The ocean is the great global regulator. It replenishes oxygen, modulates temperatures, generates weather systems and provides us with an abundance of different food resources. 

This year, World Oceans Day on 8 June celebrates the theme, “Planet Ocean: tides are changing”. At this critical point in time, it’s a theme that couldn’t be more relevant.

Changing ocean environments

With rising temperatures and changing environmental conditions, our oceans are most certainly changing, and this is happening too quickly. The changes are complex and include many different environmental variables —  such as temperature, availability of oxygen and ocean pH — that do not occur in isolation and are difficult to predict.

Changing marine conditions impact all the species that inhabit the ocean. Local extinctions, as well as the redistribution of species as a response to changing conditions, have been widely recorded in many marine ecosystems globally.

This is no longer a far-off future problem — we are already facing the impacts of climate change today.

This has far-reaching consequences not only for the ecosystems but also for the people, fisheries and livelihoods that rely on the ocean and its resources.

We hear the term “climate change” time and time again. Much like “Covid-19” back in 2020, it is a topic that is consistently in the news. It is a problem that often appears too remote to conceptualise, and, given the magnitude thereof, too difficult to resolve.

Mostly, we have come to detach ourselves from the climate change problem and associate it with something that we will only be dealing with far in the future. Oftentimes, this is exacerbated by alarming predictions of what the world will be like many years from now.

For example, in the 2021 Intergovernmental Panel on Climate Change report it was stated that by 2100, temperatures were predicted to increase by between 1°C to 5.7°C. It is challenging to understand the significance of a 5°C increase in just 77 years and the impact on life today — especially when it feels like South Africans are currently living from one bout of rolling blackouts to the next.

However, when we get advance warning, as we do with rolling blackouts, we should sit up and take note. This is no longer a far-off future problem — we are already facing the impacts of climate change today. 

There is a wealth of evidence highlighting the current impact of global climate change on a variety of marine and terrestrial species, environments and systems, and the cost to humanity is immense.

Marine species moving

Species respond to changing environmental conditions by either adapting to their current habitat, moving to find more suitable habitat or becoming locally extinct. Marine environments are tremendously vulnerable to climate change as the species are much more sensitive to changes in temperature than those living on land.

Although it may not seem like much, even a 1°C increase over the space of a decade can have a profound and compounding impact on the marine environment.

To put this into perspective, when swimming on the west coast of South Africa, one degree can sometimes be the difference between a refreshing swim or a mind-splitting brain freeze — but at least you can get out of the water.

The South African coastline has been categorised as one of 24 global climate change hotspots. These are areas where ocean warming is happening at a rate faster than the rest of the world and where rapid warming is forecast for the future.

The east coast is expected to warm at a rate of 0.5°C per decade, while in contrast, the west and south coasts are expected to cool at a rate of 0.5°C degrees per decade. 

Just like the tides and ocean temperatures can change and adapt, so can people and their behaviours.

These responses are like day and night, with one-half of our coastline rapidly cooling and the other half steadily warming, making the future of our marine ecosystems and their inhabitants far more complex and difficult to predict.

With the world changing around them, marine species will try to move to areas where the conditions are still optimal for them. Take a population of hake, for example: if their current home is getting warmer, they will gradually swim somewhere further afield to a cooler environment that better suits them.

We see this trend in several fish species on the west coast of South Africa which have already moved southward or eastward over recent decades to avoid warming temperatures.

In other parts of the world, fish are moving deeper and poleward towards cooler environments. So, the fish and other marine species are moving in response to changing temperatures.

But why is this important to you?

Knock-on effect

One of the major impacts of the movement of marine species in response to climate change is the knock-on effect this will have on global fisheries and livelihoods.

Globally, approximately 520 million people are estimated to rely on fisheries as an important source of food, income and family stability.

In South Africa, the marine environment supports multiple users. The commercial fishing sector creates jobs for approximately 150,000 people and is valued at R8-billion per year. To boot, around 30,000 people rely on the marine environment as a source of subsistence, and hundreds of thousands of people take part in recreational fishing activities.

Fisheries can adjust to this moving resource by either tracking species shifts or switching to a new target species. But when whole communities and industries are focused on these resources, changing can be complex, costly and a logistical nightmare — not to mention the vast impact on the communities involved.

This is compounded by geographic boundaries and borders. For example, if hake currently fished in South Africa move further north into Namibian waters, then this is no longer a resource that can be harvested locally. As hake contributes towards 53% of the fishing sector output in South Africa, you can see why this could pose a serious problem.

So what is next?

Just like the tides and ocean temperatures can change and adapt, so can people and their behaviours.

Change happens at different scales. When it comes to protecting our marine ecosystems and species, we, as individuals, can change our everyday behaviour. We can be mindful of and control the food we consume, the waste we produce, and the industries and change-makers we support. We can listen and react to the warning signs around us and share knowledge with those who have not yet seen the signs.

On a larger scale, scientists, policymakers, fishing communities, and recreational and commercial fisheries can come together regionally and globally to share knowledge and develop flexible and adaptive management strategies and policies.

For the most part, this is being realised and there are certainly some preparations for an uncertain future. However, the largest single impact to safeguard the future will be to reduce emissions of greenhouse gases immediately, which is everyone’s effort.

Without this, the future will be even more uncertain than it is currently, and we face disastrous consequences, with few solutions, for our actions today.

As with anything, these changes will take time, but the consequences of today’s actions will be felt several decades from now. Considering what is at stake, it is imperative that we start now to make the critical changes that will ensure the future of our oceans. DM

Courtney Gardiner is a PhD candidate at Stellenbosch University. She works on fisheries and the impact of climate change on them and people’s livelihoods, as commercial fish species shift their ranges and adapt to a changing climate.

To read all about Daily Maverick’s recent The Gathering: Earth Edition, click here.