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Arctic sea ice measured at record low

Aug. 27, 2012
Courtesy of University of Colorado at Boulder
and World Science staff

The blan­ket of sea ice float­ing on the Arc­tic Ocean has melted to its low­est ex­tent ev­er rec­orded since satel­lites be­gan meas­ur­ing it in 1979, scientists say.

On Aug. 26, the Arc­tic sea ice ex­tent fell to 1.58 mil­lion square miles, or 4.10 mil­lion square kilo­me­ters, ac­cord­ing to the mea­sure­ments from the Uni­vers­ity of Col­o­rad­o Boul­der’s Na­t­ional Snow and Ice Da­ta Cen­ter. That is 27,000 square miles, or 70,000 square kilo­me­ters, be­low the rec­ord low daily sea ice ex­tent set Sept. 18, 2007. Since the sum­mer Arc­tic sea ice min­i­mum nor­mally does not oc­cur un­til the melt sea­son ends in mid- to-late Sep­tem­ber, the re­search team ex­pects the sea ice ex­tent to con­tin­ue to dwin­dle for the next two or three weeks, said Walt Meier, a sci­ent­ist at the cen­ter.

The ex­tent of Arc­tic sea ice reached a rec­ord low in the sat­el­lite rec­ord on Aug. 26 and is ex­pected to con­tin­ue drop­ping for the next sev­er­al weeks, ac­cord­ing to a Uni­ver­si­ty of Col­o­rad­o Boul­der re­search team. (Cred­it: NSIDC, U. of Col­o­rad­o Boul­der)


“It’s a lit­tle sur­pris­ing to see the 2012 Arc­tic sea ice ex­tent in Au­gust dip be­low the rec­ord low 2007 sea ice ex­tent in Sep­tem­ber,” he said. “It’s likely we are go­ing to sur­pass the rec­ord de­cline by a fa­ir amount this year by the time all is said and done.”

On Sept. 18, 2007, the Sep­tem­ber min­i­mum ex­tent of Arc­tic sea ice shat­tered all sat­el­lite rec­ords, reach­ing a five-day run­ning av­er­age of 1.61 mil­lion square miles, or 4.17 mil­lion square kilo­me­ters. Com­pared to the long-term min­i­mum av­er­age from 1979 to 2000, the 2007 min­i­mum ex­tent was low­er by about a mil­lion square miles—an ar­ea about the same as Alas­ka and Tex­as com­bined, or 10 Un­ited King­doms.

While a large Arc­tic storm in early Au­gust ap­pears to have helped to break up some of the 2012 sea ice and helped it to melt more quick­ly, the de­cline seen in in re­cent years is well out­side the range of nat­u­ral cli­mate vari­abil­ity, said Meier. Most sci­ent­ists be­lieve the shrink­ing Arc­tic sea ice is tied to warm­ing tem­pe­r­a­tures caused by an in­crease in human-produced green­house gas­es pumped in­to Earth’s at­mos­phere.

Re­search­ers at the uni­vers­ity say the old, thick mul­ti­-year ice that used to dom­i­nate the Arc­tic re­gion has been re­placed by young, thin ice that has sur­vived only one or two melt sea­sons—ice which now makes up about 80 pe­r­cent of the ice cov­er. Since 1979, the Sep­tem­ber Arc­tic sea ice ex­tent has de­clined by 12 pe­r­cent per dec­ade.

The rec­ord-breaking Arc­tic sea ice ex­tent in 2012 moves the 2011 sea ice ex­tent min­i­mum from the sec­ond to the third low­est spot on rec­ord, be­hind 2007. Meier and his col­leagues at the uni­vers­ity say they be­lieve the Arc­tic may be ice-free in the sum­mers with­in the next sev­eral dec­ades.

“The years from 2007 to 2012 are the six low­est years in terms of Arc­tic sea ice ex­tent in the sat­el­lite rec­ord,” said Meier. “In the big pic­ture, 2012 is just an­oth­er year in the se­quence of de­clin­ing sea ice. We have been see­ing a trend to­ward de­creas­ing min­i­mum Arc­tic sea ice ex­tents for the past 34 years, and there’s no rea­son to be­lieve this trend will change.”

The Arc­tic sea ice ex­tent as meas­ured by sci­ent­ists is the to­tal ar­ea of all Arc­tic re­gions where ice cov­ers at least 15 pe­r­cent of the ocean sur­face, said Meier.

Sci­en­tists say Arc­tic sea ice is im­por­tant be­cause it keeps the po­lar re­gion cold and helps mod­er­ate glob­al cli­mate—some have dubbed it “Earth’s air con­di­tion­er.” While the bright sur­face of Arc­tic sea ice re­flects up to 80 pe­r­cent of the sun­light back to space, the in­creas­ing amounts of open ocean there—which ab­sorb about 90 pe­r­cent of the sun­light strik­ing the Arc­tic—are be­lieved to have cre­at­ed a pos­i­tive feed­back ef­fect, caus­ing the ocean to heat up and con­trib­ute to in­creased sea ice melt.


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The blanket of sea ice floating on the Arctic Ocean has melted to its lowest extent ever recorded since satellites began measuring it in 1979, according to the University of Colorado Boulder’s National Snow and Ice Data Center. On Aug. 26, the Arctic sea ice extent fell to 1.58 million square miles, or 4.10 million square kilometers, the measurements indicate. The number is 27,000 square miles, or 70,000 square kilometers below the record low daily sea ice extent set Sept. 18, 2007. Since the summer Arctic sea ice minimum normally does not occur until the melt season ends in mid- to-late September, the CU-Boulder research team expects the sea ice extent to continue to dwindle for the next two or three weeks, said Walt Meier, a scientist at the center. “It’s a little surprising to see the 2012 Arctic sea ice extent in August dip below the record low 2007 sea ice extent in September,” he said. “It’s likely we are going to surpass the record decline by a fair amount this year by the time all is said and done.” On Sept. 18, 2007, the September minimum extent of Arctic sea ice shattered all satellite records, reaching a five-day running average of 1.61 million square miles, or 4.17 million square kilometers. Compared to the long-term minimum average from 1979 to 2000, the 2007 minimum extent was lower by about a million square miles—an area about the same as Alaska and Texas combined, or 10 United Kingdoms. While a large Arctic storm in early August appears to have helped to break up some of the 2012 sea ice and helped it to melt more quickly, the decline seen in in recent years is well outside the range of natural climate variability, said Meier. Most scientists believe the shrinking Arctic sea ice is tied to warming temperatures caused by an increase in human-produced greenhouse gases pumped into Earth’s atmosphere. Researchers at the unviersity say the old, thick multi-year ice that used to dominate the Arctic region has been replaced by young, thin ice that has survived only one or two melt seasons—ice which now makes up about 80 percent of the ice cover. Since 1979, the September Arctic sea ice extent has declined by 12 percent per decade. The record-breaking Arctic sea ice extent in 2012 moves the 2011 sea ice extent minimum from the second to the third lowest spot on record, behind 2007. Meier and his colleagues at the university say they believe the Arctic may be ice-free in the summers within the next several decades. “The years from 2007 to 2012 are the six lowest years in terms of Arctic sea ice extent in the satellite record,” said Meier. “In the big picture, 2012 is just another year in the sequence of declining sea ice. We have been seeing a trend toward decreasing minimum Arctic sea ice extents for the past 34 years, and there’s no reason to believe this trend will change.” The Arctic sea ice extent as measured by scientists is the total area of all Arctic regions where ice covers at least 15 percent of the ocean surface, said Meier. Scientists say Arctic sea ice is important because it keeps the polar region cold and helps moderate global climate—some have dubbed it “Earth’s air conditioner.” While the bright surface of Arctic sea ice reflects up to 80 percent of the sunlight back to space, the increasing amounts of open ocean there—which absorb about 90 percent of the sunlight striking the Arctic—have created a positive feedback effect, causing the ocean to heat up and contribute to increased sea ice melt.