16 Feb 2014

Jet stream shift 'may change weather'

12:06 pm on 16 February 2014

Research suggests the jet stream in the upper atmosphere which helps determine the weather over Northern Europe and North America may be changing.

The study shows the so-called jet stream has increasingly taken a longer, meandering path, possibly as a result of the recent warming of the Arctic, the BBC reports.

Scientists say the new has resulted in weather patterns remaining the same for more prolonged periods.

High winds from the latest winter storm batter Newhaven on the south coast of England.

High winds from the latest winter storm batter Newhaven on the south coast of England. Photo: AFP

The work was presented at the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago.

The meandering jet stream has accounted for the recent stormy weather over the UK and the bitter winter storm in the US Mid-West remaining longer than it otherwise would have.

The jet stream is a high-speed air current in the atmosphere fuelled partly by the temperature differential between the Arctic and the mid-latitudes.

If the differential is large, the jet stream speeds up and ploughs through obstacles such as areas of high pressure that might be in its way. But if the temperature differential reduces because of a warming Arctic, the jet stream weakens and meanders every time it comes across an obstacle.

This results in weather patterns tending to becoming stuck over areas for weeks on end, and drives cold weather further south and warm weather further north.

Examples of the latter are Alaska and parts of Scandinavia, which have had exceptionally warm conditions this winter.

Professor Jennifer Francis of Rutgers University in New Jersey said it was too soon to tell whether recent patterns are due to natural variations or the result of man-made climate change.

She said the Arctic had been warming rapidly only for the past 15 years, so it is hard to get a clear signal from data over such a short time. "But as we have more data I do think we will start to see the influence of climate change," Prof Francis said.