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December 18th, 2013
Via the Sydney Morning Herald, a sobering report on global water stress:
Global water scarcity already on the rise due to exploding global populations may be amplified by up to 40 per cent due to climate change.
Research carried out by the German-based Potsdam Institute for Climate Impact Research has found significantly more people throughout the world will struggle to find the water needed for the basics of life as the planet warms.
Modelling for the study suggested the spread of water scarcity could be intensified by 40 per cent across the planet as a result of global warming, and in some scenarios could be more than 100 per cent.
As a result the institute projects that between five and 20 per cent of the world’s population may face “absolute” water scarcity as the climate changes. How far water scarcity will extend will depend on the rate of population growth and warming.
The findings are the result of a comprehensive study, produced in collaboration with research groups around the world, using 11 hydrological models driven by five climate models.
The study found changes in water availability would not be uniform worldwide or within countries. Western and southern Australia were projected to see a decline in water availability while the north may see a significant increase.
Elsewhere, areas expected to see an increase included eastern Africa, the Indian peninsula and high northern latitudes. Southern China, the Middle East and southern US would experience a decrease.
The figures examined the impact from a two degree rise in average global temperatures compared to current levels. The latest report by the United Nations’ Intergovernmental Panel on Climate Change found a high confidence in the global surface temperature exceeding a 1.5 degrees increase, compared to the average from years 1850 to 1900.
The Potsdam study found that up to 15 per cent of the world’s population would see “increases exceeding 100 per cent of today’s discharge” of water.
The researchers noted that while these increases might often improve water availability, they carry the risk of increased flooding, damage to infrastructure and declining water quality.
Water scarcity was divided into two classes: annual “blue” water availability below 500 cubic metres per capita – described as absolute water scarcity – and annual availability below 1000 cubic metes per capita – described as chronic water scarcity.
The researchers suggested that 1.5 per cent of the global population currently falls into the absolute water scarcity category, and 3 per cent faces chronic water scarcity.
Co-author Pavel Kabat, of the International Institute for Applied Systems Analysis, said: “From a risk management perspective, it becomes very clear that, if human-made climate change continues, we are putting at risk the very basis of life for millions of people, even according to the more optimistic scenarios and models.”
The study was published in the journal the Proceedings of the National Academy of Sciences