Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Extreme summer temperatures occur more frequently

16.02.2012
Extreme summer temperatures are already occurring more frequently in the United States, and will become normal by mid-century if the world continues on a business as usual schedule of emitting greenhouse gases.

By analyzing observations and results obtained from climate models, a study led by Phil Duffy of the Lawrence Livermore National Laboratory showed that previously rare high summertime (June, July and August) temperatures are already occurring more frequently in some regions of the 48 contiguous United States.


The white colored rock (approximately 100 feet high) shows the drop in the water level of Lake Mead as a result of the ongoing 10-year drought along the Colorado River. Photo courtesy of Guy DeMeo , U.S. Geological Survey


The Vegetation Drought Response Index (VegDRI) incorporates satellite observations of vegetation to monitor at a finer spatial detail than other commonly used drought indicators. Photo courtesy of U.S. Geological Survey

"The observed increase in the frequency of previously rare summertime-average temperatures is more consistent with the consequences of increasing greenhouse gas concentrations than with the effects of natural climate variability," said Duffy, who is the lead author of a report in a recent edition of the journal, Climatic Change. "It is extremely unlikely that the observed increase has happened through chance alone."

The geographical patterns of increases in extreme summer temperatures that appear in observations are consistent with those that are seen in climate model simulations of the 20th century, Duffy said.

Duffy and colleague Claudia Tebaldi, a senior scientist at the nonprofit news and research group Climate Central, showed that the models project that previously rare summer temperatures will occur in well more than 50 percent of summers by mid-century throughout the lower 48 states.

The team first compared the period 1975-2000 to the preceding 25 years, and found that both observations and results based on 16 global climate models show that summertime-average temperatures that were rare in the earlier period occurred more often in the later period, in certain regions. The agreement between observations and models demonstrates that the models are able to simulate changes in the occurrence of extreme summertime temperatures, Duffy said.

Duffy and Tebaldi performed a statistical analysis showing that the increases in rare summer temperatures seen in the later period are very unlikely to have occurred through chance weather variations.

Next, Duffy and Tebaldi assessed the present period, by using results obtained from climate models for 1995-2024; they found that summer temperatures that were extreme during 1950-1979 occur more often in the later time period. This supports the conclusion that extreme summertime temperatures are already occurring more frequently in parts of the lower 48 states. A second statistical analysis showed that this increase also is very unlikely to be due to chance weather variations alone, such as El Ninos or La Ninas.

Finally, the team evaluated model results for 2035-2064 (representing the middle of this century) and found that extreme summertime temperatures that were rare during 1950-1979 are projected to occur in most summers throughout the 48-state region in the mid-century period. For the mid-century, summertime mean temperatures that historically occurred only 5 percent of the time are projected to occur at least 70 percent to the time everywhere in the 48 state region.

"The South, Southwest and Northeast are projected to experience the largest increases in the frequency of unusually hot summers," Duffy said. "The strong increase in extremes in the Southwest and Northeast are explained by strong historical and projected warming there. This result is based upon assuming a commonly used scenario for future emissions of carbon dioxide, the main driver of human-caused climate change.

"What was historically a one in 20-year occurrence will occur with at least a 70 percent chance every year. This work shows an example of how climate change can affect weather extremes, as well as averages."

More Information

"Increasing prevalence of extreme summer temperatures in the U.S.," Climatic Change.

"Strengthening our understanding of climate change," Science & Technology Review, December 2010.

"Livermore Scientists Create Highest Resolution Global Climate Simulations To Date Using Supercomputers," LLNL news release, July 9, 2002.

Founded in 1952, Lawrence Livermore National Laboratory provides solutions to our nation's most important national security challenges through innovative science, engineering and technology. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.

Anne Stark | EurekAlert!
Further information:
http://www.llnl.gov

More articles from Earth Sciences:

nachricht New Measurement Device: Carbon Dioxide As Geothermometer
21.05.2019 | Universität Heidelberg

nachricht Cause for variability in Arctic sea ice clarified
14.05.2019 | Max-Planck-Institut für Meteorologie

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

Im Focus: A step towards probabilistic computing

Working group led by physicist Professor Ulrich Nowak at the University of Konstanz, in collaboration with a team of physicists from Johannes Gutenberg University Mainz, demonstrates how skyrmions can be used for the computer concepts of the future

When it comes to performing a calculation destined to arrive at an exact result, humans are hopelessly inferior to the computer. In other areas, humans are...

Im Focus: Recording embryonic development

Scientists develop a molecular recording tool that enables in vivo lineage tracing of embryonic cells

The beginning of new life starts with a fascinating process: A single cell gives rise to progenitor cells that eventually differentiate into the three germ...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Summit charts a course to uncover the origins of genetic diseases

22.05.2019 | Life Sciences

New study finds distinct microbes living next to corals

22.05.2019 | Life Sciences

Stellar waltz with dramatic ending

22.05.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>