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Drought - past problems and future scenarios

Drought

By Justin Sheffield and Eric F Wood
Published by Eathscan
Website: www.earthscan.co.uk
2011, 210pp, ISBN 978 1 84971 082 4 (Hb), £49.99

Drought is considered to be one of the most damaging natural hazards in terms of economic cost. Unlike more dramatic events such as earthquakes, hurricanes, forest fires and floods, "drought is a silent and pervasive disaster that creeps up over weeks and months, often without warning, to impact on human activity on a global scale," write Sheffield and Wood. "Drought can last for many years, with devastating impacts on agriculture, water supply and the environment." Agriculture and food production are totally dependent on water, and account for 77 per cent of freshwater use; in the absence of water, agriculture fails and civilisation quickly collapses, as the demise of the Sumerian, Maya, and Angkor Wat cultures has testified.

Drought - past problems and future scenarios explains how and why drought has occurred over past millennia, and the prospects under future climate change. The intended audience are undergraduate students but the book is also very readable and instructive for the general reader. While politicians and the general public in the industrialised nations have been fixated on the global financial crisis, droughts have been having serious impacts on cereal grain production in Argentina, Australia, China, Russia and the south western US. There have also been, and continue to be, impacts on water supply for industry and domestic use, power generation and transport.

"As temperatures increase, the prospect of climate change-induced increases in drought frequency and severity over the 21st century is increasingly worrisome for a planet already under considerable environmental stress," observe the authors, one a research hydrologist and the other Professor of Civil and Environmental Engineering at Princeton University, New Jersey, USA. Their examples paint a sobering view of current events: the prolonged desiccation of the Murray-Darling rivers in Australia; the dramatically reducing water levels in the giant Ogalalla aquifer which, together with the Colorado River, has sustained crop production in six south western states in the US; and the drought declared to be a Level 1 Emergency in China's main wheat growing areas.

Water is so readily 'on tap', figuratively and literally, that it is too easy to think that technology will provide answers. However, whereas it is possible to envisage a post oil-dependent world for energy, there is no substitute for finite water supplies. Moving water from areas of plenty is possible, as is desalination, but both options are hugely demanding in energy, leave large carbon footprints and have serious environmental impacts.

The alternative is for people to move, as happened in the 'dust bowl' years so graphically described by John Steinbeck in Grapes of Wrath. But what scale of migration might be needed? The authors describe a drought in the late 1500s more severe than anything experienced in the 1930s. "This drought may have extended from the west to the east coasts of the US and from Mexico to British Columbia," lasting six years across the continent, and several decades in some areas. In such a situation, migration is clearly not an option.

"In the face of potential increases in drought severity and frequency, driven by population increase, land use and climate change, addressing this challenge is ever more difficult and pressing," write Sheffield and Wood. The only way to cope is to adapt, abandoning our current profligate use of water for strict economy and constant recycling. The authors conclude: "It remains to be seen whether our current coping capacity and ability to adapt is sufficient for the potentially large changes projected for the future."

Date published: June 2011

 

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