We’ve all heard about global warming, and we know the primary cause is our profligate release to the atmosphere of carbon dioxide (CO2) from the burning of fossil fuels. That warming continues to bite us: Last year was the warmest ever across the continental United States since records have been kept, and the fifth warmest in Canada.
But there is a hidden side to ongoing CO2 emissions and it’s now biting us, too. Roughly one-third of the CO2 emitted since the Industrial Revolution has dissolved into the sea and is slowly turning our oceans acidic.
The chemistry behind this is very well understood. Each molecule of CO2 that dissolves into the sea reacts with a water molecule to form carbonic acid. And via a couple of very quick steps, that acid reacts with dissolved carbonate ions in sea water, reducing their overall concentration.
Why does this matter? Well, carbonate ions are like building blocks, and many organisms in the ocean, including corals, oysters, scallops, clams, and many species of plankton, secrete shells by biochemically combining dissolved calcium ions with carbonate. As the number of carbonate ions declines, it becomes harder and harder for organisms to find the building blocks they need to build their shells and thus survive.
A critical issue here is the rate of change. The speed at which carbonate ions are being lost from the upper sea is estimated to be many, many times faster than has happened at any time in the geological past. With such rapid change, evolution cannot work quickly enough to allow the shelled organisms to adapt to the new chemistry
The world’s leading authorities in this field are now sounding alarm bells. Ove Hoegh-Gulberg, director of Australia’s Global Change Institute at the University of Queensland, has suggested tropical coral reefs may vanish before the end of the century if CO2 emissions do not decline dramatically. Closer to home, growers in Washington State’s $270-million shellfish industry have become increasingly concerned about progressive acidification of regional waters. In response, Gov. Christine Gregoire announced on Nov. 27 that the state will fund priority actions on ocean acidification in its next budget. And in a further step, she directed state agencies to advocate for CO2 emissions reductions at global, national and regional levels.
Shellfish farmers in British Columbia are also on the front lines. Rob Saunders, CEO of Island Scallops and a leading producer of shellfish seed stock, used to grow scallop larvae in ordinary sea water drawn from Baynes Sound, north of Nanaimo. Now he must process the water to remove CO2 before introducing it to his tanks. That adds to the cost of production, illustrating that CO2 emissions have downstream economic impacts.
Indeed, Roberta Stevenson, executive director of the BC Shellfish Growers Association, noted last fall that ocean acidification has made many producers think twice about expanding their operations.
“It’s pretty scary to be investing in an ocean that will potentially no longer support shellfish farming,” she said in an interview with the Globe and Mail. And it’s pretty scary to think that coral reefs, the most biodiverse ecosystems in the sea, could be history within three or four generations if we don’t take immediate action to limit our insatiable thirst for fossil fuels.
If we care about the ocean, we must redouble our efforts to cut emissions. B.C. has been an internationally respected leader in this regard since 2008 through its carbon pricing and carbon neutrality initiatives. But being able to put B.C. scallops and oysters on our plates in the future, demands that we reinforce our climate-action efforts. We made a sound start in B.C. five years ago. Let’s continue to build on those, work with Washington, and not let down our shellfish farmers on either side of the border.
Tom Pedersen is Executive Director of the Pacific Institute for Climate Solutions and a Professor of Marine Geochemistry in the School of Earth and Ocean Sciences, both at the University of Victoria.
Tom Pedersen, Vancouver Sun, 19 January 19 2013. Article.