Article by: The Coral Reef Alliance

Most studies about coral reefs and climate change focus on the impacts that increased levels of carbon dioxide will have on reef ecosystems. Higher concentrations of carbon dioxide threaten corals with increasing sea surface temperatures, ocean acidification, sea level rise, and intensifying tropical storms. However, a recent United Nations report presents a different angle on this relationship: the conservation of coral reefs and their associated coastal marine ecosystems could actually be the key to combating climate change.

According to the report Blue Carbon: The Role of Healthy Oceans in Binding Carbon, marine ecosystems such as mangroves, salt marshes, and seagrasses capture and store between 800 and 1,650 million tons of carbon a year, equal to about half the annual emissions of the global transport sector. These marine vegetated habitats cover less than one percent of the seabed, yet account for over half of all carbon storage in ocean sediment. Furthermore, though their combined biomass amounts to less than one percent of the biomass of plants on land, they store a comparable amount of carbon, making them one of the most intense carbon sinks on the planet. These ecosystems are now referred to as “blue carbon sinks.”

Preserving and restoring marine vegetated ecosystems could contribute to offsetting up to seven percent of current fossil fuel emissions over the next two decades, and it would accomplish that task at a fraction of the cost of implementing carbon capture and storage technologies at power plants. That figure is equal to more than half of the carbon offsets projected for reducing rainforest destruction. What’s more, while carbon captured and stored on land may be locked away for mere decades, carbon stored in the oceans remains for millennia.

Unfortunately, though, coastal vegetated habitats are being lost at an increasingly rapid pace. Since 1940, more than thirty percent of both mangroves and seagrass beds have been lost, and we are currently loading between two and seven percent of our blue carbon sinks annually –a seven-fold increase over loss rates half a century ago. This rate of destruction is much faster than the rate of destruction of rainforests, and current trends might see these ecosystems nearly disappear within a few decades.

The health of coral reefs is inseparable from the health of these closely associated ecosystems; seagrass beds and mangroves, in particular are found nearly everywhere that coral reefs occur, and many species rely on a combination of these habitats over the course of their lives. It is therefore critical that the management plans and the design of marine protected areas (MPAs) consider all of these related ecosystems. Zones B and C of the Hol Chan Marine Reserve are designated areas protecting such habitats, and CORAL’s holistic Coral Reef Sustainable Destination (CRSD) model encourages just this kind of integrated thinking. CORAL supports effective management of MPAs around the world that include seagrass and mangrove habitats in addition to coral reefs, and we are also supporting community efforts to curtail the destruction of these habitats and grant them more official protections. While CRSD wasn’t designed with blue carbon sinks in mind, the new information about the great importance of marine vegetated habitats further demonstrates the value of a holistic approach to conservation. By taking into consideration the whole coral reef ecosystem and all of the factors that influence its health, CORAL’s work has been helping preserve these additional habitats that we now know are ultimately helping to protect coral reefs –and all other ecosystems – from the impacts of climate change.