A mere category 1 hurricane dumped so much water on Puerto Rico so quickly that one of its rivers has swollen to 25 feet above normal, even more than it rose during Hurricane Maria in 2017, which was a Category 5 hurricane. The island is beset by flash floods, and is getting 16-30 inches of rain. The usual average amount of rainfall received by Puerto Rico is 31 inches, so it is getting from six months’ to a year’s worth all at once in a single day. All power was knocked out, though the government is vowing to get it back on in days, not the months it took after Maria. Puerto Ricans are U.S. citizens, though it is a territory and not a state. President Biden declared a state of emergency.
I’ve been to Puerto Rico several times and really like the place, and have friends there. I’m worried about them, and about its future. The thing that struck me is how devastating this storm has been even though it is “only” a Category 1, with wind speeds of 85 miles and hour.
The ocean around Puerto Rico is much warmer than it used to be, as is the air above the ocean. That is a double whammy. Hot air can absorb more moisture. Hot water causes more moisture to evaporate into the air. So there is just more water in the sky to fall on places like Puerto Rico than there used to be. Global sea surface heating over the past century has been an extra 1.3 degrees F. The rate of heating in the northeast Caribbean, though, has doubled over the past two decades. …