Rising seas, stronger cyclones and the fight for our blue planet

The oceans — sustaining life, biodiversity, and oxygen production — face mounting threats. Rising sea levels, warming waters, coral bleaching, plastic pollution, and intensifying coastal disasters are pushing marine ecosystems towards a dangerous tipping point

Every year the world comes together to observe World Ocean Day — a moment to reflect on how deeply our lives depend on the health of our seas. Oceans cover nearly 71 per cent of Earth’s surface, produce half the oxygen we breathe, regulate the global climate, and sustain the livelihoods of over three billion people. Yet today, these vast blue expanses face an unprecedented convergence of threats: climate change, pollution, habitat destruction, overfishing, and even the environmental fallout of armed conflict.

The theme of World Ocean Day 2026 — “Reimagine: Beyond the World We Know, A New Relationship with Our Ocean” — captures the urgency of this moment. It is a reminder that humanity’s fate is inseparable from the fate of the ocean, and that meaningful change demands more than awareness. It demands action. Central to this year’s campaign is the call for strong Marine Protected Areas and the urgent implementation of the global 30×30 Goal — the commitment to place at least 30 per cent of the planet’s lands, waters, and oceans under conservation protection by 2030.

The Ocean as Earth’s Life-Support System

The oceans are far more than a scenic backdrop to human civilisation. They absorb roughly 30 per cent of all carbon dioxide emissions and about 90 per cent of the excess heat generated by those emissions. Without this enormous buffering capacity, Earth’s surface temperatures would climb rapidly, rendering vast regions uninhabitable. In this sense, the ocean is not just the planet’s lungs — it is its most critical climate regulator. But this service comes at a cost. As oceans absorb more heat and carbon dioxide, they grow warmer and more acidic, making conditions increasingly hostile for marine life. The consequences are already visible: more frequent marine heatwaves, mass coral bleaching events, disrupted migration patterns among fish species, and the intensification of tropical storms. Ocean warming is not a problem of the distant future. It is one of the defining challenges of our time.

Rising seas and coastal peril

Global mean sea levels have already risen between 21 and 24 centimetres since 1880, driven by the thermal expansion of warming water and the accelerating melt of glaciers and ice sheets. The latest IPCC projections suggest sea levels could rise by anywhere between 30 centimetres and one metre by the end of this century, depending on future emissions.

The human stakes are immense. More than 680 million people currently live in low-lying coastal zones. Major cities — Mumbai, Kolkata, Shanghai, Bangkok, Jakarta, New York, and Miami — face growing flood risks. Entire small island nations risk being submerged, with their populations displaced. For India, with over 7,500 kilometres of coastline supporting ports, industries, fishing communities, and dense urban populations, the threat is particularly acute. Rising seas combined with growing coastal populations are creating a slow-moving disaster that will define the coming decades.

Corals: Ocean’s Vanishing Rainforests

Coral reefs occupy just one per cent of the ocean floor, yet they shelter approximately 25 per cent of all marine species. They sustain fisheries, provide livelihoods through tourism, and protect coastlines by absorbing wave energy. But they are also among the most climate-sensitive ecosystems on Earth. Warmer water triggers coral bleaching — corals expel the symbiotic algae they depend on for survival, and repeated bleaching leads to colony death.  Scientists estimate that up to 50 per cent of the world’s coral reefs have already disappeared or severely degraded since 1950. A recent global bleaching event affected reefs in more than 80 countries. The loss ripples outward: declining fish stocks, diminished tourism, and coastlines vulnerable to storm surges.

Acidification and plastic: Twin silent crises

Ocean acidification — often called the “evil twin” of climate change - receives far less attention than it deserves. Since the Industrial Revolution, ocean acidity has increased by 26 per cent. This threatens species that rely on calcium carbonate to build shells and skeletons, including corals, shellfish, and plankton. As these foundational organisms struggle, the effects cascade through entire marine food webs, ultimately threatening food security for coastal communities worldwide.

Meanwhile, plastic pollution has reached catastrophic proportions. Between 19 and 23 million tonnes of plastic waste enter the oceans every year. Plastic has been found in the deepest ocean trenches and in the most remote marine environments. Sea turtles mistake plastic bags for jellyfish. Seabirds feed plastic fragments to their chicks. Abandoned fishing gear entangles and kills marine animals. As larger plastic breaks down into microplastics, these particles have turned up in seafood, drinking water, human blood, and even placental tissue. If current trends continue, plastic entering the ocean could nearly triple by 2040.

Mangroves: Nature’s frontline defence

Among the most underappreciated coastal ecosystems are mangrove forests. These remarkable trees — thriving at the boundary between land and sea — serve as nurseries for fish, crabs, and prawns, improve water quality, and function as highly efficient carbon sinks, storing more carbon per unit area than many terrestrial forests. India has approximately 4,992 square kilometres of mangrove cover, including the Sundarbans, the world’s largest mangrove forest. Critically, mangroves provide natural disaster protection. Research shows that intact mangrove belts can reduce wave height by up to 66 per cent, significantly buffering the impact of cyclones, storm surges, and floods. Communities shielded by healthy mangroves during the 2004 Indian Ocean tsunami and subsequent Bay of Bengal cyclones suffered considerably less damage than those where mangroves had been cleared. Despite this, mangroves continue to face destruction through urbanisation, aquaculture expansion, industrial development, and rising seas. Protecting and restoring them is one of the most cost-effective climate adaptation strategies available.

Cyclones, conflict, and the road ahead

Ocean warming is also fuelling more powerful tropical cyclones. While the total number of storms may not be rising dramatically, a growing proportion are reaching extreme intensity. Cyclones Fani, Amphan, Tauktae, Yaas, Biparjoy, Remal, and Dana have all devastated coastal communities across the Indian Ocean region in recent years.

When intensifying storms combine with rising sea levels, their destructive reach extends deeper inland — threatening deltas, agricultural zones, ports, and entire coastal economies. Less discussed, but equally serious, is the environmental damage caused by armed conflict. Warships, explosions, attacks on oil infrastructure, and the destruction of coastal facilities all contaminate marine ecosystems. Oil spills in strategic waterways such as those in West Asia can devastate coral reefs, mangroves, and fisheries for decades. Environmental protection must be integrated into conflict prevention and post-conflict reconstruction efforts.

A shared responsibility

The solutions are not a mystery. Governments must accelerate low-carbon transitions, expand Marine Protected Areas, restore coastal ecosystems, and strengthen environmental enforcement. Industry must reduce plastic production and embrace sustainable practices. Communities can cut plastic use, support sustainable fisheries, and participate in coastal restoration. Internationally, cooperation must deepen because oceans belong to no single nation. The ocean has sustained human civilisation for thousands of years. On this World Ocean Day, the call is clear: we must now sustain it in return.

Ocean warming is also fuelling more powerful tropical cyclones. While the total number of storms may not be rising dramatically, a growing proportion are reaching extreme intensity. Cyclones Fani, Amphan, Tauktae, Yaas, Biparjoy, Remal, and Dana have all devastated coastal communities across the Indian Ocean region in recent years

Satendra Singh, IFS, former Executive Director, National Institute of Disaster Management, GOI and Tanushree, Junior Faculty at FDDI, Ministry of Commerce and Industry, GOI; Views presented are personal.