The impact of climate change on storms might be uncertain, but their growing damage is not. Hurricanes like Maria, now barreling toward Puerto Rico, could inflict much larger losses around the world as coastlines bristle with future development.

The Federal Emergency Management Agency estimates that $11 billion in flood insurance claims will result from Hurricane Harvey, but it still has no firm estimate of the damage to Florida from Hurricane Irma, which raked the state from south to north this week.

American and Chinese scientists are examining whether tiny particles drifting over the U.S. from Asia are shading North America, helping to cool parts of Earth as the globe warms.

Hurricane Irma is a Category 5 storm and a "dangerous major hurricane," according to the National Weather Service. Longtime observers have been shocked by its power and have warned that it could be one of the most infamous storms in Atlantic hurricane history. "Irma has me sick to my stomach," Eric Blake, a scientist at the National Hurricane Center, wrote in a Twitter message. "This hurricane is as serious as any I have seen. No hype, just the hard facts. Take every life saving precaution you can."

Until last month, a report that a rainstorm might devastate one of America's largest cities seemed obscure and dubious. Then Hurricane Harvey blew into Texas, giving the United States a new benchmark by which to measure catastrophic flooding — and a national debate.