In the ocean, small plant-like organisms called phytoplankton are responsible for producing up to 50% of the world’s oxygen and capturing 40% of all carbon produced – this is 4x the amount of carbon sequestered by the Amazon rainforest. The ocean is the largest carbon sink on the planet and it is mainly down to these little organisms. When marine animals eat phytoplankton, the carbon stored inside phytoplankton builds up through the food chain and when animals die and sink to the bottom of the ocean, this carbon is then transferred and stored in the seabed for hundreds of years. These factors make the ocean a key solution in fighting climate change and is why we must protect it at all costs.
Large animals such as whales play a key role in the marine carbon cycle. Whales are incredibly important for maintaining a healthy ocean and as they are capable of storing large amounts of carbon, it makes them particularly important animals in combating climate change.
Whales are ecosystem engineers which means they are able to modify habitats in the ocean. They can do this through a mechanism known as a whale pump which is essentially how whales feed, poo, migrate and dive between the surface and depths of the ocean. This helps to circulate essential nutrients and in turn, keeps the ocean healthy. Through their feeding patterns, whales help phytoplankton thrive which increases the oceans ability to capture carbon. When whales dive down to feed and re-surface, they help to circulate essential nutrients throughout the ocean. Whales also come up to poo which provides much needed nutrients at the surface of the ocean where they are more scarce. All these nutrients delivered by whales are vital food for phytoplankton and this helps them flourish and grow in the marine environment.
In addition, whales are living carbon stores themselves. Throughout their lifetime, whales accumulate a large amount of carbon in their bodies and when they die, this stored carbon sinks to the bottom of the ocean. Studies suggest that eight species of whale, including humpbacks and blue whales, are capable of carrying as much as 30,000 tonnes of carbon to the bottom of the ocean each year. This takes carbon out of the atmosphere for centuries and is why greater whale protection is so important. If whale populations returned to their original size before whaling, this carbon sink could potentially increase to 160,000 tonnes each year.
Whales are living examples of how effective nature based solutions can be against climate change. If whale species were to recover to their previous numbers before whaling, we’d be increasing the ability of the ocean to store carbon by an incredibly high amount. Unfortunately, whales reproduce very slowly and it takes a long time for populations to grow. By recognising areas where whales are at risk and studying their habitats, conservation charities such as Sea Watch are able to safeguard these places by changing the way we use them. This includes fishing, noise pollution, marine litter, shipping and more. The ocean is the largest Carbon sink in the world but it is often overlooked as a climate solution. Protecting the ocean and its biodiversity is one of the most important ways in which we can fight the climate crisis. Nature already has the solutions, we just need more people advocating for them.
Lucy Ellis Research Intern