What Chenoweth's analysis also seems to overlook or understate is that water-rich regions may have an abundance of water but they are already sailing pretty close to the wind in terms of food output. While growth in Middle Eastern agriculture is crippled by the absence of water, it is highly unlikely that largely temperate regions, such as the EU, will be able to translate their water abundance into significantly higher agricultural production, since most of their arable land is already in use.
The current food crisis may be an early indication that we are slowly approaching an agricultural ceiling. In addition, the energy crunch suggests that the kind of globalisation of trade required to shift virtual water effectively may be unsustainable.
Then, there's the issue of food security. How can countries dependent on virtual water ensure a sufficient flow of food to sustain their populations? What if a more severe crisis in the future forces major food exporters to cut off exports? Alternatively, if wealthy and arid countries, such as the , buy up large tracts of farm land in poor countries to ensure their food security, this will help these countries to boost their agricultural output and develop their economies. But we could also be looking at future artificial famines rather like the which, interestingly, prompted the Ottoman sultan and native Americans to send humanitarian aid to Ireland.
If virtual water is to be successful in feeding the world, we need robust and effective international mechanisms to ensure that this redistribution is implemented equitably and that neither suppliers nor recipients go hungry in lean years. In addition, development programmes in poorer arid countries will need to find ways of reducing dependence on sparse local water resources and controlling population growth.
BBC News: Hurricane Ike blows past Havana
Strong winds and rains batter Havana
Hurricane Ike rattled Havana after its second landfall in Cuba but the eye of the storm has now passed out to sea, Cuban hurricane monitors say.
It destroyed at least 16 buildings in the city but no injuries were reported and the centre of the storm is now in the Gulf of Mexico.
The UN esimates the cost of the damage at between $3bn-$4bn.
Four people died in Cuba as a result of the hurricane - the first storm-related fatalities for several years.
One person was killed by a falling tree, an elderly woman died when her house collapsed and two others were electrocuted.
State television said almost 1.25 million people had been moved to shelters - more than one-tenth of the island's population.