Human-caused climate change was the driving force behind Hurricane Maria’s devastating and deadly precipitation, a new study finds.
Maria hit Puerto Rico on September 20, 2017 as a super-hurricane with 155-mile-per-hour winds. The record-breaking storm caused more than $90 billion in damage, with independent fatality estimates ranging from 2,975 deaths to “more than 5,000.”
The authors of the new Geophysical Research Letters study concluded that a Maria-level hurricane “is nearly five times more likely to form now than during the 1950s, an increase due largely to the effects of human-induced warming.”
How does global warming drive extreme deluges? As lead author David Keellings explained, it’s the combination of key long-term changes in the climate “like the atmosphere getting warmer, sea surface temperatures increasing, and more moisture being available in the atmosphere.”
These findings, along with similar studies on how climate change worsened Hurricane Harvey, underscore the warning issued by many scientists regarding the impact of Maria and other super-hurricanes: Global warming is fueling these increasingly intense and destructive storms.
“This study reaffirms what many of us have already concluded, namely that climate change has worsened the impacts of devastating recent hurricanes like Maria,” climatologist Michael Mann told Think Progress in an email. “As this study demonstrates, warmer oceans were responsible for the extreme rainfall and flooding Puerto Rico experienced. I would add that near record warm ocean temperatures also played a role in the rapid intensification of the storm into a category five monster.”
For this latest study, researchers looked at precipitation data from 35 historical weather stations for the 129 hurricanes that hit the island since 1956, which was the earliest year with dependable records.
They concluded that Maria generated the highest maximum daily rainfall for the island among those 129 storms — a stunning 1,029 millimeters (41 inches). The next closest hurricane in the historical record was 774.9 mm (30.5 inches), a full 10 inches less.
The authors then used a statistical analysis “that accounts for natural climate variability and long‐term climate change influences on extreme rainfall” to determine the influence human-caused climate change had on the rainfall.
They found a nearly five-fold increase in the chances of such an extreme deluge in 2017 compared to 1956, primarily because of climate change.
The United States clearly needs to be prepared for more Harveys and Marias, due to the warming that’s already occurred. But these super-storms and their deluges will just keep getting more and more intense in the coming decades until we slash emissions deeply enough to slow and then stop human-caused global warming.