Our Impact: How does climate change impact the Ocean?

This is part of our Four Pillars work that highlights the importance of the Ocean, the human-made threats it faces, and the solutions our Ocean provides.

Climate change impacts everything – including our Ocean

With rising temperatures and melting ice sheets, climate change has had a massive impact on the Ocean.

The changing composition of gases in the atmosphere is altering life as we know it. We must not allow this catastrophe to unravel any further.

But how did we get here?

The emerging issue of ‘climate change

Over the last century, many scientists have raised their concerns about global warming while the fossil fuel industry was booming.

Now, we know that these concerns have been validated many times over, through computer simulations and direct observations (tree rings, ice cores, etc).

According to the Intergovernmental Panel on Climate Change (IPCC) it is now widely accepted that humans are the primary drivers of climate change, owing to the advent of burning fossil fuels.

What role does the Ocean play in the climate change conversation?

Our beloved recreational activities would not be possible without the Ocean

The Ocean helps regulate land temperature and drives global weather patterns.

It absorbs the sun’s heat, transferring it to the atmosphere and distributing it around the world, warming in the winter and cooling in the summer. In fact, more than 90% of the heat from global warming is stored in the Ocean acting as one of the most important carbon sinks on Earth.

The excess of emissions in the atmosphere has tampered with the Ocean’s capacity of storing it while still being able to thrive.

How can we understand the impact of climate change on the Ocean?

There are many indicators that help us understand the effects of climate change on the Ocean:

The leading climate change indicator in the Ocean: Sea level rise.

The rise in temperatures cause water to expand and ice sheets to melt. This results in sea level rise. Globally, the changes in sea levels are a leading indicator of climate change.

People using boats in response to flooding.

During the 21st century, the global mean sea level is likely to rise at least 30 cm even assuming more moderate greenhouse gas emissions in the coming decades.

Even if adaptive measures are in place, global flood losses for coastal cities are predicted to increase from $6 billion in 2005 to $1 trillion by 2050.

Global warming of 4°C by 2100 would lead to a median sea-level rise of nearly 1 metre above the 1980 to 1999 levels. At today’s population distribution, that would threaten the lives and livelihoods of between 150 to 250 million people.

It goes without saying that the effects of sea level rise are already being felt in many parts of the world.

In Indonesia, 75% of the country’s cities are in coastal areas. With the country being prone to frequent natural disasters like flooding, tornadoes, and landslides, over 110 million people in the cities are exposed to the devastating impacts of climate change.

These impacts can often be felt alongside disruptions to agriculture (like rice fields), water resources (potential salinisation of ground water) and other resources.

Coral Bleaching

What is Ocean acidification?

As the Ocean gets warmer, we observe changes in the chemistry of the water. The reduced pH level of water has led to Ocean acidification, forming carbonic acid.

Global surface Ocean pH has declined on average by approximately 0.1 since the Industrial Revolution, with an increase in acidity of about 30%. 

This is making it harder for marine organisms (including larvae) to develop calcium carbonate shells and skeletons, increasing their vulnerability and harming their overall health. This invariably impacts food security due to the adverse effects on fisheries and aquaculture.

What’s the harm of Ocean deoxygenation?

Unfortunately, the warming Ocean also raises the oxygen demand of living organisms and as a result, there is less oxygen available for marine life.

Ocean oxygen levels have decreased by 2% in the past five decades and are expected to reduce a further 3–4% by 2100.

Oxygen depletion is one of the most serious threats to the coastal marine ecosystem including coral reefs and sea grass meadows, reducing biodiversity, limiting both the production of oxygen and sequestration of atmospheric CO2, and increasing the risk of coastal flooding.

A flooded coastal area.

The Ocean covers 70% of our planet – but it’s still impacted by climate change.

Here is a good introductory video outlining this topic:  

YouTube player
[Credit: Global Weirding with Katherine Hayhoe, YouTube]

Woah, is the fate of our Ocean already sealed?

Fortunately, not yet.

We are alive in a crucial period of time, with the window of action and opportunity closing in on us.

The IPCC’s modelling suggests that the only way to limit global warming to 1.5C is we take immediate action after 2020, which is, well, now.

A woman's hand with green painted nail polish, a wedding ring and a silver bracelet reach out into the Ocean waves. We are connected to the Ocean - it provides our every second breath and supports all life on Earth.


In this scenario, emissions are projected to peak between 2020-2025. This means that we need to reduce emissions by 43% by 2030, and 84% by 2050.

Apart from phasing out fossil fuels, reducing global carbon and methane emissions is a key solution to slow down Ocean warming. Increasing Marine Protected Areas (MPA’s) is another way of protecting large areas of the Ocean from further exploitation. We must also safeguard and restore coastal ecosystems which will benefit biodiversity and humans alike.

A healthy Ocean is key to achieving our climate goals.

If the Ocean thrives, so do we.

What can Antarctic ice cores tell us about the history of our climate? 

Subscribe

Monthly: Impact in your inbox.

OceanGeneration-Join

Our Impact: It’s not just plastic polluting our Ocean

This is part of our Four Pillars work that highlights the importance of the Ocean, the human-made threats it faces, and the solutions our Ocean provides.

It’s not just plastic polluting our Ocean

With plastic encroaching so many parts of our lives since the 1950’s, it would be hard to find a person today who hasn’t heard of this life-changing material. Despite all its uses, it is undeniable that plastic is choking our Ocean. 

But it’s not just plastic.

Marine pollution can be observed in many different forms (see figure below).

From chemical waste to noise, let’s explore the alarming ways in which we pollute the Ocean.

Types of Ocean pollution: Plastic pollution, nutrient pollution, light, noise and industrial pollution. Ocean Generation is breaking down the kinds of pollution that impact our Ocean.

We are drowning in plastic  

Plastic is the greatest concern of all the marine litter in the Ocean.  

With 80% of plastic originating from land, it is clear that our mismanagement of plastic is threatening marine life. In fact, marine debris from waste streams on land and at sea into the Ocean from rivers are estimated at 1.15–2.41 million metric tons annually.  

Plastic also reaches the Ocean as a result of extreme events and natural disasters like floods, hurricanes, and tsunamis.

One study even states that millions of tons of plastic may reach the Ocean this way, matching the magnitude of plastic from land.  

The most common way plastic harms marine life is through entanglement. This is not to mention the repercussions felt through the food chain when species ingest plastics (and microplastics) unknowingly. 

From whales, to birds, to turtles, plastic is mistaken for prey and consumed with traumatic consequences like infections and internal injuries. 

In the UN report, Second World Ocean Assessment (WOA) 2021, it was stated that scientific and medical understanding of the health threat of plastic pollution was inadequate. But since then, scientists have published studies confirming the presence of plastic in our blood and lungs.

These findings have sparked a greater support for more research into the effects of plastic on human health. 

Changes to marine communities are far from being the only effects of pollution.  

Half of the image shows a beautiful blue, clean Ocean. The other half shows a polluted, grey, Ocean with plastic bottles and nutrient pollution. Ocean Generation shares ways to tackle plastic pollution and other Ocean threats.

The nutrients we allow into the Ocean 

The increasing amount of nutrients seeping into the Ocean aid the excessive growth of algae.

This is called nutrient pollution. When the nutrients in question are nitrogen and phosphorus (from organic matter), this process is called eutrophication. It results in undesired changes to the health of coastal ecosystems.  

Nutrient changes in the Ocean threaten: 

– Carbon sequestration which limits climate change, 
– Fisheries, affecting their mortality, 
– Abundance of biodiversity, 
– Production of oxygen, and the 
– Mitigation of coastal flooding.  

The single largest source of nitrogen and phosphorus are synthetic fertilisers.

Other agricultural inputs include animal husbandry and monocultures of legumes. Another source of nitrogen is the combustion of fossil fuels, releasing nitrogen in the form of NOx. 

The most prevalent source of nutrient pollution is human sewage.

This is not a surprise considering 80% of municipal wastewater being released into the environment is untreated. Regionally, treated sewage varies from 90% in North America, 66% in Europe, 35% in Asia, and 14% in Latin America and the Caribbean to less than 1% in Africa.  

This means that across the Ocean, we see an increase in phytoplankton and a decrease in oxygen levels. This disrupts fish stocks and increases the number of waterborne diseases.  

A water treatment plant.

But nutrients are not the only thing to worry about… 

Ocean pollution – in different industries: 

Industrial pollution can be observed from many sources. They are:

Persistent Organic Pollutants (POPs):
They are a complex group of substances known for their ability to endure in the environment. At present, we have observed declines in some regions, thanks to regulatory standards set by the Stockholm Convention but POPs are still a global concern.

For example, cetaceans have been detected with PCB (a kind of POP) concentrations which also affects the food chain, increasing the risk of cancer and infertility in humans. 

Metals:
Humans are responsible for large influxes of metals being released into the environment.

This includes metals such as mercury, lead, and cadmium but also rare earth metals. Metals do not disappear over time and can be trapped in sediments.

It was found that some Artic marine mammals are at high-risk with the concentration of methylmercury in their diet. This poses a risk to the food chain, and subsequently, human health. 

Radioactivity:
The discharge of radioactive substances into the Ocean from nuclear power plants continue to decline with the help of improved technologies. 

Pharmaceuticals and Personal Care Products:
This includes all chemicals used for healthcare, cosmetics, and medical purposes. The process to remove these substances from wastewater is not efficient.

As a result, the most frequently detected compounds are antibiotics. There have been some cases like the antibiotic resistant bacteria and soil found in the Artic and Pacific but overall, there is limited data on the true impact of these products in the Ocean.  

Pharmaceuticals end up in our water stream and impact marine life. The image shows a white bowl filled with pills in different hues of blue.

Shipping:

Globally, there is a decreasing trend in oil spills (over 7 tons), possibly owing to improved surveillance and increased awareness.

Shipping also increases the likelihood of marine litter, with the World Shipping Council estimating that on average, a total of 1382 containers are lost at sea each year.  

Oil spills are catastrophic to Ocean health and hard to clean up.

Sound pollutes the Ocean (and we’re not considerate neighbours). 

Human-made noise makes its way into the Ocean via vessels, renewable energy development, sonar, and seismic exploration. Marine traffic also contributes to noise pollution.

Over the past 10 years, there’s been increasing interest in developing guidelines to regulate noise in the Ocean.  

We continue to learn and understand the impact of the noise we make on marine animals. Some of the observed examples are as follows: 

– Increased stress levels in North Atlantic right whales 
– Humpback whales: changes in foraging behaviour and vocal calls during breeding season 
– Fish and coral larvae are less able to select appropriate habitats 

Humpback whales are impacted by noise pollution. Image shows a close up of a humpback whale looking at the camera.

Hit the lights: Do you know how light pollution impacts marine life

Although all living beings are sensitive to light in the environment, if organisms are subjected to light at the wrong place and time with varying intensity, it’s known as light pollution.

This affects the behaviour of many marine mammals. For example, on one Turkish beach, light pollution from a coastal village, paper mill and a tourist resort resulted in less than 40% of logger-head turtle hatchlings being able to reach back to the shore.

They get disoriented and sometimes are at risk of predation.  

Baby turtle finding its way to the Ocean form the beach.

The most impactful way humans project artificial light is through urbanisation of coastal areas. The light we emit can be seen from space.

In fact, up to three quarters of seafloor close to coastal cities are exposed to artificial light. But other water bodies are not immune. In freshwater ecosystems, melatonin levels which are responsible for sleep or day and night cycles, are affected in freshwater fish. 

In the Ocean itself, offshore development is of concern when assessing light pollution. Artificial light at night can penetrate deep into water (over 40m) depending on the clarity of water, with humans having the most impact in the top one metre of water.  

Coastal city lit up at night near the Ocean. Cities never sleep.

What can we do to restore the Ocean?

We need to develop a wide range of solutions to combat the different types of pollution affecting the Ocean.  

To tackle plastic pollution, a Global Plastic Treaty is underway to ensure optimal waste management and promote sustainable consumption and production of plastics.

As a society however, it is still in our best interests to reduce our reliance on plastic where possible. We need to dispose plastic in the safest way possible, not allowing it in our waterways.  

Community garden featuring a middle aged Asian woman and young African child working in the garden.

Nutrient pollution can be curbed with the help of top-down approaches but also public awareness.

As a community, we can take a stronger stance and equip ourselves to monitor water quality, pushing for stronger policies. Those who have lawns and gardens can also minimise their pollutant run-off through many ways.  

Moreover, better sewage systems are needed to achieve standards set by the World Health Organisation (WHO). In India, for example, despite efforts to operate better systems, nutrient pollution still persists. Industry stakeholders must develop and promote solutions to address pollutants in the agricultural sector. Innovative solutions are needed to reduce emissions and spills in shipping.  

Lastly, there is a need to promote and fund the research required in further understanding all these issues because our Ocean is running out of time, awaiting solutions for the threats we’ve created.  

There is only one Ocean, and it connects us all. 

What can Antarctic ice cores tell us about the history of our climate? 

Subscribe

Monthly: Impact in your inbox.

OceanGeneration-Join