Four degrees - so what?

Climate Change Catastrophe by Degrees

Bob Watson rightly warns us to prepare for 4C global warming. To avoid that, we must make drastic CO2 cuts now

Who is Watson?

...he is the former chair of the Intergovernmental Panel on Climate Change (IPCC), but was kicked out at the behest of the Bush administration for being too vocal about the threat presented by global warming.

Four degrees? no problem, right?

By the time global temperatures reach four degrees, much of humanity will be short of water for drinking and irrigation: glaciers in the Andes and Himalayas, which feed river systems on which tens of millions depend, will have melted, and their rivers will be seasonally running dry. Whole weather systems like the Asian monsoon (which supports 2 billion people) may alter irrevocably. Deserts will have spread into Mediterranean Europe, across most of southern Africa and the western half of the United States. Higher northern latitudes will be plagued with regular flooding. Heatwaves of unimaginable ferocity will sear continental landscapes: the UK would face the kind of summer temperatures found in northern Morocco today. The planet would be in the throes of a mass extinction of natural life approaching in magnitude that at the end of the Cretaceous period, 65m years ago, when more than half of global biodiversity was wiped out.

Four degrees of warming would also cross many of the “tipping points” which so concern climate scientists: the Amazon rainforest would likely collapse and burn, as part of a massive further release of carbon from terrestrial ecosystems - the reverse of the current situation, where trees and soils absorb and store a good portion of our annual emissions. Most of the Arctic permafrost will lie in the melt zone, and will be steadily releasing methane, accelerating warming still further. The northern polar ice cap will be a distant memory, and Greenland will be melting so rapidly that sea level rise by the end of the century will be measured in metres rather than centimetres.

Frightening.

And since four degrees would be a catastrophe that many of us, or our children, would not survive, it is surely our absolute duty to do everything in our power to avoid it.