Warming Bay: An ongoing heatwave in India’s eastern sea is causing extreme rain in its northwest, say experts

Source: The post is based on the article “Warming Bay: An ongoing heatwave in India’s eastern sea is causing extreme rain in its northwest, say experts” published in Down To Earth on 8th July 2023

What is the News?

The northern Bay of Bengal has been experiencing an intense marine heatwave. This has led to India’s usually arid northwest receiving extreme rainfall.

What is causing heavy rainfall in Northwest India?

During the monsoon, the northern Bay of Bengal tends to be warm.

This region needs to be warm as it plays an important role in the southwest monsoon’s trajectory as it enables the monsoon winds blowing from the southwest to cross over into the Bay of Bengal and bring moisture into the Indian subcontinent.

However, the northern Bay of Bengal currently has been experiencing an intense marine heatwave. Due to this, it is warmer than usual and may be contributing to the extreme rainfall in northwest India.

What are Marine Heatwaves?

Marine heatwaves(MHW) are periods of extremely high temperatures in the ocean (above the 90th percentile). 

Such heat waves are caused by an increase in the heat content of oceans, especially in the upper layers. Worldwide, they are one of the major results of human-induced global warming.

During an MHW, the average temperatures of the ocean surface (up to a depth of 300 feet) goes 5-7 degrees Celsius above normal. 

Impact: These events cause habitat destruction due to coral bleaching, seagrass destruction, and loss of kelp forests, affecting the fisheries sector adversely. 

– An underwater survey showed that 85% of the corals in the Gulf of Mannar near the Tamil Nadu coast got bleached after the marine heatwave in May 2020.