End of April, we spoke with the UW’s Peter Ward about climate change denial, and mentioned glancingly the acidification of Puget Sound, as a test case of sorts for the larger problem of the world’s oceans.

Now Sightline is taking ocean acidification head-on, with a Northwest Ocean Acidification series. In part one, “The Acid Test,” Jennifer Langston notes that without the oceans, the level of carbon dioxide in the atmosphere would be far greater. Oceans “absorb nearly one million metric tons of carbon dioxide each hour, removing about a third of the greenhouse gases from the atmosphere that would otherwise speed up global warming.”

Operating as a carbon dioxide sink, unfortunately, means the oceans are gradually (or frighteningly fast, considering the scale) becoming more acidic. On the 0-14 pH scale, 7 is neutral; the oceans on average have dropped from 8.2 to 8.1 (it’s a logarithmic scale, so that’s a much bigger shift than it looks). So they’re not going to eat the skin of bathers’ bones–yet!–but to the marine life adapted to 8.2, things don’t feel quite right at all.

An average smooths out local variations though: as we wrote in an earlier Puget Sound story, “In the Puget Sound main basin, cruises found pHs of 7.73 in deep water in winter, and 7.77 in summer. Hood Canal gave results of 7.56 (winter) and 7.39 (summer).” Acidified waters are corrosive for shellfish, so this development has the Puget Sound shellfish industry on edge.

In Part 2, “Coming to a Shore Near You?”, Langston notes that while the oceans have grown, on average, 30 percent more acidic since the dawn of the Industrial Revolution, Hood Canal is presently 340 percent more acidic. (Hood Canal has lots of problems besides atmospheric CO2.) The big “news” is that the ocean-trapped CO2 isn’t staying put in the deeps, but is welling up to the surface. These upwellings of acidified water create stressful zones for marine life (in addition to all the other stressors out there).

Scientists hadn’t expected this, so there’s a good deal of scrambling to research the process, and to study how marine life will respond. If that feels a little esoteric still, consider that the atmosphere is an ocean of air. If it needed to be demonstrated, no one can tell you what precisely climate change is going to bring.

But if you were looking for an analogous warning–maybe stressor doesn’t sound that bad?–you might think of how heat waves kill off thousands of senior citizens. And by the time stressors go global, they can be, for all intents and purposes, irreversible.