Earth’s north polar ice cap was smaller this past winter than at any time since measurements began to be obtained by satellite, breaking a record set only last year.
NASA and the National Snow and Ice Data Center announced March 28 that the maximum extent of ice during the season was reached on March 24 and that it covered 14.52 million square kilometers.
That beat last year’s mark of 14.54 million square kilometers and continued a stretch in which the 13 most ice-free winters in the Arctic have occurred in the past 13 years.
“It is likely that we’re going to keep seeing smaller wintertime maximums in the future because in addition to a warmer atmosphere, the ocean has also warmed up. That warmer ocean will not let the ice edge expand as far south as it used to,” Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said. “Although the maximum reach of the sea ice can vary a lot each year depending on winter weather conditions, we’re seeing a significant downward trend, and that’s ultimately related to the warming atmosphere and oceans.”
During the most recent winter season the Arctic experienced record high temperatures in December, January, and February. Air temperatures were as much as 10 degrees Fahrenheit higher than average at the edge of the ice pack, Meier said.
Warm air from the south was brought by winds to the Arctic, which also would have contributed to a lessened sea ice cover.
Less winter sea ice causes the air temperature over the Arctic ocean to increase because the unfrozen ocean waters are warmer than the overlaying air mass. As the ocean water evaporates, more water vapor accumulates in the atmosphere and that, in turn, causes clouds to form. Increased cloudiness causes an increase in surface warmth.
Satellite measurements of Arctic winter ice extent began in 1979.
Since that time the Arctic has lost nearly 1,606 square kilometers of winter sea ice. That is an area twice the size of Texas.
Check out this photo showing the collapse of an iceberg in the Southern Ocean earlier this month. The iceberg broke off from a larger ice floe about twelve years ago.
Called B-15J, the iceberg was a remnant of the much larger iceberg B-15, which broke off from Antarctica’s Ross ice sheet in 2000. Before breaking into smaller pieces B-15 was about 170 miles long and about 25 miles long.
Icebergs result from the calving of ice shelves, which are the edges of glaciers. When the ice shelves break up, a phenomenon that can happen with greater frequency as Earth’s atmosphere warms, the glacier itself is likely to begin to move faster.
When they do, more ice enters the oceans, which can cause increases in sea levels.
Icebergs melt as they move into warmer waters farther away from the poles.
Photo courtesy NASA. Hat tip to the folks at Our Amazing Planet for the heads up!
A recent report by the National Oceanic and Atmospheric Administration warns that Arctic sea ice is melting faster than ever.
The release of the Arctic Report Card follows a summer in which the extent of ice melt in the Arctic was the second most extensive on record, trailing only 2007. The past five summers have seen the five lowest extents of summer ice on record.
“This report, by a team of 121 scientists from around the globe, concludes that the Arctic region continues to warm, with less sea ice and greater green vegetation,” Monica Medina, principal deputy undersecretary of commerce for oceans and atmosphere, said.
Associated Press reporter Seth Borenstein summarized the findings of the 121 scientists from around the world in a Dec. 2 article in the Anchorage Daily News:
– A NASA satellite found that 430 billion metric tons of ice melted in Greenland from 2010 to 2011, and the melting is accelerating. Since 2000, Greenland’s 39 widest glaciers shrunk by nearly 530 square miles, about the equivalent of 22 Manhattans.
– The past five years have had the five lowest summer sea ice levels on record. For two straight years, all three major passages through the Arctic have been open in the summer, which is unusual.
– Seven of 19 polar bear sub-populations are shrinking.
– This year’s temperature is roughly 2.5 degrees Fahrenheit higher than what had been normal since 1980.
These changes, among others, led NOAA to state unequivocally in the report that
record-setting changes are occurring throughout the Arctic environmental system. Given the projection of continued global warming, it is very likely that major Arctic changes will continue in years to come, with increasing climatic, biological and social impacts.
Other indications of a warming Arctic include an increase in the near-surface average air temperature over the Arctic Ocean by 2.5 degrees Fahrenheit (1.5 degrees Celsius) in 2011 from the 1981-2010 base period, an increased rate of melting of Greenland’s western ice sheet, and an increase in tundra vegetation.
The effect of global warming on Greenland has been particularly noticeable, according to the report, as measurements obtained via satellite indicate that the whole Greenland ice sheet during 2010-2011 “was the largest annual loss in the satellite record of 2002-present.”
The loss of summer sea ice means that Arctic sea waters are both warmer and less saline.
In the Bering Sea, acidification is resulting in a seasonal decline in the formation of calcium carbonate, which is the most significant component of the shells of marine organisms.
Reduction in sea ice has allowed the Northwest Passage, as well as the Northern Sea Route, to remain navigable into September.
Farther south, the warming of the Arctic is resulting in a changed wind pattern that brings more severe winter storms to eastern Canada and the eastern United States and northern Europe.
As more and more Arctic ice melts during the summer, the planet’s albedo, or ability to reflect the Sun’s heat back to space, is decreased.
As described by journalist Richard Black in a May 2007 BBC News article, the lowered albedo could have significant long-term consequences for the planet:
The Arctic is intimately tied to the global climate system, and disruptions here have the potential to create worldwide changes – albeit over long timescales.