June 30, 2013

Met Office Says "No-one in the World" Can Explain Weird Weather

My headline for today paraphrases matters only slightly. The exact words of Professor Stephen Belcher, head of the Met Office's Hadley Centre, were as follows:

We think that these are really some cutting edge science questions to be addressed here. No-one in the world can answer these questions, it's really important to emphasise.

as you can discover for yourself if you skip straight to about 4 minutues 35 seconds into the following video:

The occasion recorded for posterity was the "science workshop" held at the Met Office here in Exeter recently, on the topic of the recent "unusual seasons" in the United Kingdom. This may or may not have been the "meeting of top scientists to look at the urgent question of whether the warming of the Arctic is affecting UK weather" promised by the Met Office's Chief Scientist Julia Slingo a couple of months ago, although she was certainly present at the workshop. The Arctic was indeed mentioned by Prof. Belcher as one of the factors affecting the jet stream above the UK, which he described as:

A basket of things that can "load the dice":

  1. The El Niño.
  2. Solar variability
  3. Things in the Atlantic Ocean, and there are processes high up.
  4. A thing that has been talked about in the scientific literature a lot recently, which is as Arctic sea ice melts, can that affect the position of the jetstream?

Stephen then went on to go over the aforementioned "cutting edge science questions", which still need to be answered:

  1. The role of the ocean having an imprint on the atmosphere, and setting the jet stream. There are things going on near the Gulf Stream that we need to understand better.
  2. Things happening high up in the atmosphere in the stratosphere, above 10 km.
  3. The role of greenhouse gas emissions and climate change.

In view of all that, perhaps Stephen and Julia would care to take a look at one or two other YouTube videos. Maybe one of the one's in which Professor Jennifer Francis talks about how the melting of Arctic sea ice affects the jet stream would be a good place to start?

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Comments on Met Office Says "No-one in the World" Can Explain Weird Weather »

July 4, 2013

Jim Jim @ 1:38 pm

I've just received some useful feedback from Dr. James Screen of the University of Exeter. As he points out, James actually gave a talk at the workshop. Here are his comments:

The effect of Arctic sea ice loss on the jet stream was one of the issues that we discussed at the meeting. In fact, I gave a talk on precisely that topic. However it is important to point out that Arctic sea ice is only one of many factors that we know influence the position of the jet stream and thus, UK weather. The others factors you list are also likely to be important, and at this stage we are not sure which factors are the most important. Your headline about not understanding the causes of unusual seasons is in a sense true (we don't have all the answers), but somewhat misses the key points that we do understand that:

  1. These unusual seasons were ultimately caused by the jet stream being in an unusual location, and
  2. That we understand that there are a number of drivers that influence the position of the jet stream.

Yes, key questions remain to be answered (how are these drivers influenced by climate change, which are the most and least important) but significant progress is being made in understanding these, so the situation isn't as bleak as your headline suggests.

Your last sentence is bit misleading too. Stephen and Julia (and the wider research community) are well aware of the research into the effects of Arctic sea ice on the jet stream, and research is taking place to look at this potential influence in more detail. But, and this is a key point, Arctic sea ice is only one driver of UK weather (and probably not the most important) so it would be foolhardy to focus research effort totally on the Arctic sea ice issue. This is why our recent meeting sought to identify all the potential factors (including Arctic sea ice) that are important.

A list of James' publications on this topic are available on the University of Exeter web site.

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