October 29, 2013
Blame Britain’s Bad Weather On Retreating Arctic Ice
Brett Smith for redOrbit.com - Your Universe Online
Britons never seem to get a break from bad weather, and now one scientist believes he may have found a culprit to point the finger at: retreating Arctic sea ice.
According to a new study from the University of Exeter’s James Screen that was published in the journal Environmental Research Letters, the run of wet summers that hit northwest Europe between 2007 and 2012 was partially due to the loss of Arctic sea ice that shifted the jet stream further south than normal.
Jet streams are currents of strong winds high in the atmosphere that steer weather systems and precipitation. In the past, the jet stream has flowed between Scotland and Iceland, sending bad weather north of Britain.
"The results of the computer model suggest that melting Arctic sea ice causes a change in the position of the jet stream and this could help to explain the recent wet summers we have seen,” Screen said. "The study suggests that loss of sea ice not only has an effect on the environment and wildlife of the Arctic region but has far reaching consequences for people living in Europe and beyond."
Screen added that other possible factors could have helped to cause the recent run of wet summers, including the natural decade-long oscillations in the surface temperatures of the Atlantic Ocean. He emphasized that sea ice and the jet stream could explain up to a third of the trend towards wetter summers, according to his study.
“For the run of wet summers that we've had, the loss of sea ice and warm ocean temperatures were both acting in the same direction - pulling the jet stream south,” Screen said.
“We expect that sea surface temperatures will return to a cooler phase of their natural cycle – reducing the risk of wetter summers – but Arctic sea ice is expected to continue to melt and it is unclear how these competing effects will influence weather over the next decade or so,” he added.
Screen’s computer model considered weather patterns from when the summer sea-ice was relatively wide-ranging, as it was in the 1970s, as well as the sea ice of recent years. The model indicated that sea ice alone can affect the direction the jet stream takes as it flows from west to east.
“We have some confidence that the computer models are showing the real thing,” Screen told The Independent. “The pattern of summer rainfall we see in the computer models, when the only factor we change is the amount of sea ice in the Arctic, is very similar to what we’ve experienced over the past few years.”
The UK scientist emphasized that his model simply indicates a weather mechanism and should be correlated to specific weather events.
“I don't think we'll ever get to a position where we can link a specific event like the 2012 floods to climate change,” he said. “But we might be able to say that these changes are tipping the balance in favor of particular weather regimes, and this research is a step in that direction.”