Saturday, 22 March is World Water Day. It is an annual event to raise awareness of the global issues that limit access to fresh, safe water, and this year’s theme is the link between water and energy. The presence of water is a fundamental requirement for life on any planet, and on this particular planet, water for our particular species has never been in shorter supply.

Images from space show us as the blue planet, but only 2% of that water is fresh, and 70% of that fresh water is frozen. So, water we can use is rare stuff, and we are using up our fresh water aquifers faster than they are being replenished. Indeed, next year it is estimated that water withdrawals from aquifers will, for the first time, exceed the rate of storage in artificial dams. In other words, we will start to dry the terrestrial biosphere and fill up the oceans. Unless something changes, it is only a matter of time until terrestrial water is all but gone – and it is not a lot of time. By 2050, half of the world’s population may endure the kind of water shortages currently only experienced in sub-Saharan Africa.

Many of the serious global risks are interlinked, and water has obvious connections to food and climate risks. The link to energy, the theme of this year’s World Water Day, may be less obvious, until we realise that  around 16% of the global energy supply comes from hydroelectric power stations, and that almost everything we do with water consumes energy.

Agriculture accounts for about 70% of fresh water use globally but, tellingly, this figure is regionally sensitive. In South Asia the proportion is over 90%, while in Europe it is only 8%. That is not because Europe doesn’t do its share of agriculture; it is because of high levels of urbanisation and an economy that consumes lots of water. Increased urbanisation in China, combined with improved standards of living, means that by 2050, more than 50% of water use will be in cities. Indeed China is a good, but far from isolated, exemplar of the scale of the challenges we face.

This month, Chinese Premier Li Keqiang declared war. An offensive was launched against air, water and soil pollution with a series of initiatives that strike at the heart of the food-water-energy risk nexus. China has not only depleted its water stocks, it has been polluting them. More than 50% of China’s rivers have disappeared since 1990. Around 90% of China’s ground water is polluted, with 60% so seriously that this water represents a significant health risk. Rich Chinese no longer eat food grown in China. The nation’s extraordinary growth in recent decades has been paid for by an exorbitant rise in water consumption, and led to pollution by industry and agriculture. Coal-fired industries and excessive use of fertilisers and pesticides have polluted the air and poisoned the ground water, while eroding soils at such a rate that, by 2050, the national wheat crop alone will have declined by 40%. These problems won’t be solved overnight. Indeed, because China has 20% of the world’s population but uses only 7% of its water, things seem destined to get worse before they get better.

Extraordinary challenges require extraordinary solutions. In China, one solution is the ‘South to North Project’, which will divert water from the River Yangtze in the south, where most of the water is, to the north of the country, where most of the demand is. This is the single biggest and most expensive engineering project ever undertaken by one nation, and second only in scale to the International Space Station.

Egypt is another country where food, soil and water are in short supply. Here, the government has built infrastructure in the southern desert to attract foreign investment in food production and the development of a “second Nile Delta”. The costs, as well as the environmental and political risks, are enormous, but are matched by the risks of doing nothing in a country so exposed to volatility in the global food commodity markets. However, there is risk of escalating conflict with countries upstream, including the recent diplomatic offensive against Ethiopia’s Renaissance Dam, is high. National and regional instability due to food shortages has already contributed to regime change and massive loss of life. In nearby Syria, conflict and terrible human suffering has been fuelled by drought and food shortages. Similar stories of water shortage and socio-political instabilities apply to Yemen, Darfur, the Middle East, India and Pakistan and many to other regions.

Premier Li is correct in his view that we need to declare war on water shortages. Only a level of international co-operation on a scale historically associated with global warfare is likely to alleviate the stress on our water supplies. This co-operation must provide better, less wasteful technologies to developing countries, so they can continue to grow more food and healthier food, using less energy and with dwindling water resources. This co-operation must restore degraded soils – which currently leak 50% of available water past the roots of crop plants – and provide crops that can grow with less water.

Perhaps most importantly of all, we need to know exactly how much water we are actually using, and how much is left. We don’t currently know whether global water withdrawals for agriculture (which ultimately reach the sea in river flows and rain) have contributed significantly to the rise in sea levels in recent decades, or whether there has been a net decrease in volume flowing to the oceans, due to more dams being built, in the same time interval. It is unforgivable that we cannot account for such volumes of water.

Civilisations have risen and fallen over time with the tide of available water. Perhaps the greatest of them all, the Mongol empire of Ghengis Khan, rose during a time of water surpluses in excess of anything the region has seen either before or since. This water, providing energy in the form of food for horses and armies, left as mysteriously as it arrived, followed shortly afterwards by the empires decline. Right now, the same region is experiencing its fiercest drought in the past 1,000 years. In the coming few years, we shall see how this plays out in the global era of consumption-driven growth.

Image: A girl looks at water from the Nile flowing from a pump in the Manshiyet Nasser shantytown in eastern Cairo May 18, 2010. REUTERS/Amr Abdallah Dalsh

Author: Professor John Crawford is Scientific Director of the Sustainable Systems Programme at Rothamsted Research.