Many scientists have been concerned about global warming over the past few decades and indeed the Earth has warmed about one-quarter of a degree each decade since 1978. However, over the past 12 months we have seen a global decline in temperatures of almost one degree. The short-term cooling has likely been caused by a Pacific Ocean current named La Nina. Basically, the waters of the Equatorial Pacific Ocean get colder as La Nina takes place. At this point it is impossible to say how long La Nina will continue and whether additional global cooling will result. Meteorologists will be following the data closely over the next few years to see if a new trend develops.