Globally Extended Koppen-Geiger climate classification and temporal shifts in terrestrial climatic types

Increasing awareness of the impacts of global climate change on marine ecosystems and concerns about shifting bioclimatic and agricultural zones necessitate a reassessment of the geographical distribution of Earth's climate types. In recent years, the availability of truly global data-sets has allowed for the application of climatic types, including the Koppen-Geiger system, over the oceans. This research uses NCAR Reanalysis data to create a global 'Extended Koppen-Geiger climate classification', including the world ocean, for the 1981-2010 averaging period. The percentages of Earth's surface covered by tropical rainforest (Af), tropical monsoon (Am), and (especially) the mesothermal- mild summer (Cfc) climate types are much larger than in the terrestrial only analysis. Expanding and contracting terrestrial climate zones are also identified based on the differences in the total area through comparison with maps produced for 1901-1925, 1926-1950, 1951-1975, 1976-2000 and model-output-based predicted Koppen-Geiger types for 2076-2100. Results suggest that hot desert (BWh), hot semi-arid (BSh), and Af climatic types are projected to expand, while the tundra and most mesothermal and microthermal types will decrease in area. These results assist in projecting global impacts of climatic change.