Six years ago, an unpleasant surprise greeted plant pathologist Kari Peter as she inspected a research orchard in Pennsylvania. Young apple trees were dying—and rapidly. At first, she suspected a common pathogen, but chemical treatments didn’t help. The next year, she began to hear reports of sudden deaths from across the United States and Canada. In North Carolina, up to 80% of orchards have shown suspicious symptoms. “Rows of trees collapse for what seems like no reason,” says Peter, who works at the Pennsylvania State University Fruit Research and Extension Center in Biglerville.
The “bomb cyclone” that dumped rain on Nebraska, Iowa and Missouri and killed at least four people now threatens a wider region downstream of swollen rivers and smashed levees.
Manmade greenhouse gases trap heat in the atmosphere, warming the oceans and making the air above them more humid, scientists said. When a storm picks up and eventually spits out that moisture, it can be devastating for people caught below.
“The atmosphere is pretty close to fully saturated, it’s got all the water it can take,” said Michael Wehner, a senior scientist at the Lawrence Berkeley National Laboratory.
Big storms like the bomb cyclone and Hurricane Harvey, which smacked Houston in 2017 with record downpours, are where the impact of climate change can most clearly be seen, he said, adding that climate change’s fingerprints were all over the recent storm.