Warning of world water shortage as climate changes bite

The world's water resources will come under severe pressure from population growth and climatic changes, scientists have warned. The twin impacts of more people demanding water resources, coupled with likely changes in weather arising from global warming, would make it more difficult for people to get sufficient clean water in the future.

Delegates at the annual British Association for the Advancement of Science yesterday heard lectures from experts on water and development. Global aspects were matched with the likely impact in Europe of changed weather patterns due to global warming.

Drier summers and wetter winters in northern Europe, including Ireland, are predicted by mathematical models of climate change, according to Dr Nigel Arnell of the University of Southampton. Southern Europe can expect less rain in most seasons, with much higher average temperatures.

Maritime countries such as Ireland could expect more frequent flooding during the new rainy seasons, while summer drought could become a regular summer feature of northern Europe, he predicted.

These changes would present major difficulties and challenges to planners, he said, and the impact of floods and droughts would depend on how water was managed.

The European picture would change in many ways, he suggested. North-western Europe, for example, could expect much less snow, which in turn would reduce the flow of available water through its rivers. The traditional snowmelt surge in April and May was unlikely to be there in the future, affecting hydroelectric schemes and river navigation.

Higher water temperatures would also change the biology of our seas and rivers, with coldwater-loving species moving further north, allowing others to take their place. "You can't predict the future but you can plan for it," he said. "You can try and anticipate the circumstances."

Delegates were warned that a "crunch" was coming as world demand for water rapidly outstripped the ability to supply it. There was now a consensus that the growing scarcity of water and the decline in water quality were "critical factors" limiting growth, according to Prof Judith Rees of the London School of Economics.

"It has been realised that water has become one of the processes which allow a country to grow," she said. "The assumption was that water would be available to support urban growth. That assumption is now being questioned worldwide."

By 2025 up to a third of the world's population would be "water-stressed" or living with water scarcity. "The time we have to solve the water problem is very, very short, no more than 30 years," she warned. Only 11 per cent of all the precipitation available around the world was accessible.

"Some time between 2025 and 2050 there is going to be a crunch and many countries will reach that crunch long before that. It is not environmental change but the growth of human numbers and how those human numbers are being urbanised," she said.