How Will Europe Prepare for the Next Flood?

The widespread flooding of the past month in Germany, Austria, Switzerland, and parts of Hungary and the Czech Republic has been some of the worst in history. The situation was so dire in some places, German local governments had to resort to extreme measures.

The climatic conditions that caused the recent flooding can be attributed to a low-pressure weather system that remained stuck north of the Alps for several days, resulting in an inordinately concentrated single torrential downpour. Stuck weather systems are responsible for other extreme weather conditions, such as the European heat wave of 2003. That event was caused by the inverse condition: a high-pressure area that remained stuck over most of Western Europe for several days.

Stuck weather systems, known as "blocking events," result when one of the jet streams -- air currents that whisk around the Earth's upper troposphere 4.3 to 12 miles up -- pinches off large air masses from the normal wind flow for an extended period of time. These pinches or kinks last for several days, sometimes for weeks, and cause weather patterns simply to stall, resulting in floods, heat waves, droughts and blizzards.

NASA Goddard Space Flight Center oceanographer Sirpa Häkkinen and her team analyzed atmospheric data from the 20th century and found that blocking events now occur about 30 percent more often than they did during most of the last millennium. Since the 1990s, the trend has been upward.

How Will Europe Prepare for the Next Flood?