DEHESA, Calif. — Monsoonal moisture continues to cause flash flood warnings throughout San Diego County.

A new study warns California is due for a massive flood that could submerge cities. East County homeowner Richard Dinnen lived through the 1980 flood that submerged parts of San Diego County. 

“I was on the fire department at the time here in Dehesa and all day and all night—just pulling people and animals out of the water,” Dinnen said.

He has since added a retaining wall around his property to protect his home from similar floods.

“It washed the whole front of our property out,” Dinnen said.

Now, a new UCLA study warns that climate change is increasing our chances for “mega floods” that could displace millions of Californians and cause a trillion dollars in economic damage.

“Some of the things that come to us hold more water than several Mississippi rivers added together,” said San Diego State University Professor Emeritus of Geology Dr. Pat Abbott.

Scientists say climate change has doubled the likelihood of an extreme storm event. They say the risk of a mega storm increases with every additional degree of global warming. Scientists are calling it “the Other Big One.”

“Data show our Earth is warning and warmer air dries out to make droughts. Warmer air dries out to lead to more mega fires, but it also means warm air can hold more moisture and that more moisture can lead to floods that are ‘once in a century, once in a five century’ type floods become more common,” Abbott said.

Scientists say these “mega floods” could shut down major transportation corridors and displace five to ten million people.

“For officials in charge of facilities and predictions and the like, it’s time to gear up and explore the possibility of being prepared for something bigger,” Scripps Institution of Oceanography Marty Ralph said. 

Abbott also says as the world warms and the warmer air moves farther north, the San Diego area will be seeing more monsoonal conditions like it is seeing now and more frequent atmospheric rivers that could cause major floods.