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Author Topic: Toward a complete list of climate feedbacks  (Read 49687 times)

wili

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Re: Toward a complete list of climate feedbacks
« Reply #50 on: November 17, 2013, 07:05:41 PM »
Here's the latest (that I know if) by McPherson.

https://www.youtube.com/watch?v=QDdhL3hLP-M&feature=youtu.be

Most of the second half of the talk is a list of 26 positive feedbacks, most backed by studies in major, peer reviewed journals. (Makes me wonder if he's been reading these threads!)

Most of the feedbacks involve the Arctic (and to a lesser degree the Antarctic).

I would love to hear anyone's reactions and analysis of his collection of findings and his interpretation of them (though certain people may want to avoid listening to this if it is going to upset them too much).


ETA: I found a list of 19 of the feedbacks in an earlier article of his (non-peer reviewed):

1) Methane hydrates are bubbling out the Arctic Ocean (Science, March 2010). According to NASA’s CARVE project, these plumes were up to 150 kilometers across as of mid-July 2013. Whereas Malcolm Light’s 9 February 2012 forecast of extinction of all life on Earth by the middle of this century appears premature because his conclusion of exponential methane release during summer 2011 was based on data subsequently revised and smoothed by U.S. government agencies, subsequent information — most notably from NASA’s CARVE project — indicates the grave potential for catastrophic release of methane. Catastrophically rapid release of methane in the Arctic is further supported by Nafeez Ahmed’s thorough analysis in the 5 August 2013 issue of the Guardian.

2) Warm Atlantic water is defrosting the Arctic as it shoots through the Fram Strait (Science, January 2011).

3) Siberian methane vents have increased in size from less than a meter across in the summer of 2010 to about a kilometer across in 2011 (Tellus, February 2011).

4)Drought in the Amazon triggered the release of more carbon than the United States in 2010 (Science, February 2011).

5) Peat in the world’s boreal forests is decomposing at an astonishing rate (Nature Communications, November 2011).

6)Invasion of tall shrubs warms the soil, hence destabilizes the permafrost (Environmental Research Letters, March 2012).

7) Greenland ice is darkening (The Cryosphere, June 2012).

8) Methane is being released from the Antarctic, too (Nature, August 2012). According to a paper in the 24 July 2013 issue of Scientific Reports, melt rate in the Antarctic has caught up to the Arctic.

9)Russian forest and bog fires are growing (NASA, August 2012), a phenomenon consequently apparent throughout the northern hemisphere (Nature Communications, July 2013). The New York Times reports hotter, drier conditions leading to huge fires in western North America as the “new normal” in their 1 July 2013 issue. A paper in the 22 July 2013 issue of the Proceedings of the National Academy of Sciences indicates boreal forests are burning at a rate exceeding that of the last 10,000 years.

10) Cracking of glaciers accelerates in the presence of increased carbon dioxide (Journal of Physics D: Applied Physics, October 2012).

11)The Beaufort Gyre apparently has reversed course (U.S. National Snow and Ice Data Center, October 2012).

12) Exposure to sunlight increases bacterial conversion of exposed soil carbon, thus accelerating thawing of the permafrost (Proceedings of the National Academy of Sciences, February 2013).

13)The microbes have joined the party, too, according to a paper in the 23 February 2013 issue of New Scientist.

14) Summer ice melt in Antarctica is at its highest level in a thousand years: Summer ice in the Antarctic is melting 10 times quicker than it was 600 years ago, with the most rapid melt occurring in the last 50 years (Nature Geoscience, April 2013).

15) Floods in Canada are sending pulses of silty water out through the Mackenzie Delta and into the Beaufort Sea, thus painting brown a wide section of the Arctic Ocean near the Mackenzie Delta (NASA, June 2013).

16) Surface meltwater draining through cracks in an ice sheet can warm the sheet from the inside, softening the ice and letting it flow faster, according to a study accepted for publication in the Journal of Geophysical Research: Earth Surface (July 2013). It appears a Heinrich Event has been triggered in Greenland. Consider the description of such an event as provided by Robert Scribbler on 8 August 2013:

    "In a Heinrich Event, the melt forces eventually reach a tipping point. The warmer water has greatly softened the ice sheet. Floods of water flow out beneath the ice. Ice ponds grow into great lakes that may spill out both over top of the ice and underneath it. Large ice damns (sic) may or may not start to form. All through this time ice motion and melt is accelerating. Finally, a major tipping point is reached and in a single large event or ongoing series of such events, a massive surge of water and ice flush outward as the ice sheet enters an entirely chaotic state. Tsunamis of melt water rush out bearing their vast floatillas (sic) of ice burgs (sic), greatly contributing to sea level rise. And that’s when the weather really starts to get nasty. In the case of Greenland, the firing line for such events is the entire North Atlantic and, ultimately the Northern Hemisphere."

17) Breakdown of the thermohaline conveyor belt is happening in the Antarctic as well as the Arctic, thus leading to melting of Antarctic permafrost (Scientific Reports, July 2013).

18) Loss of Arctic sea ice is reducing the temperature gradient between the poles and the equator, thus causing the jet stream to slow and meander. One result is the creation of weather blocks such as the recent very high temperatures in Alaska. As a result, boreal peat dries and catches fire like a coal seam. The resulting soot enters the atmosphere to fall again, coating the ice surface elsewhere, thus reducing albedo and hastening the melting of ice. Each of these individual phenomena has been reported, albeit rarely, but to my knowledge the dots have not been connected beyond this space. The inability or unwillingness of the media to connect two dots is not surprising, and has been routinely reported (recently including here with respect to climate change and wildfires) (July 2013).

19) Arctic ice is growing darker, hence less reflective (Nature Climate Change, August 2013).
- See more at: http://transitionvoice.com/2013/08/19-ways-climate-change-is-now-feeding-itself/#sthash.SsTKUVlU.dpuf
« Last Edit: November 17, 2013, 08:52:20 PM by wili »
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

sidd

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Re: Toward a complete list of climate feedbacks
« Reply #51 on: November 18, 2013, 04:36:21 AM »
I am pressed for time, but i will attempt to summarize. 1950 co2 is 310 ppm, model is Russell's, albedo flip is put in by hand modelling Greenland and Antarctica as tundra. Ocean is also simplified, and convection is modelled with the moist stability criterion, with clouds parametrised. 

There are many shortcomings to this modelling scheme, which i lack the time to discuss. But Hansen apparently believes it enuf, so we should read the paper carefully.

Results:
Divide 310 ppm by 8 you get snowball earth. Albedo flip makes current sensitivity (the region around 1 in the logarithmic abcissa) to doubled CO2 to 5C. Spike in sensitivity after 8 times 310 ppm, in the 16 to 42 factor (4 to 5 doublings),  decreasing after due to cloud albedo.

sidd

wili

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Re: Toward a complete list of climate feedbacks
« Reply #52 on: November 18, 2013, 10:29:20 AM »
Thanks, sidd. That makes some sense. Am I right that 5 is higher than most of the other models for sensitivity? We're nearly half way to the first doubling of CO2 from 280 ppm to 560. Would this model imply that, if we were somehow to stay at this level of CO2 concentration, that the temperature would eventually balance out at about 2 degrees C above pre-industrial?
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

sidd

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Re: Toward a complete list of climate feedbacks
« Reply #53 on: November 19, 2013, 06:15:41 AM »
Sorry, i have no time now, but i may put up extended discussion later somewhere.

yes 5 C is high for sensitivity, this they say is due to increased albedo flip, but i think the shallow ocean also




wili

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Re: Toward a complete list of climate feedbacks
« Reply #54 on: November 20, 2013, 06:34:29 PM »
Thanks again, sidd. If you do post a further discussion some where else, perhaps you could provide a link to it for us?

Meanwhile:

Current climate change models greatly underestimate the amount of methane being released by thawing permafrost in the Canadian Arctic, according to Canada's National Institute of Scientific Research (INRS).
Quote
Canadian, French and US researchers from the INRS have been studying the methane and greenhouse gas emissions in small thaw ponds, concluding that the emissions could have a significant climate impact.

"We discovered that although the small shallow ponds we studied represent only 44 percent of the water-covered surface in a Bylot Island valley, they generate 83 percent of its methane emissions," said Karita Negandhi, a water sciences doctoral student at the INRS's Environment Research Center.

http://www.natureworldnews.com/articles/4972/20131118/ponds-canadian-arctic-release-significant-greenhouse-gasses.ht

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