<![CDATA[Grist - Comment Feed for And at what temperature Greenland’s ice sheet will melt]]> Grist Comment Feed en Comment #1 by JMG http://www.grist.org/article/a-very-good-article-on-tipping-points/ Sat, 18 Aug 2007 10:49:43 -0700 http://www.grist.org/article/a-very-good-article-on-tipping-points/1 The best book on tipping points

that I've found so far is "With Speed and Violence" by Fred Pierce.  I just got it back from a friend, who used to be a science writer for the National Park Service (in the days when Creationist tracts weren't being offered in the Grand Canyon gift shops) -- she said she couldn't finish it because it frightened her for her grandchildren too much.  It is not written that way--but the implications of the manifold carbon bombs with their fuses lit are definitely sobering.

Save the world: Reduce greenhouse gas emissions 5% annually.

]]> The best book on tipping points

that I've found so far is "With Speed and Violence" by Fred Pierce.  I just got it back from a friend, who used to be a science writer for the National Park Service (in the days when Creationist tracts weren't being offered in the Grand Canyon gift shops) -- she said she couldn't finish it because it frightened her for her grandchildren too much.  It is not written that way--but the implications of the manifold carbon bombs with their fuses lit are definitely sobering.

Save the world: Reduce greenhouse gas emissions 5% annually.

]]> Comment #2 by Colin Wright http://www.grist.org/article/a-very-good-article-on-tipping-points/ Sat, 18 Aug 2007 19:48:46 -0700 http://www.grist.org/article/a-very-good-article-on-tipping-points/2 Thanks. A great readable paper, but ...

I wonder if it is superceded by Hansen's recent work on the "albedo flip property of ice/water". For instance, compare each author's words on the Greenland Ice Sheet.
Hansen:An ice sheet response time of centuries seems probable, and we cannot rule out large changes on decadal time-scales once wide-scale surface melt is underway.

Lenton:The timescale for the ice sheet to melt is at least 300 years and often given as roughly 1000 years.
Or on the West Antarctic Ice Sheet.
Hansen:
We find it implausible that BAU scenarios ... would permit a West Antarctic ice sheet of present size to survive even for a century.

Lenton:The West Antarctic Ice Sheet (WAIS) is thought to be less vulnerable to warming than the Greenland Ice Sheet but a threshold could still be accessed this century

I'm no expert, and there could be no real contradictions here between the authors. But there does at least seem to be a difference of emphasis. The albedo-flip picture could be a more important, more holistic way to look at the Earth than a series of tipping points.

Incidentally, I heard on the radio today that the Arctic ice cap extent is at its smallest size ever -- yet we still have at least another month of summer melting to go.





]]> Thanks. A great readable paper, but ...

I wonder if it is superceded by Hansen's recent work on the "albedo flip property of ice/water". For instance, compare each author's words on the Greenland Ice Sheet.
Hansen:An ice sheet response time of centuries seems probable, and we cannot rule out large changes on decadal time-scales once wide-scale surface melt is underway.

Lenton:The timescale for the ice sheet to melt is at least 300 years and often given as roughly 1000 years.
Or on the West Antarctic Ice Sheet.
Hansen:
We find it implausible that BAU scenarios ... would permit a West Antarctic ice sheet of present size to survive even for a century.

Lenton:The West Antarctic Ice Sheet (WAIS) is thought to be less vulnerable to warming than the Greenland Ice Sheet but a threshold could still be accessed this century

I'm no expert, and there could be no real contradictions here between the authors. But there does at least seem to be a difference of emphasis. The albedo-flip picture could be a more important, more holistic way to look at the Earth than a series of tipping points.

Incidentally, I heard on the radio today that the Arctic ice cap extent is at its smallest size ever -- yet we still have at least another month of summer melting to go.





]]> Comment #3 by Delay And Deny http://www.grist.org/article/a-very-good-article-on-tipping-points/ Sun, 19 Aug 2007 01:30:22 -0700 http://www.grist.org/article/a-very-good-article-on-tipping-points/3 Greenland...mmm...


I'll have to put that on my list of now cheap places to buy land for my summer home.   Alberta Canada is a strong contender.   Ideally, I'd figure out where the land ends under the ice in the Northwest Territories and have waterfront property for water skiing on the Arctic Ocean.

John Bailo
Sutext:



]]> Greenland...mmm...


I'll have to put that on my list of now cheap places to buy land for my summer home.   Alberta Canada is a strong contender.   Ideally, I'd figure out where the land ends under the ice in the Northwest Territories and have waterfront property for water skiing on the Arctic Ocean.

John Bailo
Sutext:



]]> Comment #4 by dobermanmacleod http://www.grist.org/article/a-very-good-article-on-tipping-points/ Sun, 19 Aug 2007 16:11:22 -0700 http://www.grist.org/article/a-very-good-article-on-tipping-points/4 A more immediate tipping point

NASA defines abrupt climate change as the inability of the earth's eco-systems to keep pace with rapid climate change.  In other words, it is predictable that soon, as the earth rapidly heats up from historically unprecidented increases in atmospheric greenhouse gas levels, the eco-systems that maintain the carbon balance will go into death spirals, resulting in abrupt climate change.

Furthermore, as carbon sinks will become carbon emitters BIG TIME, it will also result in runaway global warming.

In my opinion, the IPCC severely underestimated the rate of ocean rise due to melting ice caps and glaciers, but still that will be a slow motion tipping point.  Instead, we should be very concerned about the carrying capacity of the earth abruptly dropping in the next couple of decades.

There are historical examples of more mild abrupt climate changes, and they resulted in famine, war, pestilence, and death (the Four Horsemen).  The difference is we now have a thousand times more people, and weapons of mass destruction.

Frankly, worrying about the ice caps and glaciers melting is rather naive, when the eco-systems that regulate the carbon budget are collapsing.  This is just like the false assumption that mankind will be able to so drastically cut their emissions so fast as to be able to avoid either abrupt climate change or runaway global warming.

Unless you find a cost effective way to start removing the excess CO2 from the air soon, it is all over.  The gigantic cost of completely rebuilding our energy infrastructure is predictably causing political gridlock.  Developing countries will continue to rapidly increase their emissions to "catch up" with developed countries.  Besides, nature will predictably reduce her ability to remove the CO2 from the air (a decline of 30% by 2030 has been forecast).

Yeah, go on believing that the tipping point to fear most is the rise of ocean levels-ha!  One faulty paradigm after another...perhaps mankind is too stupid to be sparred the approaching bottleneck?

]]> A more immediate tipping point

NASA defines abrupt climate change as the inability of the earth's eco-systems to keep pace with rapid climate change.  In other words, it is predictable that soon, as the earth rapidly heats up from historically unprecidented increases in atmospheric greenhouse gas levels, the eco-systems that maintain the carbon balance will go into death spirals, resulting in abrupt climate change.

Furthermore, as carbon sinks will become carbon emitters BIG TIME, it will also result in runaway global warming.

In my opinion, the IPCC severely underestimated the rate of ocean rise due to melting ice caps and glaciers, but still that will be a slow motion tipping point.  Instead, we should be very concerned about the carrying capacity of the earth abruptly dropping in the next couple of decades.

There are historical examples of more mild abrupt climate changes, and they resulted in famine, war, pestilence, and death (the Four Horsemen).  The difference is we now have a thousand times more people, and weapons of mass destruction.

Frankly, worrying about the ice caps and glaciers melting is rather naive, when the eco-systems that regulate the carbon budget are collapsing.  This is just like the false assumption that mankind will be able to so drastically cut their emissions so fast as to be able to avoid either abrupt climate change or runaway global warming.

Unless you find a cost effective way to start removing the excess CO2 from the air soon, it is all over.  The gigantic cost of completely rebuilding our energy infrastructure is predictably causing political gridlock.  Developing countries will continue to rapidly increase their emissions to "catch up" with developed countries.  Besides, nature will predictably reduce her ability to remove the CO2 from the air (a decline of 30% by 2030 has been forecast).

Yeah, go on believing that the tipping point to fear most is the rise of ocean levels-ha!  One faulty paradigm after another...perhaps mankind is too stupid to be sparred the approaching bottleneck?

]]> Comment #5 by MarkUK http://www.grist.org/article/a-very-good-article-on-tipping-points/ Sun, 19 Aug 2007 20:02:29 -0700 http://www.grist.org/article/a-very-good-article-on-tipping-points/5 sure

"the eco-systems that regulate the carbon budget are collapsing"

But they're not.

Let's not pretend we know exactly what is going to happen.

]]> sure

"the eco-systems that regulate the carbon budget are collapsing"

But they're not.

Let's not pretend we know exactly what is going to happen.

]]>