The report, which was adopted after a five-day set of discussions between scientific experts and government delegates from more than 120 countries, broke down its findings into regions for the first time.

Africa, a continent mainly composed of less developed countries, will be the hardest hit by the adverse effects of global warming, according to the report.

"New studies confirm that Africa is one of the most vulnerable continents to climate variability and change because of multiple stresses and low adaptive capacity," experts said in a 21-page summary of the whole report for policy makers.

By 2020, between 75 and 250 million people in Africa are projected to be exposed to an increase in water shortages, the report said.

As a result of climate change, the area suitable for agriculture, the length of growing seasons and yield potential are expected to decrease, which will further adversely affect food production in the continent as it was already suffering from malnutrition.

In some countries, yields from rain-fed agriculture could be reduced by up to 50 percent by 2020, the report warned.

The poverty-inflicted continent may also have to spend at least five to ten percent of their gross domestic products to cover the cost of adaptation to climate change, the report said.