Chemists first theorized the process commonly referred to as “ocean acidification” in the 1970s, but only during the past few years have researchers begun to fully appreciate the threats it poses to ocean inhabitants such as corals and fish.

With few major studies yet completed, researchers over the past few years have been encouraging the U.S. to launch a coordinated ocean acidification research program. Authorized in March but not yet funded, the program’s overarching goal will be to decipher ocean acidification’s biological and economic impacts to enable informed and adequate response to the issue.

Ocean acidification is not a climate change per se, but rather a separate, though closely linked, problem. The oceans naturally absorb huge quantities of carbon dioxide, a weak acid, from the atmosphere, which sets off a string of chemical reactions in seawater. This reaction includes conversion of calcium carbonate, which helps control pH levels and is used by many animals to build their shells into a form that is biologically unusable.

Oceans 30 Percent More Acidic than in 1750

So, more carbon dioxide in the atmosphere means more dissolving in the ocean, causing calcium carbonate concentrations to drop, along with pH. Hence, the name ocean acidification, though the oceans are actually still basic, with a pH above 8. (Journalists and other communicators educating lay audiences on important ocean acidification issues should make sure their audiences understand that the waters are indeed basic and not actually acidic.)

Monitoring shows that the oceans have already become 30 percent more acidic since 1750, a problem that Energy Secretary Steven Chu recently testified might eventually put the entire ocean food chain at risk.

In limited experiments, lower pH causes problems such as slowed coral reef building, establishing a threshold beyond which reefs actually dissolve more quickly than corals can build them. This condition doesn’t mean a reef is “dead,” but as Joanie Kleypas, a prominent acidification researcher from the National Center for Atmospheric Research in Boulder, Co., puts it, “That’s not the side of the line we want to be on.” Another concern is that the process may generally weaken corals, making them more susceptible to other problems.

Risks to Food Web, Even as Some Species May Benefit

Other animals such as sea urchins and various forms of plankton do less calcification, or shell building, as calcium carbonate levels decrease. Such changes could have major repercussions for food webs if they lead to significant population reductions. Surprisingly, though, some experiments have found that some species of lobsters, shrimp, and other crustaceans actually calcify more as carbonate levels drop.

So many questions remain open about the ways that various animals will ultimately fare, and how well they might be able to adapt, that the net effects of ocean acidification can’t yet be predicted. This concern has driven scientists to call for legislation to establish a coordinated and substantially expanded U.S. research program.

“To date the amount of research on ocean acidification has been very small,” says Richard Feely, a chemical oceanographer at NOAA’s Pacific Marine Environmental Laboratory in Seattle, Wa., and a strong advocate of expanded acidification research. Kleypas echoes that sentiment. “In the U.S., we keep saying we’ve got to get this research going, we’ve got to get this research going,” she says, “In Europe they’ve already got some pretty big programs spun up, but here we are still crying.”

Finally A Coordinated Federal Research Project

For years now, legislative champions such as Rep. Brian Baird, (D-Wa.) have pushed for a Federal Ocean Acidification Research and Monitoring Act, or FOARAM, to address the U.S. deficiency. The bills have repeatedly been voted down in light of general spending concerns. But this year, the bill finally made it through Congress after legislators folded FOARAM, the Christopher and Dana Reeve Paralysis Act, and various other legislative bits into the Omnibus Public Land Management Act of 2009. President Obama signed it into law in March.

The law calls on the interagency Joint Subcommittee on Ocean Science and Technology (JSOST) to establish a working group to develop and then execute a concerted plan for ocean acidification monitoring and research, to be conducted by agencies such as the National Oceanic and Atmospheric Administration, the National Science Foundation, and NASA. The bill authorizes funding starting at $14 million in 2009 and ramping up to $35 million per year by 2012 in funding for the program outlined. But authorizing legislation does not make funds available until Congress subsequently appropriates that funding. It has not yet done so, and the best chance for an appropriation appears to be the 2010 budget legislation, which is in the overall science bill.

Outlook for Expected Program

“The markup on both sides and the presidential request are all in harmony on this, so we’re planning around that,” says Timothy Killeen, assistant director of NSF’s geosciences program, and a co-chair of the JSOST.

Work is already well under way to map at least the basics of what the new U.S. program will look like, assuming funding does come through. Another interagency working group, called the Ocean Carbon and Biogeochemistry Scientific Steering Committee, in March released a white paper outlining key research needs and calling for $20-$30 million per year for two to three years to ramp up a program, with minimum funding of $50-$100 million a year thereafter.

As recommended in that paper, a National Academy of Sciences study has been launched and fast-tracked for completion before the end of this year. This study is to lay out in much greater detail a vision for the research. “It’s really finally taking shape,” says Kleypas, a member of the NAS panel. Though the JSOST is not legally bound to follow the NAS report, those involved say the program likely will follow the report’s recommendations closely.

Though details of that study are still under wraps, the white paper gives a good view of what can be expected. Key needs identified include:

  • improving technologies for monitoring pH, carbonate levels, and other related parameters;
  • establishing a coordinated and extensive monitoring network using such instrumentation;
  • expanding studies of the responses of various organisms to acidification; and
  • improving modeling capabilities to predict future ocean responses to various potential scenarios.

Basic Question: How Much is ‘Too Much’?

Kleypas says answering the basic question of how much acidification will be too much for ocean ecosystems will have to be a top priority. “If we’re going to go down some road and try to limit carbon dioxide emissions and we’re talking about limiting temperature increases to two degrees total,” Kleypas asks, “what about ocean acidification? How much ocean acidification can we have before we start seeing significant changes in systems or loss of things that we value?”

With understanding of ocean acidification net impacts still so limited, it’s difficult to predict what options may ultimately be open for addressing problems that will arise short of global emissions reductions. One possibility is that as researchers better understand where acidification will be more or less severe, policy makers may be able to identify locations more resistant to acidification and have them set aside as reserves to preserve biodiversity.

… and What About Geoengineering?

At the larger scale, there is at least the possibility that geoengineering options might be devised that would allow humans to reduce acidification even in the face of rising carbon dioxide levels. Several possibilities have been proposed, such as mining carbonate on land and then applying it at a grand scale to certain ocean areas.

Most geoengineering options, however, are more focused on climate change and might even increase acidification problems, for instance if atmospheric warming was reduced in some way without reducing carbon dioxide levels. Likewise, some climate change geoengineering could even exacerbate the acidification problem, for instance if carbon dioxide were buried in deep-sea marine sediments, as has been proposed.

Geoengineering was not mentioned specifically in the guiding white paper, and is not likely to be an explicit component of a FOARAM program. But such research might still include studies that would reveal potential effects of a given geoengineering idea.

“Even though I’d like to see some magical engineering solution solve our problems, a big part of me hopes that we don’t get distracted with analyzing the effects of every geoengineering idea that comes up,” says Kleypas.

“What we need to understand is how marine life is going to respond to ocean acidification,” she says, “Because with or without engineering solutions, we are committed to watching our ecosystems go through some rough decades.”

The links to the resources below will be useful for those wanting to delve further into this issue.

Mark Schrope is a freelance science writer living in Melbourne, Fla.