Projected California Warming Creates Cycle of More Heat Waves, Energy Use for 21st
July 10, 2008
Major cities in California can expect more frequent extreme-heat events caused by
As the 21st century progresses, major cities in heavily air-conditioned California can expect
more frequent extreme-heat events caused by climate change.
This could mean increased demand for electricity in the densely-populated state which
may increase the risk of power shortages during heat waves, said Katharine Hayhoe,
a climate researcher in the Department of Geosciences at Texas Tech University who
co-authored the report with researchers from the University of California, Berkeley.
If additional electricity were generated through fossil fuels, this could mean even
more emissions of heat-trapping gasses that cause climate change.
"Risk of electricity shortages can be reduced through energy conservation as well
as through reducing our emissions of heat-trapping gasses in order to limit the amount
of future climate change that can be expected," Hayhoe said.
The results were published in the online version of the Journal of Applied Meteorology and Climatology. Researchers used climate projections from three atmosphere-ocean general circulation
models to assess projected increases in temperature extremes and day-to-day variability.
Before the end of the century, increases in extreme heat days could range from approximately
twice the present-day number for inland California cities such as Sacramento and Fresno,
to up to four times the number for previously temperate coastal cities such as Los
Angeles and San Diego.
"Electricity demand from industrial and home space cooling already increases as a
near linear response to outdoor temperatures," said Max Auffhammer, an assistant professor
of agriculture and resource economics at the University of California, Berkeley. "With
widespread increase in extreme heat days across the Western U.S., the electricity
grid could be further strained and brownouts and rolling blackouts may become more
This year, California experienced an unusually early heat wave in May that set 119
new daily high temperature records. On May 19, Death Valley set a record for the earliest
day to reach 120 degrees, breaking the May 25, 1913, record. Now in its second heat
wave this summer, record high temperatures have been broken for several more California
cities in recent days.
"In the future, the state should brace for summers dominated by the heat-wave conditions,
such as those experienced this year," said Norman Miller, lead author of the study
and a climate scientist at Lawrence Berkeley National Laboratory. "Extreme heat and
heat-wave events have already triggered major electricity shortages like those seen
in the summer of 2006. Given past events, the results of this study suggest that future
increases in peak electricity demand may challenge the current and future electricity
supply and transmission capacities."
When the projected extreme heat and observed relationships between high temperature
and electricity demand for California are mapped onto current availability, the researchers
discovered a potential for electricity deficits as high as 17 percent during peak
electricity demand periods.
Similar increases in extreme-heat days are likely for other urban centers in Arizona,
New Mexico and Texas, as well as for large cities in developing nations with rapidly
increasing electricity demands.
Hayhoe and Miller also contributed to the Nobel Prize-winning United Nations Intergovernmental
Panel on Climate Change.
For a PDF copy of the report, please contact John Davis at Texas Tech University.
CONTACT: Katharine Hayhoe, associate professor, Department of Geosciences, Texas Tech
University, (806) 392-1900, or email@example.com. Norman Miller, climate scientist, Earth Sciences Division, Lawrence Berkeley National
Laboratory, (510) 495-2374 or NLMiller@lbl.gov.