Hi Alvia and all, Kevin Whilden has got the message about the Arctic sea ice, from the AGU, and deduces the need for geoengineering to save it. Kevin's posting is the very next following the last in Alvia's posting yesterday (from Bob Wallace, no. 27, Dec 20th at 2.26 am).
>From the Climate Progress blog: http://climateprogress.org/2008/12/19/agu-how-desperate-are-climate-scientists-desperate-enough-to-contemplate-geo-engineering/ 28. Kevin Whilden Says: December 20th, 2008 at 11:41 am I attended AGU, and there were a number of eye openers. Most relevant to this debate is the Arctic problem. More than anything, this will necessitate the use of geoengineering. Here is the problem: #1: The Arctic sea ice is the crux The Arctic sea ice is melting much more rapidly than anyone expected last year. No reader of this blog is unaware of that. However, what happens when the sea ice is gone? In one of the Arctic Sea Ice sessions, David Lawrence shows how rapid melting of the sea ice sets up a feedback loop that also rapidly melts arctic permafrost. His models show that within 100 years, all of the permafrost also melts. #2: The permafrost carbon reservoir is scary large. There were a number of sessions on the store of organic carbon and methane buried in permafrost, which will release rapidly upon thawing of the permafrost. It takes about 100 years for organic carbon in permafrost to be fully released as methane, and methane clathrates release probably much faster than that. Estimates of the size of the total carbon reservoir vary widely (it is one of the great unknowns, and not even included in the IPCC carbon inventory). However, it seems that there is at least 1000 GtC in organic carbon and another 1000 GtC in methane clathrates. I saw one talk that suggests the inventory is closer to 8000 GtC - I try not to think about that. #3 A 2000 GtC release from permafrost within the next 200 years is “game over”. Do the math yourself… convert C to CO2 (multiply by 3.67), and then CO2 to CH4 (multiply by 24). Divide by the historic total of human CO2 emissions (1,800 GtCO2). The total CO2-equivalent release equals 98 times the total CO2 emissions by humans since the Industrial Revolution. At this point, it doesn’t matter how much we reduce current annual CO2 emissions over the next 20 years. #4 Geoengineering is the only way to save the Arctic sea ice Reducing emissions isn’t going to do it, as we’ve already passed the tipping point of the sea ice (as Jim Hansen said in his talk, and many other talks). Sadly, the IPCC reports that Arctic sea ice will disappear sometime around 2080, but we now know that it is a wildly non-linear process and will disappear probably within ten years. We need to change the radiative forcing balance of the Arctic asap, probably within the next few years, because once the ice is gone, not even the most drastic geoengineering can get it back. That is the “game over” scenario. We had better start figuring out how to do geoengineering right. BTW, Kevin has studied permafrost in the Antarctic. http://www.climos.com/bios/kwhildenbio.html Is Kevin (still) signed onto this geoengineering googlegroup? Cheers, John --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
