Monday, March 05, 2012

Eli will have some ice with that

Since, with the coming of Spring, ice is in the air, from the Daily Conversation,

Combustion is a curse
Coal is the worst

From Jason Box (go read) another damn feedback

Summer Greenland ice sheet albedo (reflectivity)
Freshly fallen snow under clear skies reflects 84% (albedo= 0.84) of the sunlight falling on it (Konzelmann and Ohmura, 1995). This reflectivity progressively reduces during the sunlit (warm) season as a consequence of ice grain growth, resulting in a self-amplifying albedo decrease, a positive feedback. Another amplifier; the complete melting of the winter snow accumulation on glaciers, sea ice, and the low elevations of ice sheets exposes darker underlying solid ice. The albedo of low-impurity snow-free glacier ice is in the range of 30% to 60% (Cuffey and Paterson, 2010). Where wind-blown-in and microbiological impurities accumulate near the glacier ice surface (Bøggild et al. 2010), the ice sheet albedo may be extremely low (20%) (Cuffey and Paterson, 2010). Thus, summer albedo variability exceeds 50% over parts of the ice sheet where a snow layer ablates by mid-summer, exposing an impurity-rich ice surface (Wientjes and Oerlemans, 2010), resulting in absorbed sunlight being the largest source of energy for melting during summer and explaining most of the inter-annual variability in melt totals (van den Broeke et al. 2008, 2011).

Oh yes, Tamino has a word



We really ought to put arctic albedo back where we found it.

Jim Eager said...

This is a surprise?

Just monitor a pile of plowed up snow as it melts. It starts out nice and white but grows dirtier and darker as it melts, leaving all the bits of dirt and grime that had been suspended in the pile deposited on the surface. Eventually it looks like a solid pile of dirt, yet there's still snow and ice beneath the dark crust.

Steve Bloom said...

Just to be clear, Jim, the effect described here happens to undisturbed snow. Anyone living in a cold climate can see it in the winter. Over time, snow that's not covered by new falls becomes slightly gray in appearance (albeit partly due to soot, I'm sure), and acquires a crust with visibly larger grains.

Hank Roberts said...

f... f... fff ... fiddlesticks:

"... Nothing "goes away"; it is simply transferred from place to place, converted from one molecular form to another, acting on the life processes of any organism in which it becomes, for a time, lodged. One of the chief reasons for the present environmental crisis is that great amounts of materials have been extracted from the earth, converted into new forms, and discharged into the environment without taking into account that "everything has to go some- where." The result, too often, is the accumulation of harmful amounts of material in places where, in nature, they do not belong."

From Barry Commoner, The Closing Circle: Nature, Man and Technology, 1971 (N.Y., Alfred Knopf, 1971)

Jim Eager said...

Oh, I realise that, Steve. Anyone who has spent much time skiing should be quite familiar with the concept. My point was that it is more easily observed on a shorter timescale with windrows.

Anonymous said...

If you look at that albedo graph in a mirror on the ceiling and change "unitless" to "clueless", you'll have the version appearing at WUWT and other denier sites.