August 2013

The Cryosphere Ice Watch

Every year about this time, my thoughts become distinctly maudlin.  For much of human history and in many cultures still today, the death watch was a staple of the end of human life:  family and friends gathering at the bedside for days and even weeks, sitting in witness and support with the dying as life slipped away.

These weeks of August and early September have begun to feel like a death watch for the ice and snow of the Arctic region.  Each spring as the sun comes up, sea ice, snow cover and Greenland’s ice sheets begin to melt and shrink: very slowly at first, and accelerating in the month of May.  (For ICCI, this is complemented by the “fire watch” of our work in Eurasia:  watching as lines of forest and field burning sweep inexorably northwards from Kazakhstan and Ukraine into northern Russia from March to June, following the line of snow melt.)

It is a mixed feeling, this ice watch.  On the one hand, one wants the ice to last as long as possible, not set new records for minimum or melt.  We know the global climate depends on it:  for albedo (reflecting as much heat as possible back into space), for preserving the permafrost (preventing “natural” releases of methane and carbon from these frozen soils, which could equal the impact of all greenhouse gases released in the industrial era), and for preventing sea level rise. (Greenland’s loss of ice has accelerated from 50 gigatons prior to about 2004, to 200gT a year in 2004-08, to 350gT in the past four years.  1 gigaton is a square kilometer of ice — 300gT equals about a millimeter of sea level rise).

At the same time, there is a desire for attention to these changes:  to get people to realize just how much we are changing the planet from historical human norms so politicians feel empowered to take the steps they really do realize (these are not foolish people, no matter their rhetoric) are necessary.  And that means rooting for another record-breaking melt season.

Greenland’s crisis has passed for this summer.  Its peak melt usually occurs in mid-July.  After the shock of last year when 97% percent of the surface was melting, unprecedented since observations began in 1979 (and showing only a handful of similar occurrences going back 1000 years in ice cores), this year the peak melting encompassed only about 45% of the ice sheet.

But that is still twice the observed average of around 20%.

For the sea ice, the jury is still out:  the summer minimum is not normally reached until the sun goes down on September 21.  That sea ice watch used to involve whether we would break the “unprecedented” 2007 record.  Last year caught everyone by surprise, when that record was beaten not in September, but on August 22: and the decline continued well into September.  Indeed, the ice extent was not back “up” to the 2007 minimum until the last weeks of October.  As of this writing, we look to set a second low, but not a minimum:  the melt started late, though accelerated and nearly caught up to 2012 in mid-July.  Stay tuned.

I once confided this guilty ice watch to a well-known ice scientist, and was surprised when he agreed.  “We really can’t save the ice at this point anyway,” he said.  “Might as well try to get some attention out of it when it goes.  But I know what you mean, it’s a sick way of looking at things.”

We’re probably a few years away still from a real ice death watch: the summer when all of the sea ice disappears, or we see melting across all of Greenland’s surface, every year; or the new [northern hemisphere] “winter” ice watch:  the ice shelves off Antarctica during the southern hemisphere summer.  But if the researchers are right, it is only a matter of “when,” and sooner may indeed be better than later, if it motivates action.  A sick way of looking at things, indeed.

Update:  The 2013 summer minimum of 5.1 million km2 was reached on September 13; it was the sixth lowest on record, and over one million km2 below the 1981-2010 average minimum.

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