Water, soil and climate – which will crack first?

A shorter version of this post first appeared on Blogcritics.

I might never have “practiced” as an agricultural scientist, but an Australian degree in the subject has left me acutely aware of the global shortage of fresh water and quality soils – and how fast these are being degraded.

Australia might be an esspecially bad case – its ancient soils particularly ill-suited to imported European farming methods and its mostly desert interior having a desperate dryness most Europeans struggle to imagine – but erosion and degradation of soils is a huge global problem, as is shortage of water, and we have no alternative ways of producing food….

When I was studying some 20 years ago, climate change was hardly mentioned, but since then its threat to all of our futures has become glaringly obvious.

So which is going to get us first: water, soil or climate change? That sounds flippant, but it is an important question – we need to tackle all of these problems, urgently, and with every input we can muster, but there are some choices that have to be made, and some priorities selected.

Reading Lester Brown’s World on the Edge: How to Prevent Environmental and Economic Collapse, it’s clear that his calculations have produced one answer: water, not that there is any cause for comfort on the other two issues.

On soils, the tale of woe is long. In Lesotho, in the past 10 years its grain harvest has dropped by half in large part due to the soil fertility problems; Haiti, self-sufficient in grain 40 years ago, is now importing more than half; in Mongolia over the past 20 years nearly 3/4 of the wheat land has been abandoned and yields have fallen, cutting the harvest by 4/5.

But it is not just the developing world problem. Roughly one third of global crop land is losing soil at an excessive rate, and each inch means a lost 6% in grain production. We all know about America’s Dust Bowl, but since then it was the Soviet’s turn in the late 1950s. At its heart was Kazakhstan, which at its peak had more than 25 million hectares of land under grain; that has fallen to 7 million, but the average wheat yield is scarcely one tonne a hectare, compared to seven in France.

The new problems? China, which has roughly the same number of cattle as the US, but about 281 million sheep and goats, compared to America’s 9 million, and a huge problem with dust storms; India, with 24% of its land area turning into desert; and the expanding Sahara in Africa. It is estimated that land degradation across Africa costs it 8,000,000 tonnes of grain a year, about 8% of its annual harvest. This loss is expected to double by 2020.

But, as I said, it is water that comes out worst. Saudi Arabia might be taken as a parable. After 20 years of wheat self-sufficiency, the fossil aquifer on which that relied will have been emptied, probably in 2012. But it is big producers that are real concern. Forty per cent of the world’s grain harvest comes from irrigated land, 1/5 the US harvest 3/5 of India’s and 4/5 of China’s. Too often, farmers are pumping out water faster than it can be replenished, and industrial and urban demand are making alternative calls on that supply.

Brown concludes that in the US the irrigated area has “probably peaked”. But in India he quotes a World Bank report said that the grain for 175 million Indians was produced from overpumped aquifers. In China that figure is 30 million, with the problem the greatest on the highly productive North China plain, which relies in part on a fossil aquifer. Beijing meets three quarters of its water needs from underground supplies, and is now drilling five times deeper than 20 years ago.

It takes 1,000 tonnes of water to produce one tonne of grain – so every country now importing grain is relying on other’s water, but for that to continue it has to be enough to go around.

Then it’s climate change. Much of the general account here is well known, but less publicised are the potential effects on food supplies. Heat waves are a particularly great concern, especially during the pollination phase of crops. Corn is particularly vulnerable, but rice also suffers badly. More generally, there is a rule of thumb that says each 1°C rise in temperature during the growing season leads to a 10% decline in grain yields.

There is little doubt that Brown knows what he’s talking about. Not only are his credentials well-known, but the factual details, some of which raise issues that I have not come across before, are compelling. Take the goat problem. Now I have nothing personal against goats, they are lovely animals and I’ve worked with them quite a lot, but Brown has a telling point when he notes that between 1970 and 2009 while the world cattle population increased by 28% and the sheep population stayed relatively static, the goat population grew more than sixfold. That matters not because of the goats themselves, but as indicator of grassland degradation. As they deteriorate, grass is typically replaced by desert shrubs, of which goats can thrive while the other ruminants struggle.

Where this book is weakest, perhaps not surprisingly, is in the solutions it offers. A lot of it is the usual story: abandon biofuels, reduce meat consumption, ensure reproductive choice, protect ecosystems, switch to renewable energy. As you’d expect from the conclusion that water is the biggest problem, there’s also a lot about saving water, and efficient irrigation. Brown notes that rice growing is being phased out around Beijing because it is such as thirsty crop, and Egypt’s restricts rice in favour of the less thirsty wheat.

Potentially, it all seems possible, but what Brown doesn’t deal with here is the political problem. How to generate the political will, with a scant sign of it now, with the issues already clearly so pressing?

But we can also all do our bit. As I was writing this post, I was stopping regularly to stir the apple butter bubbling away on the fuel stove/heater beside me. I’m doing a crash course in food conservation (canning as the Americans call it). In the French village in which I’m writing this, there’s a huge number of fruit trees, but little of the harvest is picked. I’m going to try to do my bit to save some of the crop from the worms.


  • Mark
    April 25, 2011 - 7:27 pm | Permalink

    Water shortages certainly seem to be the elephant in the room. What is more concerning is not that supplies are being depleted but that this is occurring all around the world simultaneously. What is needed is concerted political action. I suspect we will see conflict and self interests being expressed when it is already too late.

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