Global Warming Study Warns of Dangerous Changes in Global River Flow

Just when you thought the debate over global warming and climate change couldn't get any hotter, a new study is adding fuel to the fire. According to research published Friday in the online version of Frontiers in Ecology and The Environment, global climate change will have a devastating effect on rivers impacted by dams or "extensive development."

The study, which was a collaboration between scientists from the United States, Australia, Germany and Sweden, analyzed the potential effect of climate change on river basins. The findings indicated that "significant management interventions" would be necessary to protect people and ecosystems surrounding the rivers in question.

"As a result of damming and development, major rivers worldwide have experienced dramatic changes in flow, reducing their natural ability to adjust to and absorb disturbances," said Dr. Margaret Palmer, director of the University of Maryland Center for Environmental Science Chesapeake Biological Laboratory and lead author of the study. "Given expected changes in global warming and climate needs, this could lead to serious problems for both ecosystems and people."

While global climate change is often associated with the melting of glaciers and rising sea levels, the phenomenon's affect on other bodies of water has not been widely studied or publicized. However, this study addresses such concerns.

"This report calls attention to significant risks facing many of the world's major rivers and those people who live near or depend on them for water or food," said Palmer.

Palmer and her colleagues used existing data on the effects of dams on large river basins and combined it with projected river discharge levels under different climate and water withdrawal scenarios. Discharge is the volume of water transported in a fixed amount of time, calculated by multiplying the average velocity of a river by its cross-sectional area.

The results were displayed in maps showing potential changes in discharge and water stress for both free-flowing basins and those obstructed by dams. The projections forecast dire consequences; changes in discharge will occur in every populated river basin in the world. Some of these will cause water stress resulting in inadequate water supplies for human use, while other basins will experience dramatic increases in flood flows. For example, in as little as 50 years, the mean annual river discharge will decrease by 20 percent Sacramento River in California. On the other end of the spectrum, mean annual discharge will increase by about the same percentage in the Potomac and Hudson River basins.

"Given expected changes in global climate and water needs, this could lead to serious problems for both ecosystems and people," said Palmer.

A more disturbing statistic is the amount of people that will be affected by the changes in discharge. The study found that as many as 365 million people live in basins that will "almost certainly" require action, and nearly one billion live in areas that will "likely" require action.

Due to the severity of the potential consequences, the researchers recommended taking preventative measures. In order to increase the resiliency of river ecosystems, the scientists suggested proactive river management, restoration and rehabilitation in problem areas. Specifically, dam removal, channel reconfiguration and storm water and sediment management were cited as measures that would minimize risk and prevent damage.

According to the research, the effects of global climate change will not merely be water under the bridge.

"This report calls attention to significant risks facing many of the world's major rivers and those people who live near or depend on them for water or food," said Palmer. "Many of these risks could be reduced dramatically if proactive management measures are implemented now. It's now up to the world's political leaders to decide whether or not to step forward and put in place programs designed to minimize the impacts we may see on our ecosystems and people."

SOURCES:

Press Release, University of Maryland Center for Environmental Science