Valuable seagrass is at risk from coastal development and nutrient runoff. Credit: ThinkStock Enlarge

Marine ecologists call them seagrass meadows. They once wrapped Australia's coastline providing sanctuary and food for dugongs and turtles, habitats for fish to breed and myriad other ecosystem services such as nutrient recycling and sediment stabilisation.

Now scientists believe these humble plants could be crucial in the fight to address climate change. Seagrass, it turns out, is 35 times more efficient at locking up, or "sequestering" carbon than rainforests.

Atmospheric carbon dioxide levels are now so high they risk damaging our ecological life-support systems and seagrass could play a vital role in helping reverse the earth's dangerous , says University of Technology, Sydney (UTS) scientist, Dr Peter Macreadie.

"If the amount of CO2 in the atmosphere reaches 450 parts per million, the Intergovernmental Panel on Climate Change – the world's 'climate change referee' – estimates we will only have a 50 per cent chance of avoiding the drought, famine and widespread  that is expected from a two degree increase in temperature," Dr Macreadie says.

"I don't want to leave this legacy for my children. Through my research, and that of my colleagues, I'm looking for ways to maximise  with  and minimise the amount of carbon leaking into the atmosphere.

"What seagrasses are doing is not complex. They are simply capturing and storing carbon through photosynthesis and by trapping particles in the water column. This process – known as biosequestration – is what created fossil fuels in the first place."

The ability of seagrass to absorb CO2 could be worth as much as $45 billion, based on the current  of about $23 per tonne, Dr Macreadie says. It is a conservative estimate based on only one species of seagrass, Posidonia australis.

It is a compelling reason to protect seagrass meadows around the world, which are under threat from coastal development and . NSW alone has lost 50 per cent of its seagrass, he says.

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