Extreme Rainfall Has Been Underestimated, Much More to Come

Extreme Rainfall Has Been Underestimated, Much More to Come

It’s clear to climate scientists that global warming increases rainfall because hot air can store more water vapor, making rain more common and intense. Still, the world is seeing even more rain than predicted. Last year, record-breaking rainfall hit Europe, China, Sudan, and the Northeastern US. Researchers thought this extreme weather would occur much later in the century, but a new study found that a number of climate models have been underestimating the amount of precipitation caused by global warming.The study was able to produce a more accurate result by prioritizing precipitation efficiency, which shows how much of a raindrop evaporates as it falls to the earth’s surface. When taking precipitation efficiency into account, the study also found that the volume extreme rainfall in the 21st century could double what previous studies had proposed.

Another study from UCLA also showed that extreme rainfall will occur much more frequently than initially predicted and is directly linked to greenhouse gas emissions.

Museum of Science, Boston: Sensing Our Climate: Extreme Precipitation, March 3, 2022.

Stanford Woods Institute for the Environment: AI for climate change | Stanford researchers predict extreme precipitation with machine learning, August 10, 2021.

Guardian: Climate change is making floods worse - here's how, October 19, 2021.

Why This Matters

Extreme rainfall can be incredibly dangerous. Last year, the death toll in Zhengzhou, China was nearly 400 people. Some, including Liu Junyan of Greenpeace East Asia, called the events a “wake-up call” for the nation. But already, heavy rainfall and subsequent landslides since this May has killed dozens, displaced millions, and caused economic losses costing the equivalent to hundreds of billions of dollars.

China is not alone. According to one study, nearly a quarter of the global population, the vast majority in low- and middle-income countries, are at risk of experiencing a severe flood. Also at risk of severe flooding is $9.8 trillion worth of economic activity and cities’ infrastructures that can take years to fix. Hurricane Ida, which displaced tens of thousands of people, was the single most expensive disaster last year at an estimated $65 billion.

Ironically, droughts are yet another outcome of changing precipitation patterns. Where some places are getting too much rain, places like Chile and the Western US are getting almost none. Instead, they’re seeing record-breaking droughts, wildfires, and heatwaves.

CBC: Millions displaced as India, Bangladesh see worst flooding in decades, June 23, 2022.

CNN: See the severe flooding that shut down Yellowstone National Park, June 14, 2022.

Preparing Cities For Heavy Rain

Though rainfall predictions look dire, cities can improve infrastructure in preparation of flooding. New York City, for example, has considered putting curbs at subway entrances to keep water from flowing in, and building canals to drain tunnels that flood. Meanwhile, Boston successfully installed flood barriers near a T station at the downtown waterfront, which prevented it from flooding. Cities can also pursue nature-based solutions, like planting orbital forests around the perimeter of a city to help absorb rainfall.

In the US, states can use funds provided by the bipartisan infrastructure bill to shore up their defense against climate change, and the ever-increasing threat of extreme weather.

ABC: Rainfall from climate change could affect economic growth | Study, January 12, 2022.

PBS: Europe and China endure extreme weather from heat and floods, July 17, 2022.

ABC10: How atmospheric rivers are becoming more dangerous due to climate change, December 9, 2020.

DW: Extreme weather, rising sea levels, devastating floods | The global climate crisis (Documentary), October 5, 2021.