Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

U.S. Southwest Expected to Dry Further as Climate Warms

26.01.2010
Based on a study of seasonal rainfall variations in the desert Southwest between 56,000 and 11,000 years ago as recorded in cave stalagmites, geoscientist Stephen Burns of the University of Massachusetts Amherst, with colleagues at the University of New Mexico, suggest the rapidly growing Southwest could become even more arid as global temperatures rise. Their findings are published in this week’s Nature Geosciences and are corroborated by another study presented in the same issue.

Burns is an expert in reading past climate data from the ratio of oxygen isotopes found in calcite, in speleothems—stalagmites, stalactites and other water-deposited cave features. The ratios indicate seasonal precipitation levels. Burns says data from this study covering approximately 45,000 years agree with modern evidence that the polar jet stream shifts northward in response to climate warming. Further, when the polar jet stream retreats toward the pole, winter precipitation in the Southwest decreases, reducing recharge to underground aquifers.

“We believe this cycle is controlled by the position of the polar jet stream, and that lower moisture levels reach the Southwest from the Pacific Ocean when the climate overall is warmer. Likewise, in periods when the Northern hemisphere’s climate is cooler, the polar jet stream sinks southward and winter rains increase in the desert Southwest, probably in response to advancing glaciers in Northern latitudes,” he says.

Speleothem records collected by Burns and colleagues in New Mexico for this National Science Foundation-supported study are among the first long, high-resolution records of rainfall ever collected for the region.

For such studies, the researchers collect speleothems, in this case stalagmite slices a few inches long from a cave in New Mexico. Speleothems are formed over tens of thousands of years by water seeping through cracks in bedrock and dissolving calcite and aragonite. Depending on temperature, carbon dioxide level and other cave factors, these mineral deposits can precipitate out as stalagmites, stalactites, ribbons, domes or straws.

Analysis of radioactive isotopes and stable oxygen isotopes in the calcite indicate past rainfall over many centuries. “We then try to determine what caused the observed variations at various timescales, from just a few years up to tens of thousands,” Burns says. For the current work, they compared the record with baseline data from Greenland ice cores and with speleothem data from a cave in China, halfway around the world. “This helps to show that the pattern extends across the entire Northern hemisphere,” says Burns.

This relatively new method of oxygen isotope analysis from calcite sampled from ancient speleothems is practiced by only a few research teams worldwide, but it offers more chronological control and is more precise than previous methods that used lake bed sediment records. However, some have questioned its reproducibility, Burns acknowledges. That’s why it was a very pleasant surprise when he and colleagues learned that without any prearrangement between research teams, another team is reporting very similar conclusions in the same journal issue this week, based on speleothem data from a different cave in the Southwest, but using a different laboratory for isotope analyses.

This coincidental but key validation by a completely separate investigating team should go a long way to answer doubts about the reproducibility of climate records from speleothem analysis, says Burns. “Results from our two groups reproduce each other incredibly well, which is a quite exciting and satisfying validation of the overall method.”

Stephen Burns
413-545-0142
sburns@geo.umass.edu

Stephen Burns | Newswise Science News
Further information:
http://www.umass.edu

Further reports about: Burns Climate change Dry Northern hemisphere Pacific Ocean Southwest Warms oxygen isotope

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>