Everything! Marine ecosystems depend on the food web, which starts with phytoplankton. Development of offshore wind is reported to have an impact on phytoplankton production. If we destroy phytoplankton, everything else dies. Ocean ecosystems provide 50-80% of global oxygen and are among the world’s most effective carbon sinks.  So, in short, these ecosystems are vital for regulation of climate, the air we breathe and life on earth. When the ocean breathes out, we breathe in!

Areas containing natural reefs, seagrass, kelp forests and sea-pens, are examples of marine ecosystems that very efficiently capture carbon from the atmosphere. For example, seagrass beds capture carbon 35 times faster than a rainforest. Reefs give life to our seas providing shallow, light-filled waters for phytoplankton to bloom, fish to spawn, sharks and whales to feed. Protecting whales and allowing their numbers to increase is another really effective way to capture atmospheric carbon in the ocean.

Phytoplankton captures carbon dioxide directly from the atmosphere through photosynthesis, just like trees. Unfortunately, if it is not consumed, phytoplankton can degrade and return the carbon dioxide to the atmosphere, rather than store it in the deep oceans. Whales, a vital part of the marine ecosystem, consume large amounts of phytoplankton (e.g. Blue whales feed on 16 tons per day), which they then defecate (poo out) onto the ocean floor, where it forms a stable carbon sink. In addition, the resulting release of inorganic nutrients (e.g. iron, nitrates, phosphates, silicates and calcium) from the faeces stimulates increased phytoplankton production (just like fertilising your garden). At the end of their lives, when whales die, their bodies fall to the ocean floor, resulting in even further carbon capture and storage (See image below).

Excess carbon dioxide in our atmosphere creates global problems. Globally, 10 Gt would have to be removed annually to keep the global temperature increase to below 1.5 degrees, as committed to under the Paris agreement. However, because it is present in minute concentrations (approx. 419.08 parts per million) it very difficult and inefficient to remove using man-made systems. In contrast, marine and terrestrial ecosystems (e.g., oceans, bogs, rainforest) have evolved over millions of years to become exceptionally efficient at capturing and storing carbon. While there is much talk these days about carbon capture technologies, any technology developed by humans is going to be a highly inefficient and expensive alternative to the natural carbon capture provided by healthy functioning ecosystems.