Keep marine ecosystems afloat: UN

Report says such 'blue carbon sinks' help mitigate climate change

Experts warn that if no action is taken to protect coastal ecosystems - like this mangrove sanctuary in Thailand - species, livelihoods and blue carbon sinks will be lost within decades. -- PHOTO: REUTERS

OCEANS, like forests, play a critical role in absorbing carbon dioxide to keep global warming at bay, and a new report has called for the preservation of marine ecosystems to offset climate change.

The Blue Carbon report, launched on Thursday by the United Nations, has found that up to a third of marine organisms such as mangroves, salt marsh plants and seagrasses that thrive in shallow coastal waters off India, and parts of South-east Asia and the Caribbean, have been lost since the 1940s.

'If more action is not taken to sustain these vital ecosystems, most may be lost within decades,' it noted.

Not only will species and livelihoods be lost, but a vital 'blue carbon sink' as well, said experts.

According to the UN report, marine ecosystems store up to 1.6 billion tonnes of carbon dioxide every year - roughly equivalent to half the yearly emissions of the entire global transport sector.

Much of the degradation has been caused by unsustainable fish farming practices, inadequate coastal development and waste management.

'We know that land use change is part of the climate change challenge,' said Dr Carlos Duarte, one of the report's chief scientists, who is from the Mediterranean Institute of Advanced Studies in Spain.

'Perhaps less well known is that the global loss of what we could call our 'blue carbon sinks', are actually among the key components of the increase in greenhouse gas concentrations from all land use changes,' he pointed out.

The loss of such coastal ecosystems also has an economic impact as they supply half the world's demand for fish and protect against coastal erosion and tsunamis.

Coastal systems have an estimated economic worth of US$25 trillion (S$34.8 trillion) annually.

Policymakers converging in Copenhagen for the world climate summit in December are likely to agree on a plan to preserve forests in developing countries as part of a wider agreement aimed at cutting carbon emissions, said Mr Achim Steiner, executive director of the UN Environment Programme.

The role of other ecosystems should not be overlooked, he stressed.

'If the world is to decisively deal with climate change, every source of emissions and every option for reducing these should be scientifically evaluated and brought to the international community's attention.'

The report noted that curbing deforestation on land together with a restoration of marine ecosystems could reduce up to 25 per cent of the carbon emissions to keep concentrations of carbon dioxide in the atmosphere below 450 parts per million.

This was a benchmark identified in the 2007 report by the Inter-governmental Panel on Climate Change to keep global warming below 2 deg C, to avoid the dangerous effects of climate change like severe weather patterns.

Preventing the further loss of coastal ecosystems alone can contribute to at least 10 per cent of the emission cuts needed.

Mr Patricio Bernal, assistant director-general of the UN Educational, Scientific and Cultural Organisation, said: 'Because the ocean has already absorbed 82 per cent of the total additional energy accumulated due to global warming, it is fair to say that the ocean has already spared us from dangerous climate change.

'But each day we are dumping 25 million tonnes of carbon into the ocean, turning it more acidic and hence posing a huge threat to organisms.'

amreshg@sph.com.sg

Marine ecosystems store up to 1.6 billion tonnes of carbon dioxide every year - roughly equivalent to half the yearly emissions of the entire global transport sector.