# Transcript

SPEAKER
Science writer and Times columnist Matt Ridley is with us and Tamsin Edwards who's a climate scientist at the Open University. This has obviously led to a debate. Tamsin, what's your view of what is going on?
TAMSIN EDWARDS
I think it's a fascinating story because the climate is a complex system, and it's a difficult thing to understand. Climate models are getting more and more complicated as we understand them better, and we put more, and more science into the code, and they're getting better at reproducing the climate. But there's always going to be some things that we can do better, and some things that aren't so good. And this is just one example where we don't quite understand all of the things that are going on. And therefore the climate models aren't getting it right. But they are improving, they're improving at reproducing these things.
SPEAKER
A skeptic could be forgiven for looking at the scientists there trying to use the growth in ice as evidence for climate change and global warming. And you might say, well what does that mean for the Arctic where it's in retreat? You're just using everything as evidence for climate change.
TAMSIN EDWARDS
Well, I thought that was a lovely video, actually, by Helen. One thing about models is that there's a popular skeptic view that they are biased about overestimating future climate change but actually it swings and roundabouts. So actually, in the Arctic most models are underestimating the current loss of Arctic sea ice. So it's not this simple story of, oh the climate models are overestimating the change, it's swings and roundabouts.
SPEAKER
Matt Ridley, you're a little more relaxed about climate change than the consensus, aren't you? I mean, what, it is about models, isn't it?
MATT RIDLEY
Yeah, because models predicted, and in 2007 the Intergovernmental Panel on Climate Change said, Antarctic sea ice would retreat. It was very clear about that, and it gave graphs of how much it was likely to retreat under different scenarios. And it hasn't. It's gone the other way. Now that doesn't completely invalidate the whole theory, necessarily, but it's one more example of where models got something wrong.
And what you're supposed to do is reduce your confidence in your model when the facts don't fit it. And if you put that alongside the failure of the models to predict the global temperature changing as slowly as it has over the last 35 years, and particularly over the last 15 years where something like 87 of 90 models have over predicted warming in that period then you should be revisiting your models, and seeing which assumptions you built into them that might be exaggerated.
SPEAKER
Is this a case though where the models are quite good at predicting big picture stuff? I could predict that July 2030 will be warmer than December 2030, but I'd be very nervous about predicting whether Thursday the 15th of November was going to be warmer than Friday the 15th-- the 16th of November. And so the models can be quite good at getting a big picture that when you put carbon dioxide into the atmosphere you get global warming, and they may not be very good at taking into account the wind, and the sea temperature, and all the other things that we know makes this complicated.
MATT RIDLEY
Well, models have been very bad at telling us how fast the climate will warm over the last 30, 40 years, that's clear. It's never warmed at the rate that it should according to the models.
SPEAKER
Let's see -
TAMSIN EDWARDS
I'd like to come back on that -
MATT RIDLEY
Just to finish on that. But you're absolutely right that in terms of the basic greenhouse physics there is not a problem. What we're seeing is roughly what you'd expect. What you're not seeing is the amplification that is built into the models.
TAMSIN EDWARDS
Well, Matt is like a lot of sceptically minded people in that he completely agrees that humans are causing climate change, but also he's come from science in to journalism where you like to paint a simple story. And the simple story of over the last 15 years models aren't getting the warming right is oversimplified, and we do expect, as you say, to get the long term change right, and we don't expect to get the short term bumps and wiggles right. And of course, this is a pause or a slowdown in the warming of the atmosphere. And when you look at the big picture, and you look at the oceans, you look at the ice sheets, you look at everything that's happening then the climate models are really doing a pretty good job.
MATT RIDLEY
Well let me just ask this -
SPEAKER
If the models tell us how little we understand and how there are gaps in our detailed knowledge of these things, does that mean we should be more relaxed about climate change, or does that mean we should adopt an insurance policy and say, look the models point that there really could be something going on here? It's not 100% it's not 0% it's something percent, and that means we should be pretty darn cautious.
MATT RIDLEY
But they're consistently overestimating warming. And that is very clear -
SPEAKER
Is that true?
MATT RIDLEY
- on the global atmosphere, it is true.
TAMSIN EDWARDS
That's true, if you look at a very short time period.
MATT RIDLEY
No.
TAMSIN EDWARDS
And if you look at the time period before that they're longer -
MATT RIDLEY
Looking at the whole period of the last 35 years.
TAMSIN EDWARDS
And if you look at the Arctic sea ice trend, they underestimate it so perhaps you should be just as worried about that--
MATT RIDLEY
The Arctic sea ice is one small data point. The Antarctic sea ice is just as big a data point.
SPEAKER
Matt Ridley, Tamsin Edwards, we won't resolve it now. Thanks very much indeed.