An international study shows that droughts in the Sahel region on the southern Sahara rim can be affected by cyclical changes in atmospheric pressure and sea surface temperature in the North Atlantic Ocean. 

Researchers from Columbia University, the University of Haifa, the University of San Diego, and the French National Meteorology Service studied how climate variability in one location can affect another distant location, and more importantly, were able to locate these "far-connections" and "understand their projections." Their study was published in the scientific journal Atmospheric Science Letters. 

The study analyzed a number of climate parameters in the North Atlantic which included sea surface temperature and atmospheric pressure at sea level. This research led them to discover two "natural climate signals," which consists of a multi-decadal signal of a period exceeding 40 years and a quasi-decadal signal with periodicity ranging from 8 to 14 years. 

The researchers, unsure as to whether these signals will enhance or cancel one another out, compared them with "climatic fluctuations as observed in coral and tree-ring studies, by which the temperature values of the past few hundred years can be reconstructed." According to the study, the signals were also identified.

This led the scientists to search for a correlation between the droughts in the Sahel region and the cyclical waves. The result was that when the Atlantic cools, there are droughts in the Sahel region; and when the Atlantic's temperature rises, it rains in the Sahel region. 

This isn't the first we've heard of these droughts in the Sahel region though. From the 1970's through 1990's, this region suffered from civilian desertion, starvation and other environmental  and social crises. In addition, the UN stated in 2007 that the situation in Darfur was "intensified by the ongoing drought in the Sahel region and its surroundings."

According to Dr. Shlomit Paz, a co-author in the study who works for the Department of Geography and Environmental Studies at the University of Haifa, this study is an important addition to what science already knows about climatic models, and is "improving their prediction capability." 

"Today we are able to gain a better understanding of how the oceans play an important role in the Earth's 'climate memory,'" said Paz. "Once we become familiar with the natural signals, we will be able to better understand how the human factor correlates with climate."