In 2008, I wrote a book calledClimate Wars about the science and the geopolitics of climate change, and for a couple of years afterwards I had a sort of intermittent double vision. In my mind’s eye, I would suddenly see the three-degree-hotter world overlaid on the world that existed at that time. Such afflictions, however, can usually be cured by a judicious combination of outdoor exercise and good wine – and now that you know the remedy you can be confident that reading this book will cause no similar derangement. But when I immersed myself in that world again more than a decade later, I did notice that some of the scientists I’d met first time around now seemed a bit more – what’s the word? – distracted. Not actual waking visions, you understand. Just moments lost in thought.
As the climate crisis deepens and the negative impacts multiply, public opinion and politics are finally responding, but there is no guarantee that our actions will be big and fast enough to avoid an outcome that is catastrophic for human beings and quite disruptive, at least, for the entire biosphere. We are not even sure yet how big and how fast those actions need to be, because the discipline of climate science is only about forty years old. But the answer is almost certainly: very big and very fast.
How extreme it could get depends on two main things: how intent we are on burning all the fossil fuels we already know about, and how sensitive the Earth’s climate is to that carbon injection. We could get to 8°c of warming fairly readily, but we probably wouldn’t, because it would be so catastrophic well before we reached that point that it would terminate our activities. We are still able to trigger warming of the order of 5°c globally, burning only a fraction of the fossil fuels, if we consider the feedbacks and tipping points. Very sobering for those of us who work on this day in, day out.
Tim Lenton, Professor of Climate Chan
