This post is a collaboration between Sarah Cooley, Ph.D. (Ocean Conservancy), Ryan Kelly, Ph.D., J.D. (U. Washington) and C. Mark Eakin, Ph.D. (NOAA)

Readers of this blog know that ocean acidification is here, today. They also know that states on both coasts and the federal government are working to halt its progress and manage its impacts. But the ocean is heedless of borders. A healthy ocean future will require global action. That is why we have our eyes on December’s Paris climate conference (COP21). Decisions made there will determine whether our children will inherit a changed-but-recognizable ocean that still provides humanity with goods and services, or a damaged ocean lacking many resources we want. There is still time for us to reduce emissions and slow the warming and acidification of our ocean, but we have to act now. That is one of the conclusions we reach in a paper out today in Science.

World leaders at that Paris Climate meeting aim to “reach, for the first time, a legally binding agreement that will enable us to combat climate change effectively.” Our international science team was convened to ensure they have the latest and greatest research on the health of ocean ecosystems, and clear information about the ocean futures different CO2 emissions scenarios will produce. Our work will augment the Intergovernmental Panel on Climate Change’s reports.

We found that under a “business-as-usual” CO₂ emission pathway, warming and acidification will have high to very high negative impacts on nearly every aspect of marine life we looked at, including seagrasses, warm-water corals, swimming snails, bivalve shellfish, krill, and finfish. Essentially, allowing CO₂ emissions to continue to rise is very bad for large portions of ocean life.

Essentially, allowing CO₂ emissions to continue to rise is very bad for large portions of ocean life.

That’s the story if the world doesn’t curb CO₂ emissions. If we do make rapid CO₂ emissions cuts, the risks of impacts to the marine organisms we considered are mostly moderate. There will be major damage to bivalves and warm water corals but the damage to other ocean ecosystems will be manageable. The ocean will be different from that of our ancestors, but coastal protection and key fisheries will likely remain intact. Therefore, it is essential to the oceans that we limit CO₂ emissions in ways that keep the earth under 2°C of warming.

We also found that there are four main actions that humanity can take: reducing CO₂, the cause of ocean warming and acidification; protecting ecosystems by building resilience; adapting human societies; and repairing damage that has already happened. Not surprisingly, the sooner we reduce CO₂, the more options we have to protect, adapt, and repair. The longer we wait to reduce CO₂ emissions, the more expensive and difficult it will be to guard our oceans from disruptive change… and the less likely these actions are to work.