- Discuss the impacts of climate change on monsoon.
The South-west Monsoon is a dominant weather system in the South Asian region. It lasts from June to September and is responsible for 75-80% of India’s yearly rainfall. The monsoon is vital for Indian economy as the kharif crops are largely dependent on monsoon rainfall. In addition, monsoon rainfall is critical for water supply, groundwater replenishment and generation of hydroelectricity. However, climate change is having a profound impact on monsoon.
Impacts of climate change on monsoon :
- Excess Rainfall : Researchers at Indian Institute of Tropical Meteorology Pune, refer to effects of higher temperature on monsoon rains. For every 1degree C rise in temperature, the atmosphere can hold 7% more moisture. Excess rainfall is also being caused by the rapid heating of the global ocean, which has absorbed 90% of the excess heat generated by man-made climate change in the past 50 years.
- Climate change is weakening the land-sea temperature gradient (the thermal contrast), thus drying the monsoon circulation. At the same time, there is an increase in moisture in the air because of rise in Sea Surface Temperature.
- Events in middle east : It is found that dust particles swept into the atmosphere from deserts in the Middle East grow extremely hot under sunlight. They change the air pressure over the Arabian Sea. This creates a kind of heat pump in the sky, which drives moisture from above the ocean to the Indian subcontinent, leading to a wetter monsoon season.
- Inconsistent rainfall : Wide variation in rainfall across regions is becoming a routine. In 2021, All regions saw above-normal rainfall in June. In July 2021, 3 out of the 4 regions witnessed below normal rainfall. But the South Peninsula States and UTs saw rainfall 26% above normal (July 2021). All regions except the East and North-east recorded below normal rainfall in August. At a 24% deficit, 2021 saw the first August drought since 2009.
- Similar pattern has existed in 2022 season so far with wide regional variations. 7 states have received deficient rainfall. Of them, the 3 are from the North East. Manipur recorded a deficit of 48%. Tripura and Mizoram recorded deficit of 23% and 20% respectively. Bihar has deficit of 30%. In the Northwest, Delhi has deficit of 37% and UP of 35%.
- According to the 6th Assessment Report of the Intergovernmental Panel on Climate Change, there has been a noticeable decline in rainfall, with monsoon deficits occurring with greater frequency in various regions of South Asia.
- It is also causing increased formation of Tropical Cyclones.
The Indian summer monsoon plays a crucial role in India’s agriculture and affects the livelihood of 20% of the world’s population. Erratic monsoon season poses a threat to the agriculture and the Indian economy. The Government must step up its efforts to combat the negative impacts. At the same time, these extreme events should provide a wake-up call to the global leadership regarding the impacts of climate change.