| [Update]: I saw a diary at DailyKos after posting this (still catching up on 2 weeks' worth of news, blogs, etc.) that should be top-headline news, even amongst the items currently in that spot. Arctic ice cap now smallest in at least a few thousand years. It links to a ScienceDaily article with the details: Arctic ice at low point compared to recent geologic history. The key finding is this: the rate of ice loss witnessed in the past 30 years, and that of the past century, is unprecedented over the last few thousand years. The Arctic sea ice sheet has fundamentally changed. Its existence and characteristics in the 21st century will be very different than it was in the last few millenia. President Obama talks a lot about future generations. Is this the future he is prepared to hand them?
Arctic Ice
The big change since last month has been the very rapid melting of ice that is less than one year old. This ice is the thinnest and thus the most susceptible to warmer conditions. In fact, as of the beginning of June 2010, the areal ice extent reached a modern-day record low of ~11.5 million sq. km., which is 1.5 million sq. km. below the climatological average! Unfortunately, ~2 million sq. km. of Arctic sea ice melted in May 2010. How big is that? The country of Mexico is a little smaller than 2 million sq. km. in size. The country of Saudi Arabia is a little larger than 2 million sq. km. in size. Colorado is ~270,000 sq. km. More than 7 Colorado's worth of ice melted in one month's time in the Arctic. When you read or hear that most of the warming already experienced by the Earth has happened near the poles, this is merely one effect. Rapid growth and decay of ice can and will occur. Overall, however, ice volume has decreased. Ice volume has been decreasing for decades. It is only recently that enough volume has melted that the impacts become obvious in the areal extent.
Antarctic Ice
The state of Antarctic sea ice in mid-June 2010 was much better than it was during April 2010 - exceeding the average extent relative to climatological norms by an increasing margin throughout the last month and a half. The areal extent shifted from normal to significantly more than normal during this time. The extent at the middle of June 2010 was larger than at the middle of June 2009. I haven't read anything definitive as to the reason, but given how much Antarctic ice melts and grows each year and taking into consideration the evidence of rapidly decaying and growing Arctic ice, it makes sense that Antarctic sea ice isn't very thick. Nearly all of it melts every year. It appears as though the rate of growth or decline simply shifts annually with given weather conditions.
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Here are my State of Polar Ice posts from May and April.
Pictures and Graphs
Here is a satellite representation of Arctic sea ice conditions from yesterday:
For comparison purposes, here is the similar picture from May:
Here is the time series graph of Arctic sea ice extent with the +/- 2 standard deviations as a light-gray envelope around the climatological average through yesterday:
Obviously, the satellite-derived graphic and the time-series plot show a very large amount of Arctic sea ice melting since the beginning of April. The sea ice extent has been at a modern-day record low since late May.
I was recently made aware of a slightly different Arctic sea ice extent time series - one that shows conditions since 2002. I have found that it provides additional context for comparing current conditions against the past. One of the striking things that came through was the record-setting extent of ice in early April 2010 (red curve; the largest extent occurring at the latest calendar date) shifting to the record-setting extent of ice in early June 2010. While the rapid melting observed so far this year is significant, it doesn't really indicate one way or the other what conditions this fall will be. 2007 (dark green curve) and 2008 (light green curve) witnessed very low extents. Will weather and ice conditions be conducive to repeat that sad state this year? We'll have to wait and see.
You can find the NSIDC's May report here. The page is dynamic, so if you're reading this after June 2010, that month's report will show up first. If that's the case, you can look for the May report on the top pull-down tab on the right-hand side of the page.
Here is a satellite representation of Antarctic sea ice conditions from yesterday:
For comparison purposes, here is the similar picture from May:
Here is the time series graph of Antarctic sea ice extent with the +/- 2 standard deviations through yesterday:
Contrary to Arctic sea ice conditions, the Antarctic sea ice extent has undergone a very large increase since mid-March. As the time-series above demonstrates, today's extent is very unusual (outside the +/- 2 standard deviation range).
Cross-posted at WeatherDem - the blog. |
