As the effects of global climate change continue to be felt throughout the world’s ecosystems, scientists say greenhouse gases are causing rapid changes that may irreversibly alter the composition of the Earth’s oceans.
It is estimated oceans absorb up to 30 percent of global carbon dioxide (CO2) emissions, helping to offset the overall warming of the planet. But the amount of CO2 being pumped into the atmosphere since the Industrial Revolution has skyrocketed, saturating oceans and boosting acidification.
Burgeoning ocean acidification raises the spectre of extinctions of coral, algae and shellfish – key cogs in the global food chain – with far reaching consequences for the planet’s inhabitants.
“What we have at the moment is data that says that yes, certainly some things are going to do badly, some things are going to cope. The [ocean] ecosystems are very, very likely to change significantly,” said Professor Lloyd Peck of British Antarctic Survey, a Cambridge, UK-based environmental research centre specialising on the Antarctic.
When dissolved in seawater, CO2 causes various chemical reactions, including an increase in the concentration of hydrogen ions, a decrease in the amount of carbonate ions, and an overall drop in pH levels – the measurement of water acidity.
This phenomenon is known as ocean acidification.
While ocean acidification is expected to affect marine life at varying degrees, one of the main consequences is increased difficulty for marine species to extract calcium carbonate from the water.
Calcium carbonate is the primary component marine organisms – including crabs, lobsters, snails, and coral – use to build their shells and skeletons.
If the level of calcium carbonate in seawater drops past a certain point, a wide array of marine life will not be able to develop shells, making them more vulnerable to predators. If pH levels fall low enough, skeletons of marine life will begin to dissolve.
The current average pH level of surface water in the world’s oceans is between 7.9-8.2. Anything below a pH of 7 is said to be acidic.
Since the beginning of the Industrial Revolution, it is estimated that surface water pH levels have dropped by 0.1.
Rate of changes unprecedented
According to a fact sheet released by the International Ocean Acidification Reference User Group, ocean acidity has increased 30 percent since the beginning of the Industrial Revolution.
“In terms of simply the emission of CO2 in the atmosphere, it’s 100 times faster than the natural geologic release of CO2 to the atmosphere. This relates to the magnitude of ocean acidification,” said Professor Andy Ridgwell from the University of Bristol and co-author of the paper, “Ocean Acidification in Deep Time”.
Ocean acidification is occurring at least 10 times faster today than at any other time in history, Ridgwell said. Therefore, the question that remains for scientists is how marine species and ecosystems will adapt to this unprecedented rate of change, he said.
“We can look at less extreme events, slower events, and see what the reaction was. That at least gives us a lower bound on what we might expect in the future,” Ridgwell said. “But it’s impossible to put an upper bound on it. We don’t know whether the unusual rate is going to cause large-scale extinctions.”
Professor Maoz Fine of the Interuniversity Institute for Marine Sciences in Eilat, Israel, and colleague Marco Milazzo of the University of Palermo in Italy, recently examined 10 different sites of vermetid coral reefs along the Israeli coast in the Mediterranean Sea. They found the primary builder of vermetid reefs – a sea snail called Dendropoma petraeum – had recently gone extinct.
While the exact cause of the species’ extinction remains unknown, researchers say ocean acidification and climate change may have played a major role.
“It is likely that environmental change caused the sudden mortality. Since the main builder is gone, it is likely that the reef framework will deteriorate more rapidly and eventually fall apart,” said Patrizia Ziveri, project coordinator of Mediterranean Sea Acidification in a Changing Climate (MedSeA), a project funded by the European Commission.
“Their importance is hard to ignore as these reefs serve a hotspot of biodiversity, shelter sandy beaches and prevent coastal erosion,” Ziveri added.
Changing Antarctic waters
Calcium carbonate vital for marine life changes with water temperature and pressure. Cold, deep waters are the most difficult from which to extract the much-needed mineral.
“As you go towards the poles, the solubility of the calcium carbonate is higher and its availability is less, which means you’ve got a double problem,” said Peck.
In a recent survey of four types of marine animals – clams, sea snails, lamp shells and sea urchins – living in Antarctic waters, Peck and fellow researchers found as the availability of calcium carbonate decreases, the animals’ skeletons became lighter and thinner.
“The polar regions are the ones that are changing fastest. They’re the ones where the animals appear most vulnerable,” Peck told Al Jazeera, explaining that Antarctic waters are expected to be under-saturated by about 2040, while tropical waters will reach the same point around 2100.
“We really need to understand what’s going on in those [polar] regions because what’s happening there is going to be happening [elsewhere] in 40, 50, 60, 70 years’ time, and it might give us enough understanding to be able to do something helpful for society.”
According to a 2010 survey released by the Yale Project on Climate Change Communication, 77 percent of Americans said they hadn’t read or heard anything about ocean acidification. The survey also found that less than eight percent of Americans understood that ocean acidification is caused by CO2 emissions.
“Awareness is really low. There’s a lot of work to be done,” said Hedia Adelsman, executive policy advisor for the State of Washington’s Department of Ecology.
Adelsman said Washington state is particularly vulnerable to ocean acidification because of a phenomenon known as “upwelling” – in the summer, strong winds push aside warmer surface water and bring up colder water, which is rich in carbon dioxide and has a lower pH level.
Washington witnessed a dramatic decrease in shellfish larvae between 2005-2009, Adeslman said, which could potentially have devastating consequences on an industry that employs more than 3,000 people and brings in $270m annually.
“We are calling on the White House, Congress, and so on, to really take a serious look at the problem and start to address it. We plan to really get the message out to try to get resources and to really move this thing forward [by] addressing the problem and knowing more about it,” Adelsman said.
Government action needed
Discussions about ocean acidification and other threats to the world’s oceans were held during the United Nations Conference on Sustainable Development, Rio+20, in Brazil earlier this year.
In the summit’s final adopted document, titled “The Future We Want”, participants called for widespread, international support of scientific research and documentation of ocean acidification, and of “initiatives that address ocean acidification and the impacts of climate change on marine and coastal ecosystems and resources”.
While the pledge is a step forward, many argue that governments need to more seriously work to stem the root cause of the problem: excessive greenhouse gas emissions.
“The main point is that we have to reduce global warming. If the governments act to reduce their emissions of greenhouse gases, this will be part of the solution for ocean acidification,” said Jorge Luis Valdes, head of the Intergovernmental Oceanographic Commission at the United Nations Educational, Scientific and Cultural Agency.
Valdes told Al Jazeera that governments must take the issue more seriously, since a loss of coastal reefs as a result of ocean acidification could soon affect people living in coastal territories, such as islands in the Pacific and Indian Oceans.
“With the financial crisis, I think that all the environmental problems have been moved to a different level of priority,” Valdes said. “But the environment is one of the main risks that we have for the planet and for the lives of the future generations. We have to try to modify the way the way we live.”
Jillian Kestler-DAmours, Al Jazeera, 28 November 2012. Article.