Although most of the concern about carbon emissions has focused on the atmosphere and resulting temperature changes, accumulation of carbon dioxide in the ocean also could have disturbing outcomes, experts said at the hearing, which examined legislation that would create a program to study how the ocean responds to increased carbon levels.
Ocean surface waters quickly absorb carbon dioxide from the atmosphere, so as carbon concentrations rise in the skies, they also skyrocket in the watery depths that cover almost 70 percent of the planet. As carbon dioxide increases in oceans, the acidity of the water also rises, and this change could affect a wide variety of organisms, said Scott Doney, senior scientist at the Woods Hole Oceanographic Institution, a non-profit research institute based in Woods Hole, Mass.
"Greater acidity slows the growth or even dissolves ocean plant and animal shells built from calcium carbonate," Doney told representatives in the House Committee on Energy and the Environment. "Acidification thus threatens a wide range of marine organisms, from microscopic plankton and shellfish to massive coral reefs."
If small organisms, like phytoplankton, are knocked out by acidity, the ripples would be far-reaching, said David Adamec, head of ocean sciences at the National Aeronautics and Space Administration.
"If the amount of phytoplankton is reduced, you reduce the amount of photosynthesis going on in the ocean," Adamec told United Press International. "Those little guys are responsible for half of the oxygen you're breathing right now."
A hit to microscopic organisms can also bring down a whole food chain. For instance, several years ago, an El Nino event wiped out the phytoplankton near the Galapagos Islands. That year, juvenile bird and seal populations almost disappeared. If ocean acidity stunted phytoplankton populations like the El Nino did that year, a similar result would occur -- but it would last for much longer than one year, potentially leading to extinction for some species, Adamec said.
While it's clear increased acidity makes it difficult for phytoplankton to thrive, scientists don't know what level of acidity will result in catastrophic damages, said Wayne Esaias, a NASA oceanographer.
"There's no hard and fast number we can use," he told UPI.
In fact, although scientists can guess at the impacts of acidity, no one's sure what will happen in reality. Rep. Roscoe Bartlett, R-Md., pointed to this uncertainty at Thursday's hearing.
"The ocean will be very different with increased levels of carbon dioxide, but I don't know if it will be better or worse," Bartlett said.
However, even though it's not clear what the changes will be, the risk of doing nothing could be disastrous for ecosystems, said Ken Caldeira, a scientist at the Carnegie Institution for Science, a non-profit research organization.
"The systems that are adapted to very precise chemical or climatological conditions will disappear and be replaced by species which, on land, we call weeds," Caldeira said. "What is the level of irreversible environmental risk that you're willing to take?"
It's precisely this uncertainty that the Federal Ocean Acidification Research and Monitoring Act attempts to address. The bill creates a federal committee within the National Oceanic and Atmospheric Administration to monitor carbon dioxide levels in ocean waters and research the impacts of acidification.
The funds for the project increase over time, with $25 million total allocated for the first three fiscal years, and $30 million per year from 2012 onward.
The program is vital to understanding what's going on, said Richard Feely, an oceanographer at NOAA, particularly as the problem appears increasingly imminent.
Feely and a team of researchers recently discovered corrosive waters are much more prevalent in coastal areas than predicted. The team measured acidity levels off the Pacific North American Continental Shelf, from mid-Canada to upper Mexico, and published their findings in Science magazine last month.
"We expected to see it in some places, but we saw it from Canada all the way down along Washington, Oregon and to the bottom of California, everywhere we looked," Feely said Thursday.
While carbon dioxide levels have been high in deep ocean waters for some time, scientists had not expected to see such acidic water close to shore. As the acid eats away at the shells of oysters and clams and disrupts food chains, the economic effects could be widespread, said Rep. Nick Lampson, D-Texas.
"Each year Americans spend roughly $60 billon on fish and shellfish," said Lampson, chairman of the Environment Committee. "Coastal and marine commercial fishing generates as much as $30 billion per year and supports nearly 70,000 jobs."
Some businesses already have begun to see problems that could be associated with increased acidity, including Little Skookum Shellfish Growers in Shelton, Wash.
"Recently we've seen the presence of marine bacteria in our hatcheries that's interfering with the development of our oyster larvae," said Brett Bishop, co-owner of Skookum Shellfish.
The increase in this type of bacteria, which thrives in water with low or no oxygen, appears to be correlated to acidic ocean waters, Bishop said. If acidification continues to occur unabated, it could mean disaster for shellfish farmers like Bishop.
"We would lose everything," he told UPI.