Comments on: What drove the dramatic retreat of arctic sea ice during summer 2007? http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/ The Latest on Climate Science, Solutions, and Politics Sun, 22 Nov 2009 08:16:08 -0500 http://wordpress.org/?v=2.8.5 hourly 1 By: llewelly http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15196 llewelly Mon, 30 Jun 2008 00:48:57 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15196 john: <blockquote> Examine what happened in the PETM and in the Permian die-off. If you keep an open mind that should convince you it’s at least likely, if not inevitable at this point. </blockquote> How long did the PETM take to happen? How long did the P-T warming take? I have read 10,000 years for the former, and similar figures for the latter. The carbon-cycle positive feedbacks and methane releases theorized to explain those warmings took time to do their work - probably a lot more time than 200 years. In any case, I think you've answered my question - substantial melt of EAIS in less than 200 years appears to require either positive carbon-cycle feedbacks, methane gas releases, or massive human emissions, at or exceeding the worst of the IPCC scenarios. (I will grant that positive carbon-cycle feedbacks are looking more and more likely. I will also grant that widespread coal-to-liquids could put human emissions at or exceeding the worst of the IPCC scenarios.) john:

Examine what happened in the PETM and in the Permian die-off. If you keep an open mind that should convince you it’s at least likely, if not inevitable at this point.

How long did the PETM take to happen? How long did the P-T warming take? I have read 10,000 years for the former, and similar figures for the latter. The carbon-cycle positive feedbacks and methane releases theorized to explain those warmings took time to do their work – probably a lot more time than 200 years. In any case, I think you’ve answered my question – substantial melt of EAIS in less than 200 years appears to require either positive carbon-cycle feedbacks, methane gas releases, or massive human emissions, at or exceeding the worst of the IPCC scenarios. (I will grant that positive carbon-cycle feedbacks are looking more and more likely. I will also grant that widespread coal-to-liquids could put human emissions at or exceeding the worst of the IPCC scenarios.)

]]> By: David B. Benson http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15173 David B. Benson Sun, 29 Jun 2008 18:55:04 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15173 There is no enough study of the Miocene Antarctic melt. At least I don't know much of anything about it. There is no enough study of the Miocene Antarctic melt. At least I don’t know much of anything about it.

]]> By: Joe http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15159 Joe Sun, 29 Jun 2008 12:18:56 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15159 If we go to 1000 ppm, as now seems likely, the East Antarctic Ice Sheet can't possibly survive. If we warm another 3°C, then the planet will be warmer than it was last time we were ice free, including no EAIS. We are headed to warming perhaps another 5°C -- or more. So we will probably lose much of Greenland and WAIS and a good chunk of EAIS over the next 200 years. If we go to 1000 ppm, as now seems likely, the East Antarctic Ice Sheet can’t possibly survive. If we warm another 3°C, then the planet will be warmer than it was last time we were ice free, including no EAIS. We are headed to warming perhaps another 5°C — or more. So we will probably lose much of Greenland and WAIS and a good chunk of EAIS over the next 200 years.

]]> By: john http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15153 john Sun, 29 Jun 2008 04:04:32 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15153 I won't speak for Joe, but I believe it is likely. Why? Because if we don't act to halt carbon emissions and ultimately reduce atmospheric concentrations to less than 350 ppm, we face a number of nasty feedback loops which will cause the atmosphere to heat and the ice to melt. This has happened twice before (at least -- both were due to extreme volcanic activity causing emissions comparable to what humans are causing now (albeit the volcanic emissions occurred at a much slower rate than we are now emitting). Examine what happened in the PETM and in the Permian die-off. If you keep an open mind that should convince you it's at least likely, if not inevitable at this point. I won’t speak for Joe, but I believe it is likely. Why? Because if we don’t act to halt carbon emissions and ultimately reduce atmospheric concentrations to less than 350 ppm, we face a number of nasty feedback loops which will cause the atmosphere to heat and the ice to melt.

This has happened twice before (at least — both were due to extreme volcanic activity causing emissions comparable to what humans are causing now (albeit the volcanic emissions occurred at a much slower rate than we are now emitting).

Examine what happened in the PETM and in the Permian die-off. If you keep an open mind that should convince you it’s at least likely, if not inevitable at this point.

]]> By: llewelly http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15152 llewelly Sun, 29 Jun 2008 03:43:03 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15152 <blockquote> Next stop for them — East Antarctica, which is probably good for another century or two. </blockquote> Do you really think the East Antarctic Ice Sheet is likely to melt substantially (say, more than 10%) within the next 200 years? If so, why?

Next stop for them — East Antarctica, which is probably good for another century or two.

Do you really think the East Antarctic Ice Sheet is likely to melt substantially (say, more than 10%) within the next 200 years? If so, why?

]]> By: Paul K http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15142 Paul K Sat, 28 Jun 2008 16:34:44 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15142 There's an inadvertent extra "." in Mario's link. <a href="http://www.nichols.edu/departments/Glacier/deathglacier.htm" rel="nofollow">This</a> should work. There’s an inadvertent extra “.” in Mario’s link. This should work.

]]> By: Mauri Pelto http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15134 Mauri Pelto Sat, 28 Jun 2008 11:02:43 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15134 Preconditioning from years of warmth. Where have I read-written the same words. Oh, yeah with respect to the loss of ice shelves in Antarctica. Oh, and with the loss of several glaciers in the North Cascades. http://www.nichols.edu/departments/Glacier/deathglacier.htm. This is the chorus line for losing ice. Preconiditioning from years of warmth. Preconditioning from years of warmth. Where have I read-written the same words. Oh, yeah with respect to the loss of ice shelves in Antarctica. Oh, and with the loss of several glaciers in the North Cascades. http://www.nichols.edu/ departments/ Glacier/ deathglacier.htm. This is the chorus line for losing ice. Preconiditioning from years of warmth.

]]> By: Nylo http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15133 Nylo Sat, 28 Jun 2008 08:22:34 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15133 http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.jpg http://arctic.atmos.uiuc.edu/ cryosphere/ IMAGES/ current.365.jpg

]]> By: Paul K http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15121 Paul K Sat, 28 Jun 2008 02:13:53 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15121 Joe, Yes and NASA scientists, in studies specific to recent arctic melting, found the cause of the arctic warm climate to be oscillations. That's the fact. Joe,
Yes and NASA scientists, in studies specific to recent arctic melting, found the cause of the arctic warm climate to be oscillations. That’s the fact.

]]> By: Joe http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15119 Joe Sat, 28 Jun 2008 01:41:48 +0000 http://climateprogress.org/2008/06/27/what-drove-the-dramatic-retreat-of-arctic-sea-ice-during-summer-2007/#comment-15119 Paul -- we apparently read a different abstract: "Arctic sea ice in 2007 was preconditioned to radical changes after years of shrinking and thinning in a warm climate." Paul — we apparently read a different abstract:
“Arctic sea ice in 2007 was preconditioned to radical changes after years of shrinking and thinning in a warm climate.”

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