Dec. 14 (UPI) -- New research suggests global warming was responsible for 15 percent of Hurricane Harvey's rainfall totals -- climate change boosted the storm's size and strength.
"Harvey was more intense because of today's climate, and storms like Harvey are more likely in today's climate," Antonia Sebastian, a postdoctoral research associate with Rice University's Severe Storm Prediction, Education and Evacuation from Disasters Center, said in a news release.
Until recently, scientists agreed a warmer climate was likely to encourage extreme weather and larger storms, but were most unwilling or unable to assign blame for specific storms and weather events. That's beginning to change, with improved forecasting models and advanced statistical analysis.
For the latest study, Sebastian teamed up with researchers from the United States, England and the Netherlands. The scientists used both on-the-ground rainfall data and weather models to gauge the size and intensity of Hurricane Harvey.
Advanced statistical models, fueled by historical hurricane and global warming data, helped scientists tease out the impact of climate change on the storm's strength.
"This multimethod analysis, drawing upon both observed rainfall data and high-resolution climate models, confirms that heavy rainfall events are increasing substantially across the Gulf Coast region because of human interference with our climate system," said Geert Jan van Oldenborgh, senior researcher at the Royal Netherlands Meteorological Institute.
Hurricane Harvey dropped an average of 30 inches of rain across southeast Texas. In east Harris County, the third-most populous county in the United States, the Category 4 hurricane dropped 51.89 inches over six days -- the largest precipitation total in U.S. history.
The odds of such a massive storm hitting Houston were extremely slim. It was a one-in-9,000-year event, but the odds were slightly larger thanks to manmade global warming.
Researchers say the latest findings -- detailed this week in the journal Environmental Research Letters -- are proof cities and states need to update their flood maps and mitigation plans as the odds grow.
"These results make a clear case for why climate change information should be incorporated into any plans for future improvements to Houston's flood infrastructure," Sebastian said. "The past is no longer an accurate predictor of present or future flood-related risks."
Right now, the odds of another Harvey-sized storm hitting the Gulf Coast region are less than once in 100 years. But the odds go up as the climate warms. Even if emissions are curbed enough to limit warming to 3.6 degrees Fahrenheit -- the goal set by the Paris Agreement -- the odds of another Harvey will triple.
"If we miss those targets, the increase in frequency and intensity could be much higher," said Karin van der Wiel, a postdoctoral researcher at KNMI.