The Arctic Report Card
by Bill Chameides | October 25th, 2010
posted by Erica Rowell (Editor)
Arctic sea ice, as captured in October-November 2009 during NASA’s IceBridge mission. Sea ice for 2010, a report just out reveals, continues a downward trend. (NASA)
The Arctic gets a double “C” — for “changing climate.”
Each year an international team of scientists prepares “a timely source for clear, reliable and concise environmental information on the state of the Arctic, relative to historical time series records.” Working under the auspices of the Arctic Council (an intergovernmental forum made up of the eight Arctic states: Canada, Denmark [including Greenland and the Faroe Islands], Finland, Iceland, Norway, Sweden, the Russian Federation, and the United States), the group produces the Arctic Report Card, the latest version of which has just been posted on the National Oceanic and Atmospheric Administration’s Web site. It was prepared by 69 scientists and based on more than 170 published scientific papers.
The top-line conclusion: “Return to previous Arctic conditions is unlikely. Record temperatures across Canadian Arctic and Greenland, a reduced summer sea ice cover, record snow cover decreases and links to some Northern Hemisphere weather support this conclusion.”
On Thin Ice … Still
When speaking of climate change and the Arctic, the first thing that often comes up is sea ice. Especially after the summer of 2007 when the sea-ice extent fell so precipitously that some people began predicting an ice-free Arctic in a matter of a decade or two (see here and here). But the debate heated up (if you will) when the sea-ice extents of 2008 and 2009 recovered somewhat — still well below long-term norms but higher than 2007’s low.
This summer began the debate anew. Would the sea-ice extent of 2010 continue an upward trend or head back toward the low of 2007?
Well, the results are now in and, depending on your expectation and point of view, you may feel vindicated or disappointed or simply informed. The sea-ice minimum this year was the third lowest on record. This continues the long-term downward trend and was below the minimum of 2009, but was not as low as the sea-ice minima of 2007 and 2008.
Monthly September Arctic sea-ice extent for 1979 to 2010 shows a decline of 11.5 percent per decade, relative to the 1979-2000 average. (Source: National Snow and Ice Data Center)
Sea-Ice Thickness Also Troublesome
Yet, while everyone seems focused on sea-ice extent, there is perhaps a much more profound trend at work that seems to be falling below the radar: sea-ice thickness. The older, thicker sea ice is disappearing and is being replaced by relatively thin, young ice (a lot only one year old) — ice that is much more susceptible to melting during the summer.
This is one of the reasons the scientists who prepared the report card found a “return to previous Arctic conditions unlikely.” It would take many years of consistently cold temperatures to build back the Arctic sea ice to its earlier thickness that would make it more resistant to summertime melting.
The top two images show the change in sea-ice age from spring 2010 to fall 2010. The negative phase of the Arctic Oscillation this winter slowed the export of older ice out of the Arctic in the winter, but a large amount of older ice melted out during the summer. The bottom chart gives the age composition of sea ice between 1981 and 2010 at the September minimum. Note the dramatic decrease in ice older than two years in 2010. (Source: National Snow and Ice Data Center, courtesy C. Fowler and J. Maslanik, Colorado University, Boulder)
Other Findings Include Other Ice Loss, Land Loss, and Rising Temperatures
Changes to snow, ice and permafrost on land across the Arctic continue to show signs consistent with warming. For example, 2010 marked the shortest spring snow cover for the entire Arctic since satellite observations began in 1966. In the Canadian Arctic, the land ice continues to lose mass at a rate that has been increasing since 1987. And in many areas of the Arctic, permafrost temperatures continue to rise. (More on land changes here.)
Especially hard hit by changing conditions is Greenland: 2010’s record-setting high air temperatures are one to four degrees Fahrenheit above the long-term average, making for its highest melt rate since 1958 and its highest glacial area ice loss since 1978. The report states that the evidence is now clear “that the ice area loss rate of the past decade (averaging 120 km2/year) is greater than loss rates pre-2000.”
Warm Arctic, Cold U.S.?
Do you remember the unusually snow-ridden winter that D.C. and other mid-Atlantic states experienced last winter and that parts of Europe and Asia were similarly blessed with? One of the more interesting findings in the report card is that those wintertime conditions are related to the unusually warm temperatures that held sway in the Arctic.
How could that be? Check back tomorrow to find out.filed under: Arctic, climate change, global warming, temperatures
and: Alaska, Arctic Report Card, Canada, climate, Denmark, Finland, Greenland, ice, Iceland, Norway, permafrost, Russia, Russian Federation, sea ice, Sweden, United States