(Reuters) - Los Angeles County, the second largest U.S. metropolitan area, could see its number of extremely hot days soar during the second half of this century if greenhouse gas emissions, linked to climate change, are not reined in, a study says.
Researchers at the University of California at Los Angeles found that except in the highest mountains and a narrow swath of the Pacific coastline, the Los Angeles region could expect 60 to 90 additional days a year of 95-F (35-C) temperatures and above by the end of the century. The region's average was about 12 such days a year between 1981 and 2000.
"Thus most land areas will effectively experience a new season of extreme heat," said the study, published this week in the Journal of Climate.
Using simulations of projected global greenhouse gas emissions over the coming decades, the study found downtown Los Angeles would experience a dozen or so more extremely hot days by 2050, roughly tripling from the average of about 4 days a year in 2000.
If greenhouse gas emissions continue at a projected upward trend, by the end of the century downtown Los Angeles will see 54 extremely hot days each year. Desert areas could see their total annual number of extreme heat days double, the study said.
Cold days, or days that reach below freezing, will also be reduced by half in the county's surrounding mountains, the study found.
The scientists, researchers at UCLA's Department of Atmospheric and Oceanic Sciences, said the projection improved if greenhouse gas emissions were significantly reduced over coming decades.
"Future daily temperatures will be roughly 80 percent similar to those experienced during the baseline period," the study found. The baseline period is 1981 to 2000.
The researchers said they focused on three time periods to calculate the projected temperature increases, starting with the baseline period of 1981 to 2000, the mid-century of 2041 to 2060, and end-of-century from 2081 to 2100.
Reporting by Victoria Cavaliere in Seattle; Editing by Peter Cooney