Humans Are Killing Earth's Oceans

Three ways that we’re losing marine life and what you can do about it

Julie Smith, 5/5/26

This is a summary of Chapter 9, Under The Sea, in the book, “2050: What’s it Gonna Be?”.  You can download the full chapter, as well as other chapters.  References are here.

The decimation of oceans on planet earth is even scarier than the land, if you ask me.  Why would I say that?  Well, it might have something to do with the fact that oceans cover more than 70% of the planet, yet we know very little about them.  Or maybe that 50 – 80% of all life on earth is found underwater and we know very little about it.  The National Ocean and Atmospheric Administration estimates that we understand less than 20% of the world beneath the sea.¹  We barely understand the currents that control the planet’s weather and climate, and we’re constantly discovering previously unknown and unsettling realities of oceanic chemistry and its impact on sea life and on terrestrial life.  By one estimate, more than 90% of the ocean’s species are still unclassified. 

And our relative lack of knowledge would be one thing, but at the same time we’ve pretty much trashed the ocean’s surface waters, where most oceanic life lives, as far as we know, and we have little to no idea what the impact of our unrelenting destruction is or will continue to be.  So we continue on our merry and oblivious path of destruction.  Those of us who actually pay attention just know it’s bad.  But not how bad. Most people on earth have never actually seen the ocean, though it’s probably safe to say that pretty much all of us are responsible for its destruction. 

The ocean has historically been the global dumping ground for everything from our trash to our pollution to our shit, and in the meantime we’ve been overfishing the tar out of it to feed our endlessly growing population.  There’s this misguided perception that the ocean can take it, that the ocean is endless, that anything that’s dumped into the ocean will disappear forever, and that aquatic life is endless.   But it’s not.  Maybe at one time it was, sort of, but not anymore.  We’ve managed to decimate the endless ocean, vast as it is.  And the death of life on our planet, at the end of the day, may well be driven by an oceanic rebellion, if you will.  And that’s why I’m saying the ocean is scarier than the land.

For one thing, global warming is jacking up the temperature and the chemistry.  Some parts are heating faster than others, and that temperature difference is what drives currents and weather.  And, what’s just as bad, or even worse, the CO₂ that we’re spewing that’s causing global warming is actually changing the chemistry of ocean water.  The most obvious change is the acidity, which is increasing because a portion of CO₂ in the air dissolves in the ocean, and when CO₂ dissolves in water, it forms carbonic acid, which reduces the pH.  So what?  Well, a lower pH begins to dissolve the shells of shellfish.  Do you happen to consume shrimp or clams on occasion?  Don’t get used to it.  Their shells are their bodily protection, so without their shells, they’re not long for it.  By the way, higher marine life forms, like whales and penguins and several kinds of fish, also depend on shellfish for food, so when, not if, we lose the shellfish, we’ll lose those, too.   So, if you happen to like tuna and grouper, don’t get used to those either.

While the long list of ways that humans are killing Earth's oceans and decimating marine life is endless, I think it's fair to think of our destruction in three general categories.

1. Overfishing. With our extreme population, our demands for seafood have become so high that the vast oceans can't sustain it. Even worse, the trolling and netting practices of industrial fishing are destroying reefs and bottoms to the point that the marine life can't survive there. Bycatch from nets kills unintended targets, that simply get tossed back into the sea as waste. In addition to the seafood we eat, seafood such as krill, essentially a marine insect that plays huge in the diets of many important marine species, such as whales and larger fish, are caught in nets and used for pet food the world over. It's nearly impossible to find a pet food that doesn't have krill or some other type of seafood in it. I know. I've read pretty much every ingredient list on pet food containers. We finally went to a recipe with chicken and sweet potatoes for our cat, which was cheaper than the pet food. For my aquariums, I've gone to dried tubifex worms, brine shrimp, dried water fleas and dried flies, alll of which are easily raised in captivity and low in cost. And the fish love them.

   • Stop eating seafood from the ocean. They need a break. If we stopped consuming seafood for five years, the marine life would largely recover and we could then start consuming at a more sustainable level than we do now. Switch to other fish that is farmed, without the use of yet more seafood to feed them. Or just stick with Chicken for a while.

   • If you have a pet, feed them something that doesn't include seafood.

   • Support and advocate for sanctuaries. We need a minimum of 30% of the ocean to be left alone as sanctuaries for marine life, and currently only 3 - 7% is set aside. It's already been proven that marine life is more plentiful outside the boundaries of sanctuaries, because they're more productive in protected areas. This should be a no-brainer.

   • Support and advocate for human population reduction.

2. Toxicity and Trash. The ocean is downstream of everything, so anything that is released on land and into waterways eventually finds its way to the ocean.

   • Toxic chemicals are not limited to spills and releases from factories. We are all complicit in poisoning the ocean and marine life when we consume conventional industrial foods that are grown and produced using insecticides and synthetic petrochemicals to color and flavor processed foods. We are definitely complicit if we use synthetic pesticides and fertilizers on our lawns and in our yards. We are all complicit when we eat beef and dairy because of the additional industrial crops grown for their feed, and the feedlot runoff that flows untreated into waterways. We are all complicit when we use synthetic cleaning and personal care products that contain dyes, fragrances and other petrochemicals that don't biodegrade after they run down the drains to the sewer. We are all complicit when we use single-use plastic containers, a significant portion of which reaches the ocean from inland sources. We are complicit if we take a cruise, because most cruise ships dump their untreated waste into the ocean.

   • We can help our oceans and marine wildlife a lot by avoiding the above personal choices in our everyday lives. We can eat organic foods that don't use toxins in their production, and we can use natural products for cleaning and personal care that don't contain toxins.

   • We can help by routinely picking up litter and trash in our own areas, knowing that all litter will ultimately find its way either to waterways leading ultimately to the ocean, or to the guts of unsuspecting terrestrial wildlife, sickening and killing them.

3. Global Warming. Our astronomical CO₂ emissions that are increasing temperatures are causing unforeseen consequences in the oceans, including disease outbreaks and loss of coral reefs, which are home to 25% of sea life. CO₂ is also dissolving in the ocean's waters, increasing carbonic acid, which is dissolving the shells of shellfish.

   • We are all complicit in global warming when we choose to consume fossil fuels in our homes and in transportation. We are all complicit when we consume food produced with industrial agriculture, which has a carbon footprint that is 3 - 4 times that of organic and regenerative agriculture. We are all complicit when we choose to consume beef and dairy, which have a carbon footprint of production that's 20 times that of vegetables, pork or chicken.

   • We can help by reducing our energy consumption in our homes and transportation.

   • We can help by switching to electricity fueled by renewable energy such as wind and solar.

   • We can help by consuming organic food, and eliminating or reducing beef and dairy.

   • We can help by supporting population reduction.