Desert dust has a significant impact on global climate, limiting the amount of solar radiation that reaches the Earth and influencing cloud formation and precipitation. It also affects ocean chemistry, acting as a major source of iron, which is often a limiting nutrient for plankton and other organisms.

A team led by Natalie Mahowald of Cornell University in New York measured fluctuations in desert dust over the 20th century using existing data from ice cores, lake sediments and coral. Each sample was linked with its likely source region and then used to calculate the rate of dust deposition over time. The researchers then plugged these data into a computer model in order to reconstruct the influence of desert dust on temperature, precipitation, ocean iron deposition and terrestrial carbon uptake over time.

As well as finding that the amount of dust in the atmosphere has doubled over the past century, the scientists found that dust deposited in oceans increased carbon uptake from the atmosphere by six per cent over the same time period.

They also found evidence that dust in the atmosphere can have a significant impact on regional climate and biogeochemistry. During the late 20th century in the Sahel region of North Africa, for example, periods when concentrations of atmospheric dust were high have correlated with drought conditions.

March 2011