Climate change is altering Planet Earth. Seas are rising. Weather is atypical. Many people think the cause is greenhouse gases in the air - but another problem is bubbling beneath the surface: Oceans are growing more acidic.

Nearly half the world's carbon emissions are absorbed by seas, according to a 2007 study by the National Oceanic and Atmospheric Administration. When CO2 reacts with sea water it makes carbonic acid. This chemical imbalance could disrupt everything in the food chain, and faster than expected, scientists say. When the ocean traps carbon dioxide, it slows global warming. But it harms shellfish, coral and other invertebrates that undergird food chains.

Since the Industrial Revolution, oceans have become 30 percent more acidic, says the U.N. Intergovernmental Panel on Climate Change, while atmospheric concentration of carbon dioxide is higher than it has been for at least the last 650,000 years. Both conditions will worsen if action is not taken.

Small organisms uphold food chains. Death of the tiniest species has a cascade effect, affecting larger fish and marine mammals. Calcium-based shells are dissolving. New York Times columnist Nicholas Kristof likened the situation to dropping a piece of chalk into vinegar. "The chalk will begin dissolving immediately" he wrote.

Coral, a primary breeding ground for fish, suffers most. Like shells, coral is dissolving. This will stunt reproduction because corals reach sexual maturity based on size, not age.

Before irrevocable damage is done to the world's oceans - and the human food supply - pollution remedies are needed. Despite declining oil reserves, more cars on are on the roads. Deforestation and more meat production also increase CO2 emissions.

It turns out that a cleanup of the air would help oceans, too.

Nearly half the world's carbon emissions are absorbed by seas, according to a 2007 study by the National Oceanic and Atmospheric Administration. When CO2 reacts with sea water it makes carbonic acid. This chemical imbalance could disrupt everything in the food chain, and faster than expected, scientists say. When the ocean traps carbon dioxide, it slows global warming. But it harms shellfish, coral and other invertebrates that undergird food chains.

Since the Industrial Revolution, oceans have become 30 percent more acidic, says the U.N. Intergovernmental Panel on Climate Change, while atmospheric concentration of carbon dioxide is higher than it has been for at least the last 650,000 years. Both conditions will worsen if action is not taken.

Small organisms uphold food chains. Death of the tiniest species has a cascade effect, affecting larger fish and marine mammals. Calcium-based shells are dissolving. New York Times columnist Nicholas Kristof likened the situation to dropping a piece of chalk into vinegar. "The chalk will begin dissolving immediately" he wrote.

Coral, a primary breeding ground for fish, suffers most. Like shells, coral is dissolving. This will stunt reproduction because corals reach sexual maturity based on size, not age.

Before irrevocable damage is done to the world's oceans - and the human food supply - pollution remedies are needed. Despite declining oil reserves, more cars on are on the roads. Deforestation and more meat production also increase CO2 emissions.

It turns out that a cleanup of the air would help oceans, too.