2024 was the warmest year for India and the world. But why was warming lower over India?

Because of the difference in baselines, the two pieces of data, representing the warming over India and the world as a whole in 2024, cannot be directly compared. IMD does not have temperature data over India for the 1850-1900 period to facilitate a straight comparison as its dataset begins from 1901.

How should temperature rise in India and the world be compared?

The average of 1901-1910 period might be a more useful baseline for comparing the temperature rise over India with the world as a whole. IMD data shows that temperature over India in 2024 was about 1.2 degree Celsius higher than the 1901-1910 average.

However, this is still not a good comparison because the warming over India takes into account the temperature rise only of the land surface. The global temperature rise, on the other hand, is the average of the warming seen over land as well as the oceans. Land surfaces have warmed up considerably more than the oceans. This is because oceans have a higher capacity to cool themselves through the process of evaporation. The warmer water gets evaporated, leaving the rest of the ocean relatively cooler.

The break-up of the warming over global land surface and oceans for 2024 is not available immediately, but previous data shows that land temperatures have increased by more than 1.6 degree Celsius from pre-industrial levels while oceans have warmed by about 0.9 degree Celsius.

The temperature rise over global land surface in 2024 is expected to be higher than 1.6 degree Celsius, considering that it has been an exceptionally hot year.

Reasons behind lower warming over India

The 1.2 degree Celsius warming over India is considerably less than the 1.6 degree Celsius, or higher, that has been experienced over the global land surface. This is not surprising, but it also does not mean that the threat of climate change is less in India compared to other areas.

India is located in the tropical area, quite close to the equator. The increase in global temperature has been more pronounced 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.

Most of the global landmass lies in the higher altitudes. The polar regions, particularly the Arctic, have seen substantially higher warming. According to the Intergovernmental Panel on Climate Change (IPCC), the Arctic region has seen its temperature increase by at least two times compared to the global average.

In the Arctic, current annual mean temperatures are already about 2 degree Celsius higher than pre-industrial levels. Another reason contributing to higher temperature rise in the polar regions is what is known as the albedo effect. The ice cover in the Arctic is melting, resulting in more land or water is getting exposed to Sun. Ice traps least amount of heat and reflects most of solar radiation compared to land or water.

The greater concentration of aerosols, or suspended particles, in the atmosphere over the Indian region also impacts temperature rise. Aerosols, in general, have a cooling effect because they scatter the solar radiation back into space. Aerosols also affect cloud formation which, in turn, affects how much sunlight is absorbed or reflected. Being located in the tropical region, India sees a greater amount of dust. But it is also generating huge amount of air pollution. The particulate matter and aerosols have a small unintended consequence of lowering the temperature rise.

Empowering IMD

India is not a uniform landmass. The average temperature rise over the Indian region does not capture the different levels of warming being experienced in different parts of the country. The nature and impact of temperature rise in the Himalayas, for example, is very different than that in the coastal regions. India’s vulnerability to climate change is very high, not in the least because of its large population.

Global climate models do not very well reflect the changes happening over the Indian region. Same is true for the global assessments of the impacts of climate change. As such, India needs to strengthen its capabilities in climate observation and impacts assessment. The first India-specific climate change impact assessment was carried out in the year 2020 and filled a big gap in the understanding of threats from climate change. But this has to be an ongoing exercise, just like IPCC does a global assessment every few years.

Expanding the weather observation network and strengthening of computing and analysis capabilities is a pre-requisite. The launch of Mission Mausam last year was done with this precise purpose. The vision for a Viksit Bharat in 2047 has to include a weather monitoring station in at least every village of the country.

The IMD is going to play an increasingly visible and crucial role in the social and economic life of the country. Not very long ago, it used to provide just rainfall or temperature information that were of limited use. These days, its weather information is critical to disaster management, electricity generation management, transportation, tourism, and event management. Its capabilities need to be strengthened further to make it much more effective and useful.

Similar is the case of other weather and climate-related agencies like the Indian Institute of Tropical Management in Pune, or the Indian National Centre for Ocean Information Systems (INCOIS) in Hyderabad. The observation network over the oceans surrounding the Indian landmass is extremely inadequate as of now, and needs to be corrected urgently.