"Dangerous Climate Change" is already here, and the scientists know it.

The IPCC’s new assessment report hasn’t even been released, but the denialist fog machine is already running hard.  If you’re tired of it — and, frankly, if you’re tired of the smoothly-leveled understatement that we usually get from the IPCC — take a look at Is Climate Change Already Dangerous?, a new report by David Spratt of Australia’s Climate Code Red.

I’ll not summarize this report; there’s no point because it’s already a summary, one which sticks extremely close to the original scientific literature.  But I will say that its focus is the Arctic, which as you may have noticed is getting a lot of nervous attention these days.  And this for the very good reason that it’s melting before our eyes!  Spratt’s paper is excellent on this subject – it lays out the basics of the situation and gives you the citations you need to drill deeper.  Assuming you’re up to it.  The message, after all, is that we’ve already crossed the thin red line into the days of “dangerous climate change.”

What’s happening here?  Here’s a nice overview from Professor Peter Wadhams, of Cambridge University and the Catlin Arctic Survey.  The author of a recent paper called Arctic ice cover, ice thickness and tipping points and a leading authority on the polar regions, Wadhams says:

“I have been predicting [the collapse of sea ice in summer months] for many years. The main cause is simply global warming: as the climate has warmed there has been less ice growth during the winter and more ice melt during the summer… in the end the summer melt overtook the winter growth such that the entire ice sheet melts or breaks up during the summer months. This collapse, I predicted would occur in 2015–16 at which time the summer Arctic (August to September) would become ice-free. The final collapse towards that state is now happening and will probably be completed by those dates. As the sea ice retreats in summer the ocean warms up (to +7ºC in 2011) and this warms the seabed too. The continental shelves of the Arctic are composed of offshore permafrost, frozen sediment left over from the last ice age. As the water warms, the permafrost melts and releases huge quantities of trapped methane, a very powerful greenhouse gas so this will give a big boost to global warming.” (Vidal, 2012)

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