Seeing satellite pictures from Greenland last month, scientists from NASA at first could not believe what the data were telling them. About 97 percent of the Greenland ice sheet was melting. The rate was unprecedented, with the thaw more widespread than ever as unseasonally warm weather across the Arctic took effect.
“It was so extraordinary that at first I questioned the result: was this real or was it due to a data error?” said Son Nghiem, one of the scientists responsible for the research at NASA’s Jet Propulsion Laboratory in Pasadena, California. In a normal summer, some melting is observed over about half the island’s surface area. The new data — from three satellites — raised serious concerns over the progress of global warming and the likely consequences.
For scientists at the UK Met Office’s Hadley Research Centre in Exeter, southwest England, the question was not just how fast Greenland was melting, but something much trickier. They have been crunching through years of data from dozens of satellites, trying to establish whether the conditions in the Arctic circle are related to the record-breaking washout of a summer in the UK.
When it comes to global warming, we can forget the jolly predictions of TV host Jeremy Clarkson and his ilk of a Mediterranean climate in which we lounge among the olive groves of Yorkshire.
“We will see lots more floods, droughts, such as we’ve had this year in the UK,” said Peter Stott, leader of the climate change monitoring and attribution team at the Met Office.
“Climate change is not a nice slow progression where the global climate warms by a few degrees. It means a much greater variability, far more extremes of weather,” he added.
A series of unusually wet and cold summers has afflicted the UK for several years. Five out of the past six years (2007 to 2012), have shown below-average sunshine from June to August. All have had above-average rainfall — in some cases more than 50 percent above the long-term average.
“It is not just a perception — we have had a run of relatively poor summers,” Stott said.
This year has been the worst. April was the wettest on record and so was the period from April to June. The sun was missing too — June was the second dullest ever recorded. Hopes that this month might be better were dashed when the first few days brought floods as far apart as Scotland and Somerset, forcing scores of people from their homes.
Nor has the UK been alone in suffering disastrous weather. In the US, the eastern seaboard has been hit by heatwaves and storms but even worse has been the “dustbowl effect” in Texas and across much of the nation’s agricultural heartland. India’s monsoon failed to appear on schedule, leaving millions of farmers in the sub-continent facing destitution. Floods in Beijing, after the heaviest rainfall in 60 years, caused devastation to millions.
A food crisis is now all but inevitable, according to the US secretary of agriculture. Emergency plans are being discussed in India, while in China the clear-up is accompanied by concerns that environmental degradation may be making the country’s problems worse.
Attributing any single weather event, or short pattern of events, however extreme, to climate change is always tricky. Extreme weather events occur, in the scientists’ term, stochastically — they happen by themselves, unpredictably, owing to the natural variations of the weather.