Ohio State's Jason Box On Soot, Greenland Melt & Anthropogenic Forcing

[hatrack]

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Today, Box is trying to understand the feedback loops that may be driving a melting of Greenland that is much faster and more dramatic than many scientists expected. Take, for instance, melting on the ice’s sheet surface: Warmer or melting ice (or just plain meltwater) absorbs more sunlight than does healthy, cold ice. So as warmer temperatures melt the ice, the ice sheet absorbs more solar heat—melting even more. Another example: As Greenland melts, the massive ice sheet, more than two miles above sea level at its highest point, slumps in altitude. When that happens, more of the ice sheet is bathed in the warmer atmospheric temperatures that are found at lower elevations. So—you guessed it—it melts more.

But Box is most intrigued by one of the processes occurring atop the ice sheet, on its surface. Last summer, wildfires torched large parts of the US West, and especially Box’s home state of Colorado. The soot from the fires traveled as far north as the Greenland ice sheet and, once deposited on the ice, these dark particles absorbed additional sunlight. Compounding this effect are the Arctic microbes that live off of impurities from soot—living longer as the ice warms, and releasing dark pigments to protect themselves from the sunlight.

“I’m sitting in LaGuardia on my way to Greenland, people riveted to the TV with news about fire across the US,” Box remembers. “It was really dramatic, but I’m like, ‘Hold on, we need to really measure the soot.” Thus was born the Dark Snow project, in which Box and colleagues are trying to crowd-fund an expedition to sample the ice at high elevations and determine just how much soot from global wildfires and pollution are amplifying Greenland’s melting.

The upshot of what they know so far is that Greenland is not only melting—it may be melting faster than anyone expected, including most scientists. And what’s more, we may be blowing past a point of irreversibility, where the world commits, irrevocably, to a level of sea level rise that, as it unfolds over the coming centuries, would devastate many coastal megacities.

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http://climatedesk.org/2013/01/why-greenlands-melting-could-be-the-biggest-climate-disaster-of-all/

[limpyhobbler]

1. ut oh. NT