Texas Floods Signal El Niño, Climate Change

By Renee Lewis, Al Jazeera America

28 May 15

Scientists say ferocious storms that caused flooding in Texas and Oklahoma may just be the beginning of a very wet year

he storms that slammed into Texas and Oklahoma over Memorial Day weekend may signal the beginning of an El Niño year, but their unusual ferocity could be due to climate change, scientists said Wednesday.

Torrential rains and tornadoes killed at least 17 people in the Southwest, with the death toll expected to rise as authorities in Texas continue to search for about a dozen missing people. In Houston, the nation’s fourth-largest city, record flooding damaged an estimated 4,000 structures, including homes and businesses, and led to about 1,000 calls for help, according to city officials.

Texas Gov. Greg Abbott on Monday expanded a state of emergency, which had been declared earlier in the month due to severe weather to at least 40 counties. President Barack Obama responded by assuring Abbott that the federal government would assist in the state’s recovery.

Some of the worst hit areas of the Southwest have received more than 18 inches of rain since the beginning of May — six times greater than the area typically receives in all of May.

Scientists on Wednesday warned that the heavy rains might signal that 2015 will be an El Niño, a warm phase in the equatorial Pacific Ocean characterized by intense, often dangerous storms.

“It does seem to be at least linked to El Niño, because when you have El Niño generally speaking you will see a signal in the spring time — a wet signal in Texas and into Oklahoma,” Tom DiLiberto, a meteorologist at the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center, told Al Jazeera.

The Climate Prediction Center, which says an El Niño occurs approximately every two to seven years, has forecast an 80 percent chance that one will occur this year. If so, DiLiberto says, residents across the Southwest can expect intense weather.

“Basically what happens is you see a stronger southerly jet stream, and a storm track that brings more storms across the south with an increase in precipitation,” he said.

Although the causes and effects of El Niño are not yet fully understood by scientists, they do know that the weather phenomenon results from a coupling of oceanic and atmospheric conditions, DiLiberto added.

Though the ocean warming that causes El Niño may occur naturally, climate change – which can warm ocean temperature even further – could intensify storms, putting residents caught in their route in even greater danger, said Mark Crane, professor of Earth and Climate Sciences at Columbia University.

“One of the things that happens with climate change and is very clear is that oceans have all gotten warmer,” said Crane.

While El Niño and global warming may combine to direct severe storms towards the Southwest, the same weather phenomenon may bring relief to drought-stricken California, DiLiberto said.

“Usually with El Niño what you see is a wetter signal for California,” he said. “Just because we have El Niño doesn’t mean we will observe any specific weather condition, but generally speaking there’s a wetter tilt in the odds for the California range.”

Other potential impacts of El Niño years include fewer than usual Atlantic Ocean hurricanes, while hurricane numbers increase in the eastern Pacific Ocean, Crane said. 

“But you know Hurricane Andrew occurred in an El Niño year with below-average number of hurricanes, and it was a bad one,” Crane said, referring to a Category 5 hurricane that slammed into southern Florida in August 1992.