Editorial: "Wanted: A Bob Geldof for climate change"
For the first time, we have proof that climate change has led to a humanitarian disaster. The East African drought of 2011, which resulted in a famine that killed at least 50,000 people, was partly caused by human emissions of greenhouse gases.
The drought was brought about by the failure of two consecutive rainy seasons: the "short rains" in late 2010 and the "long rains" at the start of 2011. Climatologist Peter Stott of the Met Office Hadley Centre in Exeter, UK, and his colleagues ran climate models, with and without a human influence on climate, and compared the likelihood of the rains failing.
Humanity's activities had no effect on the short rains ? they failed because of a strong La Ni?a in the Pacific. "That's natural," says Stott.
But climate change did affect the long rains, making them more likely to fail (Geophysical Research Letters, doi.org/kmv). The model could only reproduce the scale of the drought if it included greenhouse gas emissions.
Ocean influence
Natural mechanisms probably also played a role in the rain failure. Sea surface temperatures over the Indian Ocean vary, and this seems to affect rain patterns over sub-Saharan Africa. The problem is that the natural mechanism ? and the extent of its control over the rains ? is poorly understood.
The team calculate that climate change is responsible for between 24 per cent and 99 per cent of the risk of long rains failure.
"No food crisis can ever be attributed to a single causal factor," says Tracy Carty of Oxfam in Oxford, UK. "However, drought is always a trigger and this is the first occasion that a portion of the blame has been attributed to climate change."
"Climate change is not a distant future threat, but already a driver behind rising humanitarian needs," she adds.
Although Stott's findings add to the evidence that East Africa will face more droughts as the climate warms, for now, the region is slowly recovering from 2011. The short rains at the end of 2012 were good, and the latest forecasts suggest that the long rains will be roughly normal, or at least not far below that.
In the long run, studies that attribute blame in this way could be used by people attempting to sue for damages relating to climate change. A number of such cases are currently moving through US courts, spearheaded by the Alaskan village of Kivalina. The village is threatened by increased storm surges that may be linked to climate change, and its residents are suing major energy companies for the cost of evacuating.
Pin the tail on the donkey
Such cases still face significant challenges, says environmental lawyer Tracy Hester of the University of Houston in Texas. Anyone trying to bring one to court will have to link the damages they have suffered to a particular source of emissions.
"While this research points to man's activities as a contributing factor for the 2011 East African drought, it doesn't identify any particular person, company or country," he says.
In the long run, countries that suffer loss and damage from climate change may be able to claim compensation or aid from others, thanks to an agreement made at the Doha climate summit in December. But such claims are a long way away, says Hester. The negotiations have yet to establish a means to force emitters to pay for climate damages.
"Other nations are exploring whether they can bring a case before the International Court of Justice to seek relief against certain climate damages," says Hester. For instance, low-lying South Pacific nations could be swamped by rising seas. "This research could be helpful in that context."
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