Thursday, March 10, 2011

Latest Ice Sheet Mass Balance Stats

This following post is incorrect because I misread the main graph (h/t to Mike Aucott for pointing this out). I have left it here for the historical record, but you should read this one instead.



Rignot et al (who's work I have discussed in the past) have a new paper out with an evaluation of the mass balance of the Greenland and Antarctic ice sheets.  I can't find the full paper online, but the press release has the key data:

This corresponds to a contribution of 1.3mm/yr of sea level rise.  Importantly, at least so far, this isn't showing signs of rapid acceleration (there's noise, but no obvious sign of systematic departure from a linear trend in that data).  Gavin Schmidt at Real Climate notes that this contribution to sea level rise is consistent with the semi-empirical estimates of Rahmstorf and collaborators (here and here).

The key figure from the second of those papers was this one:

That is around 30-40cm (1 ft) of sea level rise by 2050, and a meter (3 ft) or so by 2100.

It seems to me that the science of sea level rise is starting to settle down a little bit from the enormous kick given to it by Zwally's discovery of the importance of basal ice sheet melting.  Sea level rise is going to be more than the IPCC AR4 projected, but still, I have trouble seeing 1m over the course of this century as a serious threat to global civilization.  It will certainly be a very expensive regional problem, requiring lots of engineering works in coastal cities, loss of certain ecosystems, damage to coastal property.  But I have trouble seeing us not being able to adapt to this, or it causing us to seriously change our ways.   The biggest potential threats from climate change would seem to be elsewhere.

8 comments:

Bern said...

I don't doubt that we can adapt to this level of sea level rise. However, this represents disaster for Island nations such as Maldives with an average elevation 1.5 meters or Tuvala with a maximum elevation of 4.5 meters.

Mike Aucott said...

Stuart,

The slope is expressed in units of Gt/y^2, not Gt/y, so it represents an accelerating trend. See the comment by Chris Dudley to the RealClimate post and Gavin's response.

kjmclark said...

It's probably disaster for Bangladesh too, but not a threat for global civilization. (http://maps.grida.no/go/graphic/potential-impact-of-sea-level-rise-on-bangladesh)

Actually, here's (http://www.globalwarmingart.com/wiki/Sea_Level_Rise_Maps_Gallery) a nice series of maps of sea level rise vulnerability. I didn't realize Iraq had a problem.

Stuart Staniford said...

Mike:

You are right - clearly I did misread it. Also, I don't think Gavin Schmidt's response is quite correct either - on this graph a flat line would be linear mass loss, but a straight line is quadratic mass loss.

I don't have time to rewrite the post right now, but clearly it needs major revision (or replacement). I will put a warning on it for now, and then hopefully fix it this evening.

Stuart Staniford said...

Also, note that I have begun deleting Kamil's climate denialist comments since I believe they will lower the quality of the conversation here.

Stuart Staniford said...

Hypnos:

Your point was a good one, but I think in this case I am going to delete all responses as well, to avoid incentivizing anyone to feed the trolls going forward.

bmerson said...

Stuart, one of the reasons I read your blog is because you are one of the relatively few bloggers who a) admits mistakes, and b) actually updates posts to show a warning or correction. I applaud the class with which you conduct this space.

Stuart Staniford said...

bmerson: the kind words are particularly appreciated when I've just made an idiot of myself :-)