Comments on: Antarctic Ice Shelf Disintegration Underscores a Warming World

By: Joe

Joe — Wed, 16 Apr 2008 22:52:03 +0000

Paulm — I’ll see what I can do.

By: paulm

paulm — Wed, 16 Apr 2008 22:19:52 +0000

Joe,
Can we get an article/blog about tipping points and what are the options depending on where were at. I think there is much confusion amongst the lay person on what the situation is and what happens when we go past one – are there appropriate responses? We need to formulate long term plans depending on each point…

By: Peter Wood

Peter Wood — Wed, 26 Mar 2008 23:22:08 +0000

Looks like Antarctica will have “seven Manhattans” less albedo quite soon.

By: Earl Killian

Earl Killian — Wed, 26 Mar 2008 21:20:20 +0000

Paul K, perhaps I misunderstood your symptom vs. effect comment then, but I still can’t figure out what it means. Leaving that behind, I am not aware of Joe claiming that the IPCC’s estimate of climate sensitivity is wrong. There are two points I know he raises on the IPCC report.

One is the IPCC comments on sea level rise. The IPCC report says that if we ignore dynamic processes, the temperature increase will have a certain effect on sea level. The IPCC ignores dynamic processes because they cannot figure out an accurate way to predict something that chaotic. However, ignoring them is also a problem because they appear to be the primary effect at work. So unfortunately they have a prediction that is of the form “If A then B” where A is very likely false. That makes the IPCC prediction in this case essentially useless, although technically true.

The second thing is that the IPCC is explicitly estimating the short-term climate sensitivity. This is how Earth responds to changes over decades. This is the fast-feedback or Charney sensitivity. James Hansen is also concerned about the long-term sensitivity. That is much more difficult to answer with climate models. Some of the relevant feedbacks are not in the models (a NCAR GCM scientist told me this), e.g. permafrost thawing. Hansen therefore turns to the paleo record to estimate both the Charney sensitivity and the long-term sensitivity. Hansen’s conclusion is the Charney sensitivity is essentially what is in the GCMs, and the long-term sensitivity is approximately twice that. I believe Joe agrees on this, but you’ll have to ask him to know for sure.

So I think rather than disputing the IPCC, Joe is trying to investigate areas in which the IPCC is reluctant to tread. It is no wonder they are reluctant; even when they get it right, they are accused. Imagine if they actually got something wrong…

By: Paul K

Paul K — Wed, 26 Mar 2008 20:05:23 +0000

Earl Killian,
Of course CO2 is a greenhouse gas, never said it wasn’t. The question is the effect. The climate catastrophe predicted here depends on assumed positive forcings and feedbacks greatly multiplying the effect of CO2 alone. These assumptions have not been confirmed. I accept the IPCC as authoritative. The IPCC gives 85% confidence to its 3C +/- 1.5C sensitivity to doubled CO2. Why should anyone have 100% confidence in the even higher sensitivity which Joe claims is the case?

By: David B. Benson

David B. Benson — Wed, 26 Mar 2008 18:11:41 +0000

Peter Foley & Nylo — The Antarctic Peninsula has definitely been warming over the last several decades. The Polar Vortex, the permanent wind around the Antarctic, has moved further south, leaving more of the Antarctic Penensula exposed to heating influences. Not so for all the area still to the south of the Polar Vortex, where it rarely even snows..

That’s how I undersand it.

By: Peter Foley

Peter Foley — Wed, 26 Mar 2008 17:40:17 +0000

Doesn’t a small part of the ice have to calve every summer to prevent the build up of the ice pack– Otherwise we have a ‘tipping point’ of runaway ice build up. Notice how the area numbers seem to grow through miracle of ice spreading over the sea to puff up the spin. The numbers needed are the fraction of annual ice-fall(snow) volume to ice loss. If much greater or lower then one–start paying attention. In other words- move on to the next spun event folks, another normal event of ice movement isn’t proof of AGW.

By: Earl Killian

Earl Killian — Wed, 26 Mar 2008 16:52:13 +0000

http://www.realclimate.org/ index.php/ archives/ 2006/ 07/ peter-doran-and-how-misleading-talking-points-propagate/
is titled “Peter Doran and how misleading talking points propagate”. Apparently they are still propagating.
“Peter Doran, the lead author on a oft-cited, but less-often read, Nature study on Antarctic climate in 2002 had an Op-Ed in the NY Times today decrying the misuse of his team’s results in the on-going climate science ‘debate’. … But like so many results in this field, it has become a politicized ‘talking point’, shorn of its context, that is mis-quoted and mis-used by many who should (and often do) know better. Doran complained about the media coverage of his paper at the time, and with the passage of time, the distortion has predictably increased. Give it another few years, maybe we’ll be having congressional hearings about it…”

By: Earl Killian

Earl Killian — Wed, 26 Mar 2008 16:33:04 +0000

Paul K, it does not comfort me that you are for replacing fossil fuels if you are going to suggest that CO2 is a symptom, when in fact the overwhelming evidence is that it is the root of the problem. Again, I ask on what basis you dispute the science that CO2 is a greenhouse gas?

By: Nylo

Nylo — Wed, 26 Mar 2008 16:16:01 +0000

Congrats Joe, you found a 5% of the Anctartica that is warming. How unlucky that the other 95% is cooling, and when averaged, the cooling trend prevails. Sea ice extension in the south continues to reach positive records year after year. In spite of AGW.

This fixation with the Peninsula thing is a classic example of cherry-picking and is what climatic science shouldn’t be about.