Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


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

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

Stephen Burns | Newswise Science News
Further information:

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

More articles from Earth Sciences:

nachricht UCI and NASA document accelerated glacier melting in West Antarctica
26.10.2016 | University of California - Irvine

nachricht Ice shelf vibrations cause unusual waves in Antarctic atmosphere
25.10.2016 | American Geophysical Union

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

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

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>