HOMER, Alaska — Kris Holderied, who directs the National Oceanic and Atmospheric Administration’s Kasitsna Bay Laboratory, said the ocean’s increasing acidity is ‘‘the reason fishermen stop me in the grocery store.’’

‘‘They say, ‘You’re with the NOAA lab, what are you doing on ocean acidification?’ ” Holderied said. ‘‘This is a coastal town that depends on this ocean, and this bay.’’

This town in southwestern Alaska dubs itself the Halibut Fishing Capital of the World. But worries about the changing chemical balance of the ocean and its impact on the fish have made an arcane scientific buzzword common parlance here, along with the phrase ‘‘corrosive waters.’’

In the past five years, the fact that human-generated carbon emissions are making the ocean more acidic has become an urgent cause of concern to the fishing industry and scientists.

The ocean absorbs about 30 percent of the carbon dioxide we put in the air through fossil fuel burning, and this triggers a chemical reaction that produces hydrogen, thereby lowering the water’s pH.

The sea today is 30 percent more acidic than preindustrial levels, which is creating corrosive water that is washing over America’s coasts. At the current rate of global worldwide carbon emissions, the ocean’s acidity could double by 2100.

What impact it is having on marine life, how this might vary by geography and species, and what can be done about it if humans do not cut their carbon output significantly are some of the difficult questions scientists and policymakers are seeking to answer.

The decline in pH will probably disrupt the food web in many ways.