Ocean Acidification – Global Warming’s Evil Twin

By John Rowe on April 24, 2013 in Other

Imagine a world without lobsters and crabs. Imagine donning your fins and mask for a Sunday snorkel at Clovelly, only to find nothing but seaweed under the water. No gropers. No drummers. No old wives. This could be a reality if ocean acidification continues.

Oceans make up 99 per cent of the living space on the planet. After pulling so much life out of the ocean, to the point where we’ve almost exhausted our wild fish resources, we are now in danger of killing the ocean itself by changing its chemistry while it is already under immense pressure from overfishing and chemical pollution. In addition to contributing to climate change, man-made carbon dioxide (CO2) in the atmosphere is absorbed by the ocean, making seawater more acidic, and this leads to numerous changes in ocean chemistry. Animals such as sea urchins, coralline algae (the pink stuff you see on rocks when you snorkel) and stony corals decline or vanish with decreasing pH.

Changes in seawater chemistry will affect marine organisms that use carbonate to build shells and skeletons. Scientific evidence suggests ocean acidification will have negative effects on corals, shellfish, squid and other marine life, with wide-ranging consequences for ecosystems, fisheries and tourism. Coral reefs are especially sensitive to ocean acidification as it means they are unable to form their skeletons. Jellyfish and seaweed are the only species likely to increase with rising CO2 over the next 100 years.

If the ocean continues to acidify, when coupled with habitat destruction, overfishing, introduced species, ocean warming, toxins and nutrient runoffs, we are likely to see it change completely. Critics say this view is alarmist and that the science used is based on models and laboratory experiments. Other views would suggest that ocean acidification is only one of many factors leading to changes in marine life. Real-life evidence for ocean acidification comes from the study of natural CO2 volcanoes in the Mediterranean Sea. Natural CO2 bubbling from the ocean in Italy acidifies the water (to a pH of 7.8), meaning no fish, or shells, just seaweed.

Scientists say that the volcanic vents have been pouring CO2 into the ocean at the site of the study for over a thousand years. Further, investigating natural volcanic CO2 vents in the Mediterranean shows that seaweeds survive at the expense of fish, shellfish, lobsters and prawns. The complexity of this issue is such that it is not possible to say that these venting sites are exactly parallel to a global-scale ocean acidification, but they are excellent real-life models.

Serious economic impacts on tourism, fisheries and possibly life as we know it on the planet will occur because of ocean acidification. Therefore, ocean acidification is a powerful reason for reducing global CO2 emissions.
And who wants jellyfish rather than shellfish, lobsters and prawns for Christmas lunch?

John Rowe is a member of Gordon’s Bay Scuba Diving Club. A full list of his references is available on request by emailing jcprowe@bigpond.net.au.