Assessment of Climate Change over the Indian Region

Report Key Findings:

• Sea surface temperatures in the tropical Indian Ocean rose by one degree Celsius on average between 1951-2015. This temperature rise was 0.3°C higher than the global average of 0.7°C.
• Sea levels in the North Indian Ocean (NIO) region rose by 3.3 millimetres every year between 1993 and 2017, almost double the maximum rate of 1.75 mm per year measured between 1874 and 2004.
• The frequency of very severe cyclones also increased in the region by one per decade in the last two decades even though overall frequency of cyclones decreased in the latter half of the last century and the first two decades of the 21st century.
• The last two years saw a significant rise in number, intensity and unpredictability of cyclones in the NIO region, the latest being super cyclone Amphan in the Bay of Bengal and very severe cyclone Nisarga in the Arabian Sea.
• Temperatures are projected to rise by 2.7°C by 2040 and 4.4°C by the end of the century.

Report Summary:

This open access report discusses the impact of human-induced global climate change on the regional climate and monsoons of the Indian subcontinent, adjoining Indian Ocean and the Himalayas. It documents the regional climate change projections based on the climate models used in the IPCC Fifth Assessment Report (AR5) and climate change modeling studies using the IITM Earth System Model (ESM) and CORDEX South Asia datasets. The IPCC assessment reports, published every 6–7 years, constitute important reference materials for major policy decisions on climate change, adaptation, and mitigation. While the IPCC assessment reports largely provide a global perspective on climate change, the focus on regional climate change aspects is considerably limited. The effects of climate change over the Indian subcontinent involve complex physical processes on different space and time scales, especially given that the mean climate of this region is generally shaped by the Indian monsoon and the unique high-elevation geographical features such as the Himalayas, the Western Ghats, the Tibetan Plateau and the adjoining Indian Ocean, Arabian Sea, and Bay of Bengal. This book also presents policy relevant information based on robust scientific analysis and assessments of the observed and projected future climate change over the Indian region.