Context:
A recent study by scientists at the Indian Institute of Tropical Meteorology (IITM), Pune highlights that the Indian Ocean is experiencing unprecedented and accelerated warming, which may continue throughout the century.
Key finding of the study
- From 1950-2020, the Indian Ocean had become warmer by 1.2°C and climate models expect it to heat a further 1.7°C–3.8°C from 2020–2100.
- “Marine heatwaves”, in the sea are linked to the rapid formation of cyclones, and are expected to increase tenfold from the current average of 20 days per year to 220–250 days per year.
- The tropical Indian Ocean will likely be in a “near-permanent heatwave state”.
- The heating of the ocean was not merely restricted to the surface but went deeper and increased the overall “heat content” of the ocean.
- The heat content of the Indian Ocean, when measured from surface to a depth of 2,000 meters, is currently increasing at the rate of 4.5 zetta-joules per decade, and is predicted to increase at a rate of 16–22 zetta-joules per decade in the future.
- Joule is a unit of energy and one zetta-joule is equal to one billion trillion joules (10^21).
Indian Institute of Tropical Meteorology (IITM)
- The government of India in February 1962 under its Third Five Year Plan (1961-1966) founded the Institute of Tropical Meteorology (ITM) on 17 November 1962 at Pune.
- Later, it transformed into an autonomous organization on 1st April 1971 under the name Indian Institute of Tropical Meteorology (IITM).
The negative impact of rising Heat content
- Accelerate coral bleaching
- Seagrass destruction
- Loss of kelp forests
- This affects the fisheries sector adversely
- Rising heat content contributes to sea-level rise
Impact on Indian Monsoon
- Heat causes the volume of water to increase, called the thermal expansion of water, and this is responsible for more than half of the sea-level rise in the Indian Ocean – larger than the changes arising from glacier and sea-ice melting.
- The positive phases of the Indian Ocean Dipole (IOD), where the western half is warmer, tend to be favourable for the summer monsoon.
- However, the frequency of extreme dipole events is predicted to increase by 66% whereas the frequency of moderate events is to decrease by 52% by the end of the 21st century.
Indian Ocean Dipole
IOD is a climate pattern affecting the Indian Ocean. During a positive phase, warm waters are pushed to the Western part of the Indian Ocean, while cold deep waters are brought up to the surface in the Eastern Indian Ocean. This pattern is reversed during the negative phase of the IOD.