I'm not sure when it started or when I first noticed it but CNN now has an Extreme Weather Desk as a regular feature in the course of their daily 24/7 news broadcasts. In my day... and I'm not kidding even though I'm only 54, in my day we didn't need an extreme weather desk! Of course occasionally the weather got crazy somewhere around the globe but that was exceptional and it was reported on then as it is today, breathlessly and with a sense of awe but you know, just not every damned day of the week!
Over at Joe Romm's blog -- an absolute essential if you want links to the peer reviewed science that unequivocally makes the case for a human footprint on global warming -- he catalogues the long year in extreme and unprecedented weather events that occurred worldwide this year. From the 1 in a 1,000 year flood in Tennessee and the "weatherbomb" that hit the mid-west in October, to extreme drought in Russia and devastating floods in Pakistan, it was a year that mimicked the climate models that the deniers love to disparage.
One of the more obvious and least discussed signs of global warming are the success of the pine beetle across North America where warmer climates have sparked an outbreak of a voracious mountain pine beetle that is having devastating consequences for whitebarks and the wildlife that depend on them both in the US as discussed in this report over at NPR, and this one from Canada's CBC, where it's reported that the beetles are expected to wipe out 80% of British Columbia's pine forests by 2013.
Now of course with snow falling in the northeast and all over Europe the deniers are pretending that these are proofs that AGW is not happening. In fact it is the opposite, this is exactly what global warming looks like during the winter months: Analysis of the ice-free regions of the Arctic Ocean has found that the higher temperatures there caused by global warming, which have melted the sea ice in the summer months, have paradoxically increased the chances of colder winters in Britain and the rest of northern Europe. More storms and more extreme weather like the recent flooding in California and Canada's maritimes.
It's not the fact that these types of storms happen that's proof of anything, it's the frequency with which they are happening. It's the same for the changes being seen around the globe. They've happened before during the history of the planet but not in such a compressed period of time -- it is that which points to the human footprint in all of this. Those greenhouse gasses that are being spewed out by humankind at historically unprecedented rates and causing rapid climate changes all over the planet. There have been rapid sea level rises before and the causes are still argued about, but the amounts of CO2 that were in the atmosphere when those changes occurred are considerably less than what we are on course for.