Is it a result of climate change or something else? Part 1.
(Page 2 of 2)
He adds, "This is probably just a perception, but I just have the feeling that the glaciers are melting, the snow capping the mountains is less than it was 12 years ago when I saw it last time."Skip to next paragraph
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The long-term trend of diminishing ice in the Arctic is well-documented. But the valley-and-peak nature of the trend, evident in this graphic, raises the possibility that during past summers, there was less ice compared with today.
During the summer of 2007, for example, Arctic ice reached the lowest extent so far recorded. So if you view photos of only today's ice and 2007's, you might conclude that ice was increasing. But it's not.
In this case, however, I'm asking, could Thirsk have seen what he thinks he saw?
According to his NASA biopage, Thirsk was last in space in June and July of 1996.
Yes, there's less ice now than then. In June 1996, there were 12.1 million square kilometers of ice; in 2009, 11.5 million. While not minuscule, the changes aren't great either. There is a larger change in sea ice thickness, but that's not, presumably, discernible with the naked eye from space.
(For sticklers, here's the orbital path of the space station and the shuttle. Yes, they seem to travel within viewing range of both the Arctic and Antarctic, but not directly over.)
So, again, could Thirsk have seen what he says he saw? Hard to say. He mentions mountain glaciers, which, given the contrast with brown earth, have probably shrunk much more obviously since his last space trip. And yet, if these images of the Upsala Glacier in 2001 and '04 are any indication, even that would be a difficult assessment to make. Only a yellow line painted on the photo makes the extent of the retreat obvious. (Here's another comparison of the San Quentin Glacier in Patagonia in 1994 and 2004.
To be fair, Thirsk, a highly trained astronaut, probably has a highly trained eye, one capable of noting subtle changes in ice coverage. The question is: Were global warming not on his mind, and did he not know what to look for, would he have?
Come back tomorrow Click here to read the second part of this post, where the writer looks at threats of desertification and "permanent drought" in Mongolia and the Fertile Crescent.