2. Climate change is part of the dangerous mix that is making hurricanes so unexpectedly powerful.

Michael struck the same week that a report by the U.N.’s scientific panel on climate change laid out dire predictions for the next 25 years, including flooded coastlines, worsening food shortages and more wildfires, as in California, above.

Avoiding the most serious damage requires transforming the world economy within just a few years, said the authors, who acknowledged the rescue was politically unlikely.

In December, experts and officials from around the world will gather in Katowice, Poland, for a new round of international climate negotiations. How the framework is set up will be crucial.