SHELTON, Washington — Tucked into a hillside of pine, just above the Puget Sound, is perhaps the world’s most prolific nursery.

On any given day, hundreds of millions of sea creatures begin life under the watchful eye of marine biologist Benoit Eudeline. He raises oysters for the Taylor Shellfish Co., the largest producer of shellfish in the U.S., processing some 60 million oysters each year.

The oysters begin life in tanks filled with seawater, going from egg to a fully swimming larvae within 24 hours — the larvae so small, they can be seen only with a microscope.

But now these newly hatched oysters are under threat from a phenomenon known as ocean acidification.

Although it doesn’t get as much attention as melting ice caps or rising sea levels, ocean acidification is one of the most serious effects of greenhouse gas emissions. Nearly a third of the world’s carbon dioxide emissions, or about 22 million tons of CO2, is absorbed by the ocean every day. Scientists say this pollution has fundamentally changed ocean chemistry.

When carbon dioxide dissolves in water, it becomes an acid. That acid can be lethal to baby oysters, preventing them from forming shells, Eudeline said. And it’s not just oysters at risk; lobsters, crabs, clams and coral reefs are feeling the effects of ocean acidification too.

Ocean acidity is projected to increase by a factor of five by the year 2100, according to the National Oceanic and Atmospheric Administration. In water that acidic, the shell of a common sea creature will dissolve in 45 days.