The Southland will routinely experience torrid heat starting later this century, raising concerns about the viability of its water supplies, according to a UCLA study released today.
According to the study, which forecasts weather patterns from 2041 to 2060, the number of days with temperatures above 95 will triple in downtown L.A. each year by the middle of the century, quadruple in parts of the San Fernando Valley and jump five-fold in a portion of the high desert in Los Angeles County.
The study is the first to model the Southland's complex geography of coastlines, mountain ranges and urban centers in high enough resolution to predict temperatures down to the level of micro climate zones, each 2 1/4 square miles.
Not only will the number of hot days increase, but the hottest of those days will break records, according to Alex Hall, lead researcher on the study by UCLA's Institute of the Environment and Sustainability. The record high for downtown is 113 degrees, set on Sept. 27, 2010.
"Every season of the year in every part of the county will be warmer," Hall said. "This study lays a foundation for the region to confront climate change. Now that we have real numbers, we can talk about adaptation."
The study, titled "Mid-Century Warming in the Los Angeles Region," raises concerns about the long-term sustainability of Los Angeles' water supplies, which are replenished by snow and water captured by local mountain chains.
Research on the effects of climate change on precipitation and groundwater will be released in the fall. A subsequent study on snowpack in the Sierra Nevada Mountains is scheduled for release in the summer of 2013.
Los Angeles Mayor Antonio Villaraigosa said the forecasts provide the groundwork for local governments, utilities, hospitals and other institutions to prepare for the hot spells to come.
The mayor touted the city's green-building standards, tree-planting program and increase of green and open space, which he said will also help the city adapt to climate change.
Villaraigosa instructed relevant city departments to prepare vulnerability and risk assessments based on the UCLA data.
The study - aided by a UCLA supercomputer able to produce climate models 2,500 times more precise than previous ones - was commissioned by the City of Los Angeles and paid for with $500,000 in U.S. Energy Department funds.