重要的滨海碳捕获系统正面临威胁Vital coastal carbon capture systems under threat

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Rainforests such as the Amazon are often the most well-known for absorbing carbon, but scientists are now uncovering the vital role coastal habitats play in carbon capture.

Seagrass and mangroves can capture carbon up to 40 times faster than forests and store it in the seabed for thousands of years.

However, scientists say those natural carbon sinks are now the "most threatened systems on Earth".

The Amazon rainforest is often referred to as the lungs of the planet - one of the biggest and most important living stores of carbon in the world.

But with deforestation proving a huge threat and greenhouse gases increasing, scientists are searching for alternative carbon sinks.

"Up until now, or recently, the focus has been on the terrestrial systems, and particularly on forests," said Dr Emily Pidgeon, a senior director at Conservation International.

"But we've realised that these coastal ecosystems - the mangroves, the seagrasses, and the salt marshes - also pull enormous amounts of carbon out of the atmosphere and the ocean and store it as large deposits mostly of sediment underneath them".

Today, Dr Pidgeon will join a working group of some of the world's top marine scientists at a meeting in Sydney.

They are trying to identify how big a role these coastal habitats can play.

"We don't see it as easily as we might see the lush forests, but these systems sequester the carbon at rates that could be up to four or five times the rate that large forests sequester carbon and they also keep sequestering that carbon for the millennium," she said.

"So you can have deposits of carbon in these coastal systems that are thousands of years old and up to 10 times greater on an area basis than can be stored in the big traditional rainforests of the tropics".

But as well as identifying the size of these massive natural carbon sinks, the scientists are also trying to improve the level of protection of this marine vegetation.

"Coastal development is putting an additional stress to these threatened habitats," said Dr Peter Ralph, from the University of Technology Sydney.

"We're been losing them and we've been losing them for years.

"Additional development off the coast - if it's not done in a sensitive and progressive way, it will increase the threats to these valuable carbon habitats, yes."

Some of these increased threats include boating, dredging and port development.

If a coastal system is damaged or degraded, these scientists warn that the marine ecosystem's capacity as a carbon sink are being significantly downgraded. And they are under threat like never before.

Dr Pidgeon says the systems are disappearing at a rate of around 2 per cent, per year, globally.

She says that figure is about four times the average rate of deforestation.

"These systems are the most threatened systems on earth for a number of reasons," she said.

"Where a lot of these systems are very dense you see aquaculture and agriculture ... being a source of destruction.

"All of these sources of degradation of these systems are leading to and causing them to become causes of climate change."

原文出处：http://www.abc.net.au/news/2013-05-16/vital-coastal-carbon-capture-systems-under-threat/4692696