Facing the floods of an altered climate

A family embraces as floodwaters from the Mississippi River rise around their mobile home in Vicksburg, Miss.
A family embraces as floodwaters from the Mississippi River rise around their mobile home in Vicksburg, Miss. (DAVE MARTIN/ Associated Press)

Warming will likely fuel more water-related disaster.

Posted: May 17, 2011

By Vinod Thomas

The dangerous surge of the Mississippi River is yet another reminder that the global incidence of floods is on the rise. What's more, the growing frequency and ferocity of such events suggest an ominous link with human-driven global warming. In the absence of timely action, uncommonly extreme weather will likely put all progress at risk.

Flooding and windstorms in particular are linked with climate change, and the number of disastrous floods and storms reported globally has tripled over the past three decades. Very heavy precipitation increased sharply in the last half-century across the globe and in the United States, especially the Northeast and Midwest.

Scientists have warned about the connections among extreme weather, global warming, and air pollution. New studies tie increases in atmospheric carbon dioxide emissions with higher sea-level temperatures and changes in precipitation, indicating that human-caused climate change doubles the risk of extreme floods.

In the wake of the recent tornadoes that tore into seven Southern states, President Obama said, "We can't control when or where a terrible storm may strike, but we can control how we respond to it." Indeed, the price of delayed response was brought home by Hurricane Katrina in 2005. But water-related calamities have increased to the extent that rapid relief efforts won't be enough.

We must also take steps to prevent and mitigate such disasters. First and foremost, that means slowing the pace of climate change. This will take time, but as President John F. Kennedy said 50 years ago, "We must think and act not only for the moment, but for our time."

The key is to reduce the amount of greenhouse gases being released, especially by shifting to a low-carbon economy. Energy prices must reflect the damage caused by emissions, especially in energy-intensive countries such as the United States. And promoting energy efficiency defers the need for more fossil-fuel plants, buying time for wind and solar power to become more competitive.

It's time to eliminate government subsidies that purportedly spur growth, including worldwide farm subsidies of $150 billion a year and fossil-fuel subsidies of $650 billion a year, which encourage energy intensity and emissions. Other steps can increase the uptake of greenhouse gases, including investment in protected forests, which are a bulwark against the deforestation that accounts for one-sixth of emissions.

Prevention also means environmental protection. Wetlands provide a buffer against flooding, but half of them worldwide - from Australia to the United States - have disappeared in the past century. Shrinking forests, meanwhile, have diminished protections against flooding and landslides. Examples of environmental solutions include the restoration of Vietnam's coastal wetlands to reduce erosion and the building of terraces in China's Loess Plateau to reduce flooding.

Housing policy is also part of the answer, and it can be a matter of life and death. People are increasingly living in harm's way, be it on riverbanks prone to flooding in the South and Midwest or on hillsides subject to mudslides in Rio de Janeiro. It pays to ensure that levees and floodgates work, relocate people from flood-prone properties, and encourage home construction using reinforced concrete, cinder block, or fired brick.

Finally, prevention entails continued investment in early-warning systems, which served Japan and the United States relatively well during recent disasters. Bangladesh, too, illustrates the value of preparedness: While the cyclone of November 1970 took about 300,000 lives, a similar one in May 1997 claimed only 188 because of better early-warning systems, shelters, and evacuation.

No longer can we respond to hazards of nature with cleanup and reconstruction alone. Climate change has introduced an unnatural dimension that calls for more preventive measures. Difficult as it is to muster the political will to do so, we must invest in slowing climate change, protecting the environment, controlling development, and improving warning systems. Only then can we lessen the fury and devastation of these events.


Vinod Thomas is director-general of the Independent Evaluation Group of the World Bank. He can be reached at vthomas@worldbank.org.

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