Key Highlights The Indian Ocean Region (IOR) has warmed by approximately 1.2°C over the past century, leading to significant changes, including expanding the Indian Ocean Warm Pool (IOWP). Warming has caused higher sea levels and shifts in climate dynamics, potentially disrupting critical rainfall patterns for countries like India. Expanding Oxygen Minimum Zones (OMZs) and declining net primary production (NPP) threaten marine life, leading to shifts in fish populations and potential declines in India’s marine fish catch by 10% to 30% by 2050. Expanding Oxygen Minimum Zones (OMZs) and declining net primary production (NPP) threaten marine life, leading to shifts in fish populations and potential declines in India’s marine fish catch by 10% to 30% by 2050. India’s blue economy, crucial for GDP and livelihoods, is threatened by coastal flooding, erosion, and infrastructure vulnerability, requiring policy interventions for re-skilling and upskilling. The Underwater Domain Awareness (UDA) framework and Marine Spatial Planning (MSP) are essential for addressing ocean governance challenges through enhanced surveillance, monitoring technologies, and adaptive strategies for sustainable resource management and coastal resilience. Introduction Over the years, the ocean’s climate change risk has been increasing alarmingly. The past decade has recorded some of the highest-ever sea surface temperatures (SST) and events like coral bleaching in several ocean regions. Given the accelerating rate of anthropogenic greenhouse gas emissions, it is very likely that in the coming years, climate change will significantly disrupt the entire marine ecosystem. This disruption will indirectly affect humanity, threatening livelihoods and reducing the contribution of the blue economy to the world. The Indian Ocean region, experiencing the highest increase in the net ocean heat content (OHC) in the 21st century compared to other oceans, is particularly vulnerable. This ocean caters to approximately 33% of the world’s population despite covering only 20% of the Earth’s water surface. Therefore, there is an urgent need to adopt a framework that addresses the climate change problem in the Indian Ocean Region (IOR), considering factors such as the unique features of tropical waters, socio-cultural, economic, and political conditions of the local people, and the impact of climate change on the underwater ecosystem. Despite the formation of various global groups like COP and UNEP and the signing of various agreements by the world leaders to tackle climate change, no impactful on-ground result has been achieved till now. Climate Change Impact: Indian Ocean The Indian Ocean (IO) is experiencing one of the fastest surface warming rates (SST) among the world’s oceans, with a rise of approximately 1.2°C over the past century. The Pacific Ocean has seen an increase of about 0.6°C, while the Atlantic Ocean’s SST has risen by approximately 0.7°C. This comparison highlights the varying impacts of global warming on different ocean basins, with the Indian Ocean showing particularly significant changes. This rapid warming has raised the temperature of the upper water layer of the IO basin above 28°C, leading to a dramatic expansion of the Indian Ocean Warm Pool (IOWP) over the past two decades, now covering nearly 100% of the northeast and central IO.Additionally, the heat content of the IO has increased abruptly, contributing to more than a quarter of the global ocean heat gain in the upper 700 meters over the recent decade. Consequently, rising sea levels and melting ice sheets significantly threaten flooding in low-lying coastal regions. “Given India’s high coastal population density, this may lead to loss of livelihood and displacement of people. Furthermore, higher SST influences climate dynamics and likely impacts the ENSO pattern, altering atmospheric circulation. This deviation from the actual pattern will ultimately harm countries like India that rely on this phenomenon for rainfall. Studies indicate that by the end of the 21st century, the IOR may experience permanent marine heat waves, exacerbating these issues.” Impact on the Underwater Ecosystem Disbalance in the Fish Population: A recent review of Oxygen Minimum Zones (OMZs) revealed that low oxygen concentrations in coastal areas of the Arabian Sea and Bay of Bengal directly threaten marine life and impact nitrogen cycles in these ecosystems. With continued warming, OMZs are expected to expand, further intensifying anoxic conditions in the coastal IO zones. Several studies have noted declining trends in net primary production (NPP) in the IO, primarily due to warming-induced stronger stratification, which reduces nutrient availability. Model simulations project declines in NPP in the tropical IO, indicating up to a 25% reduction in phytoplankton carbon in most IO regions between 1990–1999 and 2090–2099. This will lead to behavioural changes for various fish species, forcing them to migrate to other habitable zones. Recent observations confirm that many tropical marine species remain in temperate waters. Changes in spawning patterns and dietary habits will potentially lead to the overpopulation of some species and a decline in others, disrupting prey-predator relationships and, ultimately, the whole food web. By 2050, studies suggest that India’s marine fish catch could decrease by about 10% to 30% due to climate change risks. These impacts underline the urgent need for sustainable management and adaptive strategies to mitigate the effects of climate change on marine ecosystems and fisheries. Proactive measures will be essential to preserving biodiversity and securing livelihoods dependent on these critical resources. Coral Bleaching: A World Economic Forum report indicates that if anthropogenic emissions of GHGs are not kept below the threshold level, it may trigger a climate tipping point, leading to widespread coral bleaching in low-latitude waters by 2040. Coral reefs are crucial for the underwater ecosystem, supporting life for many marine species by providing food and shelter. They also support fisheries, tourism, and recreation, offering global economic benefits. In fact, India’s tourism sector significantly contributes to the economy, especially coastal tourism, which heavily depends on corals. “Increased CO2 levels cause ocean acidification, impairing the ability of corals to produce calcium carbonate, which weakens their skeletons, making them more susceptible to damage and bleaching. Rising temperatures have caused widespread coral bleaching across the IO, compromising habitats for associated marine organisms. The consequences of coral bleaching include loss of biodiversity, ecosystem collapse, and increased risks of erosion