LONDON Record melting of Arctic sea ice this year sent a "very alarming" signal about warming at the North Pole, but it couldn't all definitely be blamed on manmade climate change, the U.N.'s top weatherman said on Tuesday.
The amount of Arctic ice which melted this summer beat a previous record, set two years ago, by an area more than four times the size of Britain, a 30-year satellite record shows.
"This year was quite exceptional ... the melting of the Arctic ice ... it's quite spectacular," Michel Jarraud, secretary general of the World Meteorological Organisation, told Reuters.
"Can it all be attributed to climate change? That's very difficult. It's very, very alarming," he said. His answer to how best to interpret the melt was -- "let's do more research".
"What it means is that we have to monitor that very, very carefully. It's a warning signal."
Melting of sea ice doesn't affect sea levels because it's entire volume is already in the water, but scientists fear if it melted that could trigger more warming and melting of ice sheets over Greenland, which could raise sea levels by 7 metres.
Asked if scientists should have better predicted the rate of sea ice melting now seen Jarraud said: "I don't know the answer. It's a difficult question. Some of the models predicted faster melting than others."
The prospects for avoiding dangerous climate change depended on the world putting in place measures to cut emissions of greenhouse gases blamed for heating the planet, he said.
But things were looking up.
"There's a lot more political attention on this issue. I take it as a positive signal," he said, referring to two high-level climate meetings last week hosted by the United Nations and the United States in New York and Washington.
Vast geographical and scientific gaps in the global meteorological and oceanographic monitoring system had to be filled urgently, said Jarraud.
The world's weather centres spent $5-10 billion a year in total, and for every extra $1 billion spent up to 10 times that amount could be saved in preparing for and better reacting to climate disasters, Jarraud said.
The ultimate goal, he said, would be to refine climate change forecasting from a coarse global level down towards a regional or even national level so governments could plan in detail how to prepare.
"We are very confident that over the next five to 10 years we will be better able to answer questions of regional outlook," Jarraud said.
The U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC) this year concluded global warming was definitely happening and almost certainly manmade.
A fifth such IPCC report in six years time would yield answers to whether the increasing frequency and severity of specific extreme weather events, like hurricanes, floods and heatwaves, was linked to climate change.
"I'm confident for example that in the next report we might give a better answer with respect to the link between global warming and tropical cyclones," Jarraud said. "There seems to be a growing consensus that global warming may... lead to more of the very intense hurricanes, category 4 and 5."