Climate researchers Alexander Gershunov and Kristen Guirguis, with the Scripps Institution of Oceanography, UC San Diego, 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 be published in Geophysical Research Letters, a publication of the American Geophysical Union.
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."Notes for Journalists
number.Neither the paper nor this press release are under embargo.
California San Diego, USA.Contact information for the authors:
Novel method for investigating pore geometry in rocks
17.06.2018 | Kyushu University, I2CNER
Decades of satellite monitoring reveal Antarctic ice loss
14.06.2018 | University of Maryland
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.
From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
18.06.2018 | Materials Sciences
18.06.2018 | Physics and Astronomy
15.06.2018 | Materials Sciences