Tom Chivers: How to get it wrong on climate change and weather

An Indian farmer shows a dry, cracked paddy field in Ranbir Singh Pura, 34km from Jammu, India. Pictures / AP

Opinion

Tom Chivers, the Telegraph's Environment writer, responds to a review of 'The Age of Global Warming' by Rupert Darwell - and he's fired up.

Let us look at the following paragraph:

Most of us pay some attention to the weather forecast. If it says it will rain in your area tomorrow, it probably will. But if it says the same for a month, let alone a year, later, it is much less likely to be right. There are too many imponderables. The theory of global warming is a gigantic weather forecast for a century or more. However interesting the scientific inquiries involved, therefore, it can have almost no value as a prediction.

I was shocked to read it in The Telegraph this morning, and I was especially shocked to see that it was written by Charles Moore, who is a brilliant columnist and a fantastically clever man, a former editor of this paper and all-round polymath. He was reviewing a book called The Age of Global Warming by Rupert Darwall, which I know nothing about. There are many worthwhile criticisms to be made of the green movement, and maybe the book makes them. But whatever the merits of the book, Charles has made a howling, awful error in his very first paragraph, quoted above. Let's look at it again:

The theory of global warming is a gigantic weather forecast for a century or more.

No, it isn't.

It simply isn't. Whatever your thoughts on anthropogenic climate change, and whatever your thoughts on hockey sticks and the IPCC and "watermelons" and Climategate and urban heat islands and all these vexèd things, there is simply no sense in which "the theory of global warming is a gigantic weather forecast for a century or more".

If the weather forecast says it will rain tomorrow, I can rely on it, as Charles says, to be fairly accurate. And, as Charles says, if you go much further forward, that weather forecast becomes far less accurate. Anything more than about a week away becomes very little use for planning a picnic, say. Anyone who purports to tell you that it will rain on the third Tuesday of next month is simply making stuff up. Anyone who tells you that they know it will rain on this day next year is probably mad.

But if someone were to tell you that, on any given day next April, there will be about a 50 per cent chance of rain in England, they'd be very sensible. English weather is famously unpredictable. The English climate, however, is not. Likewise, we could predict that any given day next April in Egypt will only have about a one in 30 chance of rain.

And what climate modelling, climate forecasting, does is try to work out how those odds are going to change. As more energy is trapped in the atmosphere, how will it affect the local climates of England and Egypt? (And by extension, of course, the economies and societies of those places, which are adapted to their particular climates.) It's a complicated job, of course; the climate is an incredibly complex system. I recommend the climate scientist Tamsin Edwards's blog All Models Are Wrong for a discussion of the limitations and strengths of climate modelling.

But to call "the theory of global warming" a "gigantic weather forecast" is just wrong. Staggeringly wrong. The idea is not to say "in Leamington Spa on Saturday 7th of April 2114, it will be overcast with a chance of rain", but that "in 100 years' time, the likelihood is that rain will be more frequent in western Europe than it currently is".

Maybe the "origins of warmism" really do lie, as Charles claims, in "anti-industrial nature worship, post-colonial guilt, a post-Enlightenment belief in scientists as a new priesthood of the truth, a hatred of population growth, a revulsion against the widespread increase in wealth and a belief in world government". And certainly there are green types for whom anthropogenic climate change fits beautifully into a quasi-religious worldview, in which "the climate" is a sort of Gaia-god whom we anger at our peril. But none of that changes the fact that tiny concentrations of carbon dioxide in the atmosphere traps infrared energy into the global climate system, and that will have complex knock-on effects on other aspects of the system, some of which we can predict with greater or lesser degrees of accuracy, and some of which will be damaging to human life. It's reasonable to be concerned about economically damaging or socially authoritarian responses to the threat of climate change. But Charles has utterly misunderstood the issue, and told an entire scientific discipline that he knows best, and it's important that someone points out that he's got it wrong.