For Africa and its climate, history seems to be repeating itself. A new study suggests an increase in greenhouse gas concentrations several thousand years ago contributed to rapidly rising rainfall levels in Africa. The new findings predict that modern greenhouse emissions could have a similar affect on climate and weather patterns.

Researchers have long known about a sudden period of heightened rainfall in Africa -- a period that began roughly 14,700 years ago and lasted for more than 10,000 years. The span of heightened precipitation, known as the African Humid Period (AHP), turned portions of Africa's deserts into grasslands and savannas.

Previously, scientists had hypothesized a change in Earth's orbit and axial position was responsible for the abrupt change. But when scientists at the National Center for Atmospheric Research in Boulder, Colorado, juxtaposed the meteorological evidence of AHP with climate models, they found a near-perfect correlation.

"The fact that the model gets it right and that we can explain it, that gives us confidence that the model can tell us about future patterns of rainfall in the region," study author Bette Otto-Bliesner told Bloomberg News. "It was the rise of greenhouse gases, in particular carbon dioxide and methane, in the atmosphere that gave that region a common signal."

There are already early indications that manmade climate change is triggering increased rainfall once again -- with an uptick in vegetation growth in the Sahara desert and the Sahel region.

"They've noticed it on the ground, they've seen it in satellite measurements," Otto-Bliesner said.

If rainfall increases as expected, parts of Africa destined for growing population centers will have to attend to variety of resource management issues.

"The future impact of greenhouse gases on rainfall in Africa is a critical socioeconomic issue," Otto-Bliesner said in a press release. "Africa's climate seems destined to change, with far-reaching implications for water resources and agriculture."

The study was published this week in the journal Science.