Seafloor cores show tight bond between dust and past climates

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

Dust from China moves across Korea and Japan to the Pacific Ocean, April 2002. Click here for more information.

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.

Pacific Ocean sites where sediment cores were taken. Click here for more information.

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.