Recent Global Warming Induced Climate Changes

Climate should be regarded as a complex system, thus requiring an investigation of its complex changes. For this purpose, it is obvious to define climate types that are determined by a number of factors to be able to afterwards investigate the way they are changing. The most popular procedure so far consists in defining threshold values – as a rule for temperature and precipitation for the seasons – to determine those areas as a climate type that are within these threshold values. A popular example of this procedure is the frequently used Koppen climate classification (Koppen, 1931; Fraedrich et al., 2001). The drawback of this methodology consists in the fact that the threshold values can be absolutely plausible but need to be given subjectively in any case. The first question is: Can be a methodology developed here for the identification of climate changes in an objective way? First, all regions with a structural behavior as similar as possible are combined in one climate type and the pertaining threshold values of the meteorological parameters used are determined afterwards. Regions or areas with the same structure can be determined by means of a pattern recognition method. An extended non-hierarchic cluster analysis will be used for this purpose in the investigation. This cluster analysis provides a number of statistically separated patterns (climate types) for the climate classification on earth. So the characteristics of each climate type can be described. The second question that needs to be answered now can be formulated as follows: Are there any changes in the location and dimension of individual climate types due to the global climate changes presently observed? In order to answer this question, the shifting of the climate types during the observed period must be calculated. After calculation, an analysis of the results follows, first for the global scale as a whole and second more detailed for each continent and selected regions. So the chapter gives an overview on the actual climate changes for different scales. Section 2 describes the basis of the data and its validation. The methodology can be found in section 3 followed by the analysis of the actual climate changes for the whole earth and each continent in section 4. Finally some conclusions are made in section 5.