The world’s oceans are home to microscopic organisms invisible to the human eye. The tiny creatures, known as “prokaryotes”, comprise 30% of life in the world’s oceans.
- These organisms play an important role in keeping the oceans in balance. But new research shows this balance is at risk. This could reduce the availability of fish humans rely on for food, and hamper the ocean’s ability to absorb carbon emissions.
Prokaryotes
- Prokaryotes include both bacteria and “archaea”, another type of single-celled organism. These organisms are thought to be the oldest cell-based lifeforms on Earth.
- They thrive across the entire planet – on land and in water, from the tropics to the poles.
- Globally, about two tonnes of marine prokaryotes exist for every human on the planet. They play a crucial role in the world’s food chains, helping support the nutrient needs of fish humans catch and eat.
- Marine prokaryotes grow extremely fast – a process that emits a lot of carbon. In fact, prokaryotes to an ocean depth of 200 metres produce about 20 billion tonnes of carbon a year: double that of humans.
- This massive carbon output is balanced by phytoplankton – another type of microscopic organism which turns sunlight and carbon dioxide into energy, through photosynthesis.
- Due to human-caused climate change, Earth’s oceans are expected to warm by between 1°C and 3°C by the end of this century, unless humanity changes course.
- If the amount of carbon produced by prokaryotes does increase as predicted, it could reduce the potential of oceans to absorb human emissions. This means achieving global net-zero emissions will become even more difficult.
