Blue Carbon - the ocean and climate change

The ocean covers 70% of our planet, and produces the oxygen in every second breath we breathe. Following on from my last post about biodiversity, ocean biodiversity is as important as terrestrial biodiversity in maintaining an inhabitable planet.

Ocean biodiversity is threatened by overfishing, habitat destruction, plastic and other chemical pollution, and climate change. We need to stop dumping things into the sea, and we need to create highly protected areas where nature can thrive. The ocean’s fascinating and diverse ecosystems are out of sight and out of mind to so many people, and that’s where one of the main issues lies with creating public pressure to properly protect the ocean from human damage. Because we can’t see it, we cannot relate to it.

Maerl, an important ecosystem engineer, and blue carbon store in Scotland.

But the ocean also has another really important role in the climate and biodiversity crises.

Blue Carbon

The ocean has already absorbed 30-40% of our anthropogenic carbon emissions. And if we allow nature in the ocean to thrive, it can store even more.

Let’s take whales as a starting point, because we all love whales!

Whales are long lived, enormous vats of carbon. Carbon is stored within their tissues, and when they die, they (generally) sink to the deep ocean where that carbon is incorporated into other creatures, or where it remains buried over years and years into sediment.

A Minke whale in NW Scotland. Pic by James Appleton.

To have an ecosystem that supports whales, the plants and animals right at the bottom of the food chain need to thrive too.

Seagrass is a superplant, the only flowering plant in the sea, which not only absorbs, but sequesters 30 times more carbon than rainforests of the equivalent mass. Sequestering means the carbon is drawn down into the roots and locked away in the sediment beneath the plant over time, not just stored in its leaves. Kelp absorbs 20 times more carbon than terrestrial forests, and some of that kelp sinks to the deep sea where the carbon is stored in sediment. And BOTH of these plants form important habitats for other species, such as the plankton and fish needed to feed the whales we all love so much.

Seagrass. Pic by James Appleton

Muds and maerls, on the very bottom of the seabed, not only provide habitats, but store carbon too.

I think it’s time we started really appreciating the work the ocean does for us, and respecting and protecting it accordingly.

A recent paper concluded that bottom trawling releases as much carbon as aviation globally! This happens by disturbing the sediment and all that carbon on the seabed. It’s currently unknown whether that carbon is re-released into the atmosphere, or remains in the water column, but processes which have taken many years to take effect are disturbed in seconds.

The ocean is in crisis. Not only is climate change affecting the composition of the water, bleaching corals, warming seas and altering ecosystems, but damaging human practices are destroying nature and threatening biodiversity globally.

One of the best things we can do is to create areas of the ocean which are highly protected from human activity, to give nature a chance to thrive, to bounce back from years of damage, and to continue to do its incredible work in mitigating climate change.

What can you do about it?

1. Support ocean rewilding projects, such as Seawildling, which aims to return a million native oysters, and replant a huge seagrass meadow, in Loch Criagnish, Scotland.

2. Choose your seafood carefully. We don’t need to be eating as much seafood as we do in the West. Our ocean is all connected globally, and there are countries and communities that rely on these fish stocks for protein. Many of the industrial fishing practices in the UK are unsustainable and severely damaging to both biodiversity and to blue carbon stores.

There is currently a campaign, Our Seas, to close off the inshore 3 miles of the ocean to damaging bottom trawling practices around Scotland.

3. Reconnect to the sea. Learn everything you can about the ocean, its impact on our lives, and how we’re all connected to it.

Cal Major