Even this isn’t the worst-case scenario, however. An Earth six degrees warmer than today would have sea levels as much as 200 metres higher than they presently are with the oceans themselves too warm to sustain much life. This world would be almost entirely covered by desert, with only today’s polar regions capable of supporting extensive agriculture. Yet even all of these challenges would be trivial compared to the real game-changer: substantially increased levels of atmospheric methane. In that event, anything with lungs would struggle to breathe.
The good news is we can still avoid much of this. Indeed, we may even be able to reverse some of the damage we ’ve already caused, thereby undoing changes which at present appear inevitable. It won’t be easy, however, and will require a global transition away from fossil fuels over the next two decades. Yet if humanity can reduce carbon dioxide emissions by at least 85 per cent by 2050 that should stabilise atmospheric levels at around 400 parts per million (ppm) – slightly above those of today but enough to steer clear of runaway catastrophe.
The bad news is that while we know what needs to be done, that’s been the case for the last twenty-five years – and we ’ve only gone backwards. The Rio Earth Summit, held in 1992, was the moment climate change became a story of global significance. Yet CO levels were 61 per cent higher in 2013 than they were in 1990, with the years following the 2008 crisis recording the highest annual increases in history. Properly understood, our present course isn’t one of inaction, it’s rushing full speed to oblivion.
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