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?

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John Major's double warning for Theresa May

The former Tory Prime Minister broke his silence with a very loud rebuke. 

A month after the Prime Minister stood in Chatham House to set out plans for free trading, independent Britain, her predecessor John Major took the floor to puncture what he called "cheap rhetoric".

Standing to attention like a weather forecaster, the former Tory Prime Minister warned of political gales ahead that could break up the union, rattle Brexit negotiations and rot the bonds of trust between politicians and the public even further.

Major said that as he had been on the losing side of the referendum, he had kept silent since June:

“This evening I don't wish to argue that the European Union is perfect, plainly it isn't. Nor do I deny the economy has been more tranquil than expected since the decision to leave was taken. 

“But I do observe that we haven't yet left the European Union. And I watch with growing concern  that the British people have been led to expect a future that seems to be unreal and over-optimistic.”

A seasoned EU negotiator himself, he warned that achieving a trade deal within two years after triggering Article 50 was highly unlikely. Meanwhile, in foreign policy, a UK that abandoned the EU would have to become more dependent on an unpalatable Trumpian United States.

Like Tony Blair, another previous Prime Minister turned Brexit commentator, Major reminded the current occupant of No.10 that 48 per cent of the country voted Remain, and that opinion might “evolve” as the reality of Brexit became clear.

Unlike Blair, he did not call for a second referendum, stressing instead the role of Parliament. But neither did he rule it out.

That was the first warning. 

But it may be Major's second warning that turns out to be the most prescient. Major praised Theresa May's social policy, which he likened to his dream of a “classless society”. He focused his ire instead on those Brexiteers whose promises “are inflated beyond any reasonable expectation of delivery”. 

The Prime Minister understood this, he claimed, but at some point in the Brexit negotiations she will have to confront those who wish for total disengagement from Europe.

“Although today they be allies of the Prime Minister, the risk is tomorrow they may not,” he warned.

For these Brexiteers, the outcome of the Article 50 negotiations did not matter, he suggested, because they were already ideologically committed to an uncompromising version of free trade:

“Some of the most committed Brexit supporters wish to have a clean break and trade only under World Trade Organisation rules. This would include tariffs on goods with nothing to help services. This would not be a panacea for the UK  - it would be the worst possible outcome. 

“But to those who wish to see us go back to a deregulated low cost enterprise economy, it is an attractive option, and wholly consistent with their philosophy.”

There was, he argued, a choice to be made about the foundations of the economic model: “We cannot move to a radical enterprise economy without moving away from a welfare state. 

“Such a direction of policy, once understood by the public, would never command support.”

Major's view of Brexit seems to be a slow-motion car crash, but one where zealous free marketeers like Daniel Hannan are screaming “faster, faster”, on speaker phone. At the end of the day, it is the mainstream Tory party that will bear the brunt of the collision. 

Asked at the end of his speech whether he, like Margaret Thatcher during his premiership, was being a backseat driver, he cracked a smile. 

“I would have been very happy for Margaret to make one speech every eight months,” he said. As for today? No doubt Theresa May will be pleased to hear he is planning another speech on Scotland soon. 

Julia Rampen is the editor of The Staggers, The New Statesman's online rolling politics blog. She was previously deputy editor at Mirror Money Online and has worked as a financial journalist for several trade magazines.