Australia looks to its coastline to slow climate change
SYDNEY – Researchers on a boat off the coast of southern Australia recently began dumping some 50,000 sandbags into the ocean. Their goal is to restore about two dozen acres of seagrass on the ocean floor that will suck carbon from the atmosphere.
The move is part of an intensified push in some countries to slow the warming of global temperatures not only by preserving or restoring trees – which also absorb carbon – but also by repairing habitats along the world’s coasts.
These so-called “blue carbon” areas, which in addition to underwater seagrass prairies also include mangroves and tidal marshes, often store more carbon per acre than forests and retain it for a long time, scientists say. . From Australia to Colombia to the United States, these coastal areas are becoming a priority for conservation and restoration as researchers and policymakers begin to appreciate their potential to remove carbon from the atmosphere.
Carbon released into the atmosphere from man-made sources such as fossil-fueled power plants and cars contributes to global warming, many scientists say, which is why researchers are looking for ways to capture and store it.
“We looked at our coastal ecosystems and realized that there was actually quite a lot of potential there,” said Neil McFarlane, an official climate change strategy officer for South Australia. , one of the country’s six states. “Blue carbon is an area that we believe has not been sufficiently explored.”
Like terrestrial forests, these coastal habitats store carbon in the plants themselves. But areas like the seagrass field that Australian researchers aim to regrow are storing even more carbon in the soil below. Indeed, the soil of coastal areas that contain seagrass, mangroves and marshes is regularly covered with water and sediment, which lowers oxygen levels. This slows down decomposition, which normally releases carbon into the atmosphere.
There are blue carbon ecosystems around the world, but Australia is a hotspot for them – it has up to 32% of the world’s seagrass, mangroves and tidal marshes, study finds. This prompted the Australian government and local researchers to take a leading role in studying the ability of coastal ecosystems to store carbon, scientists say.
There is growing interest in revitalizing these areas as it is a natural solution that can slow climate change. New technologies, such as machines that remove carbon from the air, are expensive on a large scale.
“We are drawing more attention to natural solutions to climate change,” said Peter Macreadie, professor of marine sciences and director of the Blue Carbon Lab at Deakin University in Australia. “We are going to rely on nature to take back control of the thermostat on the planet.”
In the United States, scientists have already restored another type of seagrass on the east coast of Virginia, near Chesapeake Bay, and some members of Congress, including the Sens. Lisa Murkowski (R., Alaska) and Sheldon Whitehouse (D., RI), pushed to explore new opportunities for blue carbon. In Pakistan, local authorities and private investors are seeking to replant more than 800 square miles of mangroves.
In Colombia, a mangrove and swamp protection project was approved by Verra, a US-based nonprofit that oversees a carbon credit program, as the first blue carbon conservation project. This means that the project can issue Verra certified carbon credits, which represent carbon that has been reduced or removed from the atmosphere. Companies can finance a project to earn carbon credits or buy the credits to offset their own emissions.
In Australia, researchers tossing the sand-filled bags into the ocean bet that seedlings of seagrass of a local species will float and attach to the bags, which are made of burlap, using a hook. special at the base of the plant. Other restoration efforts in the country include that of the environmental group Nature Conservancy to restore mangroves and salt marshes on some 500 acres along Australia’s southern coast.
The Australian government recently said it would invest more than $ 20 million in blue carbon projects, as part of a roughly $ 75 million initiative to protect the ocean, although the Prime Minister of center-right Scott Morrison has been criticized by environmental groups for not going fast enough. to reduce emissions. Australian regulators are also working with scientists to develop their own carbon credit specifically for blue carbon initiatives.
Carbon storage in coastal areas alone is not expected to fully mitigate climate change. Blue carbon ecosystems are much smaller than terrestrial forests, so preserving and restoring coastal habitats would represent only a small part of the carbon reduction needed to meet climate goals. Additionally, rejuvenating some coastal areas, such as using divers to replant herbaria, can also be more difficult and costly than planting trees on land.
Yet failure to protect existing seagrass, mangroves and tidal marshes could allow climate change to accelerate, scientists say. If these areas are destroyed, the stored carbon is released into the atmosphere.
One study, using satellite imagery, found that 2% of the world’s mangroves, or 1,300 square miles, were lost between 2000 and 2016. In Australia, another study estimated that over 600 square miles of seagrass had been lost. lost since the 1950s due to indirect causes such as heat and mild stress.
In 2011, a marine heat wave damaged 36% of seagrass beds in Shark Bay, Western Australia, which has the largest carbon stocks of any seagrass ecosystems in the world, according to a study. A few years later, mangroves along a 600 km stretch of coastline in northern Australia died, an event scientists attribute to factors such as drought and high temperatures.
“A lot of people don’t really know what seagrass is or what it does,” said Jason Tanner, the government scientist responsible for seagrass restoration in South Australia, adding as he presented other benefits such as protection against coastal erosion and providing habitat for marine life. . “I think it’s slowly seeping into people’s consciousness.”
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