Under the Sea: How Climate Change Has Affected The Ocean & Marine Life (6/8/2023)

Jun 08, 2023 Annie Cao

Sebastian may have told Ariel, “The human world, it’s a mess/Life under the sea/Is better than anything they’ve got up there,” but climate change has unfortunately taken a toll on the oceans and the creatures that call the sea their home.

In this blog post, we’ll be diving into recent weather events and the consequences of climate change on marine biodiversity.


image via NBC News



You may or may not remember learning about El Niño and La Niña in school – for a quick refresher, El Niño warms the surface of the sea, whereas La Niña cools it down. Last year, forecasters predicted that the 2022 winter season would be the third year in a row where the Pacific Ocean would be in a La Niña cycle. Research from the University of Washington suggested that climate change is the cause of these weather patterns.

Normally, winds near the equator push warm water westward from South America to Indonesia. Cold water then rises up to the surface along the coast of South America. When we’re in a La Niña cycle, the winds are stronger, making the water a few degrees colder. This small difference ends up affecting the weather patterns around the world.

In Oceania and Asia, La Niña creates a higher chance of drought, reduced crop yields, less fish stocks for fisherman, and a smaller water supply. In other parts of the biome, such as Indonesia and Australia, they may receive more rain. And in the Southwestern United States, it may be drier than usual, while the deep Tropics deal with a more active hurricane season.


image via Oregon Live



From 2017-2019, there was a sudden jump in the number of juvenile snow crabs – at its peak, there was an estimated 8 billion snow crabs. But by 2021, the population had mysteriously plummeted to around 1 billion, which was a 90 percent decrease. In 2022, Alaskan officials canceled the 2022-2023 Bering Sea snow crab harvest for the first time since the 1990s. 

Alaska’s crab fishing industry is worth over $200 million, meaning that many families in the industry will take a hit from this season’s cancellation. Alaska is also the fastest warming state in the US, and every year, their summers and oceans are getting warmer. This means climate change will continue to affect other marine life that calls the Bering Sea their home.

Scientists have come up with a few theories for the unexpected population changes. The warmer waters may have forced snow crabs to migrate further north in search of colder temperatures. But according to an article from TIME Magazine, the rising temperatures may have led to…cannibalism. 😳 Yup, they potentially cannibalized each other. When the water warms up, cold-blooded animals have a faster metabolism and need to consume more food. Combined with the rapid population growth, it’s possible that the snow crabs ran out of their usual food sources and had to resort to cannibalism.


image via Unsplash (credit: Francesco Ungaro)



Oceans cover about 70 percent of the earth’s surface. Over 3 billion people rely on fish as a source of protein and an estimated 60 million people work in fisheries and the aquaculture industry. To top it all off, there are around 2 billion people who live in half of the megacities located along the coastline. Oceans do a lot for animals and humans…but are we doing enough to protect them?

As we can see, climate change has created unpredictable consequences. And it doesn’t end there.

  1. Oceans have absorbed around 90 percent of heat from greenhouse gas emissions. This has prevented global temperatures from rising, but marine animals have to pay the price instead. Warmer waters have caused coral bleaching and marine heat waves. In the summer of 2021, the Pacific Northwest struggled with a record-setting heat wave that killed an estimated 1 billion sea animals.

  2. Rising temperatures have led to ice melting. As the ice in colder areas continue to melt, this affects the animals that depend on this habitat for survival. In addition to penguins and polar bears, algae and krill also need sea ice – without it, they start to disappear. This in turn has a negative impact on the species that need these food sources.

    image via popsci.com

  3. The ocean absorbs about 30 percent of carbon dioxide and fossil fuels, which turns into carbonic acid. This then alters the seawater chemistry and makes the water more acidic, which is known as ocean acidification. The acidity impacts coral reefs and can dissolve the calcium carbonate shells of crabs, lobsters, and plankton.

  4. As climate change warms the oceans and changes wind patterns, this then affects animals’ migratory patterns. Currents are an important part of the Earth’s climate, and as they change, so will weather patterns such as rainfall and air temperature. In order to find better conditions, some animals might consider a mass migration, which would affect coastal communities.

  5. In the last decade, the amount of dead zones has increased. According to the National Oceanic and Atmospheric Administration (NOAA), dead zones occur when a bloom of algae sucks up all the oxygen in a given area, turning it into a biological desert. When this happens, marine animals can’t survive there anymore. In 2008, a study said that there were 400 dead zones. By 2019, this number had increased to 900.

    dead zone in the Gulf of Mexico; image via The Daily Beast

  6. Rising sea levels are a threat to humans and animals alike. As temperatures rise, more sea ice will melt. A 2019 report from the UN said that these unprecedented rising sea levels have the potential to displace over 680 million people in coastal communities. Additionally, species that thrive in shallow waters won’t be able to handle the rapidly rising sea levels. And coastal habitats, such as nesting beaches for sea turtles, will vanish as the sea levels continue to increase.


Climate change poses an ongoing threat to our oceans and our coastal communities. If it weren’t for oceans, the Earth would already be an uninhabitable place. We need to take better care of the sea to not only protect the marine creatures that live there, but to also protect humanity and future generations.


Cover image via Unsplash (credit: Felipe Portella)


Climate change and La Niña in Oceania and Asia - River Above Asia and Oceania Ecclesial Network

Study suggests La Niña winters could keep on coming | UW News

How is climate change impacting the world’s ocean | United Nations

5 ways that climate change affects the ocean

Alaska cancels snow crab season for first time after population crash - The Washington Post

Here's Why Alaskan Snow Crabs Are Disappearing | Time

World Oceans Day 2022: How climate change and warming waters are affecting the health of the oceans - ABC News

New study: 2021 heat wave created ‘perfect storm’ for shellfish die-off | UW News

Heat Wave Kills Estimated 1 Billion Sea Creatures Off Canada's West Coast : NPR

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