Assessment of Climate Change over the Indian Region

The average global temperature has risen by around 1°C since pre-industrial times. In 2018, India’s average temperature was around 0.7°C more than it was in 1901.

The mean temperature rise over the Indian region is projected to be between 2.4 to 4.4°C by the end of the 21st century, as compared to the average temperature from 1976 to 2005.

As per the climate change model RCP8.5, the frequency of summer heat waves over India is projected to be three to four times higher by 2100, as compared to the 1976–2005 baseline period. It is estimated that the average duration of heat wave events will double, and there will be an increase in their intensity and area coverage. (RCPs or Representative Concentration Pathways are climate change models adopted by the Intergovernmental Panel on Climate Change.)

The sea surface temperature of the Indian Ocean has gone up by 1°C from 1951 to 2015.

Summer monsoon precipitation in the Indian region, which occurs from June to September, reduced by six per cent between 1951 and 2015. There have been notable reductions in rainfall over the Indo-Gangetic Plains and the Western Ghats in this period. Increasing concentrations of aerosols generated by humans – such as particles released by vehicles – over the Northern Hemisphere are likely to have contributed to this decline.

A key anthropogenic cause of global climate change is the rising atmospheric concentration of aerosols. ‘Aerosol loading’ over the Indian region has substantially increased during the last few decades. This increase has been at the rate of two per cent per year for the last 30 years.

The frequency and spatial extent of droughts in India have increased significantly between 1951 and 2016. The severity of droughts has mainly increased over central India, including parts of the Indo-Gangetic Plains. RCP8.5 projections foresee an increase in the frequency, intensity and spatial extent of droughts in the country by the end of the 21st century.

The sea level in the northern Indian Ocean region rose by 3.3 millimetres per year between 1993 and 2017. The RCP4.5 climate change model estimates that the sea level will rise by 300 mm by the end of the 21st century, as compared the average sea level from 1986 to 2005.

There has been an increase in the frequency of very severe cyclonic storms during the post-monsoon season in India since 2000. Climate change models predict a rise in the intensity of tropical cyclones originating in the northern Indian Ocean region by 2100.

The frequency of extremely severe cyclonic storms over the Arabian Sea during the post-monsoon season has increased from 1998 to 2018. Studies suggest that extreme ‘sea-level events’, such as storm-surges, will frequently occur along the Indian coast, along with an increase in the mean sea level.

There has been an increase in the frequency of localised heavy rainfall occurrences across India between 1951 and 2015. Studies attribute this to causes such as urbanisation and increasing concentrations of atmospheric aerosols.

The temperature in the Hindu Kush Himalayan Region increased by 1.3°C between 1951 and 2014. The RCP8.5 model foresees a further increase of about 5.2°C by the end of the 21st century.