Scaremongering

Part of the Climate Clinic blog

The Hadley Centre, part of the Met Office, has just released some research, today, in the Climate Clinic, at the Tory conference. The main headline finding is that drought is set to double this century due to climate change. A spoil-sport serious newspaper would also mention that this figure refers to 'moderate' drought. Moderate drought can still be pretty dangerous if you don't have much in the way of resources to fall back on. Generally the agriculture in a particular area is suited to that area's climate. If you have an agricultural system which requires a lot of rainfall, such as paddy fields, then even a drought which doesn't look like a drought to the average observer could ruin your harvest and lead to a famine.

Drought isn't necessarily an absence of rain, it's a more complicated phenomenon which is based around temperature and a level of precipitation (rain to you) lower than the norm for that area. In a very dry area you might have to go without rain for quite a while before the situation qualified as a drought, whereas in a wet area etc. etc.

The knock-on effects of a drought can be quite horrific, including some that you might not expect. For example, if the drought leads to a large movement of refugees, then there is the spread of disease to consider, as well as the fact that the recipient country is likely to be almost as poor as the one people are leaving, and may soon become poorer under the burden of the new arrivals.

But wasn't climate change supposed to increase rainfall? Yes, overall, but that's a global average, and just as the UK may well get much colder, despite the rising global average temperature, some places will become much drier. Precipitation will 'clump' more, meaning that there will be more downpours but also more dry spells. Essentially everything becomes less 'moderate' and more extreme one way or the other.

OK, this drought is still 'moderate' though. We're in the realm of catastrophe, and anything 'moderate' just isn't all that scary. It's like one of those warning/advertising statements on films these days - 'contains moderate sex' or 'some scenes of moderate peril'. What, I hear you cry, about extreme drought (and, for that matter, extreme sex and peril)? If it's not extreme, it's tame, and don't even try fobbing me off with something moderate. M'kay?

OK, extreme it is.

I didn't want to go into this, but your juvenile attitude to my extremely important news about moderate drought has provoked me.

The Hadley Centre was a bit reticent about extreme drought, as the data set isn't really large enough to produce really reliable predictions, they haven't run all the possible scenarios through their model and they're the sort of scientists who regard their own credibility as sacred. They're probably going to be really annoyed with me for mentioning this, but you've made me do it. I hope you're happy.

During the last half of the last century, around one per cent of the Earth's land surface suffered from extreme drought, as defined by the Palmer Drought Severity Index. That's not a lot of land, but then we are talking about extreme drought. Currently, three per cent of the land is suffering from extreme drought. That's an increase of two hundred percent, but then, it is only three percent of the total. More than that's under ice. Probably. Depending on when you read this.

By the end of this century, according to Hadley Centre predictions, which do not take account of the various feedback loops and other complicating factors, and are based on a data set which is not everything they might have wished for, and which I probably shouldn't be telling you about anyway, but then you did ask, and you had to have your extreme fix, and I suppose there's no real harm in it, so long as you don't tell the Hadley Centre. Anyway, by the end of this century extreme drought will be affecting thirty per cent of the Earth's land mass.

The next time you hear someone say that it would be cheaper or easier to adapt to climate change than to stop it, think about that 30%. But try not to think about it too much.