Context: Recently, the India Meteorological Department (IMD)’s published its ‘Statement on Climate of India in 2020’.
Key highlights of the report:
Temperature

• 12 out of the 15 warmest years were reported between 2006 and 2020, and that the past decade (2011-2020) was the warmest decade on record.
• 2020 was the 8th warmest since India started keeping records in 1901.
• During the year 2020, the annual average temperature in the country was above the average during all the seasons except pre-monsoon season.
• The mean monthly temperatures were warmer than the normal during all months except March and June.
• India’s warming was significantly lower than the global average.
• As per the World Meteorological Organisation’s State of the Global Climate; the global mean temperature rose during 2020 was 1.2°C above pre-industrial levels.

Rainfall

• The annual rainfall over the country was 109% of the Long Period Average (LPA) calculated for the period of 1961-2010.

Tropical storms
During 2020, 5 cyclones formed over the North Indian Ocean. These are:

• The Indian Ocean region - the Arabian Sea and the Bay of Bengal, together reported five cyclones - Amphan, Nisarga, Gati, Nivar and Burevi.
• Of these, Nisarga & Gati formed over Arabian Sea, while the remaining 3 cyclones formed over the Bay of Bengal.
• Globally, the Atlantic Ocean experienced one of the most active years, with over 30 tropical storms originating here.

Extreme weather events

• Heavy rainfall, floods, landslide, thunderstorm, lightning, and cold waves led to significant loss of lives and properties in 2020.
• Uttar Pradesh and Bihar reported the highest casualties due to cold waves, lightning and thunder in 2020.

El Niño and the Southern Oscillation (ENSO) & La-Nina

• El Niño and the Southern Oscillation (ENSO) is a periodic fluctuation in sea surface temperature and the air pressure of the overlying atmosphere across the equatorial Pacific Ocean.
• It has a major influence on weather and climate patterns such as heavy rains, floods and drought.
• El Nino has a warming influence on global temperatures, whilst La Nina has the opposite effect.

Effects of La-Nina

• La Nina’s typically has a cooling effect on global temperatures, but this is now offset by global warming due to greenhouse gas emissions.
• As a result, La Nina years now are warmer than years with El Nino events of the past.
• 2020 was one of the warmest years despite having a La Nina with cool waters in the east Pacific.
• As for India, increasing trend in temperatures is the largest during the post-monsoon season and this is reflected in the 2020 post-monsoon temperatures over India, despite a full-fledged La Nina.

India Meteorological Department (IMD)

• IMD is an agency under the Ministry of Earth Sciences of the Government of India.
• It is the principal agency responsible for meteorological observations, weather forecasting and seismology.
• IMD is headquartered in Delhi.
• It has the responsibility for forecasting, naming and distribution of warnings for tropical cyclones in the Northern Indian Ocean region, including the Malacca Straits, the Bay of Bengal, the Arabian Sea and the Persian Gulf.