Chasing ice

Posted Wednesday, December 12, 2012 in Sustainable Maine

Chasing ice

Satellite image by NASA Earth Observatory

Retreat of Alaska’s Columbia Glacier over the past 25 years. The terminus, near Heather Island in 1986, retreated 12 miles up the inlet by 2011. The blue area below the 2011 terminus is floating ice calved off the leading edge.

by Paul Kando

Art and science are uniquely human skills. When the two intersect, usually something extraordinary happens. Peer into a microscope and marvel at the beauty of mold spores — those nasty things that make breathing difficult. Or go see nature photographer James Balog’s film, "Chasing Ice," which documents the disappearance of the world’s glaciers due to global warming. The film is a visual record of the breathtaking beauty of nature’s own ice sculptures combined with the terrifying spectacle of much of Earth’s stored reserves of fresh water violently drowning in the saline depths of the ocean. A friend called the mighty thunder of Greenland’s largest glacier calving Manhattan-sized icebergs “the death throes of the planet.” Leave us hope!

What is going on? How can a small — at this point about 1.5ºF — rise in Earth’s average temperature translate to the destruction of polar ice? According to the second law of thermodynamics, you will recall, heat moves from hot to cold. Your house loses heat through poorly insulated walls to the colder outdoors, and the colder it is outside, the greater the loss, and the faster the house cools. Consistent with the same law, much of Earth’s incoming solar warmth rushes up into the colder polar regions: a 1ºF temperature rise at the Equator corresponds to over 12ºF at the Arctic. Hence the dramatic ice melt — global warming’s canary in the coal mine.

As polar ice melts, huge amounts of water, heretofore not part of the ocean, drain into the sea, compounding the sea-level rise already occurring because as the oceans warm, their volume expands. Conservative estimates call for as much as a meter (almost 40 inches) of additional rise in global sea level in less than a generation. That is enough to inundate, at high tide, the lower end of Main Street, Damariscotta (not to mention the municipal parking lot, part of Bristol Road and the hospital grounds); the waterfront and much of the Iron Works in Bath; Commercial Street and much of Bayside in Portland; and scores of coastal communities. However, should all the polar ice melt, raising the sea by dozens of feet, coastal cities from New York to Shanghai would be submerged, displacing 1.5 billion people worldwide as climate refugees. As ice sheets melt, the permafrost warms as well, releasing many millennia’s worth of stored frozen methane, a greenhouse gas 23 times more potent than carbon dioxide.

Further increases in atmospheric carbon are likely to have a profound effect on the climate. Most scientists reckon that an increase of 2ºC is all the planet can accommodate without catastrophic consequences: persistent droughts that will destroy farmland on which millions of people depend for survival, intense weather disasters like heat waves and droughts, extreme ocean acidification, the collapse of vital ecosystems, wholesale species destruction, and more. Many of these effects are already apparent — witness Superstorm Sandy and the bleaching of coral reefs.

Worse, according to World Energy Outlook 2012, continuing growth in fossil-fuel consumption is likely to result in "a long-term average global temperature increase of 3.6ºC." An increase of this magnitude essentially suggests the end of human civilization as we know it. Many scientists, including Kerry Emanuel of MIT, a leading authority on hurricanes, have come to think that even 2ºC is far too lenient a target. "Any number much above one degree involves a gamble,"  Emanuel writes, "and the odds become less and less favorable as the temperature goes up." Observes Thomas Lovejoy, a former adviser to the World Bank: "If we're seeing what we're seeing today at 0.8ºC, two degrees is simply too much."

It is hard to imagine what a 3.6ºC hotter Earth might be like. The entire Greenland and Antarctica ice sheets would melt, raising sea levels by dozens of feet and completely inundating low-lying countries and coastal cities like New York and Shanghai. Other glaciers around the world, which feed our rivers, would disappear as well. Large parts of Africa, Central Asia, the Middle East, and the American Southwest would become uninhabitable due to lack of water and desertification. Huge wildfires would consume the dead forests at temperate latitudes.

What a sobering context in which to consider rosy predictions of impending U.S. oil supremacy! But that’s a subject for another day.

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