Scientists no longer debate whether global warming is happening. The big scientific questions now are how bad it will be, and what can be done.
LONDON, September 11 (Reuters) — The world will probably exceed a global warming limit which the European Union calls dangerous, scientists at Britain’s MetOffice Hadley Centre said on Tuesday, presenting a new, 5-year research program.
But not all scientists agree, demonstrating a shift in debate from whether climate change is happening — on which where there is near consensus — to how bad it will get and what to do about it.
European Union (EU) leaders reiterated in March “the vital importance” of restricting global warming to no more than 2 degrees Celsius above pre-industrial levels.
That goal is the basis for a raft of EU climate measures to cut emissions of heat-trapping greenhouse gases. MetOffice researchers doubted it was achievable.
“I think it’s well accepted that 2 degrees is likely to be exceeded,” said Vicky Pope, manager of the MetOffice Hadley Centre’s climate change research program.
“We need much more accurate, detailed information about how climate change will happen in the future,” she added.
Some scientists are optimistic about the EU target.
“This ambitious goal is not only scientifically justified but also both economically and ethical imperative,” the Director of the Potsdam Institute for Climate Impact Research, Hans Joachim Schellnhuber, told an EU Parliament hearing on Monday.
Dangerous global warming includes irreversible changes, for example runaway melting of the polar ice caps, which is expected to start above around 2 degrees warming.
“If we still cut emissions we have the chance to avoid exceeding 2 degrees,” said Malte Meinshausen, a Potsdam Institute researcher, adding that the MetOffice estimate was as valid as other studies but suggested a slightly higher risk than most.
Largely thanks to man-made greenhouse gas emissions, temperatures worldwide rose some 0.7 degrees last century, and another 0.6 degrees is locked in as the world’s oceans catch up with quicker warming over land.
Efforts to cut man-made emissions of planet-warming gases like carbon dioxide could stem the worst climate effects, and understanding this better will form one plank of the new MetOffice research program.
“A lot of work done so far has assumed we don’t mitigate,” said Pope.
In a major report in February, the Intergovernmental Panel on Climate Change (IPCC) did not take account of climate protection measures when it estimated between 1.8 and 4 degrees warming worldwide this century.
The other main focus of the 86 million pound ($173.9 million) research program, funded by ministries for environment and defense, will be into detailed, regional climate impacts and assessing the risk of catastrophe.
Evidence has emerged, for example, that the Greenland ice sheet may be melting faster than expected, with implications for global sea level rise.
“It’s about getting a handle on low probability, high impact events,” said Pope.