20140209_SK

Source: Sky News

URL: http://news.sky.com/story/1208850/weather-climate-change-to-blame-for-storms

Date: 09/02/2014

Event: Julia Slingo: quite likely climate change having a "compounding effect" on UK storms

People:

• Thomas Moore: Sky News correspondent
• Professor Julia Slingo: Chief Scientist, UK Met Office

Thomas Moore: As we're now all painfully aware, this winter the UK in general, and the southwest in particular, have been battered by an exceptional run of winter storms. In its assessment of the weather over the last three months, the Met Office says it's been the worst period of rainfall in at least 248 years. While no one storm has been exceptional, coastlines have been battered and inland areas have been flooded by a series of persistent and tightly clustered periods of wind and rain.

So, where has all this come from? The Met Office thinks we may have to go to the other side of the world, all the way to Indonesia, to find the weather events that have triggered the storms here. The story starts with persistent heavy rainfall over Indonesia, caused by higher than normal ocean temperatures in the west Pacific. Flash floods and landslides have killed hundreds of people there, this winter.

That all upset the pattern of the Asia-Pacific jet stream - the flow of air which normally tracks east, straight across the Pacific Ocean and the United States, This winter, though, the Pacific jet stream was pushed a long way north, up towards the Arctic, getting colder as it went. When it was temporarily forced back down across Canada and America, in this dramatic kink, it brought exceptionally cold weather with it. That caused the big freeze we saw across North America last month, when temperatures fell as low as minus 50 degrees, and areas as far south as Texas and Georgia saw snow for the first time in years.

The chain reaction then continued into the North Atlantic. The huge difference between cold air in the north and warm Caribbean air created a dramatic temperature gradient in the atmosphere, strengthening the jet stream by around 30%. Normally that wouldn't have had such catastrophic effects, as the jet stream usually passes north of the UK, between Scotland and Iceland. But this year the jet stream has been pushed much further south, bringing high winds and rain straight into the southwest of England and Wales.

I'm afraid the Met Office offers little hope for the future, saying that it looks like a warmer world will lead to more intense and heavy rain events in the future, meaning scenes like this [aerial video footage of flooded fields and gardens] could become more familiar over the coming years.

* * *

Julia Slingo: The science that we have says that it's quite likely that there is a contribution. There's some basic science here that points to a compounding effect, if you like, of climate change on the very extreme rainfall, very severe levels of storminess and possibly even the very prolonged clustering of storms that we've seen throughout this winter.