ASSESSING THE ABILITY OF THE KOPPEN SYSTEM TO DELINEATE THE GENERAL WORLD PATTERN OF CLIMATES

The Koppen climate classification system [Koppen, 1923] is a scheme th at provides an objective numerical basis for defining regional climati c types based on temperature and precipitation. Through the years it h as been used as a scientific and teaching tool for prescribing the gen eral world pattern of climates. Here for the first time an evaluation of the system is performed by employing coextensive temperature and pr ecipitation data over the N. Hemisphere for the last 140 years. First the global pattern of climate type sensitivity is obtained. From this pattern it is discovered that several climate types exhibit a rather s trong variability. Since all climate types depend on temperature we th en tested whether or not the above variability is due to the fact that over the last 140 years the global climate system exhibits a well doc umented positive temperature trend known as global warming. We found t hat the Koppen system is rather insensitive to the observed global war ming and concluded that overall the system performs rather poorly over Europe and Asia whereas it appears adequate over N.America and N.Afri ca.