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Author Topic: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS  (Read 228762 times)

AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #200 on: May 27, 2014, 02:20:13 AM »
The following two linked papers in Nature Geoscience (online issued May 25 2014), indicate that buried organics could release GHG if exposed for decomposition:

William C. Johnson, (2014), "Carbon cycle: Sequestration in buried soils", Nature Geoscience, doi:10.1038/ngeo2172

http://www.nature.com/ngeo/journal/vaop/ncurrent/pdf/ngeo2172.pdf

Abstract: "Rapid deposition of wind-borne silt after the end of the last glacial period buried a large reservoir of organic carbon in the deep soil. Geochemical analyses suggest that this sequestered soil carbon could be released to the atmosphere if exposed to decomposition."

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

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

Abstract: "Buried soils contain large reservoirs of organic carbon at depths that are not typically included in regional and global soil carbon inventories. One such palaeosol, the Brady soil of southwestern Nebraska, USA, is buried under six metres of loess. The Brady soil developed at the land surface on the late-Pleistocene-aged Peoria Loess in a period of warmth and wetness during which dunefields and dust sources across the region were stabilized. Abrupt climate change in the early Holocene led to increased loess deposition that buried the soil. Here, we used spectroscopic and isotopic analyses to determine the composition and stability of organic carbon in the Brady soil. We identify high levels of black carbon, indicating extensive biomass burning. In addition, we found intact vascular plant lipids in soil organic matter with radiocarbon ages ranging from 10,500 to 12,400 cal yr BP, indicating decomposition was slowed by rapid burial at the start of the Holocene. We conclude that landscape disturbance caused by abrupt climate change, fire and the loss of vegetative cover contributed to deep carbon sequestration as the soil was quickly buried under accumulating loess. We suggest that terrestrial soil carbon storage in arid and semi-arid environments could undergo landscape-scale shifts in response to rising temperatures, increased fire activity or drought."

Also see:
http://www.news.wisc.edu/22887

“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 #201 on: June 08, 2014, 07:15:21 PM »
For those who do not check the other folders too often, there are many posts in the Science folder in both the "Mauna Loa CO2" Replies 240 to 259, and in the "Southern Ocean Venting of CO2" thread at the following link, about another positive feedback factor for AGW, which is the increasing venting of CO2 from the Southern Ocean due to the increase in SH circumpolar westerly wind velocities associated with both the ozone hole over Antarctica and the increasing concentration of GHGs (particularly CO2 and CH4) in the geopotential height-well over Antarctica:

http://forum.arctic-sea-ice.net/index.php/topic,888.0.html

While this positive feedback factor has been in effect since the westerly wind started accelerating in the early 1980's, and thus is already included in the climate trends observed since that timeframe; nevertheless both: (a) as it provides positive feedback at a high latitude its effects are subject to polar amplification, and (b) as this positive feedback helps to sustain/promote high westerly wind velocities that in addition to promoting CO2 venting from mode water, also promotes upwelling of CDW that in-turn promotes ice mass loss from key Antarctic marine glaciers (and the associate SLR from this ice mass loss could raise future sea levels in the Bering Strait which would push more warm Pacific water into the Arctic, which would cause future Arctic amplification).  Thus, due to non-linear interactions the importance of this positive feedback mechanism could gain more importance in the future (this century), and it is currently poorly modeled in current GCMs and RCMs.
“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 #202 on: June 10, 2014, 05:05:31 PM »
While the following linked research presents a negative feedback mechanism, the authors warn that this negative feedback may be temporary, if future events like droughts, wildfires and beetle attacks occur:

Trevor F. Keenan, Josh Gray, Mark A. Friedl, Michael Toomey, Gil Bohrer, David Y. Hollinger, J. William Munger, John O’Keefe, Hans Peter Schmid, Ian Sue Wing, Bai Yang & Andrew D. Richardson, (2014), "Net carbon uptake has increased through warming-induced changes in temperate forest phenology", Nature Climate Change doi:10.1038/nclimate2253.

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2253.html

Abstract: "The timing of phenological events exerts a strong control over ecosystem function and leads to multiple feedbacks to the climate system. Phenology is inherently sensitive to temperature (although the exact sensitivity is disputed) and recent warming is reported to have led to earlier spring, later autumn and increased vegetation activity. Such greening could be expected to enhance ecosystem carbon uptake, although reports also suggest decreased uptake for boreal forests. Here we assess changes in phenology of temperate forests over the eastern US during the past two decades, and quantify the resulting changes in forest carbon storage. We combine long-term ground observations of phenology, satellite indices, and ecosystem-scale carbon dioxide flux measurements, along with 18 terrestrial biosphere models. We observe a strong trend of earlier spring and later autumn. In contrast to previous suggestions we show that carbon uptake through photosynthesis increased considerably more than carbon release through respiration for both an earlier spring and later autumn. The terrestrial biosphere models tested misrepresent the temperature sensitivity of phenology, and thus the effect on carbon uptake. Our analysis of the temperature–phenology–carbon coupling suggests a current and possible future enhancement of forest carbon uptake due to changes in phenology. This constitutes a negative feedback to climate change, and is serving to slow the rate of warming."

Selected quotes from the authors: ""What we find in this paper is an increase in the growing season of forests in the eastern U.S. due to recent climate change," Keenan said. "This has been beneficial for forests in the past, but we do not expect the response to continue unchecked in the future. It must also be kept in mind that this positive effect of warming is but one amid a barrage of detrimental impacts of climate change on the Earth's ecosystems."
Though the fact that forests can store more carbon is a good thing, both Keenan and Richardson warned that continued climate change could lead to more dramatic negative consequences in the future.
"If forests weren't storing additional carbon in this manner, we would be even worse off in terms of atmospheric CO2 levels, so at the moment, it's a good thing…but this is not going to solve the CO2 problem," Richardson said. "Yes, 26 million metric tons is a lot of carbon, but it's still small when compared to fossil fuel emissions.
"And climate change isn't just about warmer temperatures," he continued. "It's also about changes in precipitation patterns…so in the future, an earlier spring might not help forests take up more carbon, if they end up running out of water in mid-summer.""
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #203 on: June 11, 2014, 01:11:33 AM »
The following extracts indicate the significance of bark beetle killing boreal forest trees, as an example of a positive feedback that is not only limiting CO₂ sequestering, but also is reducing aerosol produced by such trees that promote cloud formation: 

1. According to the following Bloomberg link beetle are killing "… 25 percent of the woods in South Dakota's Black Hills"

http://my.chicagotribune.com/#section/-1/article/p2p-80437759/

2. According to the following link: "Over 64 million acres have been killed across the Rockies of North America by a native pine beetle …"

http://truth-out.org/news/item/22469-abrupt-climate-change-no-bioperturbation

3. The following quote comes from: National Research Council, NRC, (2013), Abrupt Impacts of Climate Change Anticipating Surprises, The National Academies Press, Washington D.C.

"In the last two decades, though, the bark beetle infestation that have occurred across large areas of North America have been the largest and most severe in recorded history, killing millions of trees across millions of hectares of forest from Alaska to southern California (Bentz, 2008) …"
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #204 on: June 15, 2014, 10:33:14 AM »
The following link contains information that the Antarctic ozone hole may be beginning to heal itself; however, if the GHG accumulation over the Antarctic continues at the current rate [see also Reply #201 in this thread], then by the time that the ozone hole is healed, the circumpolar westerly wind velocities will not decrease as the GHGs will maintain the geopotential height well over Antarctica which drives the wind speeds:

http://research.noaa.gov/News/NewsArchive/LatestNews/TabId/684/ArtMID/1768/ArticleID/10311/Encouraging-information-from-this-year%e2%80%99s-observations-of-the-Antarctic-ozone-hole.aspx

Caption for image: "Ozone levels at the South Pole continue to plummet every Antarctic spring, when a coincidence of environmental factors and man-made chemicals still in the atmosphere promote reactions that eat away at the protective ozone layer. This year (in red) ozone levels did not drop as low as they have in recent years. (Credit: CIRES/NOAA)"

See also:

http://www.nnvl.noaa.gov/MediaDetail2.php?MediaID=1439&MediaTypeID=3&ResourceID
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #205 on: June 16, 2014, 12:07:33 PM »
The linked reference makes it clear that the boreal forests (in the taiga, see the attached image for the extent) are at greater risk of destruction than previously realized, most significantly due to the thawing of the permafrost, which promotes fires, droughts and insect attack.  Not only would this destruction turn a large CO₂ sink into a CO₂ source, but would also eliminate a major source of aerosols emitted by the boreal forests which facilitate cloud formation (which reflects sunlight and reduces global warming):

Moen, J., Rist, L., Bishop, K., Chapin, F. S., Ellison, D., Kuuluvainen, T., Bradshaw, C. J. (2014), "Eye on the taiga: removing global policy impediments to safeguard the boreal forest", Conservation Letters, DOI: 10.1111/conl.12098

http://onlinelibrary.wiley.com/doi/10.1111/conl.12098/abstract

Abstract: "The absence of boreal forests from global policy agendas on sustainable development and climate change mitigation represents a massive missed opportunity for environmental protection. The boreal zone contains some of the world's largest pools of terrestrial carbon that, if not safeguarded from a conversion to a net source of greenhouse gases, could seriously exacerbate global climate change. At the same time, boreal countries have a strong tradition of forest management—expertise that could be effectively leveraged toward global and national carbon mitigation targets and sustainable development. Current obstacles against such contributions include weak incentives for carbon sequestration and a reluctance to embrace change by forest managers and policy makers. We discuss possible solutions to overcome these obstacles, including the improvement of ineffective incentives, the development of alternative forest management strategies, and the need to maintain ecosystem resilience through the pursuit of policy and management options."


See also the extract from the following link:

http://news.mongabay.com/2014/0604-sutherland-taiga.html

Extract: "According to Jon Moen, an author of the report, a failure of global climate change policies to properly support boreal forests could prompt forests to emit more carbon than they consume, potentially contributing significantly to increased global temperatures.

“The scary part is if the thawing permafrost, increased fires, drought and insect attacks release the carbon that is stored in the boreal zone, we might see temperatures increase even more,” Moen said."

« Last Edit: June 16, 2014, 12:31:28 PM by AbruptSLR »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #206 on: June 17, 2014, 05:18:49 PM »
Further to my Reply#201 about the Antarctic Ozone Hole, I provide the following image of the history of the Antarctic ozone hole created by anthropogenic chlorofluorocarbons (CFCs) that were once thought to be inert, but which actually broke down by solar radiation in the upper atmosphere and that the resulting chlorine released into the stratosphere ripped apart the ozone molecules, thus creating the hole (whose size fluctuates seasonally with the solar radiation).  The image is from the NRC 2013's "Abrupt Impacts of Climate Change - Anticipating Surprises", and while many view the Montreal Protocol as having solved this problem (with the hole projected to heal itself by about 2050).  We should all be aware that: (a) the increased westerly wind velocities have already triggered the ASE marine glacier into an irreversible path to collapse (so healing the ozone hole by 2050 is too late); and (b) As the GHGs over Antarctica build-up by 2050, it is most likely that the westerly wind velocities will be maintained near the optimal speed for directing warm CDW towards the WAIS.

Considerations such as these need to be included into future ice mass loss model projections for the WAIS.

edit: (need I point-out that the Antarctic Ozone Hole is a very real example of abrupt climate change, that significantly increases the probability of abrupt SLR contributions from the WAIS this century).
« Last Edit: June 17, 2014, 06:18:03 PM by AbruptSLR »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #207 on: June 19, 2014, 03:10:33 AM »
I most certainly do not like the rate at which beetles are killing northern forests and the linked article is one more example of this problem in New England:

http://time.com/2892493/invasive-beetle-posed-to-spread-into-new-hampshire/
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #208 on: June 20, 2014, 06:32:04 AM »
While I have not tracked down the original article, the following link cites research published in the Journal of Climate that indicates that as the Antarctic ozone hole heals itself (projected to be completely healed by about 2050) the austral summertime temperatures should increase; which effectively will increase the equilibrium climate sensitivity for the planet as compared to what the extant GCMs are calibrated to:

http://www.laboratoryequipment.com/news/2014/05/springs-ozone-can-predict-summers-temps

Extract: "Now, MIT researchers have found that the intensity of summer temperatures in Australia and elsewhere in the Southern Hemisphere may be better predicted as early as the previous spring by an unlikely indicator: ozone.

From their study, published in the Journal of Climate, the scientists found that as the springtime ozone hole’s severity varies from year to year, the temperatures in Australia and southern regions of Africa and South America reveal correlations: years with higher springtime ozone experience hotter summers, and vice versa.
…….
“As the ozone hole recovers this century, the masking effects of ozone depletion causing reduced summer warming over the Southern Hemisphere will disappear,” says Karoly, who did not participate in the study. “Then there will be an acceleration of the summer warming trends over Australia and South Africa, as the ozone hole recovers and the masking influence disappears."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #209 on: June 20, 2014, 04:19:19 PM »
This post is a follow-up to my last post, in order to provide the linked reference and abstract for the Bandoro et al 2014 research that indicates that as the Antarctic ozone hole heals itself the Southern Hemisphere mid-latitude (ie Australia and South Africa) austral mean summertime temperatures will increase.  This implies that one of the many influences of the Antarctic ozone hole has been to mask a portion of the true climate sensitivity for about the past three decades; which implies that the ECS will effectively increase when the Antarctic ozone hole heals itself (which is projected to occur circa 2050):
 
Justin Bandoro, Susan Solomon, Aaron Donohoe, David W.J. Thompson, and Benjamin D. Santer, (2014), "Influences of the Antarctic Ozone Hole on Southern Hemispheric Summer Climate Change", Journal of Climate, doi: http://dx.doi.org/10.1175/JCLI-D-13-00698.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00698.1?af=R

Abstract: "Over the past three decades, Antarctic surface climate has undergone pronounced changes. Many of these changes have been linked to stratospheric ozone depletion. Here linkages between Antarctic ozone loss, the accompanying circulation changes, and summertime Southern Hemisphere (SH) mid-latitude surface temperatures are explored. Long-term surface climate changes associated with ozone driven changes in the southern annular mode (SAM) at SH mid-latitudes in summer are not annular in appearance, due to differences in regional circulation and precipitation impacts. Both station and reanalysis data indicate a trend towards cooler summer temperatures over southeast and south-central Australia and inland areas of the southern tip of Africa. We also find that since the onset of the ozone hole, there have been significant shifts in the distributions of both the seasonal mean and daily maximum summertime temperatures in the SH mid-latitude regions between high and low ozone years. Unusually hot summer extremes are associated with anomalously high ozone in the previous November, including the recent very hot austral summer of 2012/13. If the relationship found in the past three decades continues to hold, the level of late springtime ozone over Antarctica has the potential to be part of a useful predictor set for the following summer’s conditions. Our results suggest that skillful predictions may be feasible for both the mean seasonal temperature and the frequency of extreme hot events in some SH mid-latitude regions of Australia, Africa, and South America."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #210 on: June 28, 2014, 02:15:16 AM »
The following linked article focuses on forest loss in Alberta Canada (which is higher than expected), but also discusses general deforestation including the following quote indicating forest loss in Brazil, Canada, the USA, and Russia.  Obviously, this is a positive feedback factor for global warming:

http://www.huffingtonpost.ca/2014/06/25/alberta-forest-loss_n_5530168.html

"The Canadian average was 3.1 per cent. Brazil's average was 4.3 per cent, the U.S. was 2.9 per cent and Russia came in at 2.2 per cent."

Furthermore, much of this forest loss is due to forest fires that also add black carbon into the atmosphere.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #211 on: June 29, 2014, 10:34:38 PM »
To me the following linked reference, and extract, from a June 11 2014 Skeptical Science article indicates that: (a) The close match of the CESM1-CAM5 Large Ensemble Community Project, LE, mean global surface warming rates (in degrees C per decade) to the observed NOAA record indicates that the 4.1 degrees C ECS value used by the LE ensemble is a very likely value, and that ESS values this century could exceed this value; and (b) finds that"… a relatively unchanged planetary imbalance during the recent hiatus period is entirely consistent with analogous periods in LE simulations."

http://www.skepticalscience.com/challenges-constraining-climate-sensitivity.html

Caption: "Fig. 2: The range of decadal trends in global mean surface temperature from the CESM1-CAM5 Large Ensemble Community Project (LE, black and grey lines, 18) along with an observed estimate based on the NOAA-NCDC Merged Land and Ocean Surface Temperature dataset. Also shown are the mean (circle) and range (lines) of simulated planetary imbalance (right axis) from 2000 through 2010 for the 10 members of the LE with greatest cooling (blue) and warming (red)."
 
Extract: "The NCAR CESM1-CAM5 Large Ensemble Community Project provides a unique framework for understanding the role of internal variability in obscuring forced changes. It currently consists of 28 ensemble members in simulations of the historical record (1920-2005) and future projections (2006-2080) based on RCP8.5 forcing.
At 4.1 C, the ECS of the CESM1-CAM5 is higher than for most GCMs. Nonetheless, decadal trends from the model track quite closely with those derived from NOAA-NCDC observations (red line), with the model mean decadal trend (thick black line) skirting above and below observed trends about evenly since 1920. In several instances, decadal trends in observations have been at or beyond the LE ensemble range including intervals of exceptional observed warming (1945, 1960, 1980) and cooling (1948, 2009). The extent to which these frequent departures from the LE reflect errors in observations, insufficient ensemble size, or biases in model internal variability remains unknown. Nonetheless, there is no clear evidence of the model sensitivity being systematically biased high. Also noteworthy is the fact that the LE suggests that due to forcing, as indicated by the ensemble mean, certain decades including the 2000s are predisposed to a reduced rate of surface warming.

The LE also allows for the evaluation of subsets of ensemble members, such as in Fig 2, where the planetary imbalances for the 10 ensemble members with the greatest global surface warming (red) and cooling (blue) trends from 2000-2010 are compared. It is found that no significant difference exists between the two distributions and the mean imbalance for the cooling members is actually greater than for the warming members. Thus the finding of a relatively unchanged planetary imbalance during the recent hiatus period is entirely consistent with analogous periods in LE simulations. While the LE does suggest that recent trends have been exceptional, this is also suggested by the instrumental record itself, which includes exceptional El Niño (1997-98) and La Niña events (2010-2012) at the bounds of the recent hiatus."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #212 on: June 30, 2014, 05:10:31 PM »
As we are just entering the fire season in the Northern Latitudes, and an El Nino event maybe currently developing, it is particularly bad news, as documented in the linked reference, that the prior estimates of how much CO₂ the tropical rainforests are releasing have been underestimated:

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

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

Abstract: "Tropical rainforests store enormous amounts of carbon, the protection of which represents a vital component of efforts to mitigate global climate change. Currently, tropical forest conservation, science, policies, and climate mitigation actions focus predominantly on reducing carbon emissions from deforestation alone. However, every year vast areas of the humid tropics are disturbed by selective logging, understory fires, and habitat fragmentation. There is an urgent need to understand the effect of such disturbances on carbon stocks, and how stocks in disturbed forests compare to those found in undisturbed primary forests as well as in regenerating secondary forests. Here, we present the results of the largest field study to date on the impacts of human disturbances on above and belowground carbon stocks in tropical forests. Live vegetation, the largest carbon pool, was extremely sensitive to disturbance: forests that experienced both selective logging and understory fires stored, on average, 40% less aboveground carbon than undisturbed forests and were structurally similar to secondary forests. Edge effects also played an important role in explaining variability in aboveground carbon stocks of disturbed forests. Results indicate a potential rapid recovery of the dead wood and litter carbon pools, while soil stocks (0–30 cm) appeared to be resistant to the effects of logging and fire. Carbon loss and subsequent emissions due to human disturbances remain largely unaccounted for in greenhouse gas inventories, but by comparing our estimates of depleted carbon stocks in disturbed forests with Brazilian government assessments of the total forest area annually disturbed in the Amazon, we show that these emissions could represent up to 40% of the carbon loss from deforestation in the region. We conclude that conservation programs aiming to ensure the long-term permanence of forest carbon stocks, such as REDD+, will remain limited in their success unless they effectively avoid degradation as well as deforestation."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #213 on: July 05, 2014, 11:21:34 PM »
The linked article in the "The Guardian" discusses numerous factors contributing to recent rapid reduction the albedo in the northern latitudes.  For convenience, I provide two key references cited in this article, which discuss the seriousness of these positive feedback factors:

http://www.theguardian.com/environment/2014/jul/05/dark-snow-speeding-glacier-melting-rising-sea-levels

Kristina Pistone, Ian Eisenman, and V. Ramanathan, (2014), "Observational determination of albedo decrease caused by vanishing Arctic sea ice", PNAS, vol. 111 no. 9, 3322–3326, doi: 10.1073/pnas.1318201111

http://eisenman.ucsd.edu/publications/Pistone-Eisenman-Ramanathan-2014.pdf

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."

M. Dumont, E. Brun, G. Picard, M. Michou, Q. Libois, J-R. Petit, M. Geyer, S. Morin & B. Josse, (2014), "Contribution of light-absorbing impurities in snow to Greenland’s darkening since 2009", Nature Geoscience, 7,509–512, doi:10.1038/ngeo2180


http://www.nature.com/ngeo/journal/v7/n7/full/ngeo2180.html

Abstract: "The surface energy balance and mass balance of the Greenland ice sheet depends on the albedo of snow, which governs the amount of solar energy that is absorbed. The observed decline of Greenland’s albedo over the past decade has been attributed to an enhanced growth of snow grains as a result of atmospheric warming. Satellite observations show that, since 2009, albedo values even in springtime at high elevations have been lower than the 2003–2008 average. Here we show, using a numerical snow model, that the decrease in albedo cannot be attributed solely to grain growth enhancement. Instead, our analysis of remote sensing data indicates that the springtime darkening since 2009 stems from a widespread increase in the amount of light-absorbing impurities in snow, as well as in the atmosphere. We suggest that the transport of dust from snow-free areas in the Arctic that are experiencing earlier melting of seasonal snow cover as the climate warms may be a contributing source of impurities. In our snow model simulations, a decrease in the albedo of fresh snow by 0.01 leads to a surface mass loss of 27 Gt yr−1, which could induce an acceleration of Greenland’s mass loss twice as large as over the past two decades. Future trends in light-absorbing impurities should therefore be considered in projections of Greenland mass loss."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #214 on: July 07, 2014, 03:31:51 AM »
While I am unsure whether the linked New York Times article (and associated attached image) is intended to focus responsibility for anthropogenic CO2 emissions away from the OECD (Organization for Economic Cooperation and Development) countries and to shine a light on non-OECD countries (particularly on China and India).  While I believe that all nations need focus on the common good (and not spend time pointing fingers at each other); nevertheless, I do believe that the attached table highlights the challenges of controlling four (1. Carbon intensity of energy supply; 2. Energy intensity of economic activity; 3. Income per person; and 4. Population size) of the main factors that primarily contribute to anthropogenic CO2 emissions by 2040.

http://www.nytimes.com/2014/07/02/business/economy/persuading-china-to-act-fast-on-climate-change.html?_r=0

This table presents moderately optimistic assumptions with regard to improvements both in carbon intensity of energy supply and in energy intensity of economic activity; and still the table indicates a relatively high increase in anthropogenic CO2 emissions by 2040, due to probable increases both in income per person and in population.  The indicated challenge in control anthropogenic forcing; is only compounded by the fact that almost all current GCM projections assume too low of values for future climate sensitivity.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #215 on: July 08, 2014, 09:32:31 PM »
The following linked reference indicates that cooling from large volcanic events is less effective than previously thought:


Michael Sigl, Joseph R. McConnell, Matthew Toohey, Mark Curran, Sarah B. Das, Ross Edwards, Elisabeth Isaksson, Kenji Kawamura, Sepp Kipfstuhl, Kirstin Krüger, Lawrence Layman, Olivia J. Maselli, Yuko Motizuki, Hideaki Motoyama, Daniel R. Pasteris & Mirko Severi  (2014), "Insights from Antarctica on volcanic forcing during the Common Era", Nature Climate Change, doi:10.1038/nclimate2293


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2293.html#access

Abstract: "Assessments of climate sensitivity to projected greenhouse gas concentrations underpin environmental policy decisions, with such assessments often based on model simulations of climate during recent centuries and millennia. These simulations depend critically on accurate records of past aerosol forcing from global-scale volcanic eruptions, reconstructed from measurements of sulphate deposition in ice cores. Non-uniform transport and deposition of volcanic fallout mean that multiple records from a wide array of ice cores must be combined to create accurate reconstructions. Here we re-evaluated the record of volcanic sulphate deposition using a much more extensive array of Antarctic ice cores. In our new reconstruction, many additional records have been added and dating of previously published records corrected through precise synchronization to the annually dated West Antarctic Ice Sheet Divide ice core, improving and extending the record throughout the Common Era. Whereas agreement with existing reconstructions is excellent after 1500, we found a substantially different history of volcanic aerosol deposition before 1500; for example, global aerosol forcing values from some of the largest eruptions (for example, 1257 and 1458) previously were overestimated by 20–30% and others underestimated by 20–50%."

See also:

http://www.livescience.com/46696-volcanoes-cooling-antarctic-ice-cores.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Livesciencecom+(LiveScience.com+Science+Headline+Feed)
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #216 on: July 11, 2014, 05:29:00 PM »
The linked reference indicates that methane emissions from livestock is greater than previously thought, and with meat consumption in Asia increasing rapidly, the coming increases livestock will contribute to increasing atmospheric methane concentrations:

Wecht, K. J., D. J. Jacob, C. Frankenberg, Z. Jiang, and D. R. Blake (2014), Mapping of North American methane emissions with high spatial resolution by inversion of SCIAMACHY satellite data, J. Geophys. Res. Atmos., 119, doi:10.1002/2014JD021551.

http://onlinelibrary.wiley.com/doi/10.1002/2014JD021551/abstract

Abstract: "We estimate methane emissions from North America with high spatial resolution by inversion of Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite observations using the Goddard Earth Observing System Chemistry (GEOS-Chem) chemical transport model and its adjoint. The inversion focuses on summer 2004 when data from the Intercontinental Chemical Transport Experiment-North America (INTEX-A) aircraft campaign over the eastern U.S. are available to validate the SCIAMACHY retrievals and evaluate the inversion. From the INTEX-A data we identify and correct a water vapor-dependent bias in the SCIAMACHY data. We conduct an initial inversion of emissions on the horizontal grid of GEOS-Chem (1/2° × 2/3°) to identify correction tendencies relative to the Emission Database for Global Atmospheric Research (EDGAR) v4.2 emission inventory used as a priori. We then cluster these grid cells with a hierarchical algorithm to extract the maximum information from the SCIAMACHY observations. A 1000 cluster ensemble can be adequately constrained, providing ~100 km resolution across North America. Analysis of results indicates that the Hudson Bay Lowland wetlands source is 2.1 Tg a−1, lower than the a priori but consistent with other recent estimates. Anthropogenic U.S. emissions are 30.1 ± 1.3 Tg a−1, compared to 25.8 Tg a−1 and 28.3 Tg a−1 in the EDGAR v4.2 and Environmental Protection Agency (EPA) inventories, respectively. We find that U.S. livestock emissions are 40% greater than in these two inventories. No such discrepancy is apparent for overall U.S. oil and gas emissions, although this may reflect some compensation between overestimate of emissions from storage/distribution and underestimate from production. We find that U.S. livestock emissions are 70% greater than the oil and gas emissions, in contrast to the EDGAR v4.2 and EPA inventories where these two sources are of comparable magnitude."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #217 on: July 11, 2014, 06:01:47 PM »
The linked article discusses both the GOSAT, and the new OCO-2, satellites that can directly measure photosynthesis in order to better monitor the possible degradation of CO₂ absorption by plants as discussed in the extract from the article focused on the Amazon rainforest:

http://spie.org/x108777.xml

Extract: "About 30% of the photosynthesis that occurs in Earth's land regions takes place in the tropical rainforest of the Amazon, which encompasses about 2.7 million square miles (7 million square kilometers) of South America. The Amazon is home to more than half of Earth's terrestrial biomass and tropical forest area -- making it one of the two most important land regions for carbon storage (the other being the Arctic, where carbon is stored in the soil).
Recent studies in the Amazon using fluorescence measurements have examined how photosynthesis rates change during wet and dry seasons. Most of the results show that during the dry season, photosynthesis slows down. According to Berry, when the air is dry and hot, it makes sense for plants to conserve water by closing their stomates (pores). "During the dry season when it would cost the plants a lot of water, photosynthesis is dialed down and the forest becomes less active," he said.
In 2005 and 2010, the Amazon basin experienced the type of droughts that historically have happened only once in a century. Greenness measurements indicated widespread die-off of trees and major changes to the forest canopy (treetops) after the droughts, but fluorescence data from GOSAT exposed even milder water stress in the dry season of normal years.
"There is the potential that as climate change proceeds, these droughts will become more severe. The areas that support tropical rainforest could decrease," Berry said. Less tropical forest means less carbon absorbed from the air.
In addition, as trees decay, they release carbon dioxide back into the atmosphere, creating a scenario whereby the biosphere potentially becomes a source of carbon rather than a sink.
"If there is a dieback of the tropical rainforest, that might add to the effect of fossil fuel carbon dioxide on climate change," Frankenberg said."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #218 on: July 15, 2014, 05:28:26 PM »
The Montreal Protocol (that helped to fight the ozone hole) is frequently held-up as a shining example of mankind's ability to cooperate across international boundaries in order to control climate as man's will.  However, this diplomatic framework only achieved the degree of success that it did because technological innovations allowed hydrofluorocarbons (HFCs) to serve as substitutes for chloroflurocarbons (CFCs).  Now recent research (see multiple links below, with free access pdfs) indicates that some of the HFCs [and hydrochlorofluorocarbon (HCFC)] are also extremely long lived GHGs that are currently accelerating climate change, and which require additional regulation (which may also have unintended side effects):

Corinna Kloss, Mike Newland, David Oram, Paul Fraser, Carl Brenninkmeijer, Thomas Röckmann, Johannes Laube. Atmospheric Abundances, Trends and Emissions of CFC-216ba, CFC-216ca and HCFC-225ca. Atmosphere, 2014; 5 (2): 420 DOI: 10.3390/atmos5020420

http://www.mdpi.com/2073-4433/5/2/420

Abstract: "The first observations of the feedstocks, CFC-216ba (1,2-dichlorohexafluoropropane) and CFC-216ca (1,3-dichlorohexafluoropropane), as well as the CFC substitute HCFC-225ca (3,3-dichloro-1,1,1,2,2-pentafluoropropane), are reported in air samples collected between 1978 and 2012 at Cape Grim, Tasmania. Present day (2012) mixing ratios are 37.8 ± 0.08 ppq (parts per quadrillion; 1015) and 20.2 ± 0.3 ppq for CFC-216ba and CFC-216ca, respectively. The abundance of CFC-216ba has been approximately constant for the past 20 years, whilst that of CFC-216ca is increasing, at a current rate of 0.2 ppq/year. Upper tropospheric air samples collected in 2013 suggest a further continuation of this trend. Inferred annual emissions peaked 421 at 0.18 Gg/year (CFC-216ba) and 0.05 Gg/year (CFC-216ca) in the mid-1980s and then decreased sharply as expected from the Montreal Protocol phase-out schedule for CFCs. The atmospheric trend of CFC-216ca and CFC-216ba translates into continuing emissions of around 0.01 Gg/year in 2011, indicating that significant banks still exist or that they are still being used. HCFC-225ca was not detected in air samples collected before 1992. The highest mixing ratio of 52 ± 1 ppq was observed in 2001. Increasing annual emissions were found in the 1990s (i.e., when HCFC-225ca was being introduced as a replacement for CFCs). Emissions peaked around 1999 at about 1.51 Gg/year. In accordance with the Montreal Protocol, restrictions on HCFC consumption and the short lifetime of HCFC-225ca, mixing ratios declined after 2001 to 23.3 ± 0.7 ppq by 2012."

See also:

Johannes C. Laube, Mike J. Newland, Christopher Hogan, Carl A. M. Brenninkmeijer, Paul J. Fraser, Patricia Martinerie, David E. Oram, Claire E. Reeves, Thomas Röckmann, Jakob Schwander, Emmanuel Witrant, William T. Sturges. Newly detected ozone-depleting substances in the atmosphere. Nature Geoscience, 2014; DOI: 10.1038/ngeo2109

Also see:
http://www.sciencedaily.com/releases/2014/06/140603193902.htm

and see:
http://www.sciencedaily.com/releases/2012/02/120224110737.htm
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #219 on: July 16, 2014, 03:59:30 AM »
The linked Smithsonian article contains the following extracts, indicating the that measured movement of magnetic north is drifting south 10 times faster than previously thought, which should locate magnetic north in Siberia in a few decades.  While the article says that people have nothing to fear about increasing risk of cosmic radiation; I wonder whether such an accelerated drift might increase seismic activity over the coming decades; which might accelerate both methane emissions from Arctic Ocean hydrates and my increase ice mass loss from marine glaciers (in the GIS and the AIS):

http://www.smithsonianmag.com/smart-news/north-pole-could-soon-drift-over-siberia-180952016/

Extract: "Researchers with the European Space Agency noticed the abnormalities in the Earth's magnetic field strength while analyzing data collected by magnetometers attached to a new three-satellite system called Swarm. Here's LiveScience:

Previously, researchers estimated the field was weakening about 5 percent per century, but the new data revealed the field is actually weakening at 5 percent per decade, or 10 times faster than thought. As such, rather than the full flip occurring in about 2,000 years, as was predicted, the new data suggest it could happen sooner.

The data, LiveScience continues, suggest that in the shorter term the magnetic North Pole might eventually relocate closer to Siberia. The magnetic north pole is currently drifting south at around 25 miles per year, says Al Jazeera, "and scientists predict it could travel from its current position in North America to Asia within a few decades."

Researchers aren't sure why things seem to be expedited, although the process--known as a geomagnetic reversal--is a natural one that has occurred many times before. The shift in the magnetic field is caused by the flux of molten metal contained beneath the Earth's surface, LiveScience explains."

edit: As a footnote, the issue of Scientific American published on-line on September 16 2014, contains the following article about the Earth's impending magnetic flip that is less alarming, but that may be because SciAm intentionally chooses to err on the side of least drama.

Annie Sneed, (Sept 16 2014), "Earth's Impending Magnetic Flip", Scientific American 311, 29 (2014), doi:10.1038/scientificamerican1014-29

« Last Edit: September 21, 2014, 04:48:35 PM by AbruptSLR »
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #220 on: July 16, 2014, 06:28:13 PM »
Sleepy,

In my Reply #219, I was merely expressing my concern that the accelerated migration of the magnetic north pole towards Siberia (due to the flux of molten metals beneath the Earth's surface) might result in more seismic activity because of the associated changes in the flow of the magma beneath the lithosphere.  Thus, I cannot reference any studies relating the measured changes in the magnetic fields to changes in seismic activity (as the last time the magnetic poles flipped was about 780,000 years ago). 

Nevertheless, I wonder whether the migration of the rotational axis of the Earth in the opposite direction (as the migration of the magnetic pole), due to the melting of the recent ice melting (see the following linked Chen et al 2013 reference [and two associate images] with a free access pdf) is helping to accelerate the migration of the magnetic pole, and will also contribute to a potential increase in future tectonic activity:

Chen, J.L., C.R. Wilson, J.C. Ries, B.D. Tapley, Rapid ice melting drives Earth's pole to the east, Geophys. Res. Lett., Vol. 40, 1-6, DOI: 10.1002/grl.50552, 2013. [Online Version] [PDF Preprint] [Nature News Coverage]

Best,
ASLR
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #221 on: July 16, 2014, 06:31:03 PM »
The linked reference (with a free access pdf) provides results of a study to try to better quantify the risks of Amazon tree mortality associated with drought-fire interaction.  This could be very important if we enter a period of frequent El Nino events that could influence frequent drought conditions in Amazonia:

Brando, P.M., J.K.Balch et al. (2014) "Abrupt increases in Amazonian tree mortality due to drought–fire interactions", PNAS, doi: 10.1073/pnas.1305499111

http://www.pnas.org/content/early/2014/04/11/1305499111.full.pdf+html

Abstract: "Interactions between climate and land-use change may drive widespread degradation of Amazonian forests. High-intensity fires associated with extreme weather events could accelerate this degradation by abruptly increasing tree mortality, but this process remains poorly understood. Here we present, to our knowledge, the first field-based evidence of a tipping point in Amazon forests due to altered fire regimes. Based on results of a large-scale, long-term experiment with annual and triennial burn regimes (B1yr and B3yr, respectively) in the Amazon, we found abrupt increases in fire-induced tree mortality (226 and 462%) during a severe drought event, when fuel loads and air temperatures were substantially higher and relative humidity was lower than long-term averages.  This threshold mortality response had a cascading effect, causing sharp declines in canopy cover (23 and 31%) and aboveground live biomass (12 and 30%) and favoring widespread invasion by flammable grasses across the forest edge area (80 and 63%), where fires were most intense (e.g., 220 and 820 kW•m−1). During the droughts of 2007 and 2010, regional forest fires burned 12 and 5% of southeastern Amazon forests, respectively, compared with <1% in non-drought years. These results show that a few extreme drought events, coupled with forest fragmentation and anthropogenic ignition sources, are already causing widespread fire-induced tree mortality and forest degradation across southeastern Amazon forests. Future projections of vegetation responses to climate change across drier portions of the Amazon require more than simulation of global climate forcing alone and must also include interactions of extreme weather events, fire, and land-use change."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #222 on: July 17, 2014, 08:49:28 PM »
Sleepy,

Thanks for the links.  I think that the magnetic pulses discussed in the linked article(s) are generated by stress in the rock near faults; however, who knows if the flipping of the magnetic poles will interact with these stressed rock induced magnetic pulses.

Best,
ASLR
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #223 on: July 17, 2014, 08:51:19 PM »
Many scientists indicate that they believe that the deductive process-based approach used by the IPCC is rigorous science and that inductive methodology (such as use in many Bayesian approaches) is based on value judgments that cannot be verified rigorously and thus are not suitable for policy making.  Such thinking does not acknowledge the many assumptions (based on value judgments) that the deductive process-based approach uses in their (typically) deductive model based projections.

One relatively clear example of the bias (erring on the side of least drama, ESLD) introduced into such process-based climate change projections, can be illustrated by the selection of what climate sensitivity to use for the calibration of the various GCM's models used in the AR5 projections.

When the IPCC process selects an equilibrium climate sensitivity, ECS, of about 3.2-3.3 (with an associated uncertainty range for sensitivity analysis) for their GCM projections, they are more, or less saying that they are entitled to assume that the conditions prevailing through the Holocene will continue for duration of the projection (typically 100 to 200 years for policy makers), and that all of the families of Recommended Concentration Pathways (RCPs) and the members within the ensemble of the projection will adequately account for the uncertainties and non-linear/non-stationary behaviors of the Earth's systems.  However, one should realize that as the GHG levels exceed the pre-industrial level (characteristic of the Holocene period), climate sensitivity will gradually increase from the ECS value to the Earth System Sensitivity, ESS, value, which prior to the Holocene was approximately 7.8 degrees C (as indicated by the first attached image from Shakun et al, 2012).  While it might be reasonable to use an ECS value for a RCP projections through 2050, there is no rational/scientific reason for using an ECS value for a RCP 8.5 projection after 2050 other than the value judgment of desiring to err on the side of least drama, as using a ESS value would just as likely to be correct as using a ECS value for a RCP 8.5 analysis between 2050 and 2100. The second attached image (from Hansen & Sato, 2011), clearly shows that during the warming phase of the Eemian the ESS was essentially linear beyond our current GHG levels, indicating that climate sensitivity should (as a first approximation) converge towards this approximately 7.8 degrees C (plus or minus, see the third attached image and the following extract from Pagani et al 2009 for the early and middle Pliocene, as an example of other ESS values that we might be converging towards) by the end of this century following RCP 8.5, as all of the feedback factors cited in this thread are engages including: (a) ocean venting of CO₂, (b) reduction of Arctic Sea Ice Extent and NH snow cover; (c) loss of NH albedo due to shrub growth; (d) decomposition of the permafrost; (e) degradation of the tropical and boreal forests (due to drought, fires, and attack by pests); (f) potential partial collapse of the WAIS, (g) reduction of Greenland albedo; (h) acidification of the oceans (and associated reduction of plankton); (i) slow-down of the AABW; (j) heat stress to plants; etc.  Again there is no rational reason for calibrating GCMs to the ECS for RCP 8.5 after 2050, rather than calibrating to the ESS, which is clear the condition that our current non-stationary world is converging to as we continue to follow the BAU.




Mark Pagani, Zhonghui Liu, Jonathan LaRiviere, Ana Christina Ravelo (2009), "High Earth-System Climate Sensitivity determined from Pliocene CO2 Concentrations", Nature geoscience, doi:10.1038/NGEO724

http://people.earth.yale.edu/sites/default/files/files/Pagani/1_2009%20Pagani_NatureGeosci.pdf

Extract from Pagani et al 2009: "Data and modelling for the middle Pliocene (~3–3.3 Myr) indicate that the global mean temperature was 2.4–2.9 "C warmer than preindustrial conditions, and ~4 "C warmer during the early Pliocene (!4–4.2 Myr; ref. 5). If changes in carbon dioxide and associated feedbacks were the primary agents forcing climate over these timescales, and estimates of global temperatures are correct, then our results imply a very high Earth-system climate sensitivity for the middle (3.3 Myr) to early (4.2 Myr) Pliocene ranging between 7.1 ± 1.0 "C and 8.7 ± 1.3 "C per CO2 doubling, and 9.6±1.4 "C per CO2 doubling, respectively."

Caption for the third attached image : "Estimated CO2 trends considering probable oceanographic changes at each site. Each line represents a modified CO2slope for each site and the dashed green line (1012(alt)) represents an alternative nutrient scenario for Site 1012 (Supplementary Information). Vertical grey lines intersect CO2 concentrations at 3.0–3.3 and 4.0–4.2 Myr, the time intervals representing the Earth-system climate sensitivity estimates presented in the text."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #224 on: July 18, 2014, 10:49:56 PM »
The linked article about current Canadian wildfires indicate that the current weather pattern contributing to the wildfires were not predicted by the GCMs to occur for another 40-yr; which to me is supporting evidence that the RCP 8.5 analysis should have used Earth System Sensitivity values instead of Equilibrium Climate Sensitivity values in their forecasts:

http://www.adn.com/article/20140717/worst-wildfire-season-decades-canada-s-northwest-territories
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #225 on: July 21, 2014, 04:17:13 PM »
While the following linked reference (with a free access pdf) discusses the influence of smoke on regional climate change models for Africa, the methodology and tools could be applied in any region of the world including for the influence of boreal wildfires on the Arctic/Sub-Arctic:

Feng Zhang et al, (2014), "Sensitivity of mesoscale modeling of smoke direct radiative effect to the emission inventory: a case study in northern sub-Saharan African region", Environ. Res. Lett. 9 075002, doi:10.1088/1748-9326/9/7/075002

http://iopscience.iop.org/1748-9326/9/7/075002/article


Abstract: "An ensemble approach is used to examine the sensitivity of smoke loading and smoke direct radiative effect in the atmosphere to uncertainties in smoke emission estimates. Seven different fire emission inventories are applied independently to WRF-Chem model (v3.5) with the same model configuration (excluding dust and other emission sources) over the northern sub-Saharan African (NSSA) biomass-burning region. Results for November and February 2010 are analyzed, respectively representing the start and end of the biomass burning season in the study region. For February 2010, estimates of total smoke emission vary by a factor of 12, but only differences by factors of 7 or less are found in the simulated regional (15°W–42°E, 13°S–17°N) and monthly averages of column PM2.5 loading, surface PM2.5 concentration, aerosol optical depth (AOD), smoke radiative forcing at the top-of-atmosphere and at the surface, and air temperature at 2 m and at 700 hPa. The smaller differences in these simulated variables may reflect the atmospheric diffusion and deposition effects to dampen the large difference in smoke emissions that are highly concentrated in areas much smaller than the regional domain of the study. Indeed, at the local scale, large differences (up to a factor of 33) persist in simulated smoke-related variables and radiative effects including semi-direct effect. Similar results are also found for November 2010, despite differences in meteorology and fire activity. Hence, biomass burning emission uncertainties have a large influence on the reliability of model simulations of atmospheric aerosol loading, transport, and radiative impacts, and this influence is largest at local and hourly-to-daily scales. Accurate quantification of smoke effects on regional climate and air quality requires further reduction of emission uncertainties, particularly for regions of high fire concentrations such as NSSA."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #226 on: July 21, 2014, 04:23:06 PM »
The linked reference (with a free access pdf) discusses the influence of surface water inundation (or not) on methane emissions from the boreal-Arctic, in recent years.  In my opinion one should not get overly optimistic that drought in some regions is reducing methane emission in roughly the same proportion as methane emission are increasing were surface water area is increasing as: the droughts lead to increases in wildfires that are very damaging both to the environment and to global warming; and we are only in the beginning stages of the degradation of the permafrost so in the future the increase in methane emissions may overwhelm the decreases:

Jennifer D Watts, John S Kimball, Annett Bartsch and Kyle C McDonald, (2014), "Surface water inundation in the boreal-Arctic: potential impacts on regional methane emissions", Environ. Res. Lett. 9, 075001, (13pp), doi:10.1088/1748-9326/9/7/075001


http://iopscience.iop.org/1748-9326/9/7/075001/pdf/1748-9326_9_7_075001.pdf


Abstract: "Northern wetlands may be vulnerable to increased carbon losses from methane (CH4), a potent greenhouse gas, under current warming trends. However, the dynamic nature of open water inundation and wetting/drying patterns may constrain regional emissions, offsetting the potential magnitude of methane release. Here we conduct a satellite data driven model investigation of the combined effects of surface warming and moisture variability on high northern latitude (⩾45° N) wetland CH4 emissions, by considering (1) sub-grid scale changes in fractional water inundation (Fw) at 15 day, monthly and annual intervals using 25 km resolution satellite microwave retrievals, and (2) the impact of recent (2003–11) wetting/drying on northern CH4 emissions. The model simulations indicate mean summer contributions of 53 Tg CH4 yr−1 from boreal-Arctic wetlands.  Approximately 10% and 16% of the emissions originate from open water and landscapes with emergent vegetation, as determined from respective 15 day Fw means or maximums, and significant increases in regional CH4 efflux were observed when incorporating satellite observed inundated land fractions into the model simulations at monthly or annual time scales. The satellite Fw record reveals widespread wetting across the Arctic continuous permafrost zone, contrasting with surface drying in boreal Canada, Alaska and western Eurasia. Arctic wetting and summer warming increased wetland emissions by 0.56 Tg CH4 yr−1 compared to the 2003–11 mean, but this was mainly offset by decreasing emissions (−0.38 Tg CH4 yr−1) in sub-Arctic areas experiencing surface drying or cooling. These findings underscore the importance of monitoring changes in surface moisture and temperature when assessing the vulnerability of boreal-Arctic wetlands to enhanced greenhouse gas emissions under a shifting climate."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #227 on: July 21, 2014, 04:32:44 PM »
The linked reference (with a free access pdf) discusses the global climate forcing contributions from developed and developing nations and particularly gives credit for reduced forcing to nations such as China and India who produce a lot of aerosols that reduce forcing.  Nevertheless, the paper concludes that the forcing contribution (after aerosol correction) for the developing world will exceed that from the developed world by 2030.  However, in my opinion one should not be too optimistic about linearly projecting this pattern into the future as many developing world countries are expected to clean-up their aerosol emissions (say by switching gradually from coal use to natural gas use [say from fracking]), which may well increase warming due to the reduction in aerosols and by increasing methane emissions into the atmosphere:

D S Ward and N M Mahowald, (2014), "Contributions of developed and developing countries to global climate forcing and surface temperature change", Environ. Res. Lett., 9, 074008, (10pp) doi:10.1088/1748-9326/9/7/074008.


http://iopscience.iop.org/1748-9326/9/7/074008/pdf/1748-9326_9_7_074008.pdf

Abstract:  "Understanding the relative contributions of individual countries to global climate change for different time periods is essential for mitigation strategies that seek to hold nations accountable for their historical emissions. Previous assessments of this kind have compared countries by their greenhouse gas emissions, but have yet to consider the full spectrum of the short-lived gases and aerosols. In this study, we use the radiative forcing of anthropogenic emissions of long-lived greenhouse gases, ozone precursors, aerosols, and from albedo changes from land cover change together with a simple climate model to evaluate country contributions to climate change. We assess the historical contribution of each country to global surface temperature change from anthropogenic forcing (ΔTs), future ΔTs through year 2100 given two different emissions scenarios, and the ΔTs that each country has committed to from past activities between 1850 and 2010 (committed ΔTs). By including forcings in addition to the long-lived greenhouse gases the contribution of developed countries, particularly the United States, to ΔTs from 1850 to 2010 (58%) is increased compared to an assessment of CO2-equivalent emissions for the same time period (52%). Contributions to committed ΔTs evaluated at year 2100, dominated by long-lived greenhouse gas forcing, are more evenly split between developed and developing countries (55% and 45%, respectively). The portion of anthropogenic ΔTs attributable to developing countries is increasing, led by emissions from China and India, and we estimate that this will surpass the contribution from developed countries around year 2030."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #228 on: July 21, 2014, 07:44:40 PM »
The following linked reference demonstrates that the recent hiatus period (see attached image) can be projected by the CMIP5 projections, when the models are phased for ENSO.  This should allow such GCM projections to forecast the impact of a new phase of more frequent El Nino's associated with a positive phase of the IPO/PDO:

James S. Risbey, Stephan Lewandowsky, Clothilde Langlais, Didier P. Monselesan, Terence J. O’Kane & Naomi Oreskes, (2014), "Well-estimated global surface warming in climate projections selected for ENSO phase", Nature Climate Change, doi:10.1038/nclimate2310


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2310.html

Abstract: "The question of how climate model projections have tracked the actual evolution of global mean surface air temperature is important in establishing the credibility of their projections. Some studies and the IPCC Fifth Assessment Report suggest that the recent 15-year period (1998–2012) provides evidence that models are overestimating current temperature evolution. Such comparisons are not evidence against model trends because they represent only one realization where the decadal natural variability component of the model climate is generally not in phase with observations. We present a more appropriate test of models where only those models with natural variability (represented by El Niño/Southern Oscillation) largely in phase with observations are selected from multi-model ensembles for comparison with observations. These tests show that climate models have provided good estimates of 15-year trends, including for recent periods and for Pacific spatial trend patterns."

See also:
http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/jul/21/realistic-climate-models-accurately-predicted-global-warming
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #229 on: July 23, 2014, 06:20:09 PM »
The linked reference by Howarth 2014 (and associated image with caption below), with a free access pdf, helps to reiterate how risky (un-wise) it is to be increasingly reliant on Shale Gas wrt to global warming:


Robert W. Howarth, (2014), "A bridge to nowhere: methane emissions and the greenhouse gas footprint of natural gas", Energy Science and Engineering 2014; 2(2): 47–60; DOI: 10.1002/ese3.35

http://onlinelibrary.wiley.com/doi/10.1002/ese3.35/abstract


Abstract: "In April 2011, we published the first peer-reviewed analysis of the greenhouse gas footprint (GHG) of shale gas, concluding that the climate impact of shale gas may be worse than that of other fossil fuels such as coal and oil because of methane emissions. We noted the poor quality of publicly available data to support our analysis and called for further research. Our paper spurred a large increase in research and analysis, including several new studies that have better measured methane emissions from natural gas systems. Here, I review this new research in the context of our 2011 paper and the fifth assessment from the Intergovernmental Panel on Climate Change released in 2013. The best data available now indicate that our estimates of methane emission from both shale gas and conventional natural gas were relatively robust. Using these new, best available data and a 20-year time period for comparing the warming potential of methane to carbon dioxide, the conclusion stands that both shale gas and conventional natural gas have a larger GHG than do coal or oil, for any possible use of natural gas and particularly for the primary uses of residential and commercial heating. The 20-year time period is appropriate because of the urgent need to reduce methane emissions over the coming 15–35 years."

Caption: "Figure 1. Comparison of the greenhouse gas footprint of shale gas, conventional natural gas, coal, and oil to generate a given quantity of heat. Two timescales for analyzing the relative warming of methane and carbon dioxide are considered: an integrated 20-year period (top) and an integrated 100-year period (bottom). For both shale gas and conventional natural gas, estimates are shown for the lowand high-end methane emission estimates from Howarth et al.. For coal, estimates are given for surface-mined and deep-mined coal, since methane emissions are greater for deeper mines. Blue bars show the direct emissions of carbon dioxide during combustion of the fuels; the small red bars show the indirect carbon dioxide emissions associated with developing and using the fuels; and the magenta bars show methane emissions converted to g C of carbon dioxide equivalents using period appropriate global warming potentials."


See also:
http://why.knovel.com/all-engineering-news/3433-new-study-indicates-methane-production-could-accelerate-global-warming.html

http://www.wiley.com/WileyCDA/PressRelease/pressReleaseId-111081.html
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #230 on: July 24, 2014, 06:49:20 PM »
While it is not clear to me why Mauna Loa is not reporting atmospheric methane readings after May 24 2014, nevertheless the attached image (from the NOAA link), clearly indicates that atmospheric methane readings are higher this year than at any time in recorded history:

http://www.esrl.noaa.gov/gmd/dv/iadv/graph.php?code=MLO&program=ccgg&type=ts
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #231 on: July 24, 2014, 07:34:56 PM »
The linked article and associated extracts and images (the first showing the location of the already approved new plants and pipelines, and the second showing the associated projected total new CO2 emissions (if all 50 plants get built) relative to other CO2 emission targets/projections) indicate that that China's plan to build 50 new coal to gas projects will increase CO₂ emissions (compared to coal fired power plants), will increase radiative forcing by a reduction of reflected solar radiation associated with aerosols (produced by current coal-fired power plants), while still producing large amount of NOX that will still damage the health of local Chinese (it seems difficult to imagine a worse policy from a climate change, and a public health, point of view):

http://www.greenpeace.org.uk/newsdesk/energy/news/china%E2%80%99s-planned-coal-gas-emit-over-1-billion-tons-co2

Extract: "There could be 50 coal-to-gas projects operational within the next decade, producing 225 billion cubic metres of synthetic natural gas [SNG] per year, if all of the planned ones go ahead, according to comprehensive new research by Greenpeace China.
These 50 would emit around 1.087 billion tons of CO2 per year if they are developed, according to the new analysis. To put this in perspective, it is around one eighth of China’s CO2 emissions in 2011 (8.71 billion tons), and much more than the CO2 cuts from coal control measures by 2020 (655 million tons).
….
But researchers at Tsinghua University have warned (Report on China’s Low-carbon Development, 2014 [in Chinese]) that the coal-to-gas technology may not effectively lower the emission of air pollutants such as NOx  - the main contributor to China’s smog problem."


See also:
http://www.nytimes.com/2014/07/24/world/asia/greenpeace-says-chinas-energy-plans-exacerbate-climate-change.html?partner=rss&emc=rss&_r=0
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #232 on: July 25, 2014, 12:55:10 AM »
Sleepy,

Thanks for the link, and for those who did not visit the link, the attached plot shows the methane readings that Sleepy cited from Zeppelin Mountain Observatory at Svalbard from June 25 2014 to July 24 2014:
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #233 on: July 29, 2014, 04:17:51 PM »
While most GCM's already explicitly model the influence of the positive feedback from increasing atmospheric water vapor on global warming, the following paper confirms that this positive feedback is due to anthropogenic causes, and will accelerate as society stays on its current BAU pathway:

Eui-Seok Chung, Brian Soden, B. J. Sohn, and Lei Shi. Upper-tropospheric moistening in response to anthropogenic warming. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1409659111

http://www.pnas.org/content/early/2014/07/23/1409659111

Abstract: "Water vapor in the upper troposphere strongly regulates the strength of water-vapor feedback, which is the primary process for amplifying the response of the climate system to external radiative forcings. Monitoring changes in upper-tropospheric water vapor and scrutinizing the causes of such changes are therefore of great importance for establishing the credibility of model projections of past and future climates. Here, we use coupled ocean–atmosphere model simulations under different climate-forcing scenarios to investigate satellite-observed changes in global-mean upper-tropospheric water vapor. Our analysis demonstrates that the upper-tropospheric moistening observed over the period 1979–2005 cannot be explained by natural causes and results principally from an anthropogenic warming of the climate. By attributing the observed increase directly to human activities, this study verifies the presence of the largest known feedback mechanism for amplifying anthropogenic climate change."
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #234 on: July 30, 2014, 12:18:07 AM »
The linked article (with a free access pdf) indicates that as global temperatures increase, methane emissions from peat bogs will also increase (see also the attached figure):

van Winden JF, Reichart G-J, McNamara NP, Benthien A, Damsté JSS (2012) Temperature-Induced Increase in Methane Release from Peat Bogs: A Mesocosm Experiment. PLoS ONE 7(6): e39614. doi:10.1371/journal.pone.0039614

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039614

Abstract: "Peat bogs are primarily situated at mid to high latitudes and future climatic change projections indicate that these areas may become increasingly wetter and warmer. Methane emissions from peat bogs are reduced by symbiotic methane oxidizing bacteria (methanotrophs). Higher temperatures and increasing water levels will enhance methane production, but also methane oxidation. To unravel the temperature effect on methane and carbon cycling, a set of mesocosm experiments were executed, where intact peat cores containing actively growing Sphagnum were incubated at 5, 10, 15, 20, and 25°C. After two months of incubation, methane flux measurements indicated that, at increasing temperatures, methanotrophs are not able to fully compensate for the increasing methane production by methanogens. Net methane fluxes showed a strong temperature-dependence, with higher methane fluxes at higher temperatures. After removal of Sphagnum, methane fluxes were higher, increasing with increasing temperature. This indicates that the methanotrophs associated with Sphagnum plants play an important role in limiting the net methane flux from peat. Methanotrophs appear to consume almost all methane transported through diffusion between 5 and 15°C. Still, even though methane consumption increased with increasing temperature, the higher fluxes from the methane producing microbes could not be balanced by methanotrophic activity. The efficiency of the Sphagnum-methanotroph consortium as a filter for methane escape thus decreases with increasing temperature. Whereas 98% of the produced methane is retained at 5°C, this drops to approximately 50% at 25°C. This implies that warming at the mid to high latitudes may be enhanced through increased methane release from peat bogs."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #235 on: July 30, 2014, 01:11:33 AM »
The linked article (and associated extract) indicates that the increasing use of refrigeration (particularly in China) is a major source of concern with regards to anthropogenic GHG emissions (and hydrofluorocarbons alone could account for up to 50% of GHG emissions by 2050, if not adequately regulated):

http://www.nytimes.com/2014/07/27/magazine/what-do-chinese-dumplings-have-to-do-with-global-warming.html?_r=0

Extracts: "Calculating the climate-change impact of an expanded Chinese cold chain is extremely complicated. Artificial refrigeration contributes to global greenhouse-gas emissions in two main ways. First, generating the power (whether it be electricity for warehouses or diesel fuel for trucks) that fuels the heat-exchange process, which is at the heart of any cooling system, accounts for about 80 percent of refrigeration’s global-warming impact (measured in tons of CO2) and currently consumes nearly a sixth of global electricity usage.
But the other problem is the refrigerants themselves: the chemicals that are evaporated and condensed by the compressors in order to remove heat and thus produce cold. Some of that refrigerant leaks into the atmosphere as a gas — either a little (roughly 2 percent a year from the most up-to-date domestic refrigerators) or a lot (on average, 15 percent from commercial refrigerated warehouses). In addition, different refrigeration systems use different refrigerants, some of which, like ammonia, have a negligible global-warming impact. But others, like the hydrofluorocarbons that are popular in China, are known as “supergreenhouse gases,” because they are thousands of times more warming than CO2. If current trends in refrigerant usage were to continue, experts project that hydrofluorocarbons would be responsible for nearly half of all global greenhouse-gas emissions by 2050."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #236 on: July 30, 2014, 04:14:58 PM »
As a follow-on to my last post (Reply #238) about unexpectedly high hydrofluorocarbon (HFC) emissions from increasing refrigeration (particularly in China), and also to my Reply #238 about the measurement of the increasing concentration of such HFCs in the atmosphere (which is not considered with any of the RCP pathways at the measured levels), I would also like to note that the IPCC is estimating now (but again not in the RCP pathways) that residential air conditioning use worldwide are projected to increase 30-fold by 2100 (see the following linked article and associated extract); which increases both CO2 emissions associated with the increased electrical demand, but just a seriously increase the HFC leakage from all of those residential air conditioning units.


http://www.csmonitor.com/Environment/Energy-Voices/2014/0331/IPCC-global-warming-report-why-air-conditioning-rises-30-fold-by-2100-video

Extract: "Energy demand for residential air conditioning in summer is projected to increase more than 30-fold: from nearly 300 terawatt-hours (TWh) in 2000 to about 4,000 TWh in 2050 and more than 10,000 TWh in 2100, according to the report. Growing middle classes in emerging markets accounts for three quarters of that increase, with the rest resulting from climate change. The uptick in artificial cooling – itself a major source of greenhouse gases – underscores energy's role as both cause and effect of climate change."

I would imagine that when new anthropogenic emission pathways are generated to replace the current RCP scenarios; that the planners will conveniently assume that most of the potential future HFC emissions will be prevented by new regulations; however, I believe that it will prove very difficult to regulate all of these new emissions (particularly from the Third World); which means that RCP 8.5 may well be a gross underestimate of coming radiative forcing.
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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #237 on: July 30, 2014, 07:04:34 PM »
The linked reference indicates that as global temperature increase, so will the variability in temperature extremes.  This is both a problem because: (a) it will give denialist more opportunity to express doubt about climate change when cold periods occur due to increasing variability, and (b) it will result in periods of unusually high temperatures which may push some local earth systems (such as Arctic Sea Ice) past a tipping-point, which may be impractical to reverse; which could result in an acceleration of positive feedback in such local earth systems:

Evan Kodra & Auroop R. Ganguly, (2014), "Asymmetry of projected increases in extreme temperature distributions", Scientific Reports, Vol. 4,5884, doi:10.1038/srep05884

http://www.nature.com/srep/2014/140730/srep05884/full/srep05884.html


Abstract: "A statistical analysis reveals projections of consistently larger increases in the highest percentiles of summer and winter temperature maxima and minima versus the respective lowest percentiles, resulting in a wider range of temperature extremes in the future. These asymmetric changes in tail distributions of temperature appear robust when explored through 14 CMIP5 climate models and three reanalysis datasets. Asymmetry of projected increases in temperature extremes generalizes widely. Magnitude of the projected asymmetry depends significantly on region, season, land-ocean contrast, and climate model variability as well as whether the extremes of consideration are seasonal minima or maxima events. An assessment of potential physical mechanisms provides support for asymmetric tail increases and hence wider temperature extremes ranges, especially for northern winter extremes. These results offer statistically grounded perspectives on projected changes in the IPCC-recommended extremes indices relevant for impacts and adaptation studies."
« Last Edit: October 26, 2014, 03:09:03 PM by AbruptSLR »
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sidd

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #238 on: July 30, 2014, 07:40:37 PM »
I cant remember if i have mentioned this before, but a similar analysis can be done for precipitation from measured data over the last few decades. I did some small analysis for precip, results are in

http://membrane.com/sidd/precip.html

and

http://membrane.com/sidd/china-rain-soil.html

I recall that Seneviratne (and others) have some nice papers on this. I have not the time right now to find the exact  references. On the road again ...

sidd


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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #239 on: July 30, 2014, 11:49:36 PM »
sidd,

Thanks for the links.

Separately, the linked reference discusses how the researcher's work  asynchronicity between Northern Hemisphere and Southern Hemisphere "… imply that climate system predictability on decadal to century timescales may be lower than expected based on assessments of external climate forcing and Northern Hemisphere temperature variations alone."  Obviously, this means that society cannot rely on the relatively low estimates of climate sensitivity used in the current generation of GCMs, and that the actual climate sensitivity may be higher than previously thought:

Neukom, R., Gergis, J., Karoly, D.J., Wanner, H., Curran, M., Elbert, J., Gonzalez-Rouco, F., Linsley, B.K., Moy, A.D., Mundo, I., Raible, C.C., Steig, E.J., van Ommen, T., Vance, T., Villalba, R., Zinke, J. and Frank, D. (2014), "Inter-hemispheric temperature variability over the past millennium", Nature Climate Change 4: 362-367; doi:10.1038/nclimate2174


http://www.nature.com/nclimate/journal/v4/n5/full/nclimate2174.html

Abstract: "The Earth’s climate system is driven by a complex interplay of internal chaotic dynamics and natural and anthropogenic external forcing. Recent instrumental data have shown a remarkable degree of asynchronicity between Northern Hemisphere and Southern Hemisphere temperature fluctuations, thereby questioning the relative importance of internal versus external drivers of past as well as future climate variability. However, large-scale temperature reconstructions for the past millennium have focused on the Northern Hemisphere, limiting empirical assessments of inter-hemispheric variability on multi-decadal to centennial timescales. Here, we introduce a new millennial ensemble reconstruction of annually resolved temperature variations for the Southern Hemisphere based on an unprecedented network of terrestrial and oceanic palaeoclimate proxy records. In conjunction with an independent Northern Hemisphere temperature reconstruction ensemble, this record reveals an extended cold period (1594–1677) in both hemispheres but no globally coherent warm phase during the pre-industrial (1000–1850) era. The current (post-1974) warm phase is the only period of the past millennium where both hemispheres are likely to have experienced contemporaneous warm extremes. Our analysis of inter-hemispheric temperature variability in an ensemble of climate model simulations for the past millennium suggests that models tend to overemphasize Northern Hemisphere–Southern Hemisphere synchronicity by underestimating the role of internal ocean–atmosphere dynamics, particularly in the ocean-dominated Southern Hemisphere. Our results imply that climate system predictability on decadal to century timescales may be lower than expected based on assessments of external climate forcing and Northern Hemisphere temperature variations alone."

Best,
ASLR
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #240 on: July 30, 2014, 11:54:41 PM »
The following reference is related to my last post (Reply #242):

Kim M. Cobb, (2014), "Palaeoclimate: A southern misfit", Nature Climate Change, Vol 4, pp 328–329, doi:10.1038/nclimate2219

http://www.nature.com/nclimate/journal/v4/n5/full/nclimate2219.html

Abstract: "Temperature reconstructions of the past millennium rely heavily on Northern Hemisphere data. Now a Southern Hemisphere temperature reconstruction is available and sheds light on the complexity of the interhemispheric temperature relationship."
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #241 on: July 31, 2014, 12:54:44 AM »
The linked reference indicates that even the best GCMs still have trouble correctly modeling the critical Tropical Pacific cloud cover.  Thus using the Precautionary Principle we should assume higher climate sensitivity values than previously assumed:

Lin, J.-L., Qian, T. and Shinoda, T. (2014) "Stratocumulus clouds in Southeastern Pacific simulated by eight CMIP5-CFMIP global climate models", Journal of Climate 27: 3000-3022, doi: http://dx.doi.org/10.1175/JCLI-D-13-00376.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-13-00376.1


Abstract: "This study examines the stratocumulus clouds and associated cloud feedback in the southeast Pacific (SEP) simulated by eight global climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) and Cloud Feedback Model Intercomparison Project (CFMIP) using long-term observations of clouds, radiative fluxes, cloud radiative forcing (CRF), sea surface temperature (SST), and large-scale atmosphere environment. The results show that the state-of-the-art global climate models still have significant difficulty in simulating the SEP stratocumulus clouds and associated cloud feedback. Comparing with observations, the models tend to simulate significantly less cloud cover, higher cloud top, and a variety of unrealistic cloud albedo. The insufficient cloud cover leads to overly weak shortwave CRF and net CRF. Only two of the eight models capture the observed positive cloud feedback at subannual to decadal time scales. The cloud and radiation biases in the models are associated with 1) model biases in large-scale temperature structure including the lack of temperature inversion, insufficient lower troposphere stability (LTS), and insufficient reduction of LTS with local SST warming, and 2) improper model physics, especially insufficient increase of low cloud cover associated with larger LTS. The two models that arguably do best at simulating the stratocumulus clouds and associated cloud feedback are the only ones using cloud-top radiative cooling to drive boundary layer turbulence."
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Bruce Steele

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #242 on: July 31, 2014, 06:14:51 PM »
Here is a paper that attempts to quantify the effects of acidification on the atmospheric Co2 content for 2100. Although this paper only projects an increase of 45 ppm Co2 by 2100 due to acidification  it uses older Mesocosm studies by Riebesell rather than more recent work that shows a change from current phytoplankton populations to future populations more dominated by pico and nano- plankton populations and potential negative effects on ballasting of particulate organic matter. So populating this model with newer data might change the results this study does show acidification contributes to increased future atmospheric Co2 levels.

http://www.biogeosciences.net/11/3965/2014/bg-11-3965-2014.pdf

sidd

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #243 on: July 31, 2014, 11:15:26 PM »
A phrase in French: "Ce saute aux yeux," it jumps  at my eyes
 
from the abstract to the Gergis paper :

"The current (post-1974) warm phase is the only period of the past millennium where both hemispheres are likely to have experienced contemporaneous warm extremes."

This tells me that human forcing in the post 1974 period exceeds natural variability over the past millennium at least. This is a strong result, if true.

sidd

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #244 on: August 01, 2014, 03:21:03 AM »
sidd,

I fully agree with you regarding the Gergis paper, and here is another important reference:

The linked reference (with a free access pdf) provides further physical evidence that the Earth System Sensitivity, ESS (or long-term climate sensitivity) is larger than previously thought; which could be very bad news for abrupt climate change this century if society stays on a BAU pathway:

Franks, P. J., D. L. Royer, D. J. Beerling, P. K. Van de Water, D. J. Cantrill, M. M. Barbour, and J. A. Berry (2014), "New constraints on atmospheric CO₂ concentration for the Phanerozoic", Geophys. Res. Lett., 41, 4685–4694, doi:10.1002/2014GL060457.


http://droyer.web.wesleyan.edu/Franks_et_al_2014_GRL_new_stomatal-CO2_proxy.pdf


Abstract: "Earth’s atmospheric CO2 concentration (ca) for the Phanerozoic Eon is estimated from proxies and geochemical carbon cycle models. Most estimates come with large, sometimes unbounded uncertainty. Here, we calculate tightly constrained estimates of ca using a universal equation for leaf gas exchange, with key variables obtained directly from the carbon isotope composition and stomatal anatomy of fossil leaves. Our new estimates, validated against ice cores and direct measurements of ca, are less than 1000 ppm for most of the Phanerozoic, from the Devonian to the present, coincident with the appearance and global proliferation of forests. Uncertainties, obtained from Monte Carlo simulations, are typically less than for ca estimates from other approaches. These results provide critical new empirical support for the emerging view that large (~2000–3000 ppm), long-term swings in ca do not characterize the post-Devonian and that Earth’s long-term climate sensitivity to ca is greater than originally thought."

Best,
ASLR
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AbruptSLR

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Re: Selected Forcing Factor for Abrupt SLR from the Collapse of the WAIS
« Reply #245 on: August 02, 2014, 02:17:46 AM »
The linked reference indicates that open biomass burning (including wildfires) will contribute significantly to global warming.  This is a higher contribution than what is accounted for the current GCM projections:

Jacobson, M. Z. (2014), "Effects of biomass burning on climate, accounting for heat and moisture fluxes, black and brown carbon, and cloud absorption effects", J. Geophys. Res. Atmos., 119, doi:10.1002/2014JD021861.

http://onlinelibrary.wiley.com/doi/10.1002/2014JD021861/abstract;jsessionid=1BEE610776F05245479DC69AFEDD35BC.f01t01

Abstract: "This paper examines the effects on climate and air pollution of open biomass burning (BB) when heat and moisture fluxes, gases and aerosols (including black and brown carbon, tar balls, and reflective particles), cloud absorption effects (CAEs) I and II, and aerosol semidirect and indirect effects on clouds are treated. It also examines the climate impacts of most anthropogenic heat and moisture fluxes (AHFs and AMFs). Transient 20 year simulations indicate BB may cause a net global warming of ~0.4 K because CAE I (~32% of BB warming), CAE II, semidirect effects, AHFs (~7%), AMFs, and aerosol absorption outweigh direct aerosol cooling and indirect effects, contrary to previous BB studies that did not treat CAEs, AHFs, AMFs, or brown carbon. Some BB warming can be understood in terms of the anticorrelation between instantaneous direct radiative forcing (DRF) changes and surface temperature changes in clouds containing absorbing aerosols. BB may cause ~250,000 (73,000–435,000) premature mortalities/yr, with >90% from particles. AHFs from all sources and AMFs + AHFs from power plants and electricity use each may cause a statistically significant +0.03 K global warming. Solar plus thermal-IR DRFs were +0.033 (+0.027) W/m2 for all AHFs globally without (with) evaporating cooling water, +0.009 W/m2 for AMFs globally, +0.52 W/m2 (94.3% solar) for all-source BC outside of clouds plus interstitially between cloud drops at the cloud relative humidity, and +0.06 W/m2 (99.7% solar) for BC inclusions in cloud hydrometeor particles. Modeled post-1850 biomass, biofuel, and fossil fuel burning, AHFs, AMFs, and urban surfaces accounted for most observed global warming."
“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 #246 on: August 02, 2014, 02:24:51 AM »
The linked reference indicates that the Earth System Sensitivity, ESS, may be bigger than previously thought; however, it does not indicate how quickly the positive feedback from the synchronization of the North Pacific and North Atlantic climates:

Summer K. Praetorius, Alan C. Mix, (2014), "Synchronization of North Pacific and Greenland climates preceded abrupt deglacial warming", Science 25 July 2014: Vol. 345 no. 6195 pp. 444-448 DOI: 10.1126/science.1252000

http://www.sciencemag.org/content/345/6195/444

Abstract: "Some proposed mechanisms for transmission of major climate change events between the North Pacific and North Atlantic predict opposing patterns of variations; others suggest synchronization. Resolving this conflict has implications for regulation of poleward heat transport and global climate change. New multidecadal-resolution foraminiferal oxygen isotope records from the Gulf of Alaska (GOA) reveal sudden shifts between intervals of synchroneity and asynchroneity with the North Greenland Ice Core Project (NGRIP) δ18O record over the past 18,000 years. Synchronization of these regions occurred 15,500 to 11,000 years ago, just prior to and throughout the most abrupt climate transitions of the last 20,000 years, suggesting that dynamic coupling of North Pacific and North Atlantic climates may lead to critical transitions in Earth’s climate system."
“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 #247 on: August 02, 2014, 05:38:22 AM »
The following quote, and link, are from zworld from a post in the Arctic folder:

"OH radicals have been decreasing in the atmosphere. A paper from the Goddard Space Center in 2009 suggested that the loss of sea ice will reduce OH numbers even further, with late-summer OH concentrations over northern high latitudes reduced 30-60% when removing sea ice in that season, due to the reduction in photo-dissociation rates.

“These results suggest that the tropospheric oxidizing capacity could change dramatically over the Arctic if summer sea ice is to retreat in the future, something that could impact the removal of important gases (methane, carbon monoxide) in this region.”

http://www.giss.nasa.gov/research/briefs/voulgarakis_01/
"
As OH in the atmosphere is required to convert methane into carbon dioxide, a marked drop on OH when the Arctic summer sea ice extent retreats, this will extend the life of the methane in the atmosphere which will increase the Global Warming Potential, GWP, of methane (which will increase equilibrium climate sensitivity, ECS.

See: Voulgarakis, A., X. Yang, and J. A. Pyle, (2009), "How different would tropospheric oxidation be over an ice-free Arctic?", Geophys. Res. Lett., 36, L23807, doi:10.1029/2009GL040541

http://onlinelibrary.wiley.com/doi/10.1029/2009GL040541/abstract
« Last Edit: August 02, 2014, 06:03:39 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 #248 on: August 02, 2014, 06:01:21 PM »
Soil-organic-carbon (SOC) processes release about 60 billion tons of carbon into the atmosphere each year (which is more than the annual anthropogenic fossil fuel contribution) so small increases in a big number can have a meaningful impact on the rate of global warming, and some recent studies (see Bond-Lamberty & Thomson [2010] at the bottom of the post) have reported increases in SOC releases; which have raised concerns.  The Giadina et al (2014) reference cited below indicates (based on research in Hawaii) that the reported increases in SOC releases may be due to transient changes in releases in litterfall and in below ground carbon flux, while over-all SOC emissions may not increase with increasing temperatures.  While this research indicates that any positive feedback mechanism associated with SOC process may not be as strong as previously feared; I would like to sound a note of caution against over-optimism as SOC releases is a complex matter (see Reply #18 discussing the influence of earthworms on soil emissions and global warming) and lessons learned in Hawaii may, or may not, be applicable to other areas around the world.

Christian P. Giardina, Creighton M. Litton, Susan E. Crow & Gregory P. Asner, (2014), "Warming-related increases in soil CO2 efflux are explained by increased below-ground carbon flux", Nature Climate Change,  doi:10.1038/nclimate2322

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2322.html

Abstract: "The universally observed exponential increase in soil-surface CO2 efflux (‘soil respiration'; FS) with increasing temperature has led to speculation that global warming will accelerate soil-organic-carbon (SOC) decomposition, reduce SOC storage, and drive a positive feedback to future warming. However, interpreting temperature–FS relationships, and so modelling terrestrial carbon balance in a warmer world, is complicated by the many sources of respired carbon that contribute to FS and a poor understanding of how temperature influences SOC decomposition rates. Here we quantified FS, litterfall, bulk SOC and SOC fraction size and turnover, and total below-ground carbon flux (TBCF) across a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forest. From these, we determined that: increases in TBCF and litterfall explain >90% of the increase in FS with MAT; bulk SOC and SOC fraction size and turnover rate do not vary with MAT; and increases in TBCF and litterfall do not influence SOC storage or turnover on century to millennial timescales. This gradient study shows that for tropical montane wet forest, long-term and whole-ecosystem warming accelerates below-ground carbon processes with no apparent impact on SOC storage."

Bond-Lamberty, B. & Thomson, A. Temperature-associated increases in the global soil respiration record. Nature 464, 579–582 (2010).
“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 #249 on: August 03, 2014, 08:47:46 PM »
The following McGregor et al (2014) linked reference about the recent (since 2002) strengthening of the Pacific trade winds (and the associated Walker Cell circulation) can largely be attributed to the recent trend of warming in the North Atlantic (see the attached figure and associated caption). 

McGregor, S., A. Timmermann, M. F. Stuecker, M. H. England, M. Merrifield, F.-F. Jin and Y. Chikamoto, (2014), "Recent Walker circulation strengthening and Pacific cooling amplified by Atlantic warming", Nature Climate Change; doi:10.1038/nclimate2330

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2330.html

Abstract: "An unprecedented strengthening of Pacific trade winds since the late 1990s has caused widespread climate perturbations, including rapid sea-level rise in the western tropical Pacific, strengthening of Indo-Pacific ocean currents, and an increased uptake of heat in the equatorial Pacific thermocline. The corresponding intensification of the atmospheric Walker circulation is also associated with sea surface cooling in the eastern Pacific, which has been identified as one of the contributors to the current pause in global surface warming. In spite of recent progress in determining the climatic impacts of the Pacific trade wind acceleration, the cause of this pronounced trend in atmospheric circulation remains unknown. Here we analyse a series of climate model experiments along with observational data to show that the recent warming trend in Atlantic sea surface temperature and the corresponding trans-basin displacements of the main atmospheric pressure centres were key drivers of the observed Walker circulation intensification, eastern Pacific cooling, North American rainfall trends and western Pacific sea-level rise. Our study suggests that global surface warming has been partly offset by the Pacific climate response to enhanced Atlantic warming since the early 1990s."
However, one of the co-authors of the McGregor et al 2014 article, Matthew England, is quoted (in the subsequent extract from the linked Discovery website) as saying: "It will be difficult to predict when the Pacific cooling trend and its contribution to the global hiatus in surface temperatures will come to an end. However, a large El Niño event is one candidate that has the potential to drive the system back to a more synchronized Atlantic/Pacific warming situation."

Caption for figure: "Atlantic and Pacific SST anomalies and their effect on SLP anomaly and wind anomalies.  a, Basin-averaged Atlantic(30 S–60 N, 70W–20 E) and Pacific (30 S–60 N, 120 E–90 W) SST anomalies from the ERSST dataset ; the solid red and blue lines represent 11-month running mean values of Atlantic and Pacific basin SST anomalies, respectively.  b, Detrended SST anomaly difference (shading; 11-month running mean TBV index) between the red and blue time series in the upper panel, western tropical Pacific (160 E–180 E and 5 S–5 N); orange (blue) shading indicates a warmer (colder) Atlantic compared to the Pacific ; detrended zonal surface wind velocity anomalies (black line) from twentieth century reanalysis24 (11-month running mean filter); and the 11-month running mean of the detrended Atlantic/Pacific SLP anomaly difference (cyan line, same areas as for SST). The table inset in b gives the correlation coefficient calculated across the three time series shown."

http://news.discovery.com/earth/global-warming/global-warming-kicks-up-record-pacific-trade-winds-140803.htm

Extract: "It will be difficult to predict when the Pacific cooling trend and its contribution to the global hiatus in surface temperatures will come to an end," co-author Matthew England said. "However, a large El Niño event is one candidate that has the potential to drive the system back to a more synchronized Atlantic/Pacific warming situation."

However, it is important to note that the following linked Praetorius et al (2014) article provides paleo-evidence that the North Pacific and the North Atlantic will likely synchronize with increasing global warming, meaning that the global cooling effect of the recent El Nino hiatus is likely to be short lived

Summer K. Praetorius, Alan C. Mix, (2014), "Synchronization of North Pacific and Greenland climates preceded abrupt deglacial warming", Science 25 July 2014: Vol. 345 no. 6195 pp. 444-448 DOI: 10.1126/science.1252000

http://www.sciencemag.org/content/345/6195/444

Furthermore, the following linked reference indicates that before 2040 CMIP5 models indicate that the amplitude of the ENSO phases will increase, indicating that when the El Nino events return for the next 25-years they are likely to be stronger than previously experienced leading to more abrupt climate change and more abrupt ice mass loss from the WAIS.

Seon Tae Kim, Wenju Cai, Fei-Fei Jin, Agus Santoso, Lixin Wu, Eric Guilyardi & Soon-Il An, (2014), "Response of El Niño sea surface temperature variability to greenhouse warming", Nature Climate Change, doi:10.1038/nclimate2326


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2326.html

Abstract: "The destructive environmental and socio-economic impacts of the El Niño/Southern Oscillation (ENSO) demand an improved understanding of how ENSO will change under future greenhouse warming. Robust projected changes in certain aspects of ENSO have been recently established. However, there is as yet no consensus on the change in the magnitude of the associated sea surface temperature (SST) variability, commonly used to represent ENSO amplitude, despite its strong effects on marine ecosystems and rainfall worldwide. Here we show that the response of ENSO SST amplitude is time-varying, with an increasing trend in ENSO amplitude before 2040, followed by a decreasing trend thereafter. We attribute the previous lack of consensus to an expectation that the trend in ENSO amplitude over the entire twenty-first century is unidirectional, and to unrealistic model dynamics of tropical Pacific SST variability. We examine these complex processes across 22 models in the Coupled Model Intercomparison Project phase 5 (CMIP5) database, forced under historical and greenhouse warming conditions. The nine most realistic models identified show a strong consensus on the time-varying response and reveal that the non-unidirectional behaviour is linked to a longitudinal difference in the surface warming rate across the Indo-Pacific basin. Our results carry important implications for climate projections and climate adaptation pathways."
« Last Edit: August 04, 2014, 07:19:49 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson