How Is Climate Change Affecting Floods?

Floods can surge all year round, in every region of the world. But discerning the relationship between any given flood and climate change is no small feat, experts say, made difficult by limited historical records, particularly for the most extreme floods, which occur infrequently.

It can be tempting to attribute all floods and other extreme events to the forces of warming planet. But weather is not climate, even though weather can be affected by climate. For example, scientists are confident that climate change makes unusually hot days more common. They’re not as sure that climate change is making tornadoes more severe.

Floods fall somewhere along the confidence spectrum between heat waves (“yes, clearly”) and tornadoes (“we don’t know yet”), said Daniel Swain, a climate scientist at University of California, Los Angeles. “I’d say, ‘yes, probably, but…’”

Flooding, like other disasters, involves a number of competing factors that may affect its frequency and intensity in opposing ways. Climate change, which is worsening extreme rainfall in many storms, is an increasingly important part of the mix.

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