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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The most terrifying thing about Donald Trump's speech? What he didn't say

No politician uses official speeches to put across their most controversial ideas. But Donald Trump's are not hard to find. 

As Donald Trump took the podium on a cold Washington day to deliver his inauguration speech, the world held its breath. Viewers hunched over televisions or internet streaming services watched Trump mouth “thank you” to the camera, no doubt wondering how he could possibly live up to his deranged late-night Twitter persona. In newsrooms across America, reporters unsure when they might next get access to a president who seems to delight in denying them the right to ask questions got ready to parse his words for any clue as to what was to come. Some, deciding they couldn’t bear to watch, studiously busied themselves with other things.

But when the moment came, Trump’s speech was uncharacteristically professional – at least compared to his previous performances. The fractured, repetitive grammar that marks many of his off-the-cuff statements was missing, and so, too, were most of his most controversial policy ideas.

Trump told the crowd that his presidency would “determine the course of America, and the world, for many, many years to come” before expressing his gratefulness to President Barack Obama and Michelle Obama for their “gracious aid” during the transition. “They have been magnificent," Trump said, before leading applause of thanks from the crowd.

If this opening was innocent enough, however, it all changed in the next breath. The new president moved quickly to the “historic movement”, “the likes of which the world has never seen before”, that elected him President. Following the small-state rhetoric of his campaign, Trump promised to take power from the “establishment” and restore it to the American people. “This moment," he told them, “Is your moment. It belongs to you.”

A good deal of the speech was given over to re-iterating his nationalist positions while also making repeated references to the key issues – “Islamic terrorism” and families – that remain points of commonality within the fractured Republican GOP.

The loss of business to overseas producers was blamed for “destroying our jobs”. “Protection," Trump said, “Will lead to great strength." He promised to end what he called the “American carnage” caused by drugs and crime.

“From this day forward," Trump said, “It’s going to be only America first."

There was plenty in the speech, then, that should worry viewers, particularly if you read Trump’s promises to make America “unstoppable” so it can “win” again in light of his recent tweets about China

But it was the things Trump didn't mention that should worry us most. Trump, we know, doesn’t use official channels to communicate his most troubling ideas. From bizarre television interviews to his upsetting and offensive rallies and, of course, the infamous tweets, the new President is inclined to fling his thoughts into the world as and when he sees fit, not on the occasions when he’s required to address the nation (see, also, his anodyne acceptance speech).

It’s important to remember that Trump’s administration wins when it makes itself seem as innocent as possible. During the speech, I was reminded of my colleague Helen Lewis’ recent thoughts on the “gaslighter-in-chief”, reflecting on Trump’s lying claim that he never mocked a disabled reporter. “Now we can see," she wrote, “A false narrative being built in real time, tweet by tweet."

Saying things that are untrue isn’t the only way of lying – it is also possible to lie by omission.

There has been much discussion as to whether Trump will soften after he becomes president. All the things this speech did not mention were designed to keep us guessing about many of the President’s most controversial promises.

Trump did not mention his proposed ban on Muslims entering the US, nor the wall he insists he will erect between America and Mexico (which he maintains the latter will pay for). He maintained a polite coolness towards the former President and avoiding any discussion of alleged cuts to anti-domestic violence programs and abortion regulations. Why? Trump wanted to leave viewers unsure as to whether he actually intends to carry through on his election rhetoric.

To understand what Trump is capable of, therefore, it is best not to look to his speeches on a global stage, but to the promises he makes to his allies. So when the President’s personal website still insists he will build a wall, end catch-and-release, suspend immigration from “terror-prone regions” “where adequate screening cannot occur”; when, despite saying he understands only 3 per cent of Planned Parenthood services relate to abortion and that “millions” of women are helped by their cancer screening, he plans to defund Planned Parenthood; when the president says he will remove gun-free zones around schools “on his first day” - believe him.  

Stephanie Boland is digital assistant at the New Statesman. She tweets at @stephanieboland