This summer's record melt suggests the Arctic may lose its ice cap seasonally sooner than expected. What impacts can we expect?
ARCTIC SEA ICE: The Arctic is losing sea ice rapidly. The varying thickness of the remaining ice can be seen here, from thin, nearly transparent ice to older, thicker, snow-covered ice. Image: Courtesy of NASA
On Sunday, September 16, the sun did not rise above the horizon in the Arctic. Nevertheless enough of the sun's heat had poured over the North Pole during the summer months to cause the largest loss of Arctic sea ice cover since satellite records began in the 1970s. The record low 3.41 million square kilometers of ice shattered the previous low?4.17 million square kilometers?set in 2007. All told, since 1979, the Arctic sea ice minimum extent has shrunk by more than 50 percent?and even greater amounts of ice have been lost in the corresponding thinning of the ice, according to the U.S. National Snow and Ice Data Center (NSIDC).
"There is much more open ocean than there used to be," says NSIDC research scientist Walt Meier. "The volume is decreasing even faster than the extent [of surface area] as best as we can tell," based on new satellite measurements and thickness estimates provided by submarines. Once sea ice becomes thin enough, most or all of it may melt in a single summer.
Some ice scientists have begun to think that the Arctic might be ice-free in summer as soon as the end of this decade?leaving darker, heat-absorbing ocean waters to replace the bright white heat-reflecting sea ice. The question is: Then what happens? Although the nature and extent of these rapid changes are not yet fully understood by researchers, the impacts could range from regional weather-pattern changes to global climate feedbacks that exacerbate overall warming. As Meier says: "We expect there will be some effect?but we can't say exactly what the impacts have been or will be in future."
On thin ice
Arctic ice influences atmospheric circulation and, hence, weather and climate. Take away the ice and impacts seem sure to follow. There's more warming to come, as well, particularly in the Arctic, which is warming faster than the rest of the globe. Given cumulative greenhouse gas emissions, there's likely at least as much warming to come as has occurred to date?a rise of 0.8 degree Celsius in global average temperatures, most of that in the past 30 years.
The biggest impacts of the loss of Arctic sea ice, of course, will be felt locally: from the potential for more snowfall (which can act like an insulating blanket keeping the ice warm and incapable of growing) to more storms with stronger winds. These will also whip up waves to pound the shore, eroding it, as well as bringing warmer temperatures to thaw the permafrost?leading to "drunken" trees and buildings as well as villages slipping into the sea. A loss of sea ice will also affect the largest animals in the Arctic: seals, walruses and polar bears. "My people rely on that ocean and we've seen some dramatic changes," said Inupiat leader Caroline Cannon at a Greenpeace event on the Arctic in New York City on September 19. "We are the gatekeepers of the ocean. We speak for the animals. They provide for us so it's our time to speak for them," by arguing to ameliorate climate change.
Noting the climate change in Cannon's backyard, the rest of the globe is indeed taking action?just not the type that could reduce greenhouse gas emissions. "The world is looking at the Arctic as a new ocean to be developed and exploited," notes Arctic system scientist David Barber of the University of Manitoba, most particularly oil as evidenced by Shell's bid to drill the first offshore well in the Chukchi Sea. The U.S. Geological Survey estimates that the Arctic holds an oil and gas bonanza?and companies from Russia to the U.S. are lining up to start exploiting it.
Source: http://rss.sciam.com/click.phdo?i=54524fb74baaff91a34d7495825bfc1a
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