July 5, 2006 — The same manmade gases that are heating up the planet are also making oceans acidic enough to dissolve the skeletons and shells of many marine organisms, according to a new scientific report released Wednesday.
Already ocean surface concentrations of carbonic acid – created by excess atmospheric carbon dioxide dissolving into the water – are high enough to eat away the skeletons of many vital reef-building corals and microscopic "calcifiers," like caulk-making phytoplankton and tiny marine snails.
"The (acidity) changes that are occurring in the oceans are truly extraordinary," said Joan Kleypas, a marine ecologist at the National Center for Atmospheric Research (NCAR) and a coauthor of the July 5 multi-agency report entitled Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers. "It will continue to change as long as carbon dioxide is rising."
Atmospheric scientists around the world agree that the additional carbon dioxide in the air and oceans has come from exponential growth in fossil fuel burning emissions since the start of the Industrial Revolution in the 19th century.
Current carbon dioxide levels are higher than they have been for at least 650,000 years, according to ice core data from the Arctic and Antarctic.
Ocean acidity has already increased 30 percent since the start of the Industrial Revolution in the early 19th century, said Richard Feely, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory in Seattle.
By the end of the 21st century that could go up to 150 percent, he said.
"This is not controversial," said Kleypas, referring to the current acidity levels. There’s an overwhelming amount of data backing it up, she said.
What isn’t known very well, however, is just how rise in acidity will change overall ocean chemistry, how much carbon dioxide the oceans can ultimately absorb, and how marine organisms will respond.
"We don’t know whether they can adapt or not," said Victoria Fabry, a marine biologist at California State University at San Marcos. At present the only studies of marine organisms under higher acidity have been done in laboratories.
"At the moment we can only speculate," Kleypas added. "We should start addressing these questions immediately."
The sooner the better, said Feely, who pointed out that many affected organisms are also food sources for many commercially important fish – like salmon.
It could also pose a critical problem for coastlines protected by coral reefs, said Chris Langdon, a coral researcher at the University of Miami.
Rising acidity inhibits the buildup of skeletons that form the foundation of reefs, said Langdon. So acidification will likely lead to reef erosion and expose shorelines to the direct assault of waves.
Add rising sea level to the picture and things start looking pretty ugly, he explained.
Also at risk are 25 percent of the world’s marine species, which spend some part of their lives on reefs, said Langdon.
"Coral reefs are kind of like the rain forests of the ocean." And like rain forests, they are home to organisms that produce pharmacologically useful compounds – like the anti-AIDS drug AZT, he said.
The new report is the result of years of work by scientists worldwide and was assembled by top researchers at the US Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the National Science Foundation (NSF), the National Center for Atmospheric Research (NCAR), and universities.
The work will also appear in the next report by the Intergovernmental Panel on Climate Change.
