Climate change is creating problems for American citizens coast to coast and costing the economy billions of dollars, as extreme weather brings flooding, droughts and other disasters to every region of the country, a federal advisory panel concluded in a report released Tuesday.

The congressionally mandated National Climate Assessment, produced by more than 300 experts overseen by a panel of 60 scientists, pins much of the increase in climate change on human behavior. The report says, however, that it isn't too late to implement...