New research suggests worst-case global warming temperatures won’t be hit
When writing about climate change and global warming, there is no such thing as good news. There’s only ‘bad news’ and ‘less bad news’. This announcement fits broadly in the latter of these – the bitter but slightly refreshing lime after a, particularly vile tequila slammer.
Researchers from the University of Exeter believe that our worst-case climate change forecasts – that the Earth will be four or five degrees Celsius hotter by 2100 – are almost certainly not correct. “Our study all but rules out very low and very high climate sensitivities,” said lead author Peter Cox, a professor at the University of Exeter told The Guardian.
Cox and his team reached that conclusion by revising the calculation of how greenhouse gases affect the planet’s surface temperature: if the amount of CO2 in the atmosphere is doubled, how much hotter will the planet be? This is known as equilibrium climate sensitivity – and with a new methodology which examined year-to-year fluctuations rather than historic temperatures, the researchers found that the range of possible outcomes could be more than halved – and that takes the 3.4°C to 4.5°C apocalyptic rise off the table altogether.
To be clear, this doesn’t mean that we can go back to burning fossil fuels like it’s 1999 – the revised estimate in the paper suggests we’re on target for an increase of some 2.2°C to 3.4°C. That exceeds the two-degree threshold that the Paris Climate Accord was based around avoiding – and even that was considered a letdown, with some particularly vulnerable island nations holding out for 1.5°C as the cut-off point.
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As Dargan Frierson, associate professor of atmospheric sciences at the University of Washington said last year: “Countries argued for the 1.5°C target because of the severe impacts on their livelihoods that would result from exceeding that threshold. Indeed, damages from heat extremes, drought, extreme weather and sea level rise will be much more severe if 2°C or higher temperature rise if allowed.”
In some ways, therefore, this isn’t even ‘less bad news’. The UN’s intergovernmental panel on climate change had previously settled on the range of 1.5°C to 4.5°C – so although the worst case scenario may no longer be realistic, neither is the best case.
As The Guardian points out, the new methodology also doesn’t take into account the possibility of rapid shifts brought on by huge environmental events. The gulf stream collapsing, carbon-rich permafrost thawing or the melting of ice sheets in Antarctica – or in a really bad era, all three – could throw a spanner in the works of this new equation, and it wouldn’t be the kind of lucky spanner shot that somehow fixes everything. Things could get worse, fast.
As I said at the start, there really is no such thing as good climate change news. This is less bad, but it’s still a long way away from being good by any real metric. But with Donald Trump unlikely to have a change of heart over the White House’s stance on climate change, “less good” is probably all we can hope for.
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