Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seafloor cores show tight bond between dust and past climates

03.03.2008
Researchers hope to shed light on proposed manmade climate 'repairs'

Each year, long-distance winds drop up to 900 million tons of dust from deserts and other parts of the land into the oceans. Scientists suspect this phenomenon connects to global climate—but exactly how, remains a question.

Now a big piece of the puzzle has fallen into place, with a study showing that the amount of dust entering the equatorial Pacific peaks sharply during repeated ice ages, then declines when climate warms. The researchers say it cements the theory that atmospheric moisture, and thus dust, move in close step with temperature on a global scale; the finding may in turn help inform current ideas to seed oceans with iron-rich dust in order to mitigate global warming. The study appears in the Feb. 28 edition of Science Express, the advance online edition of the leading journal Science.

In the past decade, scientists have documented similar dust peaks in polar ice cores, and in sediments from the Atlantic and Indian oceans, but records from Pacific were contradictory. Now that all the records have been shown to coincide, “it suggests that the whole world hydrologic cycle varies in unison, on a pretty rapid time scale,” said Gisela Winckler, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory and lead author of the paper.

“It gives us the information from where it matters—where people live, and where the real engine of climate probably lies.” Changes in the atmosphere over the Pacific, and the tropics in general, are thought to affect huge areas of the world.

The researchers studied cores of seafloor sediment representing 500,000 years of deposition, spanning about 6,000 miles of the Pacific equator, from near Papua New Guinea to near Ecuador’s Galápagos Islands—nearly a quarter of the globe’s girth. In each, they found the same thing: at the height of each of five known ice ages, accumulation of the isotope thorium 232, a tracer for land dust, shot up 2.5 times over the level of warmer “interglacial” times.

The peaks appear about every 100,000 years, with the last one at 20,000 years ago—culmination of the last glacial age. Through other isotopes, the scientists traced the dust on the western side to Asia, and that on the eastern side to South America. The reasons for the lockstep peaks are probably complex, but in general scientists say that colder air holds less moisture than warmer air, and that cold periods tend to be windier; this means both dustier land, and more dust getting blown away.

The dust probably helped make climate even colder for a while, and this has implications for the current day, said Robert F. Anderson, head of Lamont-Doherty’s geochemistry division and a coauthor. Many types of dust transported at high altitudes tend to reflect sunlight, thus lowering the energy reaching earth, said Anderson. And, when it settles into the ocean, there could be an intriguing further effect. Rich in the plant nutrient iron, the dust could have fertilized near-surface plankton on a massive scale.

Like other plants, plankton uses the greenhouse gas carbon dioxide for photosynthesis; thus, theoretically, fertilization could have caused the ocean to take larger amounts of CO2 from the air, and entomb it in the ocean. Lowering of atmospheric CO2 in turn would reduce the air’s capacity to hold heat—the opposite of what is currently happening, as the globe warms due to elevated CO2 levels from burning of fossil fuels and other human activities.

Lately, a growing number of scientists have been advocating research to see if massive, manmade iron fertilization of the oceans might induce such blooms, and thus mitigate warming. A dozen early experiments in different regions have shown that plankton growth increases when iron is artificially added, but scientists have yet to show that this could lock significant amounts of CO2 into the ocean; carbon from the plants would have to sink to the bottom for this to happen. “The new data gives us a natural experiment to see what might have happened in the past,” said Winckler. The researchers’ next step will be to analyze their cores for signs of such sunken carbon during the ice ages; they hope to do this within a year or two.

Anderson and Winckler caution that the idea of iron fertilization remains deeply complex and controversial. “Assessing the past response to natural variability of iron will enable scientists to develop more quantitative predictions about the possible efficacy of adding it ourselves in the future,” said Winckler.

Kevin Krajick | EurekAlert!
Further information:
http://www.ei.columbia.edu

More articles from Earth Sciences:

nachricht Northern oceans pumped CO2 into the atmosphere
27.03.2017 | CAGE - Center for Arctic Gas Hydrate, Climate and Environment

nachricht Weather extremes: Humans likely influence giant airstreams
27.03.2017 | Potsdam-Institut für Klimafolgenforschung

All articles from Earth Sciences >>>

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

Northern oceans pumped CO2 into the atmosphere

27.03.2017 | Earth Sciences

Fingerprint' technique spots frog populations at risk from pollution

27.03.2017 | Life Sciences

Big data approach to predict protein structure

27.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>