150 marine scientists from 26 countries have called for immediate action to reduce CO2 emissions sharply so as to avoid severe damage to marine ecosystems from increasing ocean acidification. The researchers voiced their concerns through the "Monaco Declaration" (pdf) which warns that changes in acidity are accelerating. The declaration states that ocean acidification may render most regions chemically inhospitable to coral reefs by 2050. The scientists say there is no antidote and that acidification can be controlled only by limiting future atmospheric levels of carbon dioxide.
The declaration is based on research priorities identified at The Ocean in a High CO2 World symposium held in Monaco in October 2008. It calls for immediate action to save coral reefs which “provide fish habitat, generate billions of dollars annually in tourism, protect shorelines from erosion and flooding, and provide the foundation for tremendous biodiversity, equivalent to that found in tropical rain forests.” Most marine organisms live in the oceans' sunlit surface waters, which are also the waters most vulnerable to CO2-induced acidification over the next century.
Ocean acidification is often called the “other CO2 problem” or “global warming’s evil twin”. While the severity of its impacts to marine ecosystems have been known for some time, scientists hope the declaration will made it more of a public priority. Jeremy B. C. Jackson, a coral expert at the Scripps Institution of Oceanography in San Diego, labelled the acidification of the oceans a critical problem. “Nobody really focused on it because we were all so worried about warming,” he said, “but it is very clear that acid is a major threat.”
The oceans have “subsidised” the effects of climate change by absorbing a substantial portion of the greenhouse gas carbon dioxide. Oceans store about 50 times more carbon dioxide than the atmosphere, and have absorbed a third of the carbon dioxide released by human activity. The downside is that as the gas dissolves to become carbonic acid, seawater is gradually becoming more acidic. The result is a detectable decrease in shellfish, shell weights and interference with the growth of coral skeletons. The rate of acidity is now accelerating so fast it threatens the survival of coral reefs, shellfish and the marine food web generally.
And the speed of change is alarming. According to Science Daily, ocean chemistry is now changing 100 times more rapidly than in the 650,000 years that preceded the modern industrial era. According to the pH scale the lower the measure, the more acidic it is – seawater is considered mildly alkaline with a “natural” pH of about 8.2. However, researchers at Scripps Oceanography have recorded an overall drop in the pH of the oceans from 8.16 to 8.05 in the last 20 years.
The IPCC (pdf) predicts surface ocean pH will decrease by a further 0.4 (give or take 0.1) pH units by 2100. No one can say with certainty what the biological consequences of such a drop will be. The ocean’s pH and carbonate chemistry has been remarkably stable for millions of years. The last time a major natural ocean acidification event occurred was approximately 55 million years ago and that caused mass extinctions of calcareous marine organisms, similar to modern coral.
In July 2008 a paper published in the “Science” journal warned that the ecological and economic consequences of ocean acidification are difficult to predict but possibly calamitous. The researchers of that paper led by Richard Zeebe of the University of Hawaii also said that halting the changes already underway will likely require even steeper cuts in carbon emissions than those currently proposed by international protocols. “If we continue with business as usual and don’t cut carbon dioxide emissions, carbonate reefs will ultimately start to dissolve,” said Zeebe. “This is basic chemistry.”
The Monaco Declaration urges governments to launch four types of initiatives to solve the problem. Firstly, scientists want to promote further research in the field to help improve understanding of impacts of ocean acidification. Secondly, they suggest building links between economists and scientists to evaluate the socioeconomic extent of impacts and costs for action versus inaction. Thirdly, they want to improve communication between policymakers and scientists so that policies are based on current findings and scientific studies are widened to include policy-relevant questions. Lastly and most critically, policymakers need to develop “ambitious, urgent plans to cut emissions drastically” to prevent further ocean damage. This is an unambiguous ultimatum. As James Orr of the Marine Environment Laboratories says, “The questions are now how bad will it be and how soon will it happen.”