20140306_IS

Source: BBC Radio 4

URL: http://www.bbc.co.uk/programmes/b03ws21x

Date: 06/03/2014

Event: Rival simulations: the world "as it is" or "as it might have been, without climate change"

Attribution: BBC Radio 4, Inside Science

People:

• Professor Myles Allen: Physicist and head of the Climate Dynamics group at the University of Oxford
• Dr. Lucie Green: Space scientist and solar researcher
• Dr. Nathalie Schaller: Swiss National Science Foundation research fellow, Oxford University

Lucie Green: Now, the recent extreme rainfall has left many of us asking "Is this weather linked to climate change?" Well, a new project aims to use a large citizen science experiment to answer this question. Professor of Geosystem Science Myles Allen and Dr. Nathalie Schaller, a Swiss National Science Foundation research fellow at Oxford University, came into the studio, and I asked why it's so difficult to determine if climate change is really responsible.

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Myles Allen: Well, the crucial thing is we've always had extreme weather. Britain has very variable weather, and so just because a flood happens - we've had floods before - so you can't say that just because a flood happens, it was because of climate change. But what you can say is "Has climate change increased the risk of a flood occurring?" - if you like, loaded the weather dice towards more floods - or, you know, in some cases, it might be: loaded the dice away from certain kinds of floods.

Lucie Green: So the most we can hope for is to get an idea of the changing odds of extreme weather events, in the UK.

Myles Allen: That's right. But for many things, that's all you can ever say. I mean, you can say, for example, smoking increases your risk of cancer - that's well established. But of course it doesn't mean that if you get cancer it means you're a smoker, or it doesn't always mean that if you smoke you will get cancer. There's many aspects of life where all we can ever say is how odds have changed.

Lucie Green: Okay, Myles, stay with us. Now, Nathalie Schaller, you've been leading the analysis side. How are you going to find out if climate change is able to influence extreme weather?

Nathalie Schaller: So in the past couple of weeks, we've prepared around 50,000 of simulations, and they fall into two groups. So one group is a simulation of the current winter with the conditions that we have observed, this winter - so with climate change. And the other type of experiment is basically the same, but where we have removed the effect of climate change. And then, when we get the simulations back, we will analyse these two types of experiment and see whether the one that has climate change, the odds of having had this very wet winter is larger, the same or smaller, as in the experiment when there is no climate change.

Lucie Green: And what is the main difference between these two types of models?

Nathalie Schaller: The model is the same, it's just conditions under which we run them that are different. So one type of condition simulates the world as it is, and the other type of simulation simulates the world as it might have been, without climate change.

Lucie Green: So this is: in the case that we wouldn't have levels of carbon dioxide in the atmosphere, and the associated heating?

Nathalie Schaller: Yes.

Lucie Green: What about the size of this task - if you've got these thousands of models that needs to be run, how do you go about achieving that?

Nathalie Schaller: Well, it would be very difficult for us to run that on supercomputers, for example - that's why we really need all those citizen scientists to run them on their personal computer at home.

Lucie Green: And what can the listeners of Inside Science do, to get involved? How do they actually run their simulations?

Nathalie Schaller: Well, it's actually very easy. They simply have to go to our web page, which is weatherathome.org, and then there is all the instructions, what they have to do. So basically they just have to download a little program, and when it's downloaded and installed, it will just pick one simulation from the pool of simulations that we have prepared, and it will just run in the background. And when it's done, it will send back automatically the results back to us.

Lucie Green: There's no input of data by the public, then.

Nathalie Schaller: Absolutely not, no.

Lucie Green: What are the regions that the public will be running the models over?

Nathalie Schaller: Well, we are interested in the wet winter in England, in south England, so they will run over Europe.

Lucie Green: And when will we be able to see the results?

Nathalie Schaller: We hope that we will have the first real results back in a couple of weeks.

Lucie Green: So, for the Inside Science listeners, they should check out the website and see the results coming in. Are you going to be putting them live on the website?

Nathalie Schaller: Yeah, we'll try to update the figures on the website, as we get the simulations coming back. And in a couple of weeks, when we have gotten back most of the simulations, then we can say what the final result is.

Myles Allen: One interesting part of this experiment - we really have no idea what the result will be. And we also don't know how strong the result will be. So it's a little bit like an American election - if the result's obvious, somebody calls it early on, but if it's very subtle influence, then it may take longer, it may take more simulations from the public to actually detect it. So we can't predict exactly when we're going to get a result. We're going to be watching the results - everybody can watch the results as they come in, and at some point the result will emerge, which will be very exciting.

Lucie Green: And the results could show that climate change has nothing to do with the recent wet weather, I presume.

Myles Allen: Absolutely. We don't know. We're going to find out.

Lucie Green: Once you've run your simulations and you've got an answer, does that mean that's the end of this particular area of research, or is there still more to do?

Myles Allen: Absolutely not - one of the remarkable things about these experiments is they generate vast amounts of data, and there's a lot which we will be exploring for months, possibly years to come, mining this data - in fact, it takes a supercomputer to analyse the results that people have generated on their home computers. And that's exactly where Big Data comes in to this whole problem.

* * *

Lucie Green: So, even though we can't change the weather, we can try and calculate the odds. Myles Allen and Nathalie Schaller. That's all. Adam's back next week. Goodbye.