In the months leading up to last week’s Rio+20 United Nations Conference on Sustainable Development, a number of organizations and individuals called for an increased focus on the world’s oceans. As the Global Ocean Forum argued, they are after all “the quintessential sustainable development issue… Just as one cannot do without a healthy heart, the world cannot do without a healthy ocean.”

Illustration of the effects of ocean acidification, Pre-Industrial Revolution through 2100 (Source: Ocean Acidification Research Center, University of Alaska Fairbanks)

One of the many elements of truth behind this statement is that oceans represent a massive carbon sink, having taken up approximately 48 percent of all anthropogenic carbon dioxide (CO2) released into the atmosphere since the Industrial Revolution. Through this process of ongoing absorption, the oceans have played a vital role in maintaining global balance and mitigating the climatic effects of anthropogenic emissions: the more CO2 we released into the atmosphere, the more the oceans absorbed. Unfortunately, the ocean – despite its vastness – has its limits, and this absorption comes at an enormous cost.

Once absorbed by the ocean, CO2 sets in motion a series of chemical reactions that decrease seawater’s pH level, making it more acidic and depleting the water of essential compounds like calcium carbonate that many marine organisms (including corals and mollusks) need to construct their shells. Ocean acidification – dubbed by some commentators as the other carbon dioxide problem, or ‘global warming’s evil twin’ – can also reduce respiratory efficiency in animals like squid and impair sensory ability in reef fish, making it difficult for them to locate prey.

Many of the organisms most immediately vulnerable to acidification – including krill and tiny, snail-like pteropods – lack the mainstream charisma of polar bears or whales, and seem at first unlikely to tug at public heartstrings. These creatures, however, comprise the base of many marine food chains; negative effects on their populations could cascade throughout the wider ecosystem – with disastrous consequences not only for marine biodiversity, but also for the millions of people who depend on marine and coastal systems for food and employment, echoing what the United Nations has already asserted: that threats to the world’s oceans threaten all three pillars of sustainability. Developing nations and small island states, in which a large proportion of the population often depends on reef fisheries for protein and employment, are therefore particularly vulnerable to acidification: yet another way in which those people least responsible for climate change stand to lose the most.

What happens when a pteropod's shell when placed in sea water with pH and carbonate levels projected for the year 2100 (Source: NOAA's Pacific Marine Environmental Laboratory, Carbon Dioxide Program)

Carole Turley, Senior Scientist at the Plymouth Marine Laboratory in the United Kingdom, told an audience at Rio+20 that “ten years ago, the hairs stood up” on the back of her neck when she realized the disastrous extent of acidification’s likely impacts – and that nobody was talking about it. A decade later, thanks to ongoing research and, in large part, to public outreach efforts like the film ‘Acid Test’, the problem is much more widely discussed.

But discussion – although a common feature of international summits like Rio+20 – only gets you so far. An op-ed in the New York Times called the recent conference’s adopted text, The Future We Want, “a caricature of diplomacy”, riddled with ambiguity and vague non-committal statements of support. While delegates called for support in addressing ocean acidification, and reiterated the need to work collectively in order to stop it, the document falls far short of making any solid commitment to action. This is because doing so would require an international agreement to reduce carbon emissions – the prize that has eluded and exasperated climate negotiators for so long.

Even so, the op-ed stressed, there is hope. “If you looked around in Rio last week,” wrote the columnist, “you saw where the action really is – local and national governments, companies, NGOs, labor unions finding ways to get on with it.” Despite the vast and complex interconnectedness of the various threats facing our oceans – and despite the seeming inability of the international community to fashion a meaningful framework for emission reductions – there are indeed individuals, organizations, and companies throughout the world finding ways to “get on with it.”

In the U.S. Pacific Northwest, oyster hatcheries on the verge of collapse installed water quality monitoring systems allowing shellfish farmers to protect young oysters from particularly acidic waters. Australia recently created the world’s largest network of marine reserves. Although this does not directly address acidification, the synergistic nature of environmental stressors means that protecting marine ecosystems from overfishing and habitat depletion can give organisms the strength they need to be more resilient in the face of increasing acidity.

There is also growing recognition of the need to protect certain vital marine ecosystems as carbon sinks. Although the contribution of forests in sequestering carbon is well known and supported by relevant financial mechanisms, a 2009 UNEP report determined that the critical role of oceans and coastal ecosystems has been overlooked for far too long. Critical ecosystems (including tidal salt marshes, mangroves, seagrass beds, and kelp forests) sequester CO2 more effectively and more permanently than terrestrial forests. Unfortunately, we are currently destroying these ecosystems at a rate of 7 percent per year. Organizations like The Blue Carbon Project work to provide so-called ‘blue carbon’ offsets through the conservation and restoration of coastal vegetation, in the model of well-known terrestrial mechanisms like the UN’s program for Reducing Emissions from Deforestation and Forest Degradation (REDD).

Finally, the continuing growth of renewable energies documented by REN21 and Worldwatch in the 2012 Global Status Report demonstrates the actions being taken by individuals, communities, and governments to reduce carbon emissions. As Sylvia Earle, famed oceanographer and National Geographic explorer, explained in a recent interview, there is reason to be optimistic – even in the face of post-Rio+20 disillusionment. “I think one of the reasons I am truly optimistic,” she said, “is that 50 years ago, even 20 years ago, we didn’t know. We did not have the capacity to see, to understand, what we now can see, can understand, about what we’re doing to the life support system, the systems that keep us alive.” Now we know. And we can’t wait until the next international summit to “get on with it”.

Katie Auth is a staff researcher at the Worldwatch Institute.

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biodiversity, carbon dioxide, carbon sinks, Climate Change, marine ecosystem, oceans, Rio+20