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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Want to know how you really behave as a doctor? Watch yourself on video

There is nothing quite like watching oneself at work to spur development – and videos can help us understand patients, too.

One of the most useful tools I have as a GP trainer is my video camera. Periodically, and always with patients’ permission, I place it in the corner of my registrar’s room. We then look through their consultations together during a tutorial.

There is nothing quite like watching oneself at work to spur development. One of my trainees – a lovely guy called Nick – was appalled to find that he wheeled his chair closer and closer to the patient as he narrowed down the diagnosis with a series of questions. It was entirely unconscious, but somewhat intimidating, and he never repeated it once he’d seen the recording. Whether it’s spending half the consultation staring at the computer screen, or slipping into baffling technospeak, or parroting “OK” after every comment a patient makes, we all have unhelpful mannerisms of which we are blithely unaware.

Videos are a great way of understanding how patients communicate, too. Another registrar, Anthony, had spent several years as a rheumatologist before switching to general practice, so when consulted by Yvette he felt on familiar ground. She began by saying she thought she had carpal tunnel syndrome. Anthony confirmed the diagnosis with some clinical tests, then went on to establish the impact it was having on Yvette’s life. Her sleep was disturbed every night, and she was no longer able to pick up and carry her young children. Her desperation for a swift cure came across loud and clear.

The consultation then ran into difficulty. There are three things that can help CTS: wrist splints, steroid injections and surgery to release the nerve. Splints are usually the preferred first option because they carry no risk of complications, and are inexpensive to the NHS. We watched as Anthony tried to explain this. Yvette kept raising objections, and even though Anthony did his best to address her concerns, it was clear she remained unconvinced.

The problem for Anthony, as for many doctors, is that much medical training still reflects an era when patients relied heavily on professionals for health information. Today, most will have consulted with Dr Google before presenting to their GP. Sometimes this will have stoked unfounded fears – pretty much any symptom just might be an indication of cancer – and our task then is to put things in proper context. But frequently, as with Yvette, patients have not only worked out what is wrong, they also have firm ideas what to do about it.

We played the video through again, and I highlighted the numerous subtle cues that Yvette had offered. Like many patients, she was reticent about stating outright what she wanted, but the information was there in what she did and didn’t say, and in how she responded to Anthony’s suggestions. By the time we’d finished analysing their exchanges, Anthony could see that Yvette had already decided against splints as being too cumbersome and taking too long to work. For her, a steroid injection was the quickest and surest way to obtain relief.

Competing considerations must be weighed in any “shared” decision between a doctor and patient. Autonomy – the ability for a patient to determine their own care – is of prime importance, but it isn’t unrestricted. The balance between doing good and doing harm, of which doctors sometimes have a far clearer appreciation, has to be factored in. Then there are questions of equity and fairness: within a finite NHS budget, doctors have a duty to prioritise the most cost-effective treatments. For the NHS and for Yvette, going straight for surgery wouldn’t have been right – nor did she want it – but a steroid injection is both low-cost and low-risk, and Anthony could see he’d missed the chance to maximise her autonomy.

The lessons he learned from the video had a powerful impact on him, and from that day on he became much more adept at achieving truly shared decisions with his patients.

This article first appeared in the 01 October 2015 issue of the New Statesman, The Tory tide