Science Story

02 December 2008 23:10 BST

Icelandic eruption 'caused Egyptian drought'

Volcanic eruptions that occur north of the equator can have far reaching consequences in lower latitudes, a study has shown.

Scientists from Rutgers University in the US claim that one of the effects of volcanic eruptions in Iceland during the 18th century included a historic famine in Egypt.

Ten eruptions between June 1783 and February 1784 in Iceland significantly changed atmospheric circulations across much of the northern hemisphere.

This created unusual temperature and rainfall patterns in other places, including far below normal rainfall over much of the Nile river watershed and record low river levels.

Writing at the time, the French scholar Constantin Volney said: "In 1784, the Nile again did not rise to the favourable height, and the dearth immediately became excessive. Soon after the end of November, the famine carried off, at Cairo, nearly as many as the plague."

Using a computer model developed by Nasa's Goddard institute for space studies, the researchers traced atmospheric changes that followed the 1783 eruption of the Laki volcanic system in southern Iceland.

The model showed significant warming in the region across Africa to the southern Arabian peninsula and on to India. With little or no monsoon, no clouds brought rain in Egypt, causing the drought.

Rutgers researcher Luke Oman, lead author on the study, said: "These findings may help us improve our predictions of climate response following the next strong high-latitude eruption, specifically concerning changes in temperature and precipitation.

"Many societies are very dependent on seasonal precipitation for their livelihood and these predictions may ultimately allow communities time to plan for consequences, including impacts on regional food and water supplies."