- The global warming trends over the Indian region are very different.
- An assessment of climate change over the Indian subcontinent, published by the Ministry of Earth Sciences in 2020, said annual mean temperatures had risen by 0.7 degree Celsius from 1900.
- This is significantly lower than the 1.59 degree Celsius rise for land temperatures across the world.
Why is warming over India lower?
- The increase in temperatures is known to be more prominent in the higher altitudes, near the polar regions, than near the equator.
- This is attributable to a complex set of atmospheric phenomena, including heat transfers from the tropics to the poles through prevailing systems of air circulation.
- India happens to be in the tropical region, quite close to the equator.
- The planet as a whole has warmed by 1.1 degree Celsius compared with preindustrial times.
- Different regions have seen very different levels of warming.
- The polar regions, particularly the Arctic, have seen significantly greater warming.
- The IPCC report says the Arctic region has warmed at least twice as much as the world average.
- Its current annual mean temperatures are about 2 degrees Celsius higher than pre-industrial times.
- Transfer of heat through air circulation.
- Albedo effect, or how much sunlight a surface reflects.
- The ice cover in the Arctic is melting, because of which more land or water is getting exposed to the Sun.
- Ice traps the least amount of heat and reflects most of the solar radiation when compared with land or water.
- Changes in clouds, water vapour and atmospheric temperatures.
Higher warming over land than oceans
- The 0.7 degree Celsius temperature rise over India has to be compared with the warming seen over land areas, not the entire planet.
- Land areas have become warmer by 1.59 degree Celsius.
- Land areas have a tendency to get heated faster, and by a larger amount, than oceans.
- Daily and seasonal variations in heating over land and oceans are usually explained in terms of their different heat capacities.
- Oceans have a higher capacity to cool themselves down through the process of evaporation.
- The warmer water evaporates, leaving the rest of the ocean relatively cooler.
- However, longer-term enhanced heating trends over land have to be attributed to other, more complicated, physical processes involving land-ocean-atmospheric interactions.
Impact of aerosols
- Aerosols refer to all kinds of particles suspended in the atmosphere.
- Many of these scatter sunlight back, so that lesser heat is absorbed by the land.
- Aerosols also affect cloud formation.
- Clouds, in turn, have an impact on how much sunlight is reflected or absorbed.
- Aerosol concentration over the Indian region is quite high, due to natural as well as man-made reasons.
- Emissions from vehicles, industries, construction, and other activities add a lot of aerosols in the Indian region.
- A reduction in warming could be an unintended but positive side-effect.
SOURCE: THE HINDU, THE ECONOMIC TIMES, PIB