Koppen-Trewartha climate classification as a diagnostic tool to identify pronounced changes in the projected climate by the General Circulation Models over India

Earth's changing climate will pose a major threat to terrestrial ecosystems in their present state of equilibrium that support human habitats. Understanding the underlying aspects of climate change that influence ecosystems is crucial to devise adaptation strategies and conservation efforts. To this end, climate classification schemes can be employed as an effective means for both validation of climate models and identify areas that may experience a pronounced shift in climate in the future. In this context, the current study focuses on the impact of climate change on shift in climatic regimes over the Indian sub-continent for the mid and late 21st century with respect to the reference period (1975-2005). Koppen-Trewartha climate (KTC) classification was applied to climate projections resulting from four downscaled General Circulation Models from the NASA Earth Exchange Global Daily Downscaled Climate Projections, under two RCPs (4.5 and 8.5) along with global Climate Research Unit TS-3.23 dataset which is treated as observed. Analysis of the future 21st century climate projections revealed noticeable shifts in climate types, of which expansion of arid and savannah class is the most prominent. Results indicate that the sub-continental scale analysis done at a grid cell-by-grid cell basis was able to locate potentially static and dynamic climate regions across the country with projected shifts from warmer/wetter to drier climate regime. This in turn is expected to pose serious threat to various sectors, especially agriculture, owing to its heavy dependence on water resources. The observations from the study provide information on the magnitude and pattern of change in climate types across the country and thus can serve as prospective reference to develop adequate and effective climate adaptation strategies.