The Beacon

What Do Historic CO2 Levels Mean for the Oceans?

“Keeling Curve” shows CO2 levels increase from 1958-2013. (Source: Scripps Institution of Oceanography, UCSD)


For the first time in human history, atmospheric carbon dioxide levels passed 400 parts per million
(ppm) of carbon dioxide at the historic Mauna Loa Observatory in Hawaii. This is the same location where Scripps Institution of Oceanography researcher Charles David Keeling first established the “Keeling Curve,” a famous graph showing that atmospheric carbon dioxide concentrations are increasing rapidly in the atmosphere. CO2 was around 280 ppm before the Industrial Revolution, when humans first began releasing large amounts of CO2 to the atmosphere by burning fossil fuels. On May 9, the reading was a startling 400.08 ppm for a 24-hour period. But without the help of the oceans, this number would already be much higher.

Air pollution is also ocean pollution. The ocean is absorbing so much carbon pollution that it has slowed the impacts of climate change, but this has come at a cost to marine life and people who depend on a healthy ocean.

The ocean absorbs approximately one-third of all human-caused CO2 emissions at a rate of 300 tons per second. But due to CO2 absorption, the ocean is now 30% more acidic than before the Industrial Revolution, and the rate of change in ocean pH, called ocean acidification, is likely unprecedented in Earth’s history.

Ocean acidification is already harming marine animals like oysters, mussels and clams as well as coral reefs and floating marine snails called pteropods, dubbed the “potato chips of the sea” due to their importance to marine food webs. In the last decade, ocean acidification caused massive die-offs of oyster larvae at the Whisky Creek oyster hatchery in Oregon, shrunk the shells of pteropods in the Southern Ocean and caused coral growth to slow on Australia’s Great Barrier Reef.

By burning fossil fuels, we are putting the world’s marine life through a high-risk chemistry experiment and hoping for the best. During previous changes in ocean conditions that were much slower than today, 95% of marine species went extinct. If emissions continue at current rates, we are risking a similar mass extinction event, one that could begin within our lifetimes.

The impacts will ripple up to threaten people as well, who are at the top of the ocean food web: In September 2012, an Oceana report entitled Ocean-Based Food Security Threatened in a High CO2 World ranked nations based on their vulnerability to reductions in seafood production due to climate change and ocean acidification. For many island nations, seafood is the cheapest and most readily available source of protein. Most small-scale fishermen simply aren’t capable of following fish into distant waters as climate change and ocean acidification reduce their near shore landings. Reducing CO2 emissions is the only way to address global ocean acidification and the primary means to stop climate change.

Oceana works to limit polluting emissions that threaten the ocean by stopping the expansion of offshore drilling and promoting clean energy solutions like offshore wind. In the Atlantic Ocean, oil companies are trying to take their first step towards drilling for offshore oil and gas with harmful seismic airgun surveys that would injure dolphins and whales with loud blasts. The more oil they find and the more drilling that occurs, the worse climate change become. Find out more and take action at: http://www.oceana.org/seismic


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