The Ocean's Limit: Pollution Tolerance And Future Concerns

The ocean is where most of our environmental pollution ends up, from plastic to oil to carbon emissions. The ocean is tolerant, but it has a limit. It cannot and should not be the destination for all our waste. The future of mankind depends on this vast body of water, and all the lives inside it. So, how much pollution can the oceans tolerate?

The ocean's assimilative capacity

The ocean has a finite capacity to tolerate pollution. This is known as the ocean's assimilative capacity. While it is difficult to gauge how much plastic has entered the ocean, it is estimated that at least 150 million metric tonnes of plastic is already circulating in the ocean, with another eight million metric tonnes added every year. This plastic starts to accumulate in the system and choke it.

The ocean is where most of our environmental pollution ends up, contaminated by industries from agriculture to tourism. The ocean absorbs as much as a quarter of all man-made carbon emissions, which changes the pH of surface waters and leads to acidification. This problem is rapidly worsening, with oceans now acidifying faster than they have in some 300 million years. In absorbing so much carbon, the pH level of the ocean surface has increased by an estimated 30% since the start of the industrial revolution 200 years ago.

Headline-grabbing oil spills account for just 12% of the oil in our oceans. Two to three times as much oil is carried out to sea via runoff from roads, rivers and drainpipes. Up to 12 million metric tons of plastic are dumped into the oceans each year, the equivalent of more than 100,000 blue whales.

The whole ecosystem, including our oceans, suffers from air pollution.

Plastic pollution

The ocean is where most of our environmental pollution ends up. It is estimated that at least 150 million metric tonnes of plastic is already circulating in the ocean and another eight million metric tonnes is added every year. This is the equivalent of more than 100,000 blue whales.

The whole ecosystem, including the ocean, suffers from air pollution.

Oil pollution

The ocean is where most of our environmental pollution ends up. While the ocean is tolerant, it has a limit. It cannot and should not be the destination for all our waste.

The release of crude oil from tankers, offshore platforms, drilling rigs, and wells can result in oil spills. These spills can have severe economic consequences, preventing commercial fishing and often resulting in the death or injury of many sea creatures, including birds, sea mammals, fish, algae, and coral.

It's not just oil spills that do damage; every step of oil and gas production harms ocean ecosystems, including the noise pollution it creates — especially seismic airgun surveys. Exploring, drilling, and decommissioning oil and gas infrastructure also releases dangerous chemicals.

Carbon emissions

The ocean is the world's greatest ally against climate change. It generates 50% of the oxygen we need, absorbs 25% of all carbon dioxide emissions and captures 90% of the excess heat generated by these emissions. It is the largest 'carbon sink' – a vital buffer against the impacts of climate change.

However, increasing greenhouse gas emissions have affected the health of the ocean – warming and acidifying seawater – causing detrimental changes to life under water and on land, and reducing the ocean’s ability to absorb carbon dioxide and safeguard life on the planet. Carbon pollution from fossil fuel use and land development has heated the atmosphere and the ocean. When carbon pollution enters the atmosphere, the extra gas in the atmosphere begins trapping heat that would have escaped into space. That heat then warms the land, the atmosphere, and the ocean. The ocean has absorbed about 90% of the heat caused by carbon pollution and other greenhouse gases humans have emitted.

Warming oceans are already leading to sea level rise, stronger storms, fisheries’ moving poleward, and widespread loss of sea ice and glaciers. Carbon pollution is also changing the ocean’s chemistry, slowing its ability to uptake CO2, making it more acidic, and harming shellfish and other marine life we depend on. The ocean has absorbed about 29% of global CO2 emissions since the end of the preindustrial era. In the last decade (from 2008-2017), we’ve dumped into the atmosphere about 40 gigatons of emissions of heat-trapping gases each year from the burning of fossil fuels and land-use change.

If we cut carbon pollution swiftly, we can slow down warming, acidification and deoxygenation, giving marine species and people more time to adjust to 'new normal' conditions. Keeping future conditions near a warming temperature of 1.5 degrees Celsius will help avoid social and ecological tipping points – situations where systems reshuffle so much in response to climate change that they behave in ways that are entirely new to us.

Air pollution

While the ocean is tolerant of some amount of natural and human-made perturbations, it has a limit. The ocean is where most of our environmental pollution ends up, contaminated by industries from agriculture to tourism.

The ocean absorbs as much as a quarter of all man-made carbon emissions, which changes the pH of surface waters and leads to acidification. This problem is rapidly worsening—oceans are now acidifying faster than they have in some 300 million years.

The whole ecosystem, including our oceans, suffers from air pollution. More than 3 billion people depend crucially on the oceans for their livelihoods.

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