27 Sep 2013

‘Sure as dammit’ – IPCC’s latest verdict on global warming

At a time when public opinion and political action on climate change are at an all-time low, this report may come as something of a surprise.

We could be forgiven for thinking the potential dangers of a warming planet had started to go away – especially if you read certain newspapers.

But today’s report from the IPCC has never been more strongly worded on the evidence for a warmer future. This report, remember, is endorsed by 250 scientists around the world and all the governments that are parties to the IPCC.

Warming of the planet is now, in their words, unequivocal. And that we as humans are almost certainly to blame.

By increasing their estimate for certainty over whether mankind is behind global warming from 90 per cent to more than 95 per cent, the IPCC is getting as close as scientists will ever get to “sure as dammit”.

Today’s review doesn’t increase the estimate for the amount the planet will warm by the end of the century. That remains pretty much as it has done since the first IPCC report 23 years ago: a rise of between 1.5 and 4.5 degrees by 2100.

However, because many more observations have been made since then and many more climate models run, there is less doubt about the likelihood of those predictions.

It’s why the scientists can claim more confidence on perhaps their most important conclusion. This is the first report to put a scientific context around the politically agreed target of two degrees of warming by the end of the century.

The report shows that unless global carbon dioxide emissions start to go down almost immediately (which they’re not), it is more than likely we will exceeding that limit – and possibly overshoot it by a degree or more.

The report also gives short shrift to claims made by climate change contrarians that an undeniable “pause” in global air temperature increase since 1998 shows the problem of global warming has gone away or was over-egged.

The basic idea is as incontrovertible as any well founded scientific theory. That as we add greenhouse gases to the atmosphere, more heat gets trapped on earth. And the temperature keeps on gradually rising.

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Watch from the archive: Tom Clarke talks to scientists back in 2009 about “10 ideas to save the world”, from nuclear power to mirrors in space.

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