Where are the missing data on droughts?

Climate change predictions all seem to agree that one common manifestation is a likely intensification of weather extremes, which will include flooding - we’ve seen plenty of that recently in Europe - and its counterpart, drought. And recent drought episodes in Europe and particularly the UK have helped to highlight the vulnerability of our agricultural and horticultural sectors. And this is largely because most of our production is rainfed and depends entirely on, as Cranfield University’s Ian Holman dubs it, “the capricious nature of summer rainfall”. Speaking with Chris Smith, he’s been looking at the main knowledge gaps which need to be addressed to shore up the system…

Ian - First and foremost, we don't actually know in economic terms how drought impacts agriculture. There are lots of anecdotal values bandied around, but because agriculture is so diverse, every drought is different, affecting different parts of the country, and agriculture itself is very dynamic with different crop rotations, etc., it's quite a challenge to understand what the economic impacts are. Obviously money talks. If it's developing or creating large financial losses, then there is more of an emphasis for both the businesses and the governments and regulators to support the industry.

Chris - Is this a bit like when you talk to a conservationist and they say you can't conserve something without understanding it in the first place. Are you saying we can't mitigate against this if we don't understand the impacts in the first place?

Ian - Yes. I think there's an important element: you've got to have the evidence base to say, actually this is a problem. Farmers know it's a problem because it's impacting them severely. But in terms of then how the whole supply chain, how organisations like the Environment Agency respond, they need that evidence base to support those business decisions.

Chris - So how should we go about it?

Ian - It comes back to the quality gathering of data. If we think about the irrigated agricultural sector, which provides much of our fresh vegetables and soft fruits, for example, we haven't collected data on irrigated areas, numbers of farm reservoirs, irrigation methods, in a structured way, for about 10 years. So activities that are regularly done like agricultural censuses need to better capture the data that is relevant for helping us understand the vulnerability to drought.

Chris - What about longitudinally as well? Because a lot of the time, when we look at things, we see the short, sharp shock: the acute effect, but there are often spillover or knock on effects in years downstream, whether that's because you erode the crop base, you change the soil in some way so it's more vulnerable in subsequent years. There must be so many moving parts that this probably is quite difficult to do.

Ian - Absolutely. It is a challenge with drought that a lot of the impacts or consequences of the drought appear after the drought has ended. It could be the harvest, it could be the availability of feed for the livestock to get them through the winter, and so that delayed effect when the reality of the drought has left the public imagination or the public memory and other issues come to the fore, really does, I think, diminish the attention that is paid to that recovery phase of drought. that's going to become more important because with, the changing climate, we do expect droughts - like floods - to become more frequent in the future.

Chris - It really surprises me what you're saying because we really have a track record, even back to the middle ages, of being notorious bureaucrats in the UK, especially with agriculture. I was talking to a medieval economist the other day who was showing me records of documenting how many pigs a person who was a peasant who lived on a landholding had. Yet here we are in this era with data through almost everything coming out of our ears and we don't know these fundamentals which are really crucial to our future.

Ian - The devil is always in the detail, isn't it, as to what you actually measure. As you say, we have fantastic information on crop areas and livestock numbers, but the detail in that, and as you say, the longer term performance of farm businesses. Usually, when there is a drought, the government comes together with a drought working group with the sector, but I think the limitation is that's often quite crisis driven. It's reactive rather than proactive. Really, what we need are strategies that go right from the farm level through the food supply chain to the supermarkets, to the government, to the regulators. Often, responses to drought are either left to the farmers or there isn't an appropriate risk sharing through the food supply chain.

Chris - Presumably, this also is an international problem. Because if we have a drought in one place, you're likely to have adverse weather elsewhere. And if you just assume, well, it's okay, we'll buy our food from somewhere else, everyone else is going to be doing the same thing, aren't they? So it could mean that your safeguard, your life belt, is actually already accounted for.

Ian - The UK is 60% or so self-sufficient, so 40% of food comes from overseas, and for some elements like fruits it's even higher. Now we have, at one level, created resilience to drought in our supply chains by the fact that, as you say, the supermarkets import from many different countries. But there is that concern that if drought strikes our major import areas concurrently, or several of them, that will affect our food security. And, occasionally, we have seen that in recent years with shortages of particular fresh vegetables in our supermarkets. But also, in our domestic agricultural area, now there's a lot of interest in raising water tables in lowland agricultural pea soils. These are the very organic rich soils that are some of our best food producing land, particularly for vegetables. But the drainage leads to emissions of greenhouse gases. Now, if we're going to raise the water tables in those areas to reduce the UK's contribution to climate change, there is a significant risk that some of our production in those areas might be either moved to other parts of the country, displacing some of the impacts, or even exporting the problem, removing the production into other countries with lower environmental standards.