In spring 2010, the research icebreaker Polarstern returned from the South Pacific with a scientific treasure—ocean sediments from a largely unexplored part of the vast, remote ocean that surrounds Antarctica—the Southern Ocean.
What happens in the Southern Ocean can affect the carbon budget of the entire planet. The details of how exactly carbon flows into and out of the ocean, though, aren’t fully understood yet. These new sediment cores from the South Pacific allowed my colleagues from the Alfred Wegener Institute in Germany and I to look at a million years of climate history from this key area of the planet. In our results, published this week in Science, we figured out how the amount of terrestrial dust that falls onto the ocean surface (and ends up at the bottom of the ocean, in our sediment cores) changed in sync with other climate parameters in these cores and from other parts of the southern hemisphere.
As earth’s climate warms, scientists have tried to understand why the poles are heating up two to three times faster than the rest of the planet. Airborne dust, it turns out, may play a key role.
In a new study in Nature Climate Change, researchers show that at the peak of the last ice age, some 21,000 years ago, the poles were 10 times dustier than today, while areas closer to the equator had twice as much dust. During this time of extreme cold, New York City was under two miles of ice and up to 12 degrees F colder than today while Greenland was about 45 degrees F colder. The study’s authors suggest that higher atmospheric dust concentrations at the poles during the last ice age helped to cool earth’s surface and prevent snow and sea ice from melting during summer.
Farming pushed natural drought into disaster--and could do so again.
NEW YORK – Climate scientists using computer models to simulate the 1930s Dust Bowl on the U.S Great Plains have found that dust raised by farmers probably amplified and spread a natural drop in rainfall, turning an ordinary drying cycle into an agricultural collapse. The researchers say the study raises concern that current pressures on farmland from population growth and climate change could worsen current food crises by leading to similar events in other regions.
Each year nearly 40,000 tons of cosmic dust fall to Earth from outer space. Now, the first successful chronological study of extraterrestrial dust in Antarctic ice has shown that this amount has remained largely constant over the past 30,000 years, a finding that could help refine efforts to understand the timing and effects of changes in the Earth's past climate.