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Ocean Acidification: Causes, Issues and Solutions

In this article we’ll explore the process of ocean acidification, its causes and what can be done to prevent further harm to our delicare marine ecosystems.
Ecology News
2023-06-29T00:00:00.000Z
en-us
ocean water and blue sky

The catastrophic effects of increasing levels of carbon dioxide are widely known and publicised - global warming and climate change have been described as the challenge of the century. But many people have not heard about another highly concerning impact of rising CO2 levels - the acidification of the Earth's oceans. 

Ocean acidification is a relatively new term, and it wasn't until the early 2000s that scientists first became aware of its threat to marine life. The effects of a more acidic ocean are extensive and we're only just beginning to see its impact.

👉 In this article we'll explore the process of ocean acidification, its causes and what can be done to prevent further harm to our delicate marine ecosystems.

What is ocean acidification?

The Industrial Revolution was a period of technological and scientific development that transformed societies across Europe and North America. However, this advancement came at a cost since it relied on the use of greenhouse gas emitting fossil fuels. The concentration of carbon dioxide in the atmosphere (ie. atmospheric carbon dioxide) has been on the rise ever since, upsetting the Earth's carbon cycle and disturbing its natural equilibrium.

The effects of this are catastrophic with global temperatures rising resulting in alarming changes to our climate, but it's also resulting in something that's not as widely publicised or talked about - something called ocean acidification. 

So, what exactly is ocean acidification?

Well, in order to understand ocean acidification, you first need to understand the carbon cycle, so let's start by taking a quick look at this process in more detail.

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The carbon cycle in a nutshell

The carbon cycle is the process by which carbon moves around the Earth's atmosphere.

It consists of various carbon emitting processes (for example breathing which releases carbon dioxide) which are in turn balanced out by carbon sinks (carbon sinks include the Earth's oceans, forests, vegetation and soil).

👉 The carbon cycle is a finely turned process that has a natural balance, however, human activity has interfered with this equilibrium and now it is dangerously out of sync.  

Human activity

The industrial revolution fuelled advancement, however it also resulted in huge amounts of excess carbon being poured into the atmosphere through the burning of fossil fuels - a practice that hasn't stopped ever since.

This excess carbon has nowhere else to go except into the Earth's atmosphere, which in turn traps heat and results in global warming. However, global warming isn't the only effect of rising levels of carbon dioxide.

Carbon sinks

As we've touched on, carbon sinks are part of the carbon cycle and help to counteract the excess carbon dioxide that is released into the atmosphere.

👉 The world's oceans are the biggest carbon sinks and absorb around 30% of the carbon dioxide that is released into the atmosphere.

As we continue to release ever more carbon dioxide, the levels absorbed by the oceans also continue to rise.

Ocean chemistry

It would be great if the excess carbon dioxide was simply absorbed by the ocean without any side effects, but sadly this is not the case - the excess carbon dioxide impacts the chemical composition of the seawater. 

When carbon dioxide is absorbed by the ocean water, a series of chemical reactions result which ultimately cause the concentration of hydrogen ions in the water to increase. The result of this is that the seawater becomes more acidic and levels of carbonate ions are decreased.  

For context, prior to the Industrial Revolution, the ocean's PH level was 8.2, which means that it is actually more alkaline than acidic. However, the rising levels of carbon dioxide in the water is gradually altering this PH balance and we're seeing a shift towards more acidic water - the current average PH level of the world's oceans is 8.05 on the PH scale.

This change may sound small and insignificant, but it's having huge repercussions for the world's oceans which are a finely balanced ecosystem and highly sensitive to chemical changes. The change in PH level actually equates to an increase in acidity of 40%, and by the end of the century the world's oceans are on track to be 150% more acidic than current levels.  

👉 Human activity is quite literally changing the chemical composition of our oceans. 

The effects of ocean acidification

If you're thinking that ocean acidification doesn't sound like good news - you'd be right. But up until relatively recently scientists weren't really aware of the effects.

Scientists have been tracking the ocean PH for over 30 years, however it wasn't until the early noughties that scientists became aware of the biological impact and the term ocean acidification was first coined. So what exactly are the repercussions of ocean acidification? 

white waves crashing in the ocean

Carbonate ions

Remember when we mentioned that ocean acidification results in lower levels of carbonate ions?

Well, carbonate ions are a key building block in ocean water, and falling levels can make it difficult for marine organisms such as coral and plankton to form shells and skeletons.

What's more, is that it may even cause some existing shells to dissolve. Let's take a closer look at the effects on some of the individual marine species who are the most susceptible to the changing chemical composition of the Earth's oceans.

Coral reefs

Coral reefs house coral animals and provide habitat for a huge variety of different species. Unfortunately, they're particularly vulnerable to ocean acidification because they're formed from calcium carbonate. 

Ocean acidification not only corrodes existing coral structure, it also slows the development of new skeletons and results in weaker coral structures that are more vulnerable to damage and erosion. 

However, the severity with which different coral species will be affected varies - some corals are proving to be rather resilient when it comes to ocean acidity and can produce their skeletons with bicarbonate instead of the carbonate ions, and other corals are able to temporarily survive without a skeleton.

👉 Over the coming decades we'll certainly see a change in the composition of coral reefs around the world. And since coral reefs form an important part of many marine ecosystems, this will also have profound effects on the many different organisms that rely on them for their survival.

coral reef with lots of fish

Shellfish

Ocean acidification is bad news for shellfish such as mussels, clams, and sea urchins . As is the case with coral reefs, most shellfish rely on carbonate ions to form their shells. 

👉 Research shows that by the end of the century, the shells of mussels and oysters will be decreased by around 25% and 10% respectively. Weaker calcium carbonate shells means that these creatures are more at risk of being crushed or eaten. 

And it's not just their shells that suffer. The fibres that mussels use to attach themselves to rocks are also impacted by ocean acidification - the impact being that mussels can't attach to rocks as securely. Oyster larvae are also affected - they need to form a shell to start feeding, but the lack of carbonate in the water is preventing them from doing so. This has already had a huge impact on oyster farms in the Northwest of the United States - some oyster farms have experienced a loss of up to three quarters of their oyster larvae. 

As is the case with coral reefs, the loss of these organisms is also problematic for the wider ecosystem, with other animals and creatures depending on them for food and habitat. 

Plankton

There are many different species and subspecies of plankton that are susceptible to the changing chemical balance of our oceans. These tiny organisms are often under-appreciated for the important role they play in marine ecosystems.

Take Zooplankton for example - zooplankton is an incredibly important part of the ocean food chain - nearly all marine life either eats Zooplankton, or eats larger creatures that eat zooplankton. The problem is that some subspecies of Zooplankton form shells from calcium carbonate, and in acidic conditions these shells quickly dissolve. 

Phytoplankton are another important type of plankton. Not only because they provide food for Zooplankton, but also because they form a crucial part of the carbon cycle. In fact, Phytoplankton are responsible for the majority of the transfer of carbon dioxide from the atmosphere into our oceans. Phytoplankton achieve this by consuming carbon dioxide during photosynthesis - similar to the way that the leaves of a tree convert and store carbon dioxide. 

👉 Research shows that different species of Phytoplankton respond differently to the increasingly acidic level of our oceans, with some species dying out, and others either migrating regions or flourishing. This has the potential to significantly disrupt delicate marine ecosystems and completely alter the composition of marine creatures that live within them.

underwater coral reef and vegetation

Algae

Algae are one species of marine life that actually benefit from the increased acidic conditions of our oceans. Plants and algae make their energy from carbon dioxide and so the increased levels in the water actually help them to thrive - good news right? Well… not always. 

You see, algae can actually be harmful in large quantities. Harmful algae blooms occur where algae populations grow out of control, producing high levels of toxins which can be harmful to animals, plants and even humans.

👉 Depending on the species of algae, algae blooms can even be life-threatening, or cause respiratory and gastrointestinal illness in humans.

Fish

Although fish don't have shells, they're not unaffected by ocean acidification.

The cells of fish are more alkaline in nature than that of the surrounding ocean water they swim in, this results in a acid-base regulation, which means that the cells of a fish absorb carbonic acid, resulting in a decrease (or acidification) of the PH level of the fish's blood - a condition called acidosis. 

This increased PH balance can hugely affect the physiology of the fish, resulting in increased metabolic rates and behavioural changes. For example, it's been shown that in more acidic waters, Clown Fish are unable to flee threats efficiently and that they're unable to smell their way back home. 

clown fish swimming

What human actions are causing ocean acidification?

We already know that human activity is the driving force behind the disruption to the carbon cycle, and therefore is also the reason that our oceans are becoming increasingly acidic in nature. But what human activities contribute the most to this? 

Fossil fuel consumption

The burning of fossils is the primary driving force of carbon emissions.

We use fossil fuels such as coal, gas, and petroleum for a variety of purposes - from the running of our cars, to the heating of our homes, to the fuelling of industrial operations - fossil fuels are ingrained into modern society.

In fact, fossil fuels supply around 80% of the world's energy and account for as much as 90% of global carbon dioxide emissions. 

Deforestation

Another contributing factor is deforestation.

Forests and vegetation are the Earth's other main carbon sink. Trees and plants absorb carbon dioxide for photosynthesis and store the carbon in their organic tissue.

👉 Deforestation means that this carbon is released back into the atmosphere when the trees are cut down and either decay or are burnt. This results in an increased amount of carbon dioxide in the atmosphere which places additional strain on the Earth's oceans.

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How bad is the situation?

We're already starting to see the real-life effects of ocean acidification on marine life around the world - perhaps nowhere more so than in the Northwest region of North America where oyster farms are being severely impacted. This has knock-on effects for food supply chains and the livelihoods of those who depend on the Earth's oceans for their income.

Worryingly, the issue will only get worse as carbon dioxide levels in the Earth's atmosphere continue to rise. 

The extent of future ocean acidification is directly linked to future increases in carbon dioxide in our atmosphere. If we continue on the current trajectory, seawater PH could decrease by as much as 0.4 units by the end of the century, which could prove catastrophic for many species of marine life, and hugely destabilising for ocean ecosystems. This is why urgent action is needed to prevent any further acidification of the Earth's oceans.

What can we do to prevent ocean acidification?

Reduce greenhouse gas emissions

The most obvious and effective way to prevent further ocean acidification is to drastically reduce carbon emissions. This means cutting down on - and ideally eliminating - our use of fossil fuels.

In order to make this a reality every sector of our global society needs to decarbonise. We need to find alternative energy sources and transition to renewable energy use, which means a collective effort by governments, companies and individuals.

Until we make this change, carbon emissions will continue to rise which means that our oceans will continue to become more acidic. 

Restoration of carbon sinks

Even if we entirely cut out the use of fossil fuels, there will still be a surplus of carbon dioxide in the atmosphere, we therefore also need to work to reduce this level by restoring and increasing the Earth's carbon sinks. This can be achieved through activities such as reforestation, afforestation, revegetation, and through sustainable forestry and agricultural practices.

Additionally, we can continue to invest in and develop technological carbon sinks to aid natural processes.

small tree growing in a large forest

The bottom line

The bottom line is that even if we stop all emissions and work to increase the Earth's carbon sink capacity, ocean acidification will not end immediately.

We can expect to see a lag time before feeling the benefits of our actions. We can liken it to a car - even if you slam on the breaks, the car won't come to an immediate stop.

It's the same thing with climate change and ocean acidification - even if we eliminate emissions the climate will continue to warn and we'll continue to see the effects of ocean acidification for many years to come.

What about Greenly? 

At Greenly we can help you to assess your company’s carbon footprint, and then give you the tools you need to cut down on emissions. Why not request a free demo with one of our experts - no obligation or commitment required. 

If reading this article has inspired you to consider your company’s own carbon footprint, Greenly can help. Learn more about Greenly’s carbon management platform here.

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