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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Can the disciplined Democrats defeat Trump’s maelstrom of chaos?

The Democratic National Convention has been exquisitely stage-managed and disciplined. But is it enough to overcome Trump’s news-cycle grabbing interventions?

The Democratic National Convention did not begin auspiciously.

The DNC’s chair, Debbie Wasserman Schultz, was unceremoniously launched as if by an ejector-seat from her job on the eve of the convention, after a Wikileaks dump of internal emails painted a picture of a party trying to keep the insurgent candidate, Vermont senator Bernie Sanders, from blocking Hillary Clinton’s path to the nomination.

One email, in which a staffer suggests using Sanders’ Jewish faith against him as a candidate in order to slow his insurgent campaign, was particularly damning in its optics and Schultz, who had tweeted with some hubris about her Republican opposite number Reince Priebus during last week’s Republican convention in Cleveland, had to fall on her sword.

Clinton’s pick of Tim Kaine as a running-mate – a solid, safe, and unexciting choice compared to a more vocal and radical campaigner like Elizabeth Warren – was also criticised, both by the media, with one commentator calling him “a mayonnaise sandwich on wholewheat bread”, and by the left of the party, who still held out hope that the Democratic ticket would have at least one name on it who shared the radical vision of America that Sanders had outlined.

On top of that, Kaine, who is a Catholic, also disappointed many as a vice-presidential pick because of his past personal history of opposition to abortion. Erin Matson, the co-director of the reproductive rights group ReproAction, tweeted that Kaine being added to the ticket was “tremendously disappointing”.

On the other side, Donald Trump had just received a poll bump following a terrifying speech which recalled Richard Nixon’s 1968 convention address. Both speeches appealed to fear, rather than hope; many are calling Trump’s keynote his “Midnight in America” speech. Just before the Democrats convened, analyst par excellence Nate Silver and his site, 538.com, forecast Trump’s chance of victory over Clinton in November at above 50 per cent for the first time.

On top of that, Bernie Sanders more vocal supporters arrived at the Democratic convention – in Philadelphia in the grip of a heatwave – in relative force. Protests have already been more intensive than they were at the RNC, despite all expectations to the contrary, and Sanders delegates disrupted proceedings on the first day by booing every mention of Hillary Clinton’s name.

But then, things appear to turn around.

The second day of the convention, which saw Hillary Clinton formally nominated as the first female presidential candidate in American history, was less marred by protest. Bernie Sanders addressed the convention and endorsed his erstwhile rival.

Trump’s inability to stop prodding the news cycle with bizarre non-sequiturs turned the focus of what would otherwise be a negative Democratic news cycle back onto him; an unforced error which led to widespread, if somewhat wild, speculation about his possible links with Putin in the wake of the news that Russia had been behind the email hack and lightened some of the pressure on the Democrats.

And then Michelle Obama took the stage, delivering an oration of astonishing power and grace (seriously, watch it – it’s a masterclass).

Compared with the RNC, the Democratic National Convention has so far been exquisitely stage-managed. Speakers were bookended with pithy, designed-for-virality videos. Speakers started on time; headliners played in primetime.

Both Trump and Clinton have now addressed their conventions before their headline speech remotely, via video link (Trump also engineered a bizarre early-convention pro-wrestling-style entrance), which put observers of both in mind of scenes from V for Vendetta.

But the imagery of Clinton’s face appearing on screen through a graphic of shattering glass (see what she did there?) will likely be one of the moments that sticks most in the memory of the electorate. It must kill the reality TV star to know this, but Clinton’s convention is getting better TV ratings so far than the RNC did.

Michelle Obama’s masterful speech in particular provided stark contrast with that of Melania Trump – an especially biting contrast considering that parts of the latter’s speech last week turned out to have been plagiarised from the former. 538’s forecast saw Clinton slide – barely – back into the lead.

A mayonnaise sandwich Tim Kaine might be, but he is nonetheless looking like a smart pick, too. A popular senator from a key swing state – Virginia – his role on the ticket is not to be a firebrand or an attack-dog, but to help the former secretary of state reach out to the moderate middle that Trump appears to be leaving entirely vacant, including moderate Republicans who may have voted for Mitt Romney but find Trump’s boorish bigotry and casual relationship with the truth offputting. And the electoral mathematics show that Trump’s journey to victory in the electoral college will be extremely difficult if Kaine swings Virginia for Clinton.

Ultimately, the comparison between the Democratic convention in Philadelphia so far and last week’s chaotic, slapdash and at times downright nutty effort in Cleveland provides a key insight into what this election campaign is going to be like: chaos and fear on one side, but tight discipline on the other.

We will find out in November if discipline is enough to stop the maelstrom.

Nicky Woolf is a writer for the Guardian based in the US. He tweets @NickyWoolf.