Oyster is a canary in a coal mine as oceans warm (CBS News) CARLSBAD, Calif. -- Scientists working with the United Nations said Friday they are more convinced than ever that humans are the main cause of climate change. Surprisingly, their report indicates the rise in air temperature has slowed, but greenhouse gases are profoundly changing the oceans. Last year, Dennis Peterson says his company could only get a quarter of the young oysters, or seed, they need from hatcheries in the Pacific Northwest. A company near San Diego raises oysters. Last year, Dennis Peterson says they could only get a quarter of the young oysters, or seed, they need from hatcheries in the Pacific Northwest. It cost them about $1 million in lost business. Asked why it was hard to get the seed, Peterson says, "The oceans were getting more acidic as a byproduct of increased CO2 in the atmosphere." About 70 percent of carbon dioxide produced on the planet stays in the atmosphere or is used by plants. Thirty percent is absorbed by the oceans, where it produces a weak acid. But it's strong enough to impact sea life and prevent oysters from creating their shells. Carbon emissions also trap heat. Friday's report shows oceans have absorbed 90 percent of that heat, raising ocean temperatures by half a degree. Had all that heat gone into the atmosphere, air temperatures could have risen by more than 200 degrees. Lynne Talley "The ocean is really the heavyweight in the system," says Lynne Talley, a scientist with the Scripps Institution of Oceanography. It is where most of the heat goes. Talley says oceans keep the planet from overheating, but sea levels are rising because the heat expands the water. "A lot of it's in the upper ocean, but there's a certain amount in the deep ocean, and that's well away from the atmosphere, so you're moving heat all the way down into the ocean," Talley says. Watch: Globe not warming as previously thought: U.N. report. Dennis Peterson worries about what that means for his oysters. When it comes to climate change, he says the oyster in the ocean is like a canary in a coal mine. "This is only the first thing we noticed," he says. There's going to be lots of other ramifications. He's already looking into expanding his other products, such as red algae, in case his oyster crates one day come up empty.