Growing alarm after recent findings of a very warm Arctic in the past!

June 17, 2006 by almuth

Earlier this month, Nature published a study about sea temperatures in the Arctic ocean 55 million years ago. That was the time of the last massive greenhouse warming, the so-called Paleocene-Ecovene Thermal Maximum or PETM. Those new findings suggest that sea surface temperatures (and thus air temperatures) in the Arctic were far, far higher than previously thought. About as warm as Spain today, I think. This is far worse than standard climate models suggest.

We have all read enough alarming evidence on climate change, so apologies for posting about more doom and gloom here. But the media have made very little of what could be the most alarming of all climate studies published in recent years.

I regularly read the excellent climate science blog www.realclimate.org/ , run by climate scientists. And there seems to be a growing sense of panic following the study (sorry - I don't think that those scientists would like to see the term 'panic' next to their name) - and that from scientists who have consistently warned against exaggerating the results of individual studies, and who have doubted that human civilisation is likely to end because of global warming.

Raymond Pierrehumbert, for example, explained back in April why a runaway greenhouse effect (Earth becoming like Venus with no turning back) could be virtually ruled out. When somebody quoted him on a more recent blog discussion, he replied something along the lines of "well, it's highly unlikely, but after the results from the Arctic, maybe we can't rule it out completely". I think the concern now is that the extreme warming could only have happened because of considerable additional warming from cloud-changes, and that those cloud-effects are not factored into any of the standard climate models. Indeed, some of the runs by Climate Prediction Net came up with a runaway greenhouse effect. They were dismissed as going against the general understanding of physics, and they may be re-run and examined now.

I recommend people look at the full debate under 'Positive feedbacks from the Climate Cycle' on the weblog (particularly the replies to comments).

Of course, the PETM did not lead to runaway warming, and there maybe a good lesson for us from the recent study in Nature: It suggests that climate regulation kicked in and eventually cooled the planet down - but only because of massive swamps with fern spreading very rapidly over the Arctic and pumping down tremendous amounts of CO2 (and even then, it took 80,000 to 200,000 years to actually cool the planet - and indeed a lot of the CO2 reductions would have come from the silicate weathering cycle and chemical reactions in the ocean). We might owe our existence to this carbon sink at the time! If there had been humans around then, destroying the fern and trying to grow crops in the Arctic, then climate regulation could well have failed completely.

Which very much supports my sense that human destruction of carbon sinks is as much of a disaster as the burning of fossil fuels. And that the apparent consensus within the climate change movement that we can save the planet SOLELY by drastically reducing fossil fuel burning (which of course remains an absolute priority!) might be a very dangerous one.