‘Climate change fuelling rise in extreme weather events’

Source: The post is based on the article “‘Climate change fuelling rise in extreme weather events’” published in The Hindu on 8^th August 2022.

What is the News?

Recently IMD Director-General has said that climate change has hampered the ability of forecasting agencies to accurately predict severe events. He also said that IMD is installing more radars and upgrading its high-performance computing system to meet the challenge.

What are the key highlights of his speech?

Climate change has increased the instability in the atmosphere. This leads to an increase in convective activity — thunderstorms, lightning and heavy rainfall. The severity of cyclones in the Arabian Sea is also increasing.

India has got digital data on rainfall since 1901. Parts of north, east and northeast India show a decrease in rainfall, while some areas in the west, such as west Rajasthan, show an increase.

Monsoon: Uttar Pradesh, Bihar, West Bengal, Meghalaya and Nagaland had shown significant decreasing trends in the southwest monsoon rainfall during the recent 30-year period (1989-2018).

Cloud bursts: A study by the Indian Institute of Tropical Meteorology, MoES says the frequency of mini-cloud bursts (five cm or more rainfall in an hour) is increasing in the Himalayas.

Reason for intense rainfall: Studies have proved that this increase in heavy rainfall events and decrease in light precipitation is due to climate change.

Climate change has increased the surface air temperature, which in turn has increased the evaporation rate. Since warmer air holds more moisture, it leads to intense rainfall.

How India is improving its weather forecasts?

IMD’s forecast accuracy had improved by about 30% to 40% for severe weather events such as cyclones, heavy rain, thunderstorms, heat waves, cold waves and fog in the past five years due to an improvement in the observational network, modelling and computing systems.

Firstly, the IMD is bolstering its observational network with the augmentation of radars, automatic weather stations and rain gauges and satellites to improve predictability.

IMD has put up six radars in the northwest Himalayas and four more will be installed this year.

Note: Radars are preferred because they have a higher resolution and can provide observations every 10 minutes.

Secondly, Ministry of Earth Sciences (MoES) also plans to upgrade its high-performance computing system from a capacity of 10 petaflops currently to 30 petaflops in the next two years. This will help assimilate more data into the model that can then be run at higher resolutions.

Thirdly, IMD-MoES weather modelling system has a resolution of 12 kilometres. The target is to make it six kilometres. Similarly, the resolution of the regional modelling system will be improved from three kilometres to one kilometre.