The president has had a years-long obsession with the size and scope of natural disasters.
Storm makes landfall on U.S. Virigin Islands and Puerto Rico Wednesday as Florida Keys evacuation order takes effect.
Climate change will make storms in general more severe, but scientists won't blame individual storms on it.
Hurricane Irma is the most powerful storm ever observed in the Atlantic basin, outside of the Caribbean and Gulf of Mexico, and it's picking up speed.
The storm has strengthened to a category 4 hurricane and could reach the southeast coast of the United States by the weekend.