A dustier Tibet?

Eli Kintisch in New Scientist: Sediments taken from the bottom of a lake on the Tibetan Plateau suggest that changes in wind patterns caused by global warming may be making the area dustier. That trend could accelerate the melting of crucial glaciers in the Himalayas and affect already imperiled water supplies.

Jessica Conroy, a graduate student in paleoclimatology at the University of Arizona in Tucson, and colleagues collected sediment cores from the bottom of Kiang Lake in southwestern Tibet using equipment suspended from rafts. The cores track the history of climate in the region back to 1050 C.E. According to Conroy, who presented the data here at the fall meeting of the American Geophysical Union on 15 December, the amount of fine-grained dust in the lake sediment increased over the 20th century. Finer dust arrives from distant desert regions hundreds of kilometers away, suggesting stronger winds with the power to deliver the material.

Scientists have previously noted the rise of dust in the region but attributed it to the increase in agriculture, grazing, and other relatively local developments. Data Conroy presented showed that dusty periods coincide with summers when a Northern Hemisphere atmospheric phenomenon called the Arctic Oscillation is in a "positive phase." A positive phase of this pattern in the summer leads to stronger winds in desert areas to the north of the lake as well as south of the Himalayas….

Kiang Lake in 1938, from the Bundesarchiv