Bay of Bengal Warmed and Acidified Over Six Decades
Research published in 2026 details ocean shifts that may alter underwater acoustics by the end of the century.
Updated on Oct. 3, 2026 in Environmental
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Researchers analyzing data from 1960 to 2020 found that the Bay of Bengal's upper 50 metres warmed by up to 2.2°C. Additionally, surface pH levels dropped from 8.3–8.4 in the 1960s to 8.1–8.2 after 2000, driven by rising atmospheric CO2.
Why it matters
Changes in water acidity and temperature directly affect how sound travels through the ocean, potentially increasing noise pollution and disrupting the feeding behaviors of marine life. This shift demonstrates the profound impact of rising atmospheric carbon dioxide on regional marine environments.
A 0.1 reduction in pH units can decrease sound absorption in seawater by 10% to 12%. Researchers measured heat storage increases of 0.018 × 10 joules per square metre per decade within the Bay's 32-metre average barrier layer.
The players
Sagar Maitri expedition
A research initiative focused on oceanographic data collection in the Indian Ocean.
International Indian Ocean Expedition
A historic international scientific collaboration that provided the foundational 1960s marine baseline data.
The details
The study compared data from the 1963 International Indian Ocean Expedition with 2019 measurements from the Sagar Maitri expedition. Acidification occurs as atmospheric carbon dioxide dissolves into seawater to form carbonic acid, a chemical reaction that lowers the liquid's pH. While the upper 50 metres warmed, researchers noted cooling trends in deeper waters between 100 and 200 metres.
Timeline
1960-2020: The timeframe for the collected ocean temperature and pH records.
1963: Observations made during the International Indian Ocean Expedition.
2000: The period after which lower pH levels were consistently observed.
2019: Data collection period for the Sagar Maitri expedition.
September 2, 2026: The publication date of the findings in Ocean Dynamics.
The Tech Race
This research provides a necessary updated baseline that contrasts with older environmental records. It marks a critical step in calibrating ocean models against the trajectory set by the International Indian Ocean Expedition.
Changes in underwater sound transmission could eventually affect marine industries that rely on acoustic communication or sonar monitoring. Understanding these shifts is necessary for developing future maritime environmental management strategies.
The takeaway
The research highlights that regional environmental shifts are significantly outpacing historical norms in the Bay of Bengal. Watch for future acoustic modeling studies that quantify how these chemical changes impact local marine biodiversity.
Further reading
For more on the long-term health of our oceans, read the latest findings in Environmental.
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