How does climate change influence extreme weather? Impact attribution research seeks answers

Abstract

Hurricane Harvey devastated the Houston area when it stalled over southeastern Texas in August 2017. In the weeks that followed, Hurricane Irma traveled up the mainland of Florida, and Hurricane Maria pummeled Puerto Rico. The year 2017 would become the most expensive hurricane season on record. Hurricanes Irma, Jose, and Katia, seen here moving across the Caribbean Sea and Atlantic Ocean, were three of the many hurricanes that made 2017 a record year. Impact attribution research is attempting to tease out when and to what degree climate change has exacerbated such extreme events. Image courtesy of Shutterstock/lavizzara. For decades, climate researchers using computer models have predicted that the warming ocean and atmosphere would likely increase the intensity of such natural disasters. More recently, though, high-resolution datasets and more sophisticated models have allowed researchers to find the fingerprint of climate change in individual weather events. Such analyses are exceedingly tricky, and not all experts the field agree on the best approach. But in recent years, a growing subfield of “attribution” research has produced results that are increasingly compelling—and increasingly concerning . Such work not only investigates the causes of past events but could potentially help improve forecasting for future ones. One study published in Harvey's aftermath suggests climate change likely boosted the hurricane's rainfall by 20 to 40% (1). To reach that figure, the researchers compared observed precipitation levels with those predicted by a computer model that simulated the hurricane using greenhouse gas levels from more than 60 years ago. Another analysis that pooled results from six different climate models estimated that Harvey-level rainfall was a 1-in-2,000-years event at the end of the 20th century, but by the end of the 21st century that likelihood will be 1 in 100 years (2). In May, a National Science Foundation-funded study estimated that …