Global warming to bring more floods

The flooding in Westmoreland and Allegheny counties ("FEMA Denies Funds for Flood-Ravaged Areas," July 21) underscores exactly the sort of challenges that are expected to be more commonplace as global warming brings more frequent, severe flooding to Pennsylvania and the nation.

Long-term observational data show a trend toward more heavy rainfall events and more 90-day periods with high precipitation totals. Global warming is partly to blame. Warmer air simply can hold more moisture, so heavier precipitation is expected in the years to come. By the end of the 21st century, the Midwest and Northeast could see as often as every four to six years those big storms that historically happened only once every 20 years. We must confront these realities of global warming.

First, we need to aggressively move toward a cleaner energy future and reduce emissions of greenhouse gases. This way, we can avoid the worst potential global-warming effects.

Second, we must take the trends toward more flood risk into account when managing our floodplains and watersheds. Critical steps include educating citizens about their risk and steps they can take to prepare, discouraging development in flood-prone areas and protecting wetlands and other natural systems that help to buffer against floods. We can no longer plan based on the climate we used to have.

AMANDA STAUDT
Climate Scientist
National Wildlife Federation
Washington, D.C.