NSIDC: Arctic sea ice breaks lowest extent on record

The National Snow and Ice Data Center (NSIDC) reports that Arctic sea ice has broken the previously lowest extent on record, which was in 2007.

Arctic sea ice extent fell to 4.10 million square kilometers (1.58 million square miles) on August 26, 2012. This was 70,000 square kilometers (27,000 square miles) below the September 18, 2007 daily extent of 4.17 million square kilometers (1.61 million square miles).

NSIDC scientist Walt Meier said, "By itself it's just a number, and occasionally records are going to get set. But in the context of what's happened in the last several years and throughout the satellite record, it's an indication that the Arctic sea ice cover is fundamentally changing."

According to NSIDC Director Mark Serreze, "The previous record, set in 2007, occurred because of near perfect summer weather for melting ice. Apart from one big storm in early August, weather patterns this year were unremarkable. The ice is so thin and weak now, it doesn't matter how the winds blow."

"The Arctic used to be dominated by multiyear ice, or ice that stayed around for several years," Meier said. "Now it's becoming more of a seasonal ice cover and large areas are now prone to melting out in summer."

With two to three weeks left in the melt season, NSIDC scientists anticipate that the minimum ice extent could fall even lower.

References
NSIDC: Arctic sea ice breaks lowest extent
NSIDC Media Advisory: Arctic sea ice breaks lowest extent on record
NSIDC: Arctic Sea Ice News and Analysis

Record low sea ice area

Arctic sea ice area reached a record low of 2.87746 million square km on the 230th day of 2012, as illustrated on the image below by The Cryosphere Today. Below the sea surface temperature anomaly for August 20, 2012, by the National Oceanic and Atmospheric Administration (NOAA). Rising temperatures in the Arctic threaten to trigger methane releases, as shown on the poster below. The poster forms part of the updated presentation Why act now, and how?

Record levels of greenhouse gases in the Arctic

Carbon dioxide levels are at an all time high. The image below, with hourly averages, shows recent measurements that are well over 396 ppm. Formal figure for the week started April 22, 2012, is 396.61 ppm at Mauna Loa, Hawaii.

The image below shows the atmospheric increase of CO2 over 280 ppm in weekly averages of CO2 observed at Mauna Loa. The preindustrial value of 280 ppm is close to the average of CO2 between 1000 and 1800 in an ice core from Law Dome, Antarctica. For comparison with pre-industrial times the Mauna Loa weekly data have been first deseasonalized by subtracting the observed average seasonal cycle, and then subtracting 280 ppm.

The image below shows the results for carbon dioxide global monthly averages for the period 1979-2010. The axis on the left shows the radiative forcing in Watts per square meter, relative to 1750, due to carbon dioxide alone since 1979.

The situation is even worse in the Arctic, where carbon dioxide levels can reach values over 400 ppm, as illustrated by the image below showing carbon dioxide measurements at Barrow, Alaska.

Apart from carbon dioxide, there are further forcers such as methane. The image below shows methane levels at Mauna Loa, Hawaii.

Methane levels are again higher in the Arctic, as illustrated by the image below showing methane levels at Barrow, Alaska, of well over 1900 ppb.

Figures for methane on above image are monthly averages, showing recent levels well over 1900 ppb. The situation looks even more worrying when looking at hourly averages, showing measurements of up to 2500 ppb.

The fact that such high levels occur is alarming. The danger is that radiative forcing will be extremely high in summer in the Arctic, due to high levels of greenhouse gases and other emissions, which will speed up the loss of sea ice, resulting in even further warming that increases the danger that large amounts of methane will be released from hydrates and from free gas in sediments under the water.  This danger is further increased by the many feedbacks, as depicted in the Diagram of Doom.

For a more detailed description of the many feedbacks, see the Diagram of Doom.

January 2012 shows record levels of methane in the Arctic

In January 2012, methane levels in the Arctic reached levels of 1870 ppb.

Particularly worrying is that, in the past, methane concentrations have fluctuated up and down in line with the seasons. Over the past seven months, however, methane has shown steady growth in the Arctic. Such a long continuous period of growth is unprecedented, the more so as it takes place in winter, when vegetation growth and algae bloom is minimal. The most obvious conclusion is that the methane is venting from hydrates.

Extract from: The need for geo-engioneering
and from: Methane venting in the Arctic