Marine Heat Waves (MHWs) are periods of abnormally high sea surface temperatures (SSTs) that persist for days to months, affecting a particular ocean area. These events can have significant ecological, economic, and social impacts.
There can be multiple reasons behind the occurrence of Marine Heat Waves. Global warming due to increased greenhouse gas emissions is the primary driver. Warmer atmospheric temperatures lead to warmer ocean temperatures. Changes in atmospheric circulation patterns, such as high-pressure systems, can cause prolonged periods of reduced wind and cloud cover, leading to increased SSTs. Upwelling brings cooler, nutrient-rich water to the surface. If upwelling is reduced or halted, the surface water can heat up more quickly.
It causes various impacts on the Indian Subcontinent. It leads to the migration or death of fish species that are not adapted to warmer waters, affecting the local fish market and the livelihoods of communities dependent on them. It damages the Coral reefs that are found in the Lakshadweep and Andaman and Nicobar Islands, as they are vulnerable to bleaching and mortality during MHWs. They influence the atmospheric conditions, and monsoon patterns, which are important for agriculture and water resources in the Indian subcontinent. The alteration in the temperature of ocean waters impacts marine biodiversity, which results in a change in species composition and causes the decline of certain species. The degradation of marine ecosystems can also lead to the proliferation of harmful algal blooms, which can adversely affect human health and aquatic life.
MHWs are increasingly frequent and intense, driven by climate change. Global mitigation of climate change and local ecosystem management are essential to address this issue.