The Recovery of Arctic Sea Ice Extent

During the northern Winter, much of the Arctic is covered with sea ice. Some of this ice melts during the summer, then it regrows. Over recent years, the amount of ice loss in the summer has tended to increase, almost every year, year after year. In 2012 the loss of sea ice was extreme, falling for much of the melting and re-freezing cycle below any year seen before.

The year 2013 was also extreme, with more ice melting away in the summer than almost every previous year, but not to the extent seen in 2012.

Climate science denialist used this fact to make up a story. In this case, the word "story" is a nice way of saying "lie." The denialists claimed that Arctic Sea Ice was "recovering." Well, it was, sort of. Sea ice in 2013 was more extensive than the previous year, but still at a very low level. Part of the "recovery" story was the assertion that the sea ice would not return to "normal" levels year after year. A cycle was simply repeating itself.

The problem with the cycle idea is that there is no really a cycle. In a non-global-warming world there probably would be something that looks like a cycle, or at least a decadal (or something) fluctuation from year to year. But with global warming we have seen a phenomenon called "Arctic Amplification." This is the warming of the arctic region to a greater extent than most of the rest of the plant. With Arctic Amplification we have seen sea ice extent drop nearly every year for about 20 years. I've written about the importance of this here. This does not seem to be a cycle, but rather, a downward trend. The fact that 2012 was extreme makes 2013 look like a reversal, but there is no reason to think that it is.

Now it is Winter in the Arctic. When we look at sea ice extent, we see something interesting. The current level of sea ice is hugging the 98th percentile of observed sea ice extent, at the lower margin. More interestingly, when we compare 2012, the "recovery" year, with the current ice extent, it turns out that the current ice extent is less than the "recovery."

Here's a graph from the National Snow and Ice Data Center:

Screen Shot 2014-01-15 at 2.00.48 PM

And here's the larger scale graphic for context:
Screen Shot 2014-01-15 at 1.58.53 PM

Jim Pettit, commenting here, noted, "...just wanted to note that denialists have now gone silent on the “recovery” of NH sea ice extent, since that reading is currently several hundred thousands square kilometers lower than it was on this date in 2012, the year of the record melt-out."

I can not verify Jim's statement about denialists going silent, but it seems right. I'm not sure what the best way to measure that would be (seems like a lot of work) and I don't think we have to. Paying too much attention to denialist rhetoric is a waste of time. But I think he may well be right. The answer to the statement "Global warming is not real because SEA ICE RECOVERY" was, several weeks ago, "Right ... recovery from an extreme year, but the ice is still less than almost every observed previous year." The answer to that same assertion is now "Um .... nope."

The graphic at the top of this post speaks to volume rather than extent. I put it there just to remind everyone that volume is probably even more important, as this reflects loss of long-term ice and also involves a lot more global-warming related energy. If the huge volume of sea ice wasn't there to melt in the summer, that heat would be elsewhere in the system. When there is virtually no "old ice" left ... well, that will be like the ice in your drink melting. It (your drink, the planet, whatever) will get warm and icky.

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"This is the warming of the arctic region to a greater extent than most of the rest of the plant."

What "plant" are we talking about here? Gardenias? Tulips?

By Keefer1958 (not verified) on 19 Feb 2014 #permalink