AS THE REPUBLICAN presidential primary race drags on, the politics of global warming seem ever more divorced from scientific reality. The process of scientific inquiry, meanwhile, offers yet more warnings about what might happen if fractured climate politics stymie long-term action.

Emitting massive amounts of carbon dioxide doesn’t just change the chemistry of the atmosphere; it makes the oceans more acidic. Predicting the impact on ocean ecosystems involves educated speculation, which often involves applying evidence of what has happened before. In the latest edition of the journal Science, a team of researchers reckons that today’s human-emitted CO2 is increasing ocean acidity far faster than previous, naturally occurring episodes scientists have studied, which themselves appear to have had very alarming results.

The harrowing history is recorded in mud samples millions of years old, taken from the sea floor near Antarctica: It reveals a mass extinction of single-celled organisms that no doubt caromed far up the food chain. A similar effect today could kill off coral, plankton and mollusks, constricting the diets of a range of fauna that rely on them, including salmon — and humans.

Assuming similar results now, ocean acidification’s most extreme possible effects might not occur for many years. Yet today’s rate of acidification is 10 times that of the most comparable surge in atmospheric carbon in the last 300 million years, Barbel Honisch, a scientist involved in the study, tentatively estimates.

Scientists cannot and need not be definitive about exactly what will happen and when all over the earth. As ever with climate change, there is a range of risks involving mind-bogglingly complex planetary systems that scientists can attempt to anticipate, and probably many they have not considered. The point is there are enough dangers of such magnitude and probability that humans should invest in reasonable policies to avoid them.

If, despite the political season, Congress decided to stop dawdling and finally put America in the lead of the effort to combat climate change, a handful of lawmakers have provided a solid template for discussion. To no fanfare, Rep. Pete Stark (D-Calif.) introduced a bill late last year that would put a simple tax on carbon and give most of the proceeds back to consumers, which is the best approach. Getting more attention is a bill that Sen. Jeff Bingaman (D-N.M.) introduced last week, which would require increasingly large amounts of America’s electricity mix to come from clean sources. Though less attractive policy, the idea has President Obama’s endorsement and is considered more politically viable. Would that more Republicans would begin to operate in the world of scientific reality.