Deadly flooding hit several countries at once. Scientists say this will only be more common
In the U.S., flooding claimed five lives in Upper Makefield Township, Pennsylvania, where a search is ongoing for two missing children. Flooding also struck parts of New Hampshire, Massachusetts, Connecticut, New York and New Jersey this past weekend. A state of emergency was declared in New Jersey by Gov. Phil Murphy following significant damage from flooding and landslides.
This follows last week’s relentless flooding in India, Japan, China, Turkey and the U.S.
Although the destructive floods are occurring in different parts of the world, atmospheric scientists say they have this in common: With climate change, storms are forming in a warmer atmosphere, making extreme rainfall a more frequent reality now. The additional warming that scientists predict is coming will only make it worse.
That’s because a warmer atmosphere holds more moisture, which results in storms dumping more precipitation that can have deadly outcomes. Pollutants, especially carbon dioxide and methane, are heating up the atmosphere. Instead of allowing heat to radiate away from Earth into space, they hold onto it.
While climate change is not the cause of storms unleashing the rainfall, these storms are forming in an atmosphere that is becoming warmer and wetter.
“Sixty-eight degrees Fahrenheit can hold twice as much water as 50 degrees Fahrenheit,” said Rodney Wynn, a meteorologist at the National Weather Service in Tampa Bay. “Warm air expands and cool air contracts. You can think of it as a balloon — when it’s heated the volume is going to get larger, so therefore it can hold more moisture.”
For every 1 degree Celsius (1.8 degrees Fahrenheit) that the atmosphere warms, it holds approximately 7% more moisture. According to NASA, the average global temperature has increased by at least 1.1 degrees Celsius (1.9 degrees Fahrenheit) since 1880.
“When a thunderstorm develops, water vapor gets condensed into rain droplets and falls back down to the surface. So as these storms form in warmer environments that have more moisture in them, the rainfall increases,” explained Brian Soden, professor of atmospheric sciences at the University of Miami.
Along Turkey’s mountainous and scenic Black Sea coast, heavy rains swelled rivers and damaged cities with flooding and landslides.
At least 15 people were killed by flooding in another mountainous region, in southwestern China.
“As the climate gets warmer we expect intense rain events to become more common, it’s a very robust prediction of climate models,” Soden added. “It’s not surprising to see these events happening, it’s what models have been predicting ever since day one.”