Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Droughts like 1930s Dust Bowl may have been unexceptional in prehistoric times

02.08.2004


Events like the great Dust Bowl of the 1930s, immortalized in "The Grapes of Wrath" and remembered as a transforming event for millions of Americans, were regular parts of much-earlier cycles of droughts followed by recoveries in the region, according to new studies by a multi-institutional research team led by Duke University.



Some of those prehistoric droughts in the northern Great Plains of what is now the United States also lasted longer than modern-day dry spells such as the 1930’s Dust Bowl decade, according to sediment core studies by the team.

The group’s evidence implies these ancient droughts persisted for up to several decades each. At their heights, prairie fires became uncommon because there was too little vegetation left to burn. The ages of charcoal deposits suggest instead that prairie fires occurred during intervening wet periods, with each wet-dry cycle lasting more than a century each.


A report on the research will be delivered at a session at 1:30 p.m. on Wednesday, Aug. 4, in Meeting Room D136 of the Oregon Convention Center during the Ecological Society of America’s 2004 annual meeting in Portland.

"We were looking for the effects of past climate changes on ecosystems," said Jim Clark, H.L. Blomquist Professor of Biology at Duke’s Nicholas School of the Environment and Earth Sciences. But when Clark and his colleagues began examining evidence from the mid-Holocene period of 5,000 to 8,000 years ago in parts of the Dakotas, Montana and western Minnesota, "nothing seemed to make any sense."

"The question was: Could we look at the sediments for charcoal evidence of the amount of fire, for pollen evidence of the kinds of grasses that were growing then, for sediment chemistry to show how much erosion was going on, and be able to deduce climate changes -- or the lack of them -- under way at the time?" Clark said.

When he and his colleagues finally determined the correct intervals between samplings was about once every decade, "the patterns just jumped right out at us," he recalled in an interview. "We were seeing these very coherent drought cycles.

"What would happen was that the grass would disappear. So the fuel for fire would be lost. We’d see the erosion start. The chemistry of the lakes would change. We would see these dust-bowl effects.

"And then, within several decades to a century later, the grasses would come back, fires would start back up and erosion would stop."

To make these deductions, Duke post-doctoral investigator Kendrick Brown evaluated prehistoric charcoal deposits. Joe Donovan, a geophysicist at the University of West Virginia, studied the geochemistry of the soil samples. Eric Grimm and Pietra Mueller of the Illinois State Museum in Springfield investigated pollen in the sediments.

The regularity of these ancient droughts make much more recent Great Plains droughts in the 1890s and 1930s appear "unremarkable" by comparison, Clark said, even though the contemporary ones "walloped people."

The study did not speculate how the findings might relate to anticipated future climate change, when a surge of carbon dioxide from human activities is predicted to cause Earth’s climate to warm appreciably.

"What we can say that is relevant is that these sort of drought cycles are common and most of the climate models predict increased aridity in continental interiors in the future," Clark said.

"One could speculate that the droughts could be all that much worse when you realize that it’s not only climate change from changing CO2 content in the atmosphere, but also this natural variability out there that we don’t fully understand."

Monte Basgall | EurekAlert!
Further information:
http://www.duke.edu

More articles from Ecology, The Environment and Conservation:

nachricht International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>