Climate change is one of the most urgent challenges facing humanity and the planet.
It is driven by the accumulation of greenhouse gases, such as carbon dioxide, in the atmosphere, which trap heat and alter the Earth's climate system.
To avoid the worst impacts of climate change, we need to reduce our greenhouse gas emissions and remove some of the excess carbon dioxide from the atmosphere.
One way to do this is by restoring coastal ecosystems, such as seagrass meadows and mangrove forests, which can capture and store large amounts of carbon.
What are coastal ecosystems and how do they store carbon?
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Coastal ecosystems are habitats that occur along the coastlines of continents and islands, where land meets water, as per Phys.org.
They include salt marshes, seagrass meadows, mangrove forests, coral reefs, and kelp forests.
These ecosystems provide many benefits for humans and nature, such as supporting biodiversity, protecting shorelines from erosion and storms, filtering water quality, and providing food and livelihoods for millions of people.
Coastal ecosystems are also important for mitigating climate change because they can capture and store large amounts of carbon through photosynthesis.
Photosynthesis is the process by which plants use sunlight to convert carbon dioxide and water into organic matter and oxygen.
Some of this organic matter is stored in the living tissues of plants and animals, while some are buried in the sediments below.
This carbon storage is known as blue carbon because it occurs in marine and coastal habitats.
According to a report by the Intergovernmental Panel on Climate Change (IPCC), coastal ecosystems store about 50 billion tons of carbon in their biomass and soils.
This is equivalent to about 25% of the carbon stored in all terrestrial ecosystems combined.
Coastal ecosystems also have high rates of carbon sequestration, which is the process of capturing and storing carbon over time.
For example, seagrass meadows can sequester up to 35 times more carbon per hectare than tropical rainforests.
How can we restore coastal ecosystems and enhance their carbon storage?
Unfortunately, coastal ecosystems are under threat from human activities, such as land use change, pollution, overfishing, coastal development, and climate change, as per ScienceDaily.
The IPCC estimates that about 20-50% of coastal wetlands have been lost globally since 19001, resulting in the release of up to 1.02 billion tons of carbon dioxide per year.
This is equivalent to about 3% of global fossil fuel emissions.
To reverse this trend and enhance the role of coastal ecosystems in mitigating climate change, we need to restore them to their natural state and protect them from further degradation.
Restoration involves restoring the physical structure, ecological function, and biodiversity of degraded habitats, using techniques such as planting native species, removing invasive species, reducing nutrient inputs, and restoring hydrological regimes.
Restoration can have multiple benefits for climate change mitigation.
First, it can increase the area and biomass of coastal vegetation, which can capture more carbon dioxide from the atmosphere through photosynthesis.
Second, it can enhance the accumulation and preservation of organic matter in sediments, which can store more carbon for longer periods of time.
Third, it can reduce the emissions of greenhouse gases from degraded habitats, such as methane and nitrous oxide.
Several studies have quantified the potential of coastal ecosystem restoration for climate change mitigation.
For example, a study by Duarte et al. (2013) estimated that restoring 15% of the lost area of seagrass meadows could sequester about 299 million tons of carbon dioxide per year.
This is equivalent to about 0.8% of global fossil fuel emissions.
Another study by Donato et al. (2011) estimated that avoiding further loss of mangrove forests could prevent the emission of about 316 million tons of carbon dioxide per year.
This is equivalent to about 0.9% of global fossil fuel emissions.
What are the challenges and opportunities for coastal ecosystem restoration?
Restoring coastal ecosystems is not without challenges.
Some of the barriers include lack of funding, technical expertise, political will, stakeholder engagement, and legal frameworks.
Moreover, restoration may not always be feasible or desirable in some cases, such as when habitats are severely degraded or converted to other uses.
However, there are also many opportunities for overcoming these barriers and scaling up restoration efforts.
Some of the enablers include increasing awareness, knowledge, and capacity on blue carbon science and practice; developing policies and incentives that support restoration and conservation; engaging local communities and stakeholders in participatory planning and management; integrating blue carbon into national and international climate strategies; leveraging finance from public and private sources; and monitoring and reporting on restoration outcomes.
Restoring coastal ecosystems can offer multiple benefits for climate change mitigation as well as adaptation.
By capturing and storing large amounts of carbon dioxide from the atmosphere while providing other ecosystem services such as biodiversity conservation, shoreline protection, water quality improvement, food security, livelihoods support, cultural values, tourism, recreation, education, research, etc., coastal ecosystems can contribute to both reducing greenhouse gas emissions (mitigation) and enhancing resilience to climate impacts (adaptation).
Therefore, restoring coastal ecosystems should be a priority action for addressing climate change in a holistic way.
