Variability and Long-Term Changes in Surface Air Temperatures Over the Indian Subcontinent

Abstract

In this chapter, long-term trends in annual and seasonal surface air temperatures over India for the period 1901–2010 have been examined. During the period 1901–2010, annual mean, maximum, and minimum temperatures averaged over the country as a whole exhibited a significant increasing trend of 0.60, 1.0, and 0.18 °C per hundred years, respectively. Further, the rate of increase in the annual mean temperatures since 1908s is much higher, mainly due to sharp increase in minimum temperatures. For the period 1981–2010, the increase in mean, maximum, and minimum temperatures was almost 0.2 °C per decade. On the seasonal scale, the highest increasing trend in the mean temperatures was observed in the postmonsoon and winter seasons, during the period of 1901–2010 and in the recent 30 years (1981–2010). Maximum and minimum temperatures over India showed an accelerated warming during the recent 30-year period (1981–2010). Further, the rise of the maximum and minimum temperatures, in the recent 30 years, is mostly confined to the northern, central, and eastern/northeastern parts of the country. Peninsular India experienced the least warming during the recent 30-year period (1981–2010). The annual upper-air temperature series for the country as a whole for the period 1971–2007 also showed significant increasing trend at the lower tropospheric levels, viz. 850 and 700 hPa levels.