U.N. Goals for reducing greenhouse gas emissions enough to stabilize the climate may not be aggressive enough to solve another thorny issue associated with carbon dioxide: ocean acidification.
That's according to new research published in the latest Geophysical Research Letters.
If the world is successful slowing emissions so that the concentration of atmospheric carbon dioxide is held at two times the concentration seen in pre-industrial times, it may be enough to stave off the words consequences of global warming. That, at least, is the idea that forms the underpinnings for the United Nations goals (some scientists are increasingly vocal about their belief that a more aggressive target is needed to keep vulnerable human and wildlife populations safe).
But that wouldn't save corals or other marine species -- like the plankton that hold together the oceanic food web -- according to chemical oceanographers Long Cao and Ken Caldeira of the Carnegie Institution's Department of Global Ecology. (Previous research suggests ocean uptake of CO2 may already be slowing because the water is saturated.)
Corals aren't just beautiful. They aren't just a destination for tourists who like snorkeling. They are the nurseries of the ocean, providing habitat for an amazing diversity of fish. Losing corals would likely mean a cascade of extinctions. Likewise, disruptions in plankton populations would affect a range of fish and marine organisms, including whales and ultimately humans who rely on fish for protein.
And, unfortunately, acidification isn't the only threat to oceans, which recent research warned are returning to a primordial stew because of overfishing, pollution, habitat destruction, global warming -- in addition to acidification.
The new computer model is among the first to estimate the levels of carbon in the atmosphere that would threaten the ocean environment. Even at the level now seen in the atmosphere, half of the world's corals are endangered. If the world is successful in reaching the U.N. targets, 90% of corals would still be endangered, based on expected water chemistry conditions, according to Cao. The North Pacific would be so acidic that it would violate U.S. water quality standards.
"If current trends in CO2 emissions continue unabated," says Caldeira, "in the next few decades, we will produce chemical conditions in the oceans that have not been seen for tens of millions of years. We are doing something very profound to our oceans. Ecosystems like coral reefs that have been around for many millions of years just won't be able to cope with the change."
"When you go to the seashore, the oceans seem huge," he adds. "It's hard to imagine we could wreck it all. But if we want our children to enjoy a healthy ocean, we need to start cutting carbon emissions now."
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