Like oil in the 20th century, water could be the resource that triggers armed conflicts at the end of this century, according to experts forecasting changes in the world's major rivers caused by global warming.
Big increases and decreases in the flow volume of the rivers will leave some areas parched while putting others under the constant threat of flooding, according to the research group.
The researchers included Daisuke Nohara of the Japan Science and Technology Agency and others from the Meteorological Research Institute and the University of Tokyo's Institute of Industrial Science.
They made their forecasts for the flow volumes of 24 major rivers based on expected climatic changes between 2081 and 2100.
The group will report its findings at a conference sponsored by the Meteorological Society of Japan beginning Sunday in Tokyo.
According to Nohara, the research group used 15 of the latest weather models compiled by institutes around the world to forecast temperatures and rainfall at the turn of the next century.
Temperatures around the world will rise an average of 2.7 degrees over current levels. Average temperatures on land are expected to increase by 3.7 degrees, according to the study.
Changing wind patterns are also expected to reduce rainfall in certain areas, including the river basins of the Euphrates and Danube rivers.
In fact, the region from the Mediterranean to the Middle East is expected to experience a decrease in rainfall of between 0.1 and 0.5 millimeter per day.
The drier conditions will mean that the little rain the Middle East does receive will be soaked up by the ground before reaching rivers.
That will lead, for example, to a 41-percent decrease in flow volume for the Euphrates, according to the study. The Danube flow will be reduced by 23 percent.
``In the river basins of the Euphrates and Mekong, which are also expected to be regions of population growth, there will be concerns about conflicts over water rights,'' Nohara said. ``There will be a need to think about how to use the limited water resources.''
On the other hand, the higher temperatures will melt more ice caps
and snow in regions near the North Pole, giving those areas an expected increase in rainfall of between 0.1 and 0.2 millimeter a day, according to the study.
Areas from India to East Asia are also forecast to receive similar increases in precipitation, leading to sudden surges in the flow volume of rivers, especially in Southeast Asia.
In addition to the heavy rainfall already recorded in that region, rain that is not soaked up by the ground will flow into those rivers.
The increase in the Ganges is a big cause for concern.
The Ganges flow volume is expected to rise by 15 percent in periods of the year with heavier rainfall. There will likely be a greater risk of flooding in the region.
Another river expected to experience a large increase in flow volume is the Yukon, with a 23-percent jump, according to the study.
But the Rio Grande, which serves as a border between the United States and Mexico, will experience a 26-percent decrease, according to the study.
No predictions were made for changes in Japanese rivers because the models were ambiguous as to whether rainfall here would increase or decrease in the late 21st century.
The Central Environment Council issued a report Thursday calling for measures to keep the rise in temperatures due to global warming in 2100 within 2 degrees of levels of the 18th and 19th centuries prior to the Industrial Revolution.
A rise over 2 degrees would have serious effects on the global environment, which could damage human health, water resources and food production, the council said.(IHT/Asahi: May 14,2005)
