Since the beginning of the industrial revolution, the oceans have acted as a big sink, absorbing 30% of the CO2 that has been pumped into the atmosphere at a rate of 22 million tons a day. That would seem like good news; less atmospheric CO2 means less warming. But there’s a catch: the CO2 doesn’t just go into the ocean and stay there – it has an impact on ocean chemistry. When CO2 dissolves in the ocean, it lowers the pH, making the ocean more acidic.
For you chemistry buffs, here’s how it works:
- CO2 (from the atmosphere) + H2O (seawater) ⇌ H2CO3 (carbonic acid)
- H2CO3 (carbonic acid) ⇌ H+ (acid) + HCO3− (bicarbonate ion) ⇌ 2H+ (more acid) + CO3−− (carbonate ion)
When CO2 reacts with seawater, the reduction in seawater pH also reduces the availability of carbonate ions, which play an important role in shell formation for a number of marine organisms such as corals, marine plankton, and shellfish.
The scientific community is taking this issue very seriously. In January 2009, experts on the issue of “the Ocean in a High-CO2 World” stated that “We scientists who met in Monaco to review what is known about ocean acidification declare that we are deeply concerned by recent, rapid changes in ocean chemistry and their potential, within decades, to severely affect marine organisms, food webs, biodiversity, and fisheries.” The declaration was clear about the solution: “ocean acidification can be controlled only by limiting future atmospheric CO2 levels.” In June 2009, the Interacademy Panel (IAP), which represents the science academies of 69 member countries, issued a statement calling on “world leaders to acknowledge that ocean acidification is a direct and real consequence of increasing atmospheric CO2, is already having an effect at current concentration and is likely to cause grave harm to important marine ecosystems.”
Now, two new documentaries are drawing public attention to the issue of ocean acidification, what some scientists call “the other carbon problem.”
- “Acid Test – The Global Challenge of Ocean Acidification,” produced by the Natural Resources Defense Council and narrated by actress Sigourney Weaver, premieres tonight August 12, 2009 @ 10:30pm on Planet Green.
- “A Sea Change: A World Without Fish” follows retired educator Sven Huseby as he visits several sites where research is underway to understand the impacts of climate change on ocean chemistry. The next screening will be at the Museum of Natural History in NYC on September 13, 2009 @ 4pm. (It’s free).
For more information, check out the films and these other links, which have lost of great – and accessible – information about ocean acidification: