This is not a good news story. But it is an extremely important one. We’re talking about ocean acidification.
While we’re pumping carbon emissions into the atmosphere, the ocean is absorbing it, in greater and greater quantities. And now it looks like the levels of carbon being absorbed in the oceans are causing the seas to turn acidic. This acid – known as carbon acid – will have a series of very serious knock-on effects for ecosystems both in and out of our oceans.
Firstly, the ocean acidity has an effect on the ability of shellfish and corals to develop their calciferous shells and structures. We don’t know if these creatures will be able to adapt to the increase in acidity, and there is a chance that their numbers will be significantly depleted.
This has a knock-on effect for all those species that depend on shellfish and coral reefs for survival. That’s a lot of species. One in four species in the ocean live and depend upon coral reefs for survival. If those ecosystems start to decline and those species go hungry, then what happens? Those species (including us) that feed on them also start to go hungry.
It’s a challenging prospect, and one that is getting some serious attention from scientists and policy makers. It’s an issue that threatens millions of people around the world who depend on the oceans for food and livelihoods. And of course it threatens the lives of millions of oceanic species.
Ocean acidification and two scenarios: high carbon emissions and reduced carbon emissions. Click image to enlarge.
So what sort of timescales are we talking about?
Well, a major report prepared for the UN meeting in Copenhagen warned world leaders that by 2050, the ocean acidity could increase by 150 per cent. This is far faster than predicted only several years earlier, and already the impact of carbonic acid in oceans is being observed in various sites around the world.
‘This dramatic increase is 100 times faster than any change in acidity experienced in the marine environment over the last 20 million years, giving little time for evolutionary adaptation within biological systems’, the study says. Click here or here to read more.
And what can be done?
Only the rapid reduction of carbon dioxide in the atmosphere by at least 50 per cent by 2050 can avoid ‘substantial damage’ to ocean life, according to the report.
In addition, improving the health of the oceans is an equally important step. Creating marine protected areas (essentially national parks for the sea) and stopping destructive fishing practices would increase the resiliency of marine ecosystems and help them withstand acidification.
Evidence suggests that coral reefs in protected ocean reserves are less affected by global threats such as global warming and ocean acidification, demonstrating the power of ecosystem protection.
Ultimately, though, reducing the amount of carbon dioxide absorbed into the oceans may be the only way to halt acidification. The same strategies needed to fight global warming on land can also help in the seas.
Click on the following links for more information:
BBC – Acid oceans ‘need urgent action’ – The world’s marine ecosystems risk being severely damaged by ocean acidification unless there are dramatic cuts in CO2 emissions, warn scientists.
Catalyst –Ocean Acidification: The BIG Global Warming Story – For decades we’ve been acidifying our oceans and we haven’t been aware of it.
NRDC – Ocean Acidification: The Other CO2 Problem – Earth’s atmosphere isn’t the only victim of burning fossil fuels. About a quarter of all carbon dioxide emissions are absorbed by the earth’s oceans, where they’re having an impact that’s just starting to be understood.
Scientific American – Ocean Acidification Hits Great Barrier Reef – The largest coral reef system in the world—and the biggest sign of life on Earth, visible from space—is not growing like it used to. A sampling of 328 massive Porites coral from across the 344,000-square-kilometre reef reveals that growth of these colonies has slowed by roughly 13 percent since 1990.
Catalyst – Southern Ocean Sentinel – Watch this great piece on the way tiny plankton and massive currents hold clues to how rapidly the Southern Ocean is changing.