Ocean protection 101

Ocean protection

Oceans are amazing: enormous is their size, majestic are their animals like blue or humpback whales, magic are the coral reefs with their abundance of life and colour, mysterious is the deep sea with its strange-looking creatures and astounding are the connections between tides, currents, plankton and all other plants and animals in the oceans.

Over the last decades, we have caused severe damage to the oceans and their wonderful inhabitants: Overfishing, pollution, coastal destruction and the rise in water temperature due to climate change disrupts the greatest ecosystem of all.

All life is connected to the oceans. It is therefore of utmost importance to protect these gigantic habitats and all creatures that live within the oceans.

If we want to protect the oceans, we first have to understand what the threats are. We will give you an overview of the greatest threats to our oceans, how it affects us humans, and what can be done to reduce these threats. Every threat is a topic by itself and we will provide deep dives into these areas over the next months. This is an introduction to the topic.

Ocean warming due to climate change

Oceans play a critical role in climate change. The oceans absorb 93% of the heat that is trapped by the greenhouse gases on our planet. That, of course, heats up the water. If they did not do that, the air temperature on earth would heat up even faster than it already does.

Ocean warming disrupts many ecosystems in the sea: coral bleaching is one of the most obvious to humans: beautifully coloured corals that have grown over decades turn white and eventually die.

Besides losing amazing creatures in these habitats, rising ocean temperatures result in sea level rise. This is due to two effects: 1) warmer water expands and takes up more room and 2) warmer water causes the decline in ice sheets and glaciers.

 Ocean warming has powerful effects on our weather and can cause extreme weather events: storms become rainier and more intense, coastlines flood more frequently, and the downpours get bigger also causing floods.

In September 2019, Hurricane “Dorian” striking the Bahamas was the strongest storm at landfall ever recorded in the Atlantic Ocean with winds up to 295 kph (185mph) and 150cm (60 inches) of rainfall in 40 hours causing damage of 10 billion USD.

Ocean acidification

The oceans absorb large amounts of the carbon dioxide (CO2) released into the atmosphere by human activities (around 25-50%). The amount of CO2 absorbed by oceans changes every year but has been rising over the past 20 years. Through this process the chemistry of the seawater changes: the seawater pH decreases continuously causing “acidification” of the oceans. The drop in pH affects marine life: shell-building animals like sea snails or oysters are endangered because the shells can dissolve in the more acidic waters.

Acidification also threatens organisms that rely on carbonate skeletons such as corals.

Many of these organisms are pretty close to the bottom of the food chain and are essential for the life of many fish and mammals in the sea. Or they provide the habitat for other species. Therefore, acidification of the ocean threatens some species directly and a lot of others indirectly.

Overfishing and destructive fishing

Overfishing is an easy to understand issue that has been around for too many years: way too much fish is being caught in a non-sustainable way. That means that the fishing vessels catch fish faster than the fish populations can reproduce.  

The Food and Agriculture Organization (FAO) estimated that in 2013 around 31.4% of fish stocks were fished at a biologically unsustainable level and therefore overfished.

 Unfortunately, the increasing ocean temperature is enhancing the effect and also contributes to the decline of fish population.

 In addition to that, destructive fishing techniques like bottom trawling and trawl nets that are (still) being used kill other marine life that is not even the target of the fishing activity, like dolphins, whales, seals and turtles.

 And don’t even get us started on commercial whaling: thousands of whales are still being killed despite an international ban on commercial whaling.

The consequences of all these activities are destroyed ecosystems in the ocean that are very difficult – if not impossible – to restore and many species that are close to extinction.

Scientists estimate that commercial fisheries around the world kill or seriously injure more than 650,000 marine mammals every year

According to the NRDC report in 2014

Pollution of all kinds

There are numerous sources of pollution of the ocean: Plastics, untreated sewage from factories, pesticides, fertilizers and nutrients, oil spills of ships and offshore drilling sites, rubbish dumping, and old fishing nets. Air pollution also affects the oceans.

The numbers are horrifying: more than 8 million metric tons of plastic enter the ocean each year. The great pacific garbage patch is an accumulation of ocean plastic between Hawaii and California and is about three times the size of France.

These pollutants either kill marine animals and plants directly or, like in the case of microplastics, they get taken up by marine organisms and enter the food chain.

With this abundance of pollutants, it might seem difficult, where to start to solve these problems. But the answer can also be quite simple: every plastic bottle avoided is an important step towards cleaner oceans!

More threats

There are other threats to the oceans like sea level rise that seriously affects the coastal regions. And there is ocean deoxygenation, which is the decrease of oxygen in the water due to nutrient run-offs from land, deposition of nitrogen from the burning fossil fuels as well as the earlier mentioned ocean warming. Less oxygen in the ocean makes it harder to “breathe” for the organisms that rely on oxygen. Effects on many organisms have already been shown, for example on plankton, kelp, mangroves, corals, and tunas.

Unfortunately, the list of threats to our oceans is very long and we want to at least mention some more like habitat destruction and the introduction of invasive species.

The amount and severity of these threats hopefully make it very clear that we all have to help to protect our oceans. But for those, who are not convinced yet, we would like to point out the direct effects on humans.

How do these changes in the oceans affect humans?

First of all, we are losing the abundance and diversity of wildlife in the seas. Some ignorant people may believe that that does not concern us humans directly. But all ecosystems on our planet are connected and the threats and changes to the oceans already have a large effect on humans and the impacts will become greater over the years to come.

Here are some examples of direct effects on humans:

Large populations of fish are in danger. These fish are food and income source for millions of people around the world.

Ocean warming results in severe weather events as mentioned above: Tropical storms like Hurricanes become more intense and longer lasting causing many people to die or lose their homes and also causing severe damage to infrastructure.

Downpours have also been shown to get bigger resulting in floods in many regions around the world.

Coastal areas already flood and will continue to flood more frequently when reef and other costal vegetation, like mangroves, lose the battle against rising ocean temperatures and decline.

The sea level rise due to thermal expansion of water and melting glaciers and ice sheets is a whole tragic topic by itself with wide-ranging effects. We will name a few here: soil contamination with salt, destructive erosion, flooding of low-lying coastal areas forcing people to migrate or invest large amounts of money in protective measures.

And finally, if the ocean temperature rises, the water absorbs less CO2 – therefore more CO2 stays in the atmosphere and the greenhouse effect causing global warming with all its consequences on human beings will progress much faster.

What needs to be done?

  • More marine parks and sanctuaries need to be established
  • Destroyed marine and coastal ecosystems need to be restored wherever possible
  • Destructive fishing methods like bottom trawling and trawl nets need to be stopped
  • Commercial whaling needs to be stopped
  • Governments need to introduce policies on precautionary catch limits to prevent overfishing
  • Fishermen need to be able to use sustainable fishing techniques and still maintain their livelihoods
  • The emission of greenhouse gases needs to be dramatically reduced to stop (or at least slow down) the warming, deoxygenation, and acidification of oceans

What can you do? – Green Deeds to protect the ocean

Each of us can do something to protect our oceans. Please consider each of the following protective measures carefully and think about which green deeds you can do.

  • Ask in restaurants, where the fish is from and how it was caught
  • When buying seafood, check for labels like the ones from the Marine Stewardship Council (MSC), although this label has been criticized for not being strict enough in the past, so don’t rely on it alone
  • Avoid plastics and other kinds of trash
  • Participate in (or even organize) a clean-up close to a river or ocean
  • Support an NGO that protects marine life – financially or become a volunteer
  • Do not travel to countries that do not protect the ocean
  • Sign petitions for the establishment of marine parks
  • Demand actions of policymakers to protect the oceans

Sources and further reads

One of the scientific papers that describes the warming of the ocean: S. Levitus et al., 2012; “World ocean heat content and thermosteric sea level change (0–2000 m), 1955– 2010“, GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L10603


A very detailed report on ocean warming and its consequences published by the International Union for Conservation of Nature (IUCN) in 2016: „Explaining Ocean Warming:  Causes, scale, effects and consequences”. https://portals.iucn.org/library/node/46254

 A map of the CO2 that is absorbed by the oceans per year: https://www.climate.gov/news-features/featured-images/2017-state-climate-ocean-uptake-human-produced-carbon

The article describing the oceans’ increased CO2 uptake in 2017 compared to the years before: https://www.nature.com/articles/542169a

 The report of the FAO on the state of the fisheries and aquaculture (2016): http://www.fao.org/3/a-i5555e.pdf 

 The NRDC report on killing or marine mammals in foreign fisheries:


The often cited publication that estimated how much plastic end up in the ocean every year: https://science.sciencemag.org/content/347/6223/768