We can thank our clouds for saving us from a fate worse than Venus's

Clouds are essential as they reflect and scatter sunlight back into space - but nobody knows how hot the planet can become before the clouds no longer help us.

No one wants to think about cloudy skies in August but if they’re up there, be grateful. According to research published in Nature Geoscience on 28 July, we can thank clouds for saving us from a fate worse than Venus’s.

Venus – a barren, hot planet – suffered from the “runaway greenhouse effect” when its temperature rose past a critical point. That, it seems, arose from having too much thermal insulation resulting from the heat-storing greenhouse gases in the planet’s atmosphere.

On Venus, as on earth, carbon dioxide was an important contributor. Our planet is wet and heating it creates a lot of water vapour, a far more potent insulator than carbon dioxide. The more water vapour there is, the faster warming occurs.

Once you hit the point of no return at which the runaway effect starts, it would take only a few thousand years for life on earth to become untenable.

The recently published calculations show that the Venus effect could happen here – if it weren’t for clouds. They look white and fluffy to us because they scatter light. The tops of the clouds do the same, scattering and reflecting sunlight back into space before it has the chance to warm the earth and take it into the runaway scenario.

There’s still some uncertainty in the calculations, however: we don’t know exactly how hot we can let the planet become before the clouds can no longer help us. Unfortunately, uncertainty in other areas is pushing us in the right direction to find out.

The Intergovernmental Panel on Climate Change (IPCC) will publish its fifth assessment report next year. A draft report of some of its data, leaked to the Economist, suggests that increasing carbon-dioxide levels won’t warm the atmosphere as much as we had previously thought. In 2007, the IPCC stated that concentrations of between 445 and 490 parts per million (ppm) of carbon dioxide were likely to result in a rise in temperature of 2° to 2.4° Celsius above the temperatures before the Industrial Age. The new data suggests that 425 to 485ppm would give a rise of 1.3° to 1.7° Celsius.

The Economist threw in plenty of caveats (“The two findings are not strictly comparable”; the data comes “from a draft version of the report, and could thus change”) but evidently felt the burden of reducing carbon emissions is not as onerous as it once seemed. “It is clear,” the paper declared, “that some IPCC scientists think the projected rise in CO2 levels might not have such a big warming effect as was once thought.”

As it turns out, it’s not just carbon dioxide that we need to worry about. US researchers have been mapping the gas leaks from pipelines in urban areas. Boston has more than 3,000 leaks in the pipelines that deliver gas to homes and industries. Preliminary data from Washington, DC indicates that the capital is just as prone to leaks. It’s of huge concern because methane is 25 times more potent as a greenhouse gas than carbon dioxide. If similar figures apply to every other major city with an ageing gas infrastructure, perhaps the chances of earth slipping into a runaway greenhouse effect need revising upwards.

We can be sure those figures won’t be in the IPCC report, however. As for the ones in the Economist, we’ll just have to wait and see. In many ways, it doesn’t matter: the numbers are out there now and will be put to work by those keen to make sure we don’t punish carbon emitters. Such a leak is not going to make governments feel inclined to do something about the problem – they can just keep their head in the clouds.

Sunset over Tiananmen Square after a day of heavy pollution in Beijing. Photograph: Getty Images.

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 12 August 2013 issue of the New Statesman, What if JFK had lived?

Ukip's Nigel Farage and Paul Nuttall. Photo: Getty
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Is the general election 2017 the end of Ukip?

Ukip led the way to Brexit, but now the party is on less than 10 per cent in the polls. 

Ukip could be finished. Ukip has only ever had two MPs, but it held an outside influence on politics: without it, we’d probably never have had the EU referendum. But Brexit has turned Ukip into a single-issue party without an issue. Ukip’s sole remaining MP, Douglas Carswell, left the party in March 2017, and told Sky News’ Adam Boulton that there was “no point” to the party anymore. 

Not everyone in Ukip has given up, though: Nigel Farage told Peston on Sunday that Ukip “will survive”, and current leader Paul Nuttall will be contesting a seat this year. But Ukip is standing in fewer constituencies than last time thanks to a shortage of both money and people. Who benefits if Ukip is finished? It’s likely to be the Tories. 

Is Ukip finished? 

What are Ukip's poll ratings?

Ukip’s poll ratings peaked in June 2016 at 16 per cent. Since the leave campaign’s success, that has steadily declined so that Ukip is going into the 2017 general election on 4 per cent, according to the latest polls. If the polls can be trusted, that’s a serious collapse.

Can Ukip get anymore MPs?

In the 2015 general election Ukip contested nearly every seat and got 13 per cent of the vote, making it the third biggest party (although is only returned one MP). Now Ukip is reportedly struggling to find candidates and could stand in as few as 100 seats. Ukip leader Paul Nuttall will stand in Boston and Skegness, but both ex-leader Nigel Farage and donor Arron Banks have ruled themselves out of running this time.

How many members does Ukip have?

Ukip’s membership declined from 45,994 at the 2015 general election to 39,000 in 2016. That’s a worrying sign for any political party, which relies on grassroots memberships to put in the campaigning legwork.

What does Ukip's decline mean for Labour and the Conservatives? 

The rise of Ukip took votes from both the Conservatives and Labour, with a nationalist message that appealed to disaffected voters from both right and left. But the decline of Ukip only seems to be helping the Conservatives. Stephen Bush has written about how in Wales voting Ukip seems to have been a gateway drug for traditional Labour voters who are now backing the mainstream right; so the voters Ukip took from the Conservatives are reverting to the Conservatives, and the ones they took from Labour are transferring to the Conservatives too.

Ukip might be finished as an electoral force, but its influence on the rest of British politics will be felt for many years yet. 

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