Rainfall reduction linked to industrial emissions.

• Position: Ecology

Clues left behind in a cave in Central America have allowed an international, multidisciplinary team of researchers, including several from the University of New Mexico, Albuquerque, to produce a paleoclimate rainfall record that illustrates the contribution of manmade industrial emissions to less rainfall in the northern tropics.

The team reconstructed a rainfall record stretching back 450 years from unprecedented speleothem samples from Yok Balum cave in Belize using uranium thorium dating from the chemical composition in the speleothems containing aragonite, which is high in uranium.

The research highlights the effects produced through manmade usage of fossil fuels. The results identified a significant drying trend beginning around 1850 that parallels the steady rise in sulphate aerosols in the atmosphere linked to the industrial boom in Europe and North America.

"We are inherently interested in this tropical climate not just simply because of the impact on human culture, but because there is also a climate story," says Yemane Asmerom, professor in the Department of Earth and Planetary Sciences.

"The moisture transport across Central America from the Atlantic and Pacific Oceans is presumably one of the key relays that modulates ocean currents and long-term climate variability."

As part of the research, scientists identified...