by Gareth on July 24, 2013
Reading this press release about a new paper in Palaeogeography, Palaeoclimatology, Palaeoecology spoiled my day. It might not be obvious to a casual reader just glancing through the morning news — but a couple of paragraphs leapt out at me:
Atmospheric carbon dioxide concentrations recently reached 400 parts per million for the first time since the Pliocene Epoch, three million years ago. During this era, Arctic surface temperatures were 15-20 degrees Celsius warmer than today’s surface temperatures.
Ballantyne’s findings suggest that much of the surface warming likely was due to ice-free conditions in the Arctic. That finding matches estimates of land temperatures in the Arctic during the same time. This suggests that atmospheric carbon dioxide concentrations of 400 ppm may be sufficient to greatly reduce the spatial extent and seasonal persistence of Arctic sea ice.
In other words, losing Arctic sea ice brings huge warming to the lands around the Arctic Ocean. This is extremely bad news for a number of reasons:
- We’re losing the Arctic sea ice well ahead of any schedule derived from model predictions. The sea ice summer minimum could drop below 1 million km2 within a decade. I have argued that it might be even sooner…
- Arctic warming and sea ice losses are already impacting northern hemisphere weather patterns.
- Once the summer sea ice has gone, it’s only a question of how long it will take for the winter ice to disappear. When I last looked at this issue, three years ago, I suggested this might happen much sooner than anyone expected — perhaps by the 2040s.
- When I wrote that post, I suggested that — if we were unlucky — winter ice loss could be within the current climate commitment — that is, within the warming we would expect to see from current levels of greenhouse gases. Ballantyne et al’s new paper explicitly supports that view.
- The consequences of warming of 10ºC to 20ºC on the lands around the Arctic Ocean are horrendous. Recent research suggests that total warming of as little as 1.5ºC could be enough to start major releases of methane as permafrost in Alaska, Canada and Siberia melts. There are also huge deposits of methane beneath the East Siberian Shelf (ESS) that are already beginning to discharge to the atmosphere as their permafrost cap begins to disintegrate under a warming ocean.
- A persistent large scale release of methane would transform the global climate system and make efforts to contain warming by reducing anthropogenic emissions more or less futile. We would be heading far beyond 2ºC deep into the realms of catastrophe.
- Just to complete my bad day, this Guardian report on a new paper modelling the economic costs of a 50 Gt methane release from the ESS suggests that the impact would generate an “extra $60 trillion (net present value) of mean climate change impacts” — comparable to total global GDP at present. World economy over, in other words.
This should be headline news. It should be plastered all over the front pages of newspapers and web sites around the world. TV pundits should be demanding action from the politicians who have put action on emissions reductions in the “too hard” basket. The evidence is beginning to suggest that Wally Broecker’s angry beast, fed up with being prodded with ever bigger sticks, is going to bite back hard — and bite back soon. Is there time to stop all this happening? Perhaps — but it will take a huge effort, a wartime response when the world is being led by billionaires, ideologues and their appeasers intent on denying reality. We’re sleepwalking to disaster. By the time we wake up, it will be too late.