Climate Change: Strengthening Atmospheric Rivers

Posted at 7:28 AM, Sep 19, 2019
and last updated 2019-09-21 15:14:56-04

SAN DIEGO (KGTV) -- Ahead of the United Nations Climate Summit next week, 10News is diving deeper into the affects of climate change.

Climate change is leading to more dangerous and deadly wildfires and so often after fires scorch the ground in the fall, the heavy winter rains in atmospheric rivers lead to mudslides and flooding.

The scary reality is that these types of storms are going to get stronger. According to Alexander Gershunov, a research meteorologist at the Scripps Institution of Oceanography at UCSD, "we know for certain that atmospheric rivers are going to get stronger in the future, in a warmer atmosphere more water vapor can be held so atmospheric rivers are basically plumes of very intense concentrated moisture and they're just going to get wetter as they get warmer. As those wetter atmospheric rivers hit the coast and coastal mountain ranges the moisture is squeezed out of them and we get more extreme precipitation events."

He goes on to say, "climate change is definitely making atmospheric rivers warmer and wetter as well as longer and fatter so they carry more moisture. In the future they will produce even more of the precipitation extremes and be an even bigger contributor to the water resources of the region as well as to flooding."

Climate change may lead to a more devastating threat, called the ARkStorm.

The ARkStorm is patterned after the historic flooding of 1861 to 1862, but uses modern modeling methods and data from large storms in 1969 and 1986. The ARkStorm draws heat and moisture from the tropical pacific, forming a series of atmospheric rivers that approach hurricane-strength and then slam the west coast creating a statewide disaster.

In 2010, scientific experts met to create the ARkStorm Scenario Report for the USGS, imagining aspects of flooding of biblical proportions reaching the Western U.S. with weeks of rain and snow followed by catastrophic floods, landslides and property and infrastructure damage which would cripple California's economy.

-- A growing wildfire season
-- Sea-level rise and the impacts to San Diego
-- Living in a warming world

"What was found that the cost could exceed $800 billion. To put that into perspective, the economy of California is $2.7 trillion so that’s almost a third of our state product," explained Tom Corringham, a post-doctoral research economist at the Scripps Institution of Oceanography at UCSD.

Move these flooding models yourself: click here.

Models in the ARkStorm report show multiple areas of submergence in central San Diego. Mission Beach, which routinely sees flooding during heavy rain, is underwater in the ARkStorm scenario. Fiesta island, ordinarily dry, disappears under Mission Bay.

West-facing beaches, including those near Highway 1 in north county, are covered in water and Imperial beach fares no better in its known run-off spots.

"The ARkStorm scenario isn’t too far-fetched and it becomes increasingly possible with the effects of climate change." Says Tom Corringham.

The timing of the next ARkStorm is uncertain, according to the National Weather Service, it could be next year, or it could be 120 years from now.