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PDFClimate warming greenhouse gas reaches 400 parts per million for the first time in human history
The Guardian Friday 10 May 2013
For the first time in human history, the concentration of climate-warming carbon dioxide in the atmosphere has passed the milestone level of 400 parts per million (ppm). The last time so much greenhouse gas was in the air was several million years ago, when the Arctic was ice-free, savannah spread across the Sahara desert and sea level was up to 40 metres higher than today.
These conditions are expected to return in time, with devastating consequences for civilisation, unless emissions of CO2 from the burning of coal, gas and oil are rapidly curtailed. But despite increasingly severe warnings from scientists and a major economic recession, global emissions have continued to soar unchecked….
But the extreme speed at which CO2 in now rising – perhaps 75 times faster than in pre-industrial time – has never been seen in geological records and some effects of climate change are already being seen, with extreme heatwaves and flooding now more likely. Recent wet and cold summer weather in Europe has been linked to changes in the high level jetstream winds, in turn linked to the rapidly melting sea ice in the Arctic, which shrank to its lowest recorded level in September.
“We are creating a prehistoric climate in which human societies will face huge and potentially catastrophic risks,” said Bob Ward, policy director at the Grantham Research Institute on Climate Change at the London School of Economics. “Only by urgently reducing global emissions will we be able to avoid the full consequences of turning back the climate clock by 3 million years.”
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