A U.S. scientific agency recently said that climate change may not be the only threat to coral reefs. In fact, rapidly-increasing acidity levels in the oceans may present just as significant a risk to the integrity of the reefs. The acidity causes a kind of “ocean osteoporosis” as it impairs the formation of coral skeletons.
Jane Lubchenco, chief of the National Oceanic and Atmospheric Administration, called the increasing acidity levels the “equally evil twin” of climate change in an interview with The Associated Press. She says that the combination of climate change and increased acidity levels places tremendous stress on the reefs, adding “it’s a very serious situation.”
At first, scientists did not recognize the risk the increased acidity presented to the reefs. They predicted that water from different ocean depths would mix, thus diluting potential sources of increased ocean acidity. But they found that the chemical changes in the ocean are localized near the ocean surface, thus presenting a major threat to the coral reefs.
The problems of climate change and increased acidity, though they act on the reefs in different ways, may be related problems. The acidity originates from increased carbon dioxide levels in the atmosphere. Ocean waters absorb the excess carbon dioxide, leading to chemical reactions that increase acidity. Carbon dioxide is also one of the most significant greenhouse gases contributing to climate change.
A number of charts put together by the U.S. Environmental Protection Agency, reveal several key findings about the relationship between climate change and ocean acidity. Data demonstrates that ocean carbon dioxide levels have risen, accompanied by an increase in acidity. Data also suggests that over the last several-hundred years, ocean acidity has risen globally, especially in the Atlantic.
Measurements made over the last few decades have demonstrated that ocean carbon dioxide levels have risen, accompanied by an increase in acidity (that is, a decrease in pH) (see Figure 1).
Dr. Lubchenco says of the increasing acidity: “It’s yet another reason to be very seriously concerned about the amount of carbon dioxide that is in the atmosphere now and the additional amount we continue to put out.”
Increased acidity poses a threat to more than just the reefs. Acid also slows the growth rate of shelled organisms such as oysters. Some species of fish may also be impacted as the acidity can dull their sense of smell, damaging their ability to detect predators. The implications may be far greater, though much research remains to be done. Some fish may be unable to find food sources and salmon may be unable to find their natal streams if the effects of increased acidity turn out to be particularly damaging.
There are, at the moment, no long-term solutions to the problem of ocean acidity. Measuring instruments that detect acidity levels can warn oyster growers and others concerned with ocean acidity of increases in acidity levels in time to find other sources of water than the ocean.
Better solutions are necessary. According to Dr. Lubchenco, “The carbon dioxide that we have put in the atmosphere will continue to be absorbed by oceans for decades. It is going to be a long time before we can stabilize and turn around the direction of change simply because it’s a big atmosphere and it’s a big ocean.”
Also on Monday, NOAA announced that it has upgraded its methods of predicting and monitoring coral bleaching. Coral bleaching–or the whitening of coral–can now be predicted up to four months into the future with a new global seasonal outlook system.
“This advance in bleaching warning systems represents another milestone in our efforts to save the world’s critically important reef systems,” said Dr. Lubchenco in a statement. “The state of reefs today should raise concerns for everyone. Reef ecosystems are globally important, and healthy reefs are the life-line for local communities. Their continued existence is a moral imperative for the global community.”
NOAA says that healthy coral reefs provide millions of dollars to local economies through tourism and fishing.