Back on August 17 the Associated Press reported that “there was less sea ice in the Arctic … than ever before on record,” according to satellite measurements by the National Snow and Ice Data Center (NSIDC). There were 2.02 million square miles of Arctic ice on August 17; as of August 22 it was down to 1.89 million square miles (4.92 million square kilometers). The graphic shows the ice on August 21, compared to a pink outline of the median sea ice extent in August from 1979-2000. (Picture credit: National Snow and Ice Data Center)
The NSIDC site notes that between August 17 and 22, the Arctic ice shrank by 131,000 square miles — an amount larger than the state of New Mexico. The AP reported that the melting was happening faster than climate models predicted.
The previous record for the least amount of ice present during summer was set in 2005, at 2.05 million square miles. The ice usually reaches its smallest extent in September, so there is more melting to come this year.
Each year the sea ice shrinks during the summer melting season from March to September. Then the ice grows back again from September to March. The summer minimum has been occuring later in recent years because of a longer melting season, according to the NSIDC’s FAQs. As a result, during winter the ice has not been growing back as much. The sea ice maximum extent in March 2007 was the second-lowest on record at 5.7 million square miles. Scientists have beem monitoring the sea ice since 1978.
Why is all of this important? Because as the NSIDC Web site points out, “Arctic sea ice keeps the polar regions cool and helps moderate global climate. Sea ice has a bright surface, so 80 percent of the sunlight that strikes it is reflected back into space. As sea ice melts in the summer, it exposes the dark ocean surface. Instead of reflecting 80 percent of the sunlight, the ocean absorbs 90 percent of the sunlight. The oceans heat up, and Arctic temperatures rise further.”
Temperature increases at the poles can lead to greater warming over time. The loss of sea ice can potentially speed up global warming trends and alter climate patterns.
NSDIC senior research scientist Mark Serreze told the AP that at this year’s rate of melt, the summer sea ice extent could shrink to zero in 2030.
Stay tuned in September to see how low the sea ice will go.
Wow, 2030 seems like the very near future to be completely out of sea ice (even in the summer).
Dan, compelling story. I am still amazed that some people don’t accept the fact of human-caused global warming. Why don’t they, I wonder?
Deborah
I’m not a professional just an ex-sceptic who’s now become a climate science reading hobbyist. (sorry for the date-format, I’m British)
A better graph than that showing extent might be figure 3 of 28/8/07 (NSIDC’s page is in date segments.) which compares sea ice concentration for 27/8/07 and 27/8/05. Also figure 4, an animated gif that charts the disappearance of old ice since 1982.
The significance of old (or perennial) ice is that new ice is thinner and more easily broken up and rafted out by storms. Losing old ice means a structural weakening of the ice cap.
What seems to have happened this year is a rapid intensification of the already observed pattern of a thinning and structural weakening of the ice cap. Now it looks as if although the reasons for the early record breaking low of 14/8/07 were coincidental (discussed by figure 5 of 14/8/07), their effect could actually impact coming years.
Until the recent data I’d have not considered talk of an Arctic free of Summer ice by 2020 as realistic. We will of course have to see what happens next year, but there is now reason to expect next year to be as bad, or worse. This years record may be the start of a new trend, it cannot now be easily dismissed as “just a blip”.
That sea ice extent continues to decrease per NSIDC news. I tried to send you the link earlier, but I was warned it was caught by your spam filter. (You might be able to find it.)
Unfortunately, Antarctica has not done too well in recent years either, with NASA reporting yesterday “NASA Researchers Find Snowmelt in Antarctica Creeping Inland” using data collected from 1987 to 2006.
Thanks for the comments. As of Sept. 20, the National Snow and Ice Data Center is saying that the Arctic sea ice appears to have hit its minimum on Sept. 16. See http://nsidc.org/news/press/2007_seaiceminimum/20070810_index.html
The ice this year shrank to an area 23 percent smaller than the previous record low in 2005. NSIDC will have a full report in early October, at which time I’ll write a new post about their final data and conclusions.
Regarding Antarctica, I did see this news report from Sept. 24 about how NASA scientists have documented that snow is melting farther inland and at higher altitudes. See this link, http://www.sciencedaily.com/upi/index.php?feed=Science&article=UPI-1-20070924-13194600-bc-us-snowmelt.xml