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 Plant seeds survive machine washing - Dispersal of invasive plants with clothes
11.09.2018 | Gesellschaft für Ökologie e.V.

nachricht Air pollution leads to cardiovascular diseases
21.08.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz

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: Storage & Transport of highly volatile Gases made safer & cheaper by the use of “Kinetic Trapping"

Augsburg chemists present a new technology for compressing, storing and transporting highly volatile gases in porous frameworks/New prospects for gas-powered vehicles

Storage of highly volatile gases has always been a major technological challenge, not least for use in the automotive sector, for, for example, methane or...

Im Focus: Disrupting crystalline order to restore superfluidity

When we put water in a freezer, water molecules crystallize and form ice. This change from one phase of matter to another is called a phase transition. While this transition, and countless others that occur in nature, typically takes place at the same fixed conditions, such as the freezing point, one can ask how it can be influenced in a controlled way.

We are all familiar with such control of the freezing transition, as it is an essential ingredient in the art of making a sorbet or a slushy. To make a cold...

Im Focus: Micro energy harvesters for the Internet of Things

Fraunhofer IWS Dresden scientists print electronic layers with polymer ink

Thin organic layers provide machines and equipment with new functions. They enable, for example, tiny energy recuperators. In future, these will be installed...

Im Focus: Dynamik einzelner Proteine

Neue Messmethode erlaubt es Forschenden, die Bewegung von Molekülen lange und genau zu verfolgen

Das Zusammenspiel aus Struktur und Dynamik bestimmt die Funktion von Proteinen, den molekularen Werkzeugen der Zelle. Durch Fortschritte in der...

Im Focus: Dynamics of individual proteins

New measurement method allows researchers to precisely follow the movement of individual molecules over long periods of time

The function of proteins – the molecular tools of the cell – is governed by the interplay of their structure and dynamics. Advances in electron microscopy have...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

5th International Conference on Cellular Materials (CellMAT), Scientific Programme online

02.10.2018 | Event News

Major Project: The New Silk Road

01.10.2018 | Event News

"Boston calling": TU Berlin and the Weizenbaum Institute organize a conference in USA

21.09.2018 | Event News

 
Latest News

Physics: Not everything is where it seems to be

15.10.2018 | Physics and Astronomy

Microfluidic molecular exchanger helps control therapeutic cell manufacturing

15.10.2018 | Life Sciences

Link between Gut Flora and Multiple Sclerosis Discovered

15.10.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>