Blue carbon can’t wait | Science

When the United Nations released its World Ocean Assessment in 2015, it was clear that the oceans were seriously degraded, with stressors on these environments projected to increase. The 2021 Assessment, released in April, shows that they have further declined, bringing us ever closer to losing the structure, function, and benefits of Earth’s marine systems. One way forward might be to focus on “blue carbon” ecosystems and the incentives they offer through carbon credits linked to decreasing carbon emissions.

Blue carbon ecosystems include seagrass meadows, tidal marshes, and mangroves, all of which are among Earth’s most efficient absorbers and long-term storers of carbon. This capacity for carbon storage also makes them sources of CO₂ emissions when they are degraded or destroyed.

As the United Nations Environment Programme states in its April 2021 report Making Peace with Nature, “Ecosystem restoration can simultaneously mitigate climate change, slow and reverse biodiversity decline and increase the benefits that people get from nature.” Restoring blue carbon ecosystems could remove about 0.5% of current global emissions, with co-benefits for local ecosystems and livelihoods. These include improved water quality; increased marine and terrestrial biodiversity; preservation of livelihoods, cultural practices, and values of local and traditional communities; and the protection of shorelines and their resilience in the face of climate change. That’s quite a return on investment.

We can start by ensuring that blue carbon ecosystems already identified for protection get the support they need. For example, the 50 United Nations Educational, Scientific and Cultural Organization (UNESCO) marine World Heritage sites make up just 1% of the world’s oceans but host 21% of the world’s blue carbon ecosystems and 15% of the world’s stored blue carbon—equal to 10% of annual global greenhouse gas emissions. Protecting those blue carbon ecosystems will keep billions of additional CO₂ emissions from entering the atmosphere. Their carbon stores are nominally protected from degradation by the legal commitment of over 190 signatory countries to the 1972 UNESCO World Heritage Convention. But local management of these sites is often underfunded and understaffed, and the sites face a variety of threats from pollution, coastal development, and climate change. For the 79% of blue carbon ecosystems outside of UNESCO protection—harboring the remaining 85% of the ocean’s stored carbon—marine protected areas (MPAs) can benefit climate mitigation by keeping billions of additional CO₂ emissions from entering the atmosphere. At the same time, MPAs also have been shown to protect biodiversity and boost fishery yields.

Where will the funding come from to support conservation? In part, through the use of blue carbon credits. Blue carbon ecosystems can help nations avoid releasing additional CO₂ and other greenhouse gases. The growing blue carbon credit market allows organizations and countries that conserve and restore blue carbon ecosystems to claim or sell credits in global carbon credit markets. For example, a country that protects seagrass meadows, and hence reduces the risk of future carbon emissions, may receive carbon credits that fund their future protection. Carbon credits can also be claimed for areas damaged by natural events. Wherever blue carbon habitats have suffered losses, blue carbon credits may help support their restoration.

So far, few countries have incorporated blue carbon strategies into their climate change mitigation policies. The Blue Carbon Initiative, created by UNESCO’s Intergovernmental Oceanographic Commission, the International Union for Conservation of Nature, and Conservation International, encourages more countries to develop comprehensive methods for assessing blue carbon stores and emissions.

But momentum is gathering. One of the largest seagrass restorations to date, in the United States, has applied for blue carbon credit certification. On the other side of the globe, Madagascar’s Tahiry Honko and Kenya’s Mikoko Pamoja mangrove restorations will be the first MPAs funded by blue carbon credits. At Tahiry Honko, revenues generated through carbon credits will cover recurring park costs associated with its mangrove protection and support education and infrastructure projects for the local community.

As the world aims for carbon neutrality in the decades ahead, we can take actions today to help slow climate change. The return on investing in blue carbon ecosystems is clear, meaningful, and immediate. We can’t afford to wait.