Weather 101Weather 101Weather 101 is a Mashable series that answers leading and provocative questions about the global warming climate.
A deadly flood in China recently trapped passengers on a subway train with water crawling up their necks. In fact, in our planet in continuous warming the the rains are getting more and more extreme, the most devastating floods.
Atmospheric scientists know why. When the air temperature is warmer, the atmosphere can naturally contain more water vapor (heat causes water molecules to evaporate into water vapor), which means there is more water in the air, especially in many humid or rainy regions. Consequently, this increases the chances of powerful storms such as thunderstorms, mid-latitude cyclones, atmospheric rivers, or hurricanes flooding places with more water.
"Once you have more moisture in the air, you have a bigger bucket that you can empty," explained Andreas Prein, a scientist who investigates extreme weather events in the National Center for Atmospheric Research. As research shows, this can lead to heavy downpours. "It can release more water in a shorter period of time - there is very little question about that," Prein said.
Massive floods occur. The summer of 2021 is littered with vivid and sometimes jaw-dropping examples. Damaging and sometimes extremely deadly floods struck recently Europe, New York, India, porcelain, Detroit, and beyond.
Importantly, hot weather does not mean that it will always rain heavily. It means that strong storms are more likely to pick up additional water vapor in the atmosphere, resulting in these extreme deluges dropping many inches of rain in just a few hours.
"You're loading the dice," emphasized Brian Tang, an atmospheric scientist at the University of Albany. "It will increase the risk of a lot of rain in a short period of time."
For every 1.8 degrees Fahrenheit of warming (or one degree Celsius) the air remains about seven percent more water vapor. The earth has been warmed by just more than 2 degrees Fahrenheit since the late 1800s, resulting in significantly more juicy storms with more water. This is how urban areas, even with flood control infrastructure, can be overwhelmed by water. And sometimes storms stagnate over land, resulting in Massive and unprecedented flooding, such as during Hurricane Harvey's record rains.
No one expects the rains to subside. Of civilization The energy system is certainly going in a significantly cleaner direction., but the global economy is still largely dominated by fossil fuels that they emit powerful heat-trapping gases in the atmosphere, which means that the world they will almost certainly continue to heat up for a few decades, if not much further. Expect extreme or unusual flooding, particularly in places that receive heavy storms, such as the Northeast. (The amount of precipitation during the strongest rain events in the Northeast already increased by 71 percent between 1958 and 2012, and other regions of the US have also seen significant increases).
"Our best knowledge is that they will continue to increase," Tang said, referring to the heavy rains in the northeast. "Expect more heavy rain and more flash floods."
"You're loading the dice."
It is certainly true that flood protection infrastructure such as diversion canals (see the Los Angeles river), levees and reservoirs, can limit major flooding. But at some point, with intensified rains, there may be too much water to hold.
"You can only prepare for so much," Prein said. "It is really difficult to build an infrastructure that can keep up with those flood volumes."
That is the reality on a warming planet. When the rains come, the chances are increased that the water will soak the land in a severe, if not unprecedented way. It is one of the clearest consequences of a warmer world.
"What surprises me is seeing the rate of change," Prein said. "It is getting worse very fast, we are living in climate change now. You can see it all over the world."
