The destructive floods that ravaged parts of the United States in early April have been linked to climate change, according to a recent analysis. This flooding affected states such as Tennessee, Arkansas, and Kentucky from April 2 to 6, resulting in the deaths of at least 15 individuals. Simultaneously, a series of tornadoes swept through the southern Midwest and southeastern U.S., claiming the lives of at least 9 people.
A study conducted by World Weather Attribution (WWA) has shed light on the role of climate change in exacerbating these extreme weather events. The research suggests that human-induced climate change increased the probability of the flooding by approximately 40% and its intensity by about 9%. Despite these findings, scientists acknowledge the challenges in precisely quantifying human impact due to varying climate models, and the report notes that an effective emergency response helped mitigate further disaster.
The severe flooding was triggered by heavy rainfall when a high-pressure system over the East Coast and southeastern U.S. collided with a low-pressure system to the west. This stalling of weather systems resulted in persistent rainfall over the same region. Additionally, moisture was transported into the area by the jet stream from the eastern Pacific, along with surface moisture from the Gulf of Mexico.
Researchers analyzed historical data from the central Mississippi River valley alongside April’s rainfall data to assess climate change’s impact. The study found that increased sea surface temperatures and regional weather patterns contributed to heightened moisture levels. This is supported by evidence that rising global temperatures have led to greater evaporation rates in the Gulf of Mexico, thereby increasing moisture availability during the rains.
While understanding the extent of human influence on extreme weather remains complex, it is evident that activities such as burning fossil fuels contribute to global warming. The researchers noted that, with current warming levels, extreme rainfall events like April’s could occur every 90 to 240 years. However, these events would be significantly less frequent if the climate were cooler by 2.3 degrees Fahrenheit (1.3 degrees Celsius). According to the report, this degree of warming makes such events two to five times more likely, with a 13% to 26% increase in intensity.
In response to the climate crisis, world leaders signed the Paris Agreement in 2015, aiming to limit global temperature rise to below 2.7 F (1.5 C) and well below 3.6 F (2 C). Despite these efforts, recent data from the European Union’s Copernicus Climate Change Service indicates that April was the 21st month in the last 22 to exceed this 2.7 F limit.
The report’s authors caution that, without significant action, global temperatures could rise by 4.7 F (2.6 C) by the century’s end. Climate models predict that continued warming will lead to more frequent and intense rainfall events in certain regions. At these projected levels of warming, such extreme events are expected to double in frequency and increase in intensity by 7%.
Original Story at www.livescience.com