• Victoria Cornelio

Why is the Ocean So Important?: The Impact of Pollution & Overfishing


The impact of climate change and pollution on the ocean

Covering over 70% of the surface of the Earth, the ocean is home to more than a million species and contributes around 50-70% of the world’s oxygen.


The phytoplankton, considered the planet’s most abundant photosynthetic organism, can release millions of oxygen particles in one drop of water. In addition to providing humans with oxygen, the ocean is key to regulating climate and influencing weather patterns around the globe.


However, as pollution and human activity continue to threaten marine life and climate change accelerates, our oceans are in trouble.



How do our actions affect the ocean?


The biggest threat to the ocean is human activity, as our actions directly or indirectly affect the health of marine life. Through unnatural constructions such as underwater pipelines and chemical spillages in the ocean, humans have destroyed marine habitats and endangered many underwater species.


Also, as our CO2 emissions continue to rise, ocean warming leads to the loss of marine fauna and flora due to increased acid levels of the water. Interestingly, noise pollution from beachside activities (from mining to parties) affect the natural behaviour of marine animals close to the shore.


And, of course, the very public ocean enemy… plastic. Not only do hundreds of marine species fall victims to plastic by ingestion, suffocation, or entanglement, but plastic also spreads invasive bacteria which affect the ecosystem.


Coral bleaching and the impact of climate change on marine life

The importance of the food chain and overfishing


Since greenhouse gas emissions have skyrocketed in the past years, there has been a huge loss of the oceans’ marine life through coral bleaching, organisms dying and animals’ inability to detect predators, all of which are results of ocean acidification. This happens when the ocean plants absorb too much CO2, unleashing a domino effect in the oceanic food web.


The whole marine food chain is altered when organisms that serve as food for others disappear, and when predators lose their hunting skills, because it leads to an imbalance in the ecosystem. Marine predators are very important for maintaining the health of the oceans by controlling the number of fish populating an area. This is key because the plants and kelp that the fish eat store carbon dioxide which helps to clear the atmosphere and is later turned to oxygen.


Imagine the following scenario: if top predators did not stop herbivore ocean species from eating too many tiny plants that produce organic carbon and make more than 50% of the oxygen we breathe, both marine animal population and human population would decrease drastically.


The impact of overfishing on the environment

On the other hand, overfishing reduces the stock of fish in the sea which leads to both environmental and economic problems. Environmentally, when a species is exploited, it upsets the natural food web. When prey species disappear, predators are left to starve or to hunt each other, and when predator species disappear, there is no way to regulate invasive species and fish populations. For example, overfishing of species like sharks that reproduce very slowly and have a late sexual maturity can result in the shark population decreasing tremendously and the balance of marine life being disrupted, with the Discovery Channel estimating around 10 million sharks are killed every year.


"in the last 60 years, fish stock in the ocean has declined by 90%"

Conversely, less fish in the sea means coastal communities that rely in fishing for local food supply and economic activities are left without any stock. The patterns of fishing are unsustainable and do not allow species to replenish. The Food and Agriculture Organization of the United Nations (FAO) estimates that in the last 60 years, there has been a 90% decline of fish stock in the ocean, leading to food insecurity and unemployment.


The high demands for seafood and marine animals parts is off the charts, making the supply and demand necessities impossible to meet, with scientists claiming there will be a big strain on fish and seafood in general by 2050. This will lead many people in the fishing industries to lose their jobs and will result in many communities suffering from malnourishment, as fish prices increase due to the little supply and immense demand.


Climate change and ocean pollution could lead to more extreme weather patterns

The weather and the ocean


Our oceans have a huge impact in regulating weather patterns. One of its key roles is keeping the Earth warm, by absorbing sun rays and storing them at the equator. From here, the hot water particles travel around the globe and as they evaporate, they increase temperature and humidity in surrounding areas. These evaporated particles also turn into rain, with 90% of rainfall on land coming from the ocean and may eventually turn into storms that are carried by the wind. Ocean currents carry water particles from the equator to the rest of the globe, regulating global climates around the world.


However, as our oceans trap more heat and sea surfaces become warmer, more extreme weather patterns will be present. For example, hotter waters lead to stronger storms, threatening communities at the equator that will be hit with hurricanes and potential flooding. In contrast, as temperatures drop as you move away from the equator, fewer places would be habitable. Due to climate change, the Geophysical Fluid Dynamics Laboratory has warned of an increase in frequency and intensity of tropical storms around the world.



Our oceans can save us


The climate crisis seems to have reached a point where mitigation solutions are being replaced by adaptation, as the effects of climate change become irreversible. However, by helping the ocean, the ocean can save us.


Restoring and protecting marine habitats can help these ecosystems store significant amounts of carbon (four times more than terrestrial forests), leading to decreased global warming, while also providing a chance for implementing renewable energy sources depending on the location, including offshore wind energy and opportunities for hydroelectric plants.


Also, by keeping our oceans healthy, we make them more resilient to the impact of climate change and in return, prepare coastal communities to face these effects.


Some loss might be unavoidable, but we need to stop overlooking the ocean when addressing the climate crisis, and its role in stopping it.



For more resources on environmental issues, head to our dedicated Climate Crisis section.


Edited by Caoimhe Glover

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