A 2008 study found that in the northwestern Pacific where Haiyan formed, the top 1 percent of the strongest tropical cyclones over the past 30 years are getting on average about 1 mph stronger each year — a phenomenon some scientists suspect is a consequence of global warming.

“The strongest storms are getting stronger” said study co-author James Kossin of the National Climatic Data Center. Haiyan “is what potentially could be a good example of the kind of the things we’re finding.”

Similarly, the Philippines has seen its sea rise nearly half an inch in the past 20 years — about triple the global increase, according to R. Steven Nerem of the University of Colorado. Higher sea levels can add to storm surge, creating slightly greater flooding.