Details of AR5 (the 5th IPCC Assessment Report) are emerging in Stockholm and the signs are not good. At this stage it’s difficult to know exactly who is saying what – the scientists or the journalists. The Mail on Sunday’s David Rose is there of course, wasting everyone’s time – of course.
One thing is clear: evaluations of the danger we face are still based on the assumption that we can live with the consequences of a 2° rise in global mean temperatures. And that leaves me shaking my head in disbelief.
The changes we can see already (extreme weather events, shifting rainfall patterns, ice melt, etc.) are the effect of a mere 0.8° rise. Or rather – and this is important – the beginning of that effect. That 0.8° is still working its way through the system, the vast and horrendously complex system that is our biosphere. Its full effect will not be known for another… what, another 20-30 years? If global warming stopped tomorrow, the Earth would not stabilise as we see it today. Change would continue until the visible, measurable effects catch up on the additional heat that’s already been pumped into the system.
In other words, we still have no idea what the effect of even a 1° rise will be. So, someone – please! – explain to me how we can assume that a 2° rise will be somehow OK.