I’ve just been reading some news articles about Copenhagen. The latest is a (confidential) UN report that states that even with the best offers on the table, the world will warm an average of 3 degrees Celsius.
I actually think this is being optimistic.
The trouble is that the Earth is not a ball of rock that heats up and cools down in a simple linear manner. There is an amazingly complex web of interactions (that we don’t fully grasp yet.) For instance, take the current level of warming, not even 1 degree Celcius, and yet the summer artic ice will be gone in a matter of a few years:
Real vs projected Ice-loss
Most scientists until just a couple of years ago, would never have expected the loss to be so rapid (see how the real loss compares with projected losses by the IPCC.)
It’s even worse that that though. The measure that is more valuable is not the area of ice covered, but volume, and that has been declining even faster than the graph above shows. As we lose the artic ice (which acts effectively like a mirror, reflecting heat away) the surrounding area warms up even more rapidly, defrosting vast tracts of Siberian permafrost. This permafrost contains immense stores of carbon dioxide and methane (a greenhouse gas which is shorter lived in the atmosphere, but much more potent.) These gases are locked up in these so-called “clathrates” which are stable only because of the freezing temperatures. Once these start to let-rip, they will further amplify the warming. This is a classic positive feedback. (negative feedbacks, which reduce the effects of global-warming, are unfortunately harder to find – an example would be people dying due to increased heatwaves.)
So, it’s like a tragic domino-effect, with one system affecting many others, which in turn affect others in a vicious cycle. If we can’t control it now, we’ll have no chance once this process gets under way.
Many scientists say that 2 degrees Celcius is a major ‘tipping point’ after which we’ll lose control, but in reality, it’s just an educated guess. It may be 1 degree – we may have already crossed this invisible boundary. There’s just no way of knowing. Look at the artic-ice decline projections again. We’re already tracking much worse than all modelling predictions from just a few years ago. Expect the science to become ever more alarming as the models are refined.
The trouble is that the Earth is much more dynamic, complex and subtle than anyone will likely ever realise. We should be aiming for immediate-as-humanly-possible cessation of emissions that we can control, even if it entails substantial sacrifice, because the alternative will be much, much worse.
Steve, I agree. Many in the media and politics fail to realize that uncertainty cuts both ways. The fact that we don’t fully understand the climate system should make the necessity of action more urgent, not less.