Rising sea temperatures across the Indian Ocean have reached alarming levels, triggering widespread concern among scientists and policymakers. A new warning issued by the Indian National Centre for Ocean Information Services highlights that large parts of the ocean are currently experiencing marine heatwaves, posing serious threats to coral reefs, fisheries, and millions of people who depend on marine resources.
Widespread marine heatwaves across key regions
According to INCOIS, marine heatwaves have now spread across multiple basins, including the Arabian Sea, Bay of Bengal, and surrounding waters. As of April 2026, the Arabian Sea has emerged as the most affected region, followed closely by the Bay of Bengal.
Scientists classify marine heatwaves based on how much sea temperatures rise above long-term averages. Conditions are categorised as “Watch,” “Alert,” or “Warning” depending on the intensity of warming. In the Arabian Sea, around 22 percent of the area is under Watch, 9 percent under Alert, and 1 percent has already reached Warning levels, indicating severe temperature anomalies.
These elevated temperatures stretch along India’s western coastline, covering states from Gujarat to Kerala, and extending westwards toward Oman. Such widespread warming is unusual and signals growing instability in marine ecosystems.
Bay of Bengal and Andaman waters under stress
In the Bay of Bengal, nearly 19 percent of the region is under Watch conditions, with Alert levels recorded in several areas. The most intense warming has been observed around the Andaman and Nicobar Islands, with heat spreading further toward Southeast Asia, including Myanmar and Thailand.
Other affected regions include parts of the South China Sea, where a significant portion of waters is already under Warning conditions. Repeated marine heatwaves in these areas are increasing pressure on some of the world’s most biodiverse coral reef systems.
Threat to coral reefs and marine ecosystems
Experts warn that rising sea temperatures can have devastating ecological consequences. One of the most immediate risks is coral bleaching, a process in which corals expel the algae that provide them with energy, causing them to turn white and potentially die.
In addition to coral damage, marine heatwaves can disrupt fish migration patterns, reduce ocean productivity, and alter plankton populations, which form the base of the marine food chain. These changes can ripple through entire ecosystems, affecting biodiversity on a large scale.
The report also points to impacts in regions such as the Red Sea and Persian Gulf, as well as the southern Indian Ocean near Madagascar, Mauritius, and Seychelles, where warming waters may disrupt tuna migration routes.
Livelihoods and food security at risk
The consequences of these changes are not limited to the environment. Millions of people, particularly in coastal communities, depend on fisheries for their livelihoods and food security. Disruptions in fish availability and declining ocean productivity could directly impact incomes, nutrition, and economic stability.
Scientists warn that prolonged marine heatwaves could lead to long-term damage, making recovery difficult for both ecosystems and communities.
The current situation reflects the broader impact of climate change on the world’s oceans. As global temperatures rise, oceans absorb much of the excess heat, leading to more frequent and intense marine heatwaves.
Experts stress the need for continuous monitoring, improved forecasting, and stronger climate action to reduce future risks. Without timely intervention, the warming of the Indian Ocean could have far-reaching consequences, not only for marine life but also for human populations that rely heavily on it.