Bronte Wells
The Indian Ocean is the world's third-largest ocean, covering about 20% of the Earth's surface. It is a habitat to diverse marine species, including sharks, dugongs, whales, and sea turtles, and is a migration route for wildlife. It is also a major tourist destination, with its turquoise waters, breathtaking islands, and immaculate white sandy beaches.
However, the Indian Ocean is under threat from various sources of pollution. An international group of scientists documented widespread pollution covering about 10 million square kilometres of the tropical Indian Ocean. This pollution is caused by the emission of large quantities of pollutants from Asia and the Indian subcontinent, which are then carried to the Indian Ocean by monsoon winds.
One of the primary sources of pollution in the Indian Ocean is plastic waste. The Indian Ocean receives a large proportion of plastics, with some of the most plastic-polluted rivers emptying into it. This plastic waste comes from coastal sources, such as wind and tides, and riverine sources. It is estimated that the Indian Ocean contains the second-largest plastic load in the ocean after the North Pacific Ocean.
Another source of pollution in the Indian Ocean is oil spills. It is estimated that 3-5 million tonnes of oil and petroleum are discharged into the Indian Ocean annually, accounting for approximately 40% of the total petroleum spill in the world's oceans.
Other sources of pollution in the Indian Ocean include heavy metals, sewage, and agricultural chemicals. Climate change also poses a significant threat to the Indian Ocean, with heat absorption from the atmosphere leading to marine heatwaves, sea-level rise, ice melting, and ocean acidification.
| Characteristics | Values |
|---|---|
| Type of pollution | Aerosols, soot, sulfates, nitrates, organic particles, fly ash, mineral dust, carbon monoxide, various organic compounds, sulfur dioxide, plastic, oil, petroleum, heavy metals, sewage, agricultural chemicals |
| Polluted area | 10 million square kilometers |
| Polluted region | Arabian Sea, Bay of Bengal, equatorial Indian Ocean |
| Polluted countries | India, Thailand, Malaysia, Indonesia, Bangladesh, South Africa, Pakistan, Myanmar |
| Polluted rivers | Ganges, Indus |
Oil spills
The MV Wakashio oil spill in July 2020, which leaked heavy fuel oil in a biodiversity hotspot near Mauritius, is a prime example of the consequences of oil spills. The spill endangered rich marine ecosystems that are home to 1,700 species, including 800 types of fish, 17 kinds of marine mammals, and two species of turtles. The turquoise waters around Mauritius turned black, its mangrove wetlands were polluted, and its wildlife was coated in sticky fuel oil. Experts say it will take decades to repair and restore the biodiversity of the region.
The impact of oil spills is not limited to the ocean. Oil spills can also cause significant economic damage to industries and communities, with estimated costs ranging from USD 8 billion to USD 2500 billion.
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Chemical pollution
The Indian Ocean region is home to some of the world's most densely populated nations, with India being the highest, and most countries in the region are developing countries with little regulation. This has led to widespread use of fertilisers, which wash up with rainwater and enter nearby water bodies that eventually join the ocean. Coal burning is also common in the region, and coal contains a harmful substance called mercury, which vaporises and enters the atmosphere when burned.
The dumping of untreated sewage and radioactive materials generated during mining is also a significant concern. Chemical pollution leads to a phenomenon called algal bloom, where phytoplankton, a photosynthesising alga, uses nutrients like nitrogen and phosphorus, which become present in excess due to chemical pollutants in the ocean. The algae cover a large surface of the water, blocking sunlight from reaching the ocean floors and causing a severe reduction in the water's oxygen level. This creates "dead zones" in the ocean, where the survival of marine organisms is difficult.
In addition, the Indian Ocean region accounts for around 40% of the world's offshore oil production, and certain events like oil spills are tremendously damaging to the ocean. Oil spills can occur due to accidental leaks, careless release of oil and its products in water bodies, and illegal discharges from shipping operations. Oil spills can have a deadly effect on aquatic life and marine birds as they contain highly toxic residual matter.
Another significant source of chemical pollution in the Indian Ocean is plastic waste, with a large percentage of plastic waste predicted to enter the ocean. Most of the countries contributing to the highest amount of plastic pollution worldwide are located in the Indian Ocean region, and two of the world's largest and most polluting rivers, the Ganges and the Indus, flow into the Indian Ocean.
To reduce the growing pollution in the Indian Ocean, regional governments should invest in building improved waste disposal facilities, conduct frequent inspection drives in industries, and take stringent measures against those flunking the rules.
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Plastic pollution
Sources of Plastic Pollution
The Indian Ocean is surrounded by 34 countries with an average population density of around 100 people per square kilometre. The countries with the highest population densities in the world are located along the Indian Ocean rim. The mismanagement of plastic waste is a concern in many of these rim states.
The main sources of plastics are rivers (terrestrial sources), with the majority of input in the Northern Indian Ocean, particularly the Bay of Bengal. There are also land-based sources from Indonesia into the Southern Indian Ocean. The Ganges and Indus rivers, two of the largest and most polluting rivers, empty into the Indian Ocean.
The Indian Ocean is one of the busiest international maritime transportation routes and neighbours some of the largest plastic polluters, such as China, Indonesia, and Sri Lanka. Shipping-related debris is another important source of plastics to the Indian coast.
Impact of Plastic Pollution
Addressing Plastic Pollution
The Indian government has taken several concrete initiatives to combat plastic pollution. These efforts will also contribute to global commitments, such as UN SDG 14. Identifying plastic accumulation zones is one of the key tools to understand marine plastic dynamics.
Some solutions to plastic pollution include:
- Mapping the distribution of marine plastics based on in-situ sample collection, citizen science, or the latest scientific tools.
- Modelling studies to confirm the identified accumulation zones and identify additional zones that will help to develop an effective plastic removal program.
- Developing a platform to support the integration and the analysis of all monitoring data.
- Promoting detailed studies on smaller polluting rivers to develop removal strategies, as removing litter from smaller rivers will be more practical than larger river basins.
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Climate change
According to scientific studies and the Intergovernmental Panel on Climate Change (IPCC) report, the key climatic parameters of the Indian Ocean are expected to undergo substantial changes. The annual mean sea surface temperature (SST) is projected to increase by more than 2.5°C, with the highest increase of around 3.4°C in the northern part of the Arabian Sea and the Persian Gulf. These changes in SST will have a significant impact on the marine ecosystem and biological productivity.
The sea surface salinity (SSS) will also exhibit strong spatial variability, with the highest freshening over the northern Bay of Bengal and increased salinity in the Persian Gulf and northern Arabian Sea. Changes in precipitation patterns will result in increased rainfall in some areas, such as the eastern coast of the Bay of Bengal, while decreasing in others, including the western Bay of Bengal and northern Indian states.
The Indian Ocean region is home to a diverse range of flora and fauna, and the environmental threats posed by climate change have significant implications for the fishing community as well. The warming ocean temperatures, intensified monsoons, and altered rainfall patterns will impact the livelihoods of millions of fisherfolk who depend on the region's natural resources.
Moreover, the Indian Ocean Rim Association (IORA) has been identified as a potential catalyst for collective action to address the climate crisis in the region. The organisation includes island nations like the Maldives, Mauritius, and Seychelles, which are highly vulnerable to the impacts of climate change. The IORA can play a unifying role in environmental conservation and sustainability, as well as providing alternative solutions for communities dependent on the ocean's resources.
In conclusion, climate change is a critical issue for the Indian Ocean region, and collective efforts are necessary to mitigate its impacts and ensure a sustainable future for the diverse ecosystems and communities that depend on it.
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Deep sea mining
Deep-sea mining is the extraction of minerals from the seabed of the deep sea. The International Seabed Authority (ISA) regulates all mineral-related activities in international waters and has granted 31 exploration licenses so far. The ISA has also entered into 17 contracts with private companies and national governments in the Clarion–Clipperton zone (CCZ) in the Pacific Ocean, one contract with the Government of India in the Central Indian Ocean Basin (CIOB), and one contract with a Chinese contractor in the Prime Crust Zone (PCZ) in the Western Pacific.
The main ores of commercial interest are polymetallic nodules, which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain. These nodules typically range in size from 4–14 cm (1.6–5.5 in) in diameter, though some can be as large as 15 cm (5.9 in). They are rich in metals including rare earth elements, cobalt, nickel, copper, molybdenum, and yttrium. The Clarion–Clipperton zone (CCZ) alone contains over 21 billion metric tons of these nodules, with minerals such as copper, nickel, and cobalt making up 2.5% of their weight. It is estimated that the global ocean floor holds more than 120 million tons of cobalt, five times the amount found in terrestrial reserves.
The most common commercial model of deep sea mining involves a caterpillar-track hydraulic collector and a riser lift system bringing the harvested ore to a production support vessel with dynamic positioning, and then depositing extra discharge down the water column. Other technologies include robotic mining machines, surface ships, and offshore and onshore metal refineries.
The environmental impact of deep sea mining is controversial. Environmental advocacy groups such as Greenpeace and the Deep Sea Mining Campaign claimed that seabed mining has the potential to damage deep sea ecosystems and spread pollution from heavy metal-laden plumes. Critics have called for moratoria or permanent bans. Opposition campaigns enlisted the support of some industry figures, including firms reliant on the target metals.
India has been allotted a site of 75,000 sq. km for exploitation of polymetallic nodules. The National Institute of Ocean Technology (NIOT) recently conducted an exploratory deep-sea mining trial in the Andaman Sea. The scientists at NIOT, under the Ministry of Earth Sciences, India, employed a machine called Varaha-3, specially designed for this location. Varaha-3 weighs six to seven tonnes underwater and has a comb-type collector mechanism to pick up the embedded nodules from the sea floor.
The resistance to deep-sea mining is simultaneously at an all-time high, globally. More than 900 scientists and policy experts have recommended a pause on deep-sea mining, citing the stress and impact of seabed mining on the marine ecosystem and biodiversity.
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Frequently asked questions
The Indian Ocean is the second most polluted ocean in the world. It receives approximately 15% of global coastal plastic and 20% of riverine plastic. The ocean is also affected by oil spills, with an estimated 3-5 million tonnes of oil and petroleum discharged into the ocean annually.
Pollution in the Indian Ocean has a detrimental effect on marine life. Plastic pollution, for example, can result in the ingestion of plastic by marine animals, entanglement, and the transportation of invasive species. Oil spills can cause the paralysis of the entire ecosystem below the water surface.
The Indian Ocean absorbs approximately 80-90% of the heat from the Earth's surface, minimising the adverse impacts of climate change. However, the ocean's capacity to mitigate global warming is declining due to the effects of climate change, such as marine heatwaves and ocean acidification.
The Indian Ocean is a source of food security for many coastal communities, providing a significant amount of the world's seafood. It is also a major tourist destination, sustaining the economies of the numerous nations it borders.
Greenpeace is actively campaigning to address the threats faced by the Indian Ocean, including overfishing, climate change, deep-sea mining, seismic blasting, plastic pollution, coral reef degradation, and coastal development.
