Featured Research

from universities, journals, and other organizations

California heatwaves to move toward coastal areas: Researchers reassess heatwaves against the backdrop of rising temperatures

Date:
August 29, 2012
Source:
University of California - San Diego
Summary:
A new study suggests that the nature of California heatwaves is changing due to global warming. Climate researchers have detected a trend toward more humid heatwaves that are expressed very strongly in elevated nighttime temperatures, a trend consistent with climate change projections. Moreover, relative to local warming, the mid-summer heatwaves are getting stronger in generally cooler coastal areas.

Climate researchers have detected a trend toward more humid heatwaves that are expressed very strongly in elevated nighttime temperatures, a trend consistent with climate change projections. Moreover, relative to local warming, the mid-summer heatwaves are getting stronger in generally cooler coastal areas.
Credit: Rafael Ben-Ari / Fotolia

A new study by researchers at Scripps Institution of Oceanography, UC San Diego, suggests that the nature of California heatwaves is changing due to global warming.

Climate researchers Alexander Gershunov and Kristen Guirguis detected a trend toward more humid heatwaves that are expressed very strongly in elevated nighttime temperatures, a trend consistent with climate change projections. Moreover, relative to local warming, the mid-summer heatwaves are getting stronger in generally cooler coastal areas. This carries implications for the millions of Californians living near the ocean whose everyday lives are acclimated to moderate temperatures.

"Heatwaves are stressful rare extremes defined relative to average temperatures," said Gershunov. "We've known for a while that humid heatwaves that are particularly hot at night are on the rise in California as the climate warms. Here, we sharpen the geographic focus to consider sub-regions of the state."

Gershunov added that in this new sharper and "non-stationary" perspective, coastal heatwaves express much more intensely than those inland where the summertime mean warming is stronger. This translates to a variety of impacts on the typically cool, un-acclimated coast.

Classic California heatwaves have been characterized as interior desert and valley events that are hot during the day and marked by dryness and strong nighttime cooling. Gershunov and Guirguis said their analysis of observations and computer model data indicates that the emerging flavor of heatwaves marked by greater humidity, greater expression in nighttime temperatures, and greater expression in coastal areas relative to the generally cooler coast are intensifying and will keep intensifying in coming decades. Both coastal and desert heatwaves will continue to be more common as climate changes relative to the past, but the desert heatwaves are becoming less intense relative to strong average warming observed and projected for the interior of the state.

The study, "California heat waves in the present and future," will appear in the American Geophysical Union journal Geophysical Research Letters.

The "non-stationary" approach reflects an acknowledgment by scientists that what has been considered extreme heat is gradually becoming commonplace. The rate of climate warming necessitates a measure of extreme heat relative to the changing average climate rather than to historical climate norms. So, instead of defining heatwaves relative to fixed temperature thresholds, the researchers projected heatwave intensity against a backdrop of increasing average summertime temperature. This causes the definition of heatwaves -- temperatures in the warmest 5 percent of summertime conditions -- to evolve with the changing climate and reflect extreme conditions relevant to the climate of the time.

"The advantage of using this evolving 'non-stationary' definition is that heatwaves remain extreme events even under much warmer climate," said Gershunov. "If they change in this evolving framework, it's because the variance of temperature is changing, not just the average."

The authors point out that the trend could precipitate a variety of changes in California's coastal communities, where stronger heat will lead to the installation of air conditioners in homes traditionally not in need of cooling. This lifestyle trend would in turn affect energy demand in coastal areas, its magnitude and timing. In the absence of technological or physiological acclimatization, high humidity and the lingering of heat through the night is expected to have strong public health implications, placing added stress on many of the more than 21 million Californians who live in coastal counties. The same would be true for animals and plants living in the highly populated and diverse coastal zone.

"This trend has important human health implications for coastal California where most of the state's population lives," said Guirguis. "Coastal communities are acclimated to cooler mean temperatures and are not well prepared for extreme heat either physiologically or technologically through air conditioning use. Populations tend to adapt to changes in their average conditions but extreme events can catch people off guard. An increase in heat wave intensity relative to average conditions could mean much more heat-related illness during heat waves unless effective heat emergency plans are implemented."


Story Source:

The above story is based on materials provided by University of California - San Diego. Note: Materials may be edited for content and length.


Journal Reference:

  1. Alexander Gershunov, Kristen Guirguis. California heat waves in the present and future. Geophysical Research Letters, 2012; DOI: 10.1029/2012GL052979

Cite This Page:

University of California - San Diego. "California heatwaves to move toward coastal areas: Researchers reassess heatwaves against the backdrop of rising temperatures." ScienceDaily. ScienceDaily, 29 August 2012. <www.sciencedaily.com/releases/2012/08/120829151243.htm>.
University of California - San Diego. (2012, August 29). California heatwaves to move toward coastal areas: Researchers reassess heatwaves against the backdrop of rising temperatures. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2012/08/120829151243.htm
University of California - San Diego. "California heatwaves to move toward coastal areas: Researchers reassess heatwaves against the backdrop of rising temperatures." ScienceDaily. www.sciencedaily.com/releases/2012/08/120829151243.htm (accessed September 1, 2014).

Share This




More Earth & Climate News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Lightning Hurts 3 on NYC Beach

Lightning Hurts 3 on NYC Beach

AP (Sep. 1, 2014) A lightning strike injured three people on a New York City beach on Sunday. The storms also delayed flights and interrupted play at the US Open tennis tournament. (Sept. 1) Video provided by AP
Powered by NewsLook.com
Thailand Totters Towards Waste Crisis

Thailand Totters Towards Waste Crisis

AFP (Sep. 1, 2014) Fears are mounting in Bangkok that poor planning and lax law enforcement are tipping Thailand towards a waste crisis. Duration: 01:21 Video provided by AFP
Powered by NewsLook.com
Washington Wildlife Center Goes Nuts Over Baby Squirrels

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Reuters - US Online Video (Aug. 30, 2014) An animal rescue in Washington state receives an influx of orphaned squirrels, keeping workers busy as they nurse them back to health. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Raw: Volcano Erupts on Papua New Guinea

Raw: Volcano Erupts on Papua New Guinea

AP (Aug. 29, 2014) Several communities were evacuated and some international flights were diverted on Friday after one of the most active volcanos in the region erupts. (Aug. 29) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins