A new study has revealed that climate change intensified floods in several U.S. States at the start of April.
Between April 2-6, at least 15 people died from the floods that devastated Tennessee, Arkansas, and Kentucky. At least nine people were killed by multiple tornadoes in the southern Midwest, as well as parts of the southeast U.S.
Researchers have now studied the role climate change could have played in historic floods and extreme weather. According to World Weather Attribution, which examines how climate changes influence extreme weather events, they estimated that climate change caused by humans increased flooding’s likelihood by 40% and their intensity by 9%.
Scientists are still unable to accurately quantify the impact of human activity on weather patterns around the world. The researchers’ estimates, they noted, were conservative because there was a discrepancy between climate models. A report highlighted the fact that an emergency response could have prevented a larger disaster.
Extreme rainfall was the cause of historic flooding. The rains were caused by a clash between a system of high pressure over the East Coast, southeastern U.S., and one to the west. As the boundary between the two systems was stalled the rain kept falling in the same place. The jet stream brought moisture from the east Pacific, while surface moisture from the Gulf of Mexico was also carried into the area.
Researchers analyzed rainfall data for April and historical data on the Mississippi River Valley to estimate how climate change affected the intensity and likelihood of flooding. According to the study, the team discovered that regional weather patterns and increased sea surface temperatures contributed to more water being available during rainstorms.
The report, for example highlighted climate change as a factor in increased humidity coming from the Gulf of Mexico. Global warming is increasing sea surface temperatures. The team discovered that the higher temperatures caused a higher rate of evaporation within the Gulf of Mexico. This increased the moisture in the U.S. when rains came.
Scientists still aren’t sure how much human activity is responsible for extreme weather events, but we know that burning fossil fuels has caused the earth to warm. The researchers looked only at the overall climate warming and concluded that extreme rain events like those in April are expected to happen every 90-240 years. However, it would be rarer if temperatures were just 2.3 degrees Fahrenheit (1.33 degrees Celsius). According to the estimates, this amount of global warming increased the likelihood that an event like the one in April would occur between 2 and 5 times. It also caused it to be more intense by 13% to 26 %.
The Paris Agreement was signed by world leaders in 2015. It is an international treaty which promises to keep global warming below 2.7 F and ideally below 3.6 F. Earth has consistently exceeded that goal, and April was the 21st month in the past 22 to exceed the preferred limit of 2.7 F, according to European Union’s Copernicus Climate Change Service.
Authors of the report warn that the world is heading towards 4.7 F (2,6 C) by end of century. As the climate continues to heat up, models suggest that rainfall extremes will increase in some regions.
According to the report, at those temperatures, extreme rain events are likely to double in frequency, and become 7% stronger.
Patrick Pester, the writer of Live Science’s trending news stories. He has also published his work on BBC Science Focus, Scientific American and other websites. Patrick returned to journalism after a career in wildlife conservation and zoos. The Master’s Excellence Scholarship allowed him to complete a Master’s Degree in International Journalism at Cardiff University. His second degree is in conservation, biodiversity and evolution in action. It was earned at Middlesex University London. Patrick is a journalist who investigates human remains when he’s not writing.
