The increasing acidity of the world’s oceans – and that acidity’s growing threat to marine species – are definitive proof that the atmospheric carbon dioxide that is causing climate change is also negatively affecting the marine environment, says world-renowned Antarctic marine biologist Jim McClintock, Ph.D., professor in the University of Alabama at Birmingham (UAB) Department of Biology.
“The oceans are a sink for the carbon dioxide that is released into the atmosphere,” says McClintock, who has spent more than two decades researching the marine species off the coast of Antarctica. Carbon dioxide is absorbed by oceans, and through a chemical process hydrogen ions are released to make seawater more acidic.
“Existing data points to consistently increasing oceanic acidity, and that is a direct result of increasing carbon dioxide levels in the atmosphere; it is incontrovertible,” McClintock says. “The ramifications for many of the organisms that call the water home are profound.”
A substance’s level of acidity is measured by its pH value; the lower the pH value, the more acidic is the substance. McClintock says data collected since the pre-industrial age indicates the mean surface pH of the oceans has declined from 8.2 to 8.1 units with another 0.4 unit decline possible by century’s end. A single whole pH unit drop would make ocean waters 10 times more acidic, which could rob many marine organisms of their ability to produce protective shells – and tip the balance of marine food chains.
“There is no existing data that I am aware of that can be used to debate the trend of increasing ocean acidification,” he says.
McClintock and three co-authors collected and reviewed the most recent data on ocean acidification at high latitudes for an article in the December 2009 issue of Oceanography magazine, a special issue that focuses on ocean acidification worldwide. McClintock also recently published research that revealed barnacles grown under acidified seawater conditions produce weaker adult shells.
…
Andrew Hayenga, UAB Media Relations, 3 February 2010. Full article and video.
“The ramifications for many of the organisms that call the water home are profound.”
But if the earth has endured multiple warmings and coolings over the last 20,000 years along with corresponding increases and decreases in atmospheric CO2 levels. The oceans have also been consuming and exuding CO2 in response and oceans acidity has risen and fallen as a result. What profound effects have occurred to these marine organisms during the multiple acidifications that have happend over the past 20k years?
If the effects are profound today, what were they before?
This is a very good question. It is the rapidity of the change that makes this so unprecedented. Marine organisms adapt to environmental changes generally over the time scale of centuries or even millenia. These ongoing increases in ocean acidity due to the oceanic uptake of atmospheric carbon dioxide are occuring in some geopgraphic regions (e.g. high latitude seas) on time scales of just decades. As such, it is likely that many marine organisms may have a very difficult time adapting to the increasingly acidic conditions in time to offset negative impacts on their growth, calcification (if they have shells or skeletal elements), reproductive output, and very survival.