I’m in foggy Monterey, California, this week for a big once-every-four-years gathering of scientists who study how the carbon dioxide we’re belching into the air is also altering our oceans. And, man, is there a lot of bad news: shrinking coral reefs, increasingly toxic algal blooms, threatened seafood sources … the list goes on. All of these are due to a phenomenon known as ocean acidification (basically, as we pump more pollution into the atmosphere, more carbon dioxide gets absorbed into the oceans, making them increasingly acidic and less healthy for many forms of life -- see my story on the Pacific Northwest’s “Great Oyster Crash,” for just one example). One presentation after another is filled with reports and indices showing our seas are in trouble.

So before I get to all that, let’s take some time to consider some more hopeful numbers.

It’s been just nine years since Stanford earth scientist Ken Caldeira coined the term “ocean acidification” when writing in the prestigious journal Nature about changing ocean pH. The following year, 125 marine scientists gathered in a single room in Paris to trade notes about this emerging problem. Ocean acidification hadn’t even been their original concern: the meeting had been convened to explore several then-fashionable proposals for sequestering more greenhouse gas in the ocean, as a way of slowing down global warming. But at a 2003 planning session, the Monterey Bay Aquarium Research Institute’s Peter Brewer urged broadening the agenda to consider the impacts of the CO₂ that was already diffusing into the seas from the air.

“After a few minutes’ discussion, we all agreed,” Brewer recalls­, and the first international symposium on the ocean in a high-CO₂ world­ was born. It put the until-then esoteric subject of ocean acidification front and center on the science agenda; researchers and policymakers began to see the sea as potentially the most carbon-threatened resource of all, rather than as a handy dumping ground for this as for so many other forms of pollution.

Those 2004 pioneers heard just 24 presentations­ -- nearly as many as the total number of papers published on acidification worldwide that year. The next symposium, held in Monaco in 2008, drew 227 researchers and 44 presentations. The third international symposium, the one I’m at this week in Monterey, aimed to attract at least 300 researchers. Instead it drew 542 from across the world to a sprawling warren of packed halls a few hundred yards from Monterey Bay’s frolicking sea otters and lolling harbor seals.

Gifted young scientists are diving into the field at a much faster pace than they did in the long, slow build-up of climate change research, and learning about CO2’s impact on the seas much faster than we were able to comprehend the changes to our atmosphere. At the same time, their mentors and elders are pounding their heads over what may be an even more elusive challenge: how to communicate their findings to the public, press, and politicians without getting mired in the sort of trumped-up controversies and anti-science attacks that have hindered action on global warming.

Still, although we’re figuring out ocean acidification faster than we did climate change, what we’re learning isn’t happy news. The scientists here in Monterey braved a rapid-fire succession of 146 presentations on a head-spinning range of marine-carbon topics. Many were dire or ominous. Some of the lowlights:

• Working in concert, increased heat and carbon can kill critters where one or the other alone wouldn’t phase them. Edible crabs and scampi, two northern species beloved by European gourmands, can cope with higher CO₂ levels when the temperature of the water around them stays below 10 degrees Celsius (50 Fahrenheit). But raise the temp to 18 Celsius and the crabs’ carapaces start bleeding calcium and dissolving. The scampi’s long front claws grow so weak and brittle, they snap off. Tough luck, gourmands.
• Even brief exposure to high-CO2 levels when they’re in the larval stage leads to stunted growth later in life for the Olympia oyster, a native icon of America’s Pacific Coast.
• Warming weather has already been tagged as a factor in the rise of toxic algal blooms­, which cost shellfish harvesters about $100 million a year and produce occasional mass poisonings of birds, marine mammals, and even humans. Now there’s evidence that more CO_2, and less of certain minerals, makes these algae produce as much as 10 times more nasty toxins. Yikes.
• Coral reef researchers have begun to identify the point at which reefs can no longer grow due to the change in ocean pH, thus depriving thousands of ocean species of critical habitat. We’re getting very close to that threshold for reefs around the world. Chris Langdon, a celebrated coral biologist at the University of Miami, described the reduced build-up of Caribbean reefs. “There’s not too much farther these rates can decline without net decalcification,” he said, meaning the reefs would start to shrink.
• On Australia’s Great Barrier Reef, considered “the best-managed reef in the world,” coral cover has declined by half in the last 27 years. Other culprits also play roles, but they too may be carbon-related: more frequent and severe typhoons, and the growth of reef-munching organisms such as sea stars that thrive when the water turns sour (until their food runs out, anyway).

Some of these findings point to a transformation in acidification science itself. Researchers are moving beyond documenting discrete changes in ocean chemistry and effects on individual species. They’re starting to tease out more complex, synergistic effects between multiple species, multiple stressors, and the water and atmosphere together.

Some are documenting winners as well as losers in the altered seas -- species that may benefit, at least for a time, from elevated CO₂. (More on that to come.) Others are hunting for the genetic mechanisms that enable some organisms to adapt to changing chemistry, with an eye toward selective breeding to speed evolution and bolster resilience, even in wild species.

This work leant a surprisingly hopeful note to some of the proceedings. The assembled scientists and a few policy makers pondered ways to leverage their efforts, integrate and communicate a fast-growing sea of data, and perhaps even mitigate acidification’s effects. For possible further guidance, many looked toward a suite of recommendations due at the end of October from Washington State’s Blue Ribbon Panel on Ocean Acidification, the first such official body convened in this country. (Disclosure: I’m helping write a report that will go to that panel.)

But any such successes will get swamped if humankind keeps pumping ever more carbon dioxide into the air and, via the air, our oceans. On this score, however, one marine-governance expert, Stockholm University’s Beatrice Crona, offered perhaps the most encouraging note of all, in a final session: ocean acidification “may be more clear and comprehensible” to the broader public than climate change, and may prove less controversial. The coral reefs offer a “compelling narrative” -- a more vivid, tangible demonstration of the damage we’re doing to our world than complex climate trends.

If that is indeed the case, ocean scientists might succeed where their climate brethren have failed, by actually galvanizing the public to action. That’s a feedback loop worth rooting for.

Image: Bleached staghorn coral/Matt Kieffer via Flickr