Cyclone Michuang is the result of the trio of El Nino, the Indian Ocean Dipole and Madden-Julian Oscillation.
El Nino is a weather phenomenon that causes the warming of the ocean surface, or above-average sea surface temperatures, in the central and eastern tropical Pacific Ocean.
The 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.
The lesser known Madden-Julian Oscillation (MJO) is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverses the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average.
What made Cyclone Michuang extremely powerful was a coming together of the three phenomena. El Ninos peak around Christmas.
As oceans absorb more than 93 per cent of the additional heat from global warming, El Niños are also getting stronger.
“They are not little boys anymore but monsters of the sea. Changes in ocean-cyclone interactions have emerged in recent decades in response to Indian Ocean warming and are to be closely monitored with improved observations since future climate projections demonstrate continued warming of the Indian Ocean at a rapid pace along with an increase in the intensity of cyclones in this basin,” said Dr Roxy Mathew Koll, Climate Scientist at the Indian Institute of Tropical Meteorology.
The not so little boy was helped by IOD and MJO—both associated with positive rainfall over Indian landmass which were in favourable zones. These, along with anomalous high sea surface temperatures, provided conducive dynamic and thermodynamic conditions for the cyclone.
Ocean warming due to greenhouse gases and sea surface temperature (SST) changes are both contributing to intensive cyclonic activity in India, but the magnitude of the role both are playing is still not clear.
Recent observations indicate that cyclones in the north Indian Ocean are now exhibiting rapid intensification, intensifying by more than 50 knots in just 24 hours, in response to SSTs much higher than 30°C, prominently due to the rapid warming in the region. From 2000 onwards, the frequency of cyclones undergoing rapid intensification in the north Indian Ocean has increased. The percentage of cyclones undergoing rapid intensification in the north Indian Ocean is higher (38 per cent) than the cyclones in the northwest Pacific Ocean, where this rate is 22 per cent.
Due to the eastward shift of the cyclogenesis location in the Bay of Bengal, the cyclones are now travelling for a long time over the ocean and drawing more thermal energy released from the warm ocean waters, thereby enhancing the chances of developing into a very severe cyclone with intensity greater than 65 knots.
