Weather Balloons Track Global Warming 'Blanket'

Scientists are flying weather balloons into the upper atmosphere to build a more precise picture of the carbon dioxide 'blanket' that causes global warming.

Sky News filmed one of the first balloon flights carrying a carbon dioxide monitor and GPS tracker. The balloon soared 20 miles into the stratosphere, collecting data every five metres during its climb.

Scientists from Reading and Cambridge universities hope to determine how carbon dioxide varies with altitude and whether there are geographical "pockets" of the gas downwind of pollution sources.

Dr Paul Smith, a climate researcher from Cambridge, said: "You've got the troposphere and lower boundary level, the first 2-3km, (where our weather happens) and that's where a lot of the pollution may be trapped.

"But it is gradually transported higher into the atmosphere.

"That extra warming in the lower atmosphere can have an influence on the dynamics and mixing in the upper stratosphere. These things are known about, but they are not properly understood."

The global carbon dioxide level has been tracked since 1959 at an observatory on top of a volcano in Hawaii. Over that time the concentration has soared from just over 300 parts per million (ppm) to 400ppm.

But measuring the gas at a single fixed point at an altitude of 3,400m only gives a snapshot of changes to the atmosphere, the scientists argue.

Balloons could also be used to verify a country's commitment to cut carbon emissions following the United Nations climate summit in Paris.

Ministers from 190 countries are negotiating a historic deal that would cap the rise in global temperatures at 2.7 degrees, and possibly two degrees in future.

That would mean reducing carbon emissions by 40-70% by 2050 and 100% by the end of the century.

But when carbon dioxide levels in the atmosphere were last at their current level, three million years ago, the average temperatures were 3-4 degrees higher than today and sea level was 25m higher.

Prof Bill Collins, a climate scientist at Reading University, said it may already be too late, with huge ice caps at the poles set to melt over the next 200-300 years, if the warming trend continues.

"What we have done to raise temperatures might have already set in train processes that cause the West Antarctic ice sheet to collapse. That would increase sea level by a few metres.

"The trouble is it's difficult for us to get our heads round this time scale. We will never see that, but (our descendents) might have good cause to blame us for things we did in the 20th and 21st century."