A landmark study released today by Partnerships in Environmental Management for the Seas of East Asia (PEMSEA), Conservation International and The Nature Conservancy examines the science and policy of “blue carbon” in East Asia and the opportunities for countries to advance their commitments to addressing climate change through the conservation and restoration of coastal wetlands.
The study, “Understanding Strategic Coastal Blue Carbon Opportunities in the Seas of East Asia,” describes the important role of coastal blue carbon ecosystems, which include mangroves, tidal marshes and seagrass meadows. These ecosystems provide a number of critical services, including shoreline protection and nursery grounds for fisheries, as well as maintaining water quality, buffering coral reefs from sediment runoff and sequestering carbon.
“We know that healthy coastal ecosystems sustain local economies across the region. We are also learning that by improving their management, countries can take steps to address climate change, advancing their commitments to both the Paris Climate Agreement and the Sustainable Development Goals,” said PEMSEA’s Executive Director, Stephen Adrian Ross.
Despite their importance, blue carbon ecosystems are some of the most threatened ecosystems on Earth, with 800,000 hectares destroyed each year. When degraded or destroyed, they switch from being carbon sinks to a significant source of greenhouse gas emissions. The biomass and organic soils in these ecosystems can release thousands of years of sequestered carbon in only a few decades. Although the combined global area of blue carbon ecosystems is only 2-6% of tropical rain forest area, its ongoing losses account for up to 10-20% of the emissions from global deforestation, a total of ½ billion tons of carbon dioxide each year.
Historically, but mostly within the last century, 3.4 million hectares of mangroves and tidal marshes have been converted to other uses, and in the process are estimated to have released 3.5 billion tons of carbon dioxide. By comparison, this is an emission equivalent to 42% of that from the entire economy of China each year.
East Asia is a global hotspot for the remaining blue carbon ecosystems, and it is experiencing high rates of loss.
In all, there are 4 million hectares of mangroves in East Asian tropical countries, representing around 30% of the global total. The full extent of tidal marshes is not well known, but is likely less than 57,000 hectares. Hidden beneath the tides, seagrasses may cover up to an area of 3 million hectares across the region. Collectively, these ecosystems are conservatively estimated to hold 13.7 billion tons of carbon dioxide in biomass and soils that are vulnerable to human disturbance. The 22.4 million tons of carbon dioxide they sequester each year from the atmosphere is equivalent to removing 4.5 million cars from the road.
By providing a clear picture of the status of coastal blue carbon ecosystems across East Asia, the report seeks to identify opportunities for countries to reduce climate change pressures and support the long-term well-being of coastal communities, outlining policy options that countries can consider.
Lead author of the study, Dr. Stephen Crooks of Silvestrum Climate Associates, notes that “while losses of blue carbon ecosystems continue, there are actions that countries, individually or collectively, can take to improve management and reduce greenhouse gas emissions, potentially supported by international finance.”
At COP21, countries supported the Paris Climate Agreement by identifying their “Nationally Determined Contributions (NDCs)” to reduce greenhouse gas emissions. These commitments create a powerful incentive for action and serve as a roadmap for potential investment. Almost all East Asian countries have started to address blue carbon ecosystems in their NDCs, but the climate change reduction benefits have largely been overlooked. The next round of NDCs will permit for a more comprehensive focus. This may set the stage for expanded bilateral and regional cooperation, devel