The report explained that 2008 was the coolest year of the decade in the southern hemisphere due to a strong La Nina phenomenon, which cooled the tropical Pacific Ocean below average temperatures.

To some extent we're seeing the results of a natural phenomenon, La Nina - a periodic event in which water in the equatorial Pacific becomes cooler than normal.

In 2010 the westward slopping of cooler water across the tropical Pacific, a phenomenon called La Nina, made itself felt on weather around the world.