The escalating climate crisis makes it clear that the world must deploy every possible method to mitigate and adapt to our changing climate. This must include the use of carbon removal and storage to lower historic carbon dioxide emissions. The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that we cannot achieve net zero greenhouse gas emissions without the use of carbon removal and storage strategies on a global scale.[i] This will include emerging technologies, but we also cannot ignore the critical role of natural carbon cycles in sequestering atmospheric carbon dioxide.
One of the first biology lessons that many of us learn is that trees draw in carbon dioxide from the air and then produce oxygen. But we cannot ignore that oceans cover almost 71% of the Earth’s surface and they, too, participate in the carbon cycle. Oceans and coastal ecosystems play a critical role in carbon removal and storage. This sequestered carbon is known as “blue carbon”.[ii] Mangrove forests, seagrass beds, and salt marshes are particularly efficient carbon sinks. According to National Oceanic and Atmospheric Administration (NOAA) research, mangroves and salt marshes sequester carbon ten times faster than tropical forests. Seagrass meadows alone are responsible for storing 11% of the ocean’s carbon, even though they cover only 0.1% of the seafloor.[iii]
Unfortunately, the world is rapidly losing these vital coastal ecosystems. The Blue Carbon Initiative estimates that we are losing acreage at a rate of 1-2% per year. Salt marshes have lost up to 50% of their historic range. The loss of these ecosystems not only results in the release of up to 1.02 billion tons of carbon dioxide every year, it also means coastal communities lose a critical buffer against increasingly strong storms and flooding. In addition, it means the loss of habitat necessary for the function of healthy fisheries. One estimate puts the worth of these ecological services at $1.6 billion each year.[iv]
In addition to restoring coastal ecosystems, there are exciting new opportunities for humanity to leverage the ocean’s natural abilities to store carbon. One proposal involves cultivating massive seaweed farms to capture carbon dioxide. The seaweed can then be harvested as a feed additive that could reduce methane emissions from livestock. Seaweed can also be used as a biofuel, a substitute for chemical fertilizers, and as a protein source for people.[v]
Another proposal from the University of California Los Angeles (UCLA) would remove carbon directly from seawater to free up space for the ocean to absorb more carbon. Seawater is drawn into a flow reactor plant, and a chemical reaction is triggered by running an electric current through calcium and magnesium solids. The carbon in the seawater reacts with the calcium and magnesium to form limestone. The newly carbon-free seawater is then pumped back into the ocean. The limestone can be used for concrete and other construction materials. However, the UCLA team cautions that they are still at the prototype stage, and don’t fully understand the effects their plant could have on marine ecosystems.[vi]
Even though these new technologies have great potential, the best way to safely store blue carbon is to restore coastal ecosystems. There are many ways your average person can help protect these endangered habitats, such as the following suggestions. If you live in any of the Chesapeake Bay states, you can support the work of the Chesapeake Bay Foundation, which is working to protect wetlands throughout the Bay watershed.[vii] Write to your local officials and encourage them to address stormwater runoff that carries pollution to the coasts. See if there are any local groups working to create tree buffers around waterways to reduce soil erosion and water pollution. Reduce your individual plastic use to decrease the amount of plastic pollution entering the ocean. Finally, start choosing your seafood wisely by looking for the label of the Marine Stewardship Council (MSC), an independent organization that certifies fisheries as sustainable. Globally, shrimp farming was accountable for 30-50% of mangrove loss from the 1970s-1990s.
Together, we can make a difference, and save the coastal ecosystems that are essential for combating climate change, protecting coastal communities, and providing habitat for wildlife.[viii]