So, the latest New Scientist is out, and Fred Pearce, author of the superlative "The Last Generation" (among many others) has a frankly terrifying piece called "Arctic meltdown is a threat to humanity".
It starts grim:
'"I AM shocked, truly shocked," says Katey Walter, an ecologist at the University of Alaska in Fairbanks. "I was in Siberia a few weeks ago, and I am now just back in from the field in Alaska. The permafrost is melting fast all over the Arctic, lakes are forming everywhere and methane is bubbling up out of them."and just gets grimmer.
'Back in 2006, in a paper in Nature, Walter warned that as the permafrost in Siberia melted, growing methane emissions could accelerate climate change. But even she was not expecting such a rapid change. "Lakes in Siberia are five times bigger than when I measured them in 2006. It's unprecedented. This is a global event now, and the inertia for more permafrost melt is increasing."'
'The rapid warming in the Arctic means that a global temperature rise of 3 °C, likely this century, could translate into a 10 °C warming in the far north. Permafrost hundreds of metres deep will be at risk of thawing out.'and grimmer
'Schuur estimates that 100 billion tonnes of this carbon could be released by thawing this century, based on standard scenarios. If that all emerged in the form of methane, it would have a warming effect equivalent to 270 years of carbon dioxide emissions at current levels. "It's a kind of slow-motion time bomb," he says.'There's the usual bit where scientists admit that they have (for understandable and normally admirable reasons) underestimated the speed and scope of the changes:
'Put together, the latest research paints a disturbing picture. Since existing models do not include feedback effects such as the heat generated by decomposition, the permafrost could melt far faster than generally thought. "Instead of disappearing in 500 years, the deepest permafrost could disappear in 100 years," Ciais says.
And the talik thing?
' What's more, if summer melting depth exceeds the winter refreezing level then a layer of permanently unfrozen soil known as a talik forms, sandwiched between the permafrost below and the winter-freezing surface layer. "A talik allows heat to build more quickly in the soil, hastening the long-term thaw of permafrost," says Lawrence.'