When we think of “carbon sinks” and ways to capture carbon dioxide from our atmosphere, many of us think of forests and particularly rainforests. We are likely to picture beautiful large tropical trees which we know are a great way to absorb and store CO2. However, even if this is a good way to store CO2, with the increase in deforestation around the world (it is heart-breaking and needs to be reversed!!), the carbon in those trees will be released and emitted back into the atmosphere as soon as they are cut down. This poses a risk that forests in the future might be releasing more CO2 than they are absorbing because they are unable to keep up with humans changing their environment.
In terms of carbon capture efficiency, forests are the fifth most efficient ecosystem in the carbon storage cycle behind salt marshes, mangrove forests, seagrass meadows and, best of all, tundra. And whilst forests and tundras are losing the capacity to retain carbon storage (due to deforestations and climate change), another often forgotten ecosystem that is bringing hope to the environmental crisis is SEAGRASS.
Seagrass is a flowering plant that grows entirely underwater and covers ~0.2% of our ocean floors. There are currently 72 species of seagrass that often form in dense underwater meadows (some of which are large enough to be seen from space!) residing in shallow waters along coastlines in most parts of the world.
Seagrass meadows have an excellent capacity to absorb and store carbon by using the sun's energy to convert CO2 and water into sugar and oxygen to grow through the process of photosynthesis.
Seagrass meadows store a majority of the captured CO2 in the oxygen-free sediment it sits in, where it decomposes much slower than on land and can remain buried for hundreds of years. It is so efficient, that it captures CO2 from the atmosphere up to 35 times faster than tropical rainforests and it accounts for 10% of annual ocean carbon storage despite only taking up 0.2% of the seafloor. This is why it is one of the most efficient carbon storage environments and an important part to tackle climate change.
Seagrass has so many amazing qualities that our planet depends on for survival. However, human activity puts seagrass under threat - from reductions in water clarity, pollution, oil spills, coast development and damage from boat propellers and chain moorings. Global seagrass coverage is diminishing at a rate of 1.5% a year, or about two football fields each hour. Estimates suggest that 29% of seagrass meadows have died in the past century, being replaced with unvegetated mud and sand soils.
The real danger of seagrass meadows retracting is that we are not only capturing less carbon from the atmosphere but there is a risk that millennia-old carbon stocks could be released back into the environment. This would mean seagrasses would shift from being carbon sinks to carbon sources, thereby accelerating climate change.
Despite all this gloom, there is hope for seagrass! In recent years, scientists and countries are calling for global action to protect seagrass meadows, and there are several initiatives currently in place to restore seagrass territories and it's full potential as an environmental hero.
So, on this Earth Day, we want to raise awareness for an environmental hero that brings life to our oceans, reduces CO2 from our atmosphere, and produces oxygen for our lungs.
Written by the Nature Unite team