New Delhi: The Indian Ocean has been warming rapidly over the past few decades, with a sea surface temperature estimate recording 0.15°C increase per decade between 1951 and 2015, the Ministry of Earth Sciences (MoES) said in the Lok Sabha on Wednesday.
“The Indian Ocean has been warming rapidly over the last few decades. An estimate based on Enhanced Reconstructed Sea Surface Temperature (ERSSTv4) indicates that the tropical Indian Ocean is warming at a rate of 0.15 degC per decade during 1951–2015,” minister of earth sciences Jitendra Singh said.
He added that the Northern Arabian Sea is also seeing an escalated warming.
“The Sea Surface Temperature (SST) trend during 1982–2019 for the Arabian Sea indicates that annual anomalous warming of 1.5 deg C in the recent decade is limited to the northern part of the Arabian Sea and 0.75 deg C in some parts of the southern Arabian Sea,” he said.
The minister was responding to a question by Bharatiya Janata Party (BJP) MP Parshottam Khodabhai Rupala on (1) the reason for Ocean Areas suffering the most due to intense adverse effects of climate events; (2) whether it is due to overground and underground salinity ingress apart from cyclones and (3) the details of the Action plan and its actual progress thereof, State/UT-wise including Gujarat.
The minister, in his response, said decaying phase of El Niño is the most influential mode contributing to more than 70 %–80% of observed heatwave days in the Indian Ocean basin.
Further, apart from the effects of cyclones and other extreme weather events, overground and underground salinity ingress are significant contributors to the suffering of coastal regions and ocean areas, he said.
“Owing to this rapid warming, the duration (frequency) of Marine Heat Waves (MHW) exhibits a rapidly increasing trend of ~ 20 days per decade in the northern Arabian Sea and the southeastern Arabian Sea close to the west coast of India, which is a multi-fold increase in MHW days (frequency) from the 1980s. Moreover, longer heatwave days are also associated with dominant climate modes,” he said.
“In coastal areas where storm surges from frequent cyclones occur, salinity can increase rapidly, further affecting both human settlements and ecosystems. Overground salinity ingress leads to the degradation of freshwater habitats, reduced agricultural productivity and loss of critical ecosystems like wetlands and mangroves,” Singh added.
HT had reported last year that the Indian Ocean basin, the fastest warming basin will record further accelerated warming at a rate of 1.7°C–3.8°C per century during 2020–2100, a new research paper has projected.
This will lead to increase in severe weather events; prolonged marine heat waves; extreme Indian Ocean Dipole events that will influence the monsoon and cyclone development; prolonged marine heat waves and major drop in marine productivity by end of century, the paper warned. The authors used observed data for the historical period and Intergovernmental Panel on Climate Change’s climate simulations under low-to-high emission scenarios to simulate future conditions in the Indian Ocean.
“The future increase in heat content is comparable to adding the energy equivalent of one Hiroshima atomic bomb detonation every second, all day, every day, for a decade,” said Roxy Mathew Koll, climate scientist and author of the paper.
Indians experienced unusually high temperatures during December to January
In a separate development, an analysis by US based Climate Central found that India ranked fifth in the top 10 countries in Asia with the highest average temperature anomalies during December 2024 to February 2025 period.
Over 358 million people across 12 states in India experienced daily average temperatures that were strongly influenced by climate change for at least one-third of the season (30 or more days), it said. Also, more than 150 million people in Maharashtra and Mizoram experienced average temperatures that were 1.6 degree C above their 1991-2020 normals, the highest across India.
“Climate change is not a distant threat but a present reality to millions,” said Kristina Dahl, VP of Science at Climate Central in a statement. “The increasing frequency and severity of heat events around the world reveal a dangerous pattern of heat exposure that will only worsen if the burning of fossil fuel continues.”
Globally, at least one in five people felt a strong climate change influence every day from December 2024 to February 2025. Hundreds of millions experienced heat-related health risks: Nearly 394 million people were exposed to 30 or more days of risky heat added by climate change, 74% of whom live in Africa. Risky heat days are defined as days with temperatures hotter than 90% of local temperatures recorded from 1991 to 2020.
In 287 cities worldwide, residents felt the influence of climate change on temperatures for at least a month (30 days or more), the analysis said.