African dust complicates climate predictions
Dust emissions from Africa that spread as far as the Caribbean have been unusually intense because of widespread drought in the Sahel, according a new study. The finding could complicate assessment of climate change processes.
Two US-based researchers measured the amount of soil carried by winds from North Africa to the Caribbean island of Barbados from 1965 to 1998. They report in this week's Science that dust emissions were unusually intense in response to persistent drought in the Sahel.
The results have implications for future climate change because dust emissions block sunlight and modify cloud properties. "Future changes in climate could result in large changes in emissions from African and other arid regions that, in turn, could lead to impacts on climate over large areas," the researchers write.
A separate group of researchers reported last month that natural processes — not human practices such as overgrazing — were responsible for the drought in the Sahel (see Farmers freed of blame for Sahel drought).
The results contradict the widely held assumption that human activity is mainly to blame for variations in amounts of atmospheric dust during the past several hundred years.
Reference: Science 302, 1024 (2003) / Science 302, 999 (2003)