On World Oceans day, Monday 8th June 2020, BBC4 aired a documentary titled ‘Ocean Autopsy: The Secret Story of Our Seas’.

As this an incredibly important topic, this article summarises some of the key findings. However, if the subject interests you, I would highly recommend watching the documentary if you can, which is available on BBC iPlayer for 30 days after it was broadcasted. This article is not an substitute for watching it; rather, it is serves as being complementary. It’s one thing reading about it, and another seeing the devastating impacts for yourself.

In line with Dr Czerski’s views, this article will refer to the ‘ocean’, not ‘oceans’, as they are all interconnected. This also moves away from a human standpoint of borders and territories to the appreciation that the responsibility for taking care of our oceans should be shared.

Disclaimer

I am by no means an expert on this subject matter. The information I have gained is from the BBC4 documentary. All information and facts I am using in this article are from the BBC 4 documentary, unless stated otherwise. In the event that I have made a mistake, feel free to let me know in the comments section below.

North Sea

The North Sea is situated between the UK and Northwestern Europe (see the map above). The North Sea has been polluted, alas and alack, more than any other sea in the planet. Over the past 50 years, the North Sea has warmed at an alarming rate: more than twice the rate of the Earth’s oceans. Consequently, as the North Sea is more polluted, some look to the north sea as an indicator to how the world’s oceans may end up. On board the Pelagia, an Oceanographic research ship, Dr Helen Czerski joins Professor Helge Niemann and his team to conduct an autopsy of the north sea.

Professor Niemann’s team have estimated that 1/4 of a million tonnes of plastic are floating on the world’s ocean. Yet, this is only a mere fraction of the total amount of plastic that we have thrown into the sea. If that isn’t saddening enough, we don’t know where most of it is. Professor Niemann and his crew are a part of a worldwide search for the 99% of plastic that has gone missing.

Plastics

Plankton are the foundation of the food chain in the ocean, a crucial part of the ocean food web. Plankton have been found to have eaten some of the plastic that we have dumped into the ocean.

Plastics have been designed so that they don’t break down easily in the environment (even biodegradable plastic bags according to one report).

Professor Niemann is of the view that plastic changes at a very small scale and becomes chemically reactive. As this is a new discovery, we don’t yet know what effect these chemically reactive nanoplastics will have.

Effect on us

From an anthropocentric viewpoint, dumping plastic into the ocean can also come back to, for want of a better phrase, bite us. Take salmon, for instance. According to Professor Niemann, a large proportion of the sardines caught in the West African coast contain plastic particles in them. As we’re at the top of the food chain, if we’re eating sardines, or other marine life, that contain plastic, we’ll end up with plastic inside us. We don’t yet know how harmful microplastics (plastics that disintegrates into smaller pieces) will be when living organisms consume them. It may be the case that plastics could pass through the gut without causing any harm. Alternatively, toxins that stick to plastics such as PCBs (polychlorinated bipheynyls) could be inside us. I could be beating on the wrong drum here, but I picked up on the choice of the words: how harmful microplastics could be rather than whether.

Moreover, 1/5 of the protein humans consume is from seafood. We share the same hormone receptors as other sea life that PCBs can harm.

The number of people with diabetes has doubled over the past 40 years. Scientists think that this oculd be caused by our hormones getting affected by PCBs and other hormone-disrupting pollutants. Some epidemiological studies have concluded that people with higher exposures to PCBs are at higher risk from type 2 diabetes. This is particularly concerning given that diabetes is a leading cause of death, being the cause of death for around 12% of deaths in the United Status, according to an article in 2016 in WebMD.

Possible hope

Hope may come in the form of fungi. Fungi are good are breaking complex organic matter, such as wood. While not yet conclusive, fungi may be able to also break down plastic. If this is true, then fungi may be able to start cleaning the ocean if we put an end to polluting it. This goes with a broader point of nature being able to fight back against the harms we are doing to it if we only we give it a chance (more on this in the Wallasea Island section).

Dead zones

In 2019, an 8000 square mile stretch of sea at the mouth of the river Mississippi was classified as a dead zone. Scientists worry that excess nutrients in the water and warmer water are to blame as O₂ levels dropped in many areas of the ocean. While jellyfish can thrive in such an environment, creatures like sharks and turtles can suffocate.

The documentary points towards the need to develop new strains of crops and more sustainable farming methods so that we can spray less fertiliser onto our crops, which could revitalise the dead zones killing our seas.

Noise pollution

Porpoises use echolocation to move through total darkness. They can also use echolocation to tell what animals are nearby, whether those animals are prey or mates, how far away they are, where it’s going, which way it’s heading and more.

Human sounds can affect marine life. As porpoises rely on sound, they can’t hear one another if we’re making lots of noise and they understanably find it stressful (so would we if we were in a construction site without any protective hearing gear, such as ear defenders). Loud sounds from hammering in the foundations of wind turbines to deep oil sea mining can deafen them.

Pharmaceuticals

In addition to plastics and noise pollution, pharmaceuticals are also a concern. When we consume pharmaceutical drugs and then excrete them, they go down the sewage system, through the Thames before eventually finding their way into the North Sea. From his research in the Thames, Professor Alistair Boxall (University of York) found that Metformin tablets are a big culprit. 220 Metformin tablets find their way into the Thames every hour. This equates to over 5000 tablets every day. We don’t tend to think about pharmaceuticals as being a pollutant that can be damaging to marine life, but it can.

The advice here is to return any unused medicine to your pharmacy; they can ensure that the medicine is disposed of safely.

Global warming and climate change

Energy on Earth comes from the sun. The energy moves across Earth, through the ocean and the atmosphere before getting radiated back into space. Greenhouse gases, like carbon dioxide, slow the flow out of energy. More energy comes in than leaves. This is global warming. Since 1970, 93% of the extra energy has ended up in our ocean.

A large hurricane can spend as much energy as 10,000 nuclear bombs. A hotter Earth is likely to increase their power. Moreover, scientists predict that by the year 2050, once in a century floods could occur as often as once a year. Thirdly, 3 degrees warming by 2100 could mean that cities like Miami, Shanghai and Osaka could be engulfed by the sea.

Since the last ice age a few thousand years ago, sea levels had risen by over 30 metres. Today, sea levels are rising at a faster level than any point since the last ice age. As the documentary saddeningly explicitly points us, this time we have caused it.

The fight with, not against, nature at Wallasea Island

Wallasea Island, 50 miles from London, is at the mouth at the Thames. It is home of the UK’s largest coastal wetland creation project, and is led by Jeff Kew. According to Kew, it is also the largest coastal restoration site in Europe.

A sea wall was built on the site circa 1500. A sea wall – an earth bank with some concrete slabs – was made on the assumption that there would always be salt marsh in front. However, the salt marsh has been eroded away, which has opened it up to being hit by the water which in turn has meant that the wall has eroded. With sea levels rising, this will continue to happen repeatedly.

When the sea comes in filled with silt, the silt falls, gets trapped by the plant vegetation that has grown and the ground rises. In other words, the ground rises as sea levels rise. An added benefit is that the salt marshes can trap atmospheric carbon, more than 50 times a forest of the same size would.

Avocet birds have flocked to the area, with around 150 avocet birds now living at Wallasea all year. This is more than any other Avocet site in the UK.

What this goes to show is that nature-based approaches to tackling rising sea levels can be employed in order to protect coastal communities not just in the UK but worldwide.

Ocean: a carbon sink that comes at a price

The ocean consumes between around 25-35% of all of the extra carbon dioxide we have emitted that is going up into the atmosphere. Even though the ocean is natural carbon sink, we’re emitting a quite a lot of carbon dioxide.

The cost of the ocean taking in the excess CO₂ is ocean acidification – our oceans, which are naturally alkaline, are becoming more acidic. This is damaging the sealife, such as coral reefs. Coral reefs are very important: while they consume less than 1% of the ocean floor, they support over 25% of ocean life. The hard parts of the corals, as well as the shells of shell fish, are made from calcium carbonate. Calcium carbonate is particularly sensitive to acidic conditions. As our ocean is becoming less alkaline (by around 0.1 pH, which may seem insignificant, but it is far from it), the acid dissolves the calcium carbonate. Scientists think that all coral reefs could be lost by 2100.

Unfortunately, it’s too late to stop ocean acidification. If we’re not careful, the same could be said about climate change.

Methane, another greenhouse gas

Methane contributes about 1/5 to global warming. It’s 30 times more powerful than CO₂ and can hold more heat from the sun than CO₂.

In the 1980s, scientists discovered a type of methane ice, called methane hydrate, that forms naturally at the bottom of the ocean. Scientists have estimated that over 1000 trillion cubic metres of methane ice is frozen in ocean sediments. For context, this is more than all of the world’s carbon and gas reserves combined. Needless to say, the warming effect could be terrible if the sea floor metahne escapes to the atmosphere. What we have here is a positive feedback loop: the warmer it gets, the more methane will come from the ocean and, therefore, the warmer it will get in turn.

Methane release is one of the reasons why the UN wants to limit future warming to 1.5°C.

Some solace in wind farms

Wind farms in the UK have helped us reduce our carbon footprint by nearly 40% since 1990! Wind produces about a 1/5 of Britain’s electricity. The aim is to have wind produce a 1/3, which would require an extra 5000 new turbines.

Offshore wind farms have become popular, especially in the public eye as people like wind turbines unless they can see it (not true in my case). One of the issues with offshore wind farms is that there can be a significant amount of noise when building the foundations for the turbines into the sea bed. However, this does not have to be the case. Shielding could be used to limit the noise caused and the developers could strategically choose where to place them such that they minimise disruption to local marine life. There’s also a silver lining: the bottom of the turbines can be a home for animals, forming a sort of artificial reef.

Further reading

If you’re interested, I recently wrote an article on the damage we’re doing to our oceans. Dr Helen Czerski, an oceanographer and excellent science communicator, was the speaker of a Cheltenham Science Festival 2020 at home talk that was the foundation of the article (Dr Czerski was also in this BBC 4 documentary). Dr Czerski has also written an article about the documentary.