugenholtz, Virginia I. Rich & Gene W. Tyson, (2014), "Discovery of a novel methanogen prevalent in thawing permafrost", Nature Communications, 5,3212doi:10.1038/ncomms4212
http://www.nature.com/ncomms/2014/140214/ncomms4212/full/ncomms4212.html

Abstract: "Thawing permafrost promotes microbial degradation of cryo-sequestered and new carbon leading to the biogenic production of methane, creating a positive feedback to climate change. Here we determine microbial community composition along a permafrost thaw gradient in northern Sweden. Partially thawed sites were frequently dominated by a single archaeal phylotype, Candidatus ‘Methanoflorens stordalenmirensis’ gen. nov. sp. nov., belonging to the uncultivated lineage ‘Rice Cluster II’ (Candidatus ‘Methanoflorentaceae’ fam. nov.). Metagenomic sequencing led to the recovery of its near-complete genome, revealing the genes necessary for hydrogenotrophic methanogenesis. These genes are highly expressed and methane carbon isotope data are consistent with hydrogenotrophic production of methane in the partially thawed site. In addition to permafrost wetlands, ‘Methanoflorentaceae’ are widespread in high methane-flux habitats suggesting that this lineage is both prevalent and a major contributor to global methane production. In thawing permafrost, Candidatus ‘M. stordalenmirensis’ appears to be a key mediator of methane-based positive feedback to climate warming."


See also:


http://www.abc.net.au/science/articles/2014/02/20/3948946.htm

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #146 on: February 26, 2014, 04:06:00 PM »
The mid-Pliocene Warm Period occurred 3 million years ago; and as global mean temperatures then were 2 to 3 degrees C higher than today, it can provide valuable historical boundary conditions for calibrating key aspects of the new generation of Earth System Sensitivity as estimated by such models as the HadCM3, see:

http://www.see.leeds.ac.uk/research/essi/palaeoleeds/current-research/plio-ess-pliocene-constraints-on-earth-system-sensitivity/ 

The following two linked references (with a free access pdfs), show climate change projections are more pronounced when using the Earth System Sensitivity approach, and that changes in albedo are particularly important with regard to assessing polar amplification.  While such paleo-calibration exercises are works in progress; nevertheless these preliminary findings are not good news with regard to societal safety from climate change, or from the risks of ASLR.



Pound, M. J., Tindall, J., Pickering, S. J., Haywood, A. M., Dowsett, H. J., and Salzmann, U.: Late Pliocene lakes and soils: a global data set for the analysis of climate feedbacks in a warmer world, Clim. Past, 10, 167-180, doi:10.5194/cp-10-167-2014, 2014.

http://www.clim-past.net/10/167/2014/cp-10-167-2014.html


"Abstract. The global distribution of late Pliocene soils and lakes has been reconstructed using a synthesis of geological data. These reconstructions are then used as boundary conditions for the Hadley Centre General Circulation Model (HadCM3) and the BIOME4 mechanistic vegetation model. By combining our novel soil and lake reconstructions with a fully coupled climate model we are able to explore the feedbacks of soils and lakes on the climate of the late Pliocene. Our experiments reveal regionally confined changes of local climate and vegetation in response to the new boundary conditions. The addition of late Pliocene soils has the largest influence on surface air temperatures, with notable increases in Australia, the southern part of northern Africa and in Asia. The inclusion of late Pliocene lakes increases precipitation in central Africa and at the locations of lakes in the Northern Hemisphere. When combined, the feedbacks on climate from late Pliocene lakes and soils improve the data to model fit in western North America and the southern part of northern Africa."




Hill, D. J., Haywood, A. M., Lunt, D. J., Hunter, S. J., Bragg, F. J., Contoux, C., Stepanek, C., Sohl, L., Rosenbloom, N. A., Chan, W.-L., Kamae, Y., Zhang, Z., Abe-Ouchi, A., Chandler, M. A., Jost, A., Lohmann, G., Otto-Bliesner, B. L., Ramstein, G., and Ueda, H.: Evaluating the dominant components of warming in Pliocene climate simulations, Clim. Past, 10, 79-90, doi:10.5194/cp-10-79-2014, 2014


http://www.clim-past.net/10/79/2014/cp-10-79-2014.html


"Abstract. The Pliocene Model Intercomparison Project (PlioMIP) is the first coordinated climate model comparison for a warmer palaeoclimate with atmospheric CO2 significantly higher than pre-industrial concentrations. The simulations of the mid-Pliocene warm period show global warming of between 1.8 and 3.6 °C above pre-industrial surface air temperatures, with significant polar amplification. Here we perform energy balance calculations on all eight of the coupled ocean–atmosphere simulations within PlioMIP Experiment 2 to evaluate the causes of the increased temperatures and differences between the models. In the tropics simulated warming is dominated by greenhouse gas increases, with the cloud component of planetary albedo enhancing the warming in most of the models, but by widely varying amounts. The responses to mid-Pliocene climate forcing in the Northern Hemisphere midlatitudes are substantially different between the climate models, with the only consistent response being a warming due to increased greenhouse gases. In the high latitudes all the energy balance components become important, but the dominant warming influence comes from the clear sky albedo, only partially offset by the increases in the cooling impact of cloud albedo. This demonstrates the importance of specified ice sheet and high latitude vegetation boundary conditions and simulated sea ice and snow albedo feedbacks. The largest components in the overall uncertainty are associated with clouds in the tropics and polar clear sky albedo, particularly in sea ice regions. These simulations show that albedo feedbacks, particularly those of sea ice and ice sheets, provide the most significant enhancements to high latitude warming in the Pliocene."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #147 on: February 27, 2014, 07:55:22 PM »
The linked reference indicates that the fingerprint of global warming is evident in the extreme temperature records, even during the current hiatus period:

Sonia I. Seneviratne, Markus G. Donat, Brigitte Mueller, & Lisa V. Alexander (2014), "No pause in the increase of hot temperature extremes", Nature Climate Change, 4,161–163, doi:10.1038/nclimate2145.

http://www.nature.com/nclimate/journal/v4/n3/full/nclimate2145.html

Abstract:  "Observational data show a continued increase of hot extremes over land during the so-called global warming hiatus. This tendency is greater for the most extreme events and thus more relevant for impacts than changes in global mean temperature."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #148 on: February 27, 2014, 09:58:05 PM »
You probably saw this already, but two of the authors, Mueller and Seneviratne wrote a nice oaoer from 2012


http://www.pnas.org/cgi/doi/10.1073/pnas.1204330109

showint that (local) extreme temperature maxima were associated with (local) preceding precipitaion deficit. Now we know that high temperature extremes are increasing. I did an analysis a while ago that showed the same pattern in precipitation rate
as temperature (a la Hansen)

http://situ.com/precip.html

we are moving toward higher precip rates. Although this is not pointed out in my page, looking at total monthly precip on land from the university of delaware corpus, we see that months with lo precip have increased since 1900s. I enclose a rudimentary histogram (the y axis is arbitrary scale, proportional to the number of months with precip in cm. given by the x axis.) I have not the time to refine this analysis right now, i hope to return to it at some point.



AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #149 on: February 27, 2014, 11:31:21 PM »
sidd,

Thanks for the interesting information.  Obviously, as things warm-up around the world we will need to keep learning new climate patterns, particularly at the extreme end of precipitation and temperature events.

Best,
ASLR
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson