Coastal Carbon Sinks in Dire Need of Protection

Posted on 11 December 2009 by editor

 

Mangroves, like these in Timor-Leste, may store 50 times the amount of carbon than tropical forests. Credit: Lofor/Creative Commons

Mangroves, like these in Timor-Leste, may store 50 times the amount of carbon than tropical forests. Credit: Lofor/Creative Commons

By Stephen Leahy

COPENHAGEN (IPS/TerraViva) What would it be like if the air we breathe was 30 percent more acidic? The oceans are already 30 percent more acidic, and on their way to becoming 120 percent more acidic in 50 years at the current rates of carbon dioxide emissions.

Acidification is already affecting coral reefs, algae and plankton, the base of many marine food chains, according to a new report released here by the International Union for Conservation of Nature (IUCN).

“In the last 10 years, the growth of coral reefs in many areas has declined 15 percent,” said Carl Gustaf Lundin, head of the IUCN’s Global Marine Programme.

“That’s a dramatic shift,” Lundin told TerraViva.

The oceans absorb some carbon dioxide (CO2) from the atmosphere, but the vast quantity being emitted – mainly from the burning of fossil fuels – has altered basic ocean chemistry, turning it sour. That’s also affecting shell-forming plankton and disrupting the growth rates of other species, Lundin said.

The stated goal of many countries to stabilise global temperatures within an increase of no more than 2.0 degrees C. is still “a death sentence for most coral reefs”, he said. The 2.0 C. target implies a level of CO2 in the atmosphere of 450 parts per million (ppm), well up from the historical average of 280 ppm.

The acid death march has already begun in the Arctic. Research carried out this summer in the Norwegian archipelago of Svalbard shows that in many regions around the North Pole, seawater is likely to reach corrosive levels within 10 years. This will dissolve the shells of mussels and other shellfish, researchers wrote in the Nov. 20 edition of Science.

Shellfish are eaten by baleen whales, salmon, herring and various seabirds, and their disappearance would have a major impact on the entire marine food chain. Cold waters are at far greater risk for acidification because they absorb more CO2 from the atmosphere than warmer tropical waters.

Unknown to most is the abundance of cold-water coral species in the icy regions of the planet. “There are far more Arctic coral species than tropical, they just don’t form the same kind of reef structures,” explained Lundin.

By 2100, the entire Arctic may well be too acidic for most species, researchers wrote. The only one way to stop the relentless acidification of the oceans is to urgently limit CO2 emissions, Lundin said. “This is not debatable. It is basic chemistry,” he stressed.

Lundin also warned there is also a time lag involved. Even if all carbon emissions halted today, oceans will grow more acidic and it will take hundreds of years before they return to their pre-industrial norm.

“We also must reduce fishing pressure, pollution and other impacts on the oceans to help them retain some resilience to withstand what’s coming,” he said.

Meanwhile, IUCN researchers have now documented that coastal marine habitats like mangroves, salt marshes and seagrass meadows may store 50 times the amount of carbon that tropical forests do on a per hectare basis.

“Seagrass meadows may well be more effective in sequestering carbon than forests,” Lundin said.

However, two-thirds of seagrass meadows near inhabited areas have already been lost due to pollution and siltation. “Investments in protecting coastal ecosystems might be a very cost-effective way to sequester carbon,” he said.

Countries are largely unaware of this fact and marine habitats are not part of any international or national climate accounting systems. The IUCN believes it is urgent that the marine equivalent of a Reducing Emissions from Deforestation and Forest Degradation (REDD) scheme be created to safeguard these coastal carbon sinks.

“Future generations will judge us harshly if we don’t act urgently,” Lundin said. “They will understand that we did not have to make any large adjustments and that there were lots of practical things we could do right now.”

“This is a global problem. We can’t resolve this with individual actions or countries,” he emphasised.

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