Climate change has been having tremendous effects on India. Rising temperatures on the Tibetan Plateau are the result of the retreat of the Himalayan glaciers, which is a threat to the flow of water in the Ganges, Brahmaputra, Yamuna, and other major rivers. Frequency of heat waves is also increasing in India due to climate change.
Extreme Weather Conditions in India
The increase in the frequency and intensity of extreme weather conditions is considered to be an impact of the changing climate patterns all over the Indian region as well as the world.
Not only is the surface getting hotter due to the rise in temperature but the water-holding capacity of the troposphere has also been increasing. When the atmosphere has the capacity to hold more moisture, it would have the capacity to cause more rainfall.
In July 2021, there were heavy rains in Maharashtra, which claimed several lives. When the south west monsoon began retreating from the subcontinent in October 2021, Kerala and Uttarakhand received heavy rainfall. There have been variations in the pattern and intensity of rainfall in other parts of the country as well. The unprecedented set of extreme weather events has badly impacted the western coast of India. Since 2018, cyclones have come very close to the west coast, and Kerala has experienced widespread floods.
In case of Kerala, the two rain-bearing active ‘low pressure systems’ in the Arabian Sea, and in the Bay of Bengal contributed to heavy rains in September 2021. Moreover, there were western disturbances, i.e., periodic influxes of the moisture-laden clouds from the Mediterranean, which caused rain in northern India. The warmth in the Bay of Bengal usually causes heavy rainfall to several parts of the North-Eastern India.
Warming in the Indian Ocean is at the fastest rate. Some regions like the western Indian Ocean, including the Arabian Sea, have been registering long-term average above 1.2 °C, which is causing an increase in storms and extreme rain events in the Indian Ocean rim countries. The Arabian Sea, too, has been warmer due to rise in temperature and has been leading to significant cyclonic activity. The Arctic Ocean, too, is getting warmer and has been drawing colder air from the poles with greater intensity. This has been adding increased moisture, leading to more intense western disturbance activity over North India.
Between 1950 and 2017, 285 flooding events were reported in India, which affected millions of people, killing many and leaving many homeless, besides causing enormous economic damage. According to a recent study from the Ministry of Earth Sciences, the floods, cyclones, heat and cold waves, and lightning have taken about 1.4 lakh lives during the past five decades.
Multiple extreme weather events have also overlapped and increased the impact of cyclones. Due to global warming, there is more moisture in the air that cyclones would absorb and pour over land. The back-to-back cyclones in 2020 and 2021 generated storm surges with high tides, pushing seawater onto land. Accompanied by heavy rains, the storms flooded the coastal regions.
The temperature rise has been more in the northern, central, and eastern parts, and less over peninsular India.
There has been a decrease in the number of light and moderate rainfall days, while the number of extreme rainfall events have increased. This trend could be seen in the central belt of India. Kerala, Jharkhand, and adjoining areas have witnessed a decrease in rainfall activity but there has been an increase in rainfall activity in West Bengal, western Uttar Pradesh, and parts of Karnataka. In the central and northern parts of India, there have been heatwaves. However, cold wave conditions may decrease due to rise in temperature. Lightning and thunderstorm events are increasing.
Impact of Temperature on Natural Environment
Temperatures in India have risen by 0.7 °C between 1901 and 2018. A study in 2018 projected droughts to increase in north and north-western India in the near future. The year 2024 has already seen extremely hot days. Around the end of the century, most parts of India might face more severe droughts. Similarly, severe landslides and floods have been projected to become increasingly common in states such as Assam, etc. Above normal increases in temperatures before expected have an adverse impact on crops on the field, leading to a bad harvest.
Impact of Rising Sea-Level on Ecosystems
There are concerns in Meghalaya and other north-eastern states that rising sea levels would submerge much of Bangladesh and lead to a refugee crisis for these states. Bangladesh and parts of India that border Bangladesh might lose vast tracts of coastal land if severe climate change takes place. Low-lying islands in the Sundarbans have been submerged due to ongoing rise in sea level, leading to thousands of people having been displaced.
Rising temperatures have already led to ecological disasters, such as a coral bleaching event in 1998, which killed more than 70 per cent of corals in the reef ecosystems off Lakshadweep and the Andamans.
Recurring Pattern due to Climate Change
According to the World Meteorological Organization (WMO), the global average temperatures would breach the 1.5 °C rise as an annual average in the next five years. Though the global climate system would not collapse suddenly with the occurrence of extreme weather events even if we cross 1.5 °C, warming leaves its marks. Moreover, the 1.5 °C threshold accounts only for the changes in global surface temperatures; oceans, too, absorb more than 93 per cent of the additional heat from global warming.
According to the India Meteorological Department (IMD), the number and intensity of the cyclones have increased in the Arabian Sea since the 1980s, a threat to the densely populated western coast of India. Cyclone Tauktae, in May 2021, indicated the third consecutive year when the cyclone came very close in the Arabian Sea and impacted Kerala, Karnataka, Goa, Maharashtra, and Gujarat, and the islands and territories of Lakshadweep on the west coast.
Intense Heatwaves
India saw one of its worst heatwaves in the months of May–June 2024 with temperature reading above 50 °C in many parts of the country. As per the Intergovernmental Panel on Climate Change (IPCC), heatwaves that used to occur at an interval of about 10 years as a natural weather phenomenon are now likely to occur once every 3.6 years and are warmer by about 1.5 °C because of climate change caused by burning of fossil fuels and other human activities.
Changing Monsoon Patterns
The IMD, in a report released in 2020, observed the variability and change in pattern of monsoon rainfall in 29 states and union territories, at the state and district levels. The study used data from a period of 30 years (1989–2018). The importance of the southwest monsoon is well known. According to the IMD study, between 1989 and 2018, the five states of Uttar Pradesh, Bihar, West Bengal, Meghalaya, and Nagaland showed significant decreasing trends in southwest monsoon rainfall. The annual rainfall in Arunachal Pradesh and Himachal Pradesh also showed significant decreasing trends. At the same time, there has been a significant increasing trend in the frequency of heavy rainfall days in Saurashtra and Kutch, south-eastern Rajasthan, northern Tamil Nadu, Andhra Pradesh, and adjoining areas of south-west Odisha.
Of the Indian states and union territories considered, 23 had normal rainfall, i.e., between 19 per cent above and 19 per cent below the long period average (LPA) in 2021. Deficient rainfall between 20 per cent and 59 per cent below the LPA was experienced in 8 states, while 6 had excess rainfall of 20 per cent and 59 per cent above the LPA. Arunachal Pradesh, Assam, Meghalaya, Nagaland, Manipur, Mizoram, Tripura, and Chandigarh less rainfall than normal. In the same year, Andaman and Nicobar, Haryana, Delhi, Dadra and Nagar Haveli, Telangana, and Tamil Nadu received excess rainfall. Across India, rainfall was two per cent above the LPA of 956.5 mm or in the ‘normal’ range.
Accuracy of Weather Prediction
The accuracy of monsoon forecasts, especially of extreme rainfall events, has increased from about 60 per cent, 10 years ago, to over 80 per cent, now. While cyclone forecasting has improved, leading to lives being saved, the rapid intensification of cyclones, a change of 55 km/hr wind speed in less than 24 hours, has become a challenge for both forecasters and disaster management authorities. Cyclone Tauktae was immediately followed by Cyclone Yaas on the east coast, flooding the Odisha and Bengal coastline for days.
India falls in the tropical region. Cyclones, monsoon, and thunderstorms are characteristic of tropical weather systems. Tropical weather is linked with convective forces of the atmosphere. The intense heating of the Earth’s surface has been playing a dominant role in the genesis, evolution, characteristics, propagation, and movement of the weather in India. In tropical zone, the weather is a little less predictable.
The IMD is now able to predict the potential zone of occurrence of thunderstorms, five days in advance. It is not easy to predict thunderstorms because they are localised in about a 1–10 km area, and are expected to last barely for half an hour to three hours. The IMD is able to predict the specific location of thunderstorm at least three hours in advance. Prediction and accuracy by the IMD is among the best in the world.
India is one of the very few countries that have been providing lightning forecasts. The IMD has been able to identify the potential hotspots about two weeks in advance. Lightning warnings are issued every three hours on the day of occurrence from over 1,000 stations across the country. The IMD has also developed an application (app) called ‘Damini’, which has been providing location-specific information about the occurrence of lightning during the past 5, 10, and 15 minutes, and a lightning forecast for the next 45 minutes.
The IMD also provides heatwave predictions with great accuracy. With accurate forecasting, and the effective communication and dissemination of information, deaths due to heatwaves have been reduced considerably.
The IMD is also working on cold wave predictions.
The IMD is trying to improve impact-based forecasts by incorporating hazards, vulnerability, and risk analysis for four significant severe weather events, namely, tropical cyclones, heavy rainfall, thunderstorms, and heatwaves.
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