Climate Change to Leave 'No Corner' of the Ocean Unchanged

We know climate change is affecting the world's oceans. There have been lots of studies about what's going to happen (or what's already happened) when you take the world's oceans and add a couple feet of water on top, or add a degree or two, or make it slightly more or less acidic. But scientists are still trying to solve the 400 parts-per-million-piece puzzle of what happens when you put all those changes together.

In the end, the future of our oceans looks kind of one of those abstract paintings where you spend a couple minutes trying to figure out what's going on. Predicting what's going to happen 90 years out—as researchers at the University of Hawaii tried to do in a paper published in PLOS Biology Tuesday—is tough, but we get the general idea.

"There is no corner of the planet where the oceans are going to be free of the changes we'll see," said Camilo Mora, lead author of the study. "There are studies based on temperature changes and pH levels, but there are other things like oxygen and general productivity that haven't been studied as closely. When we put it all together, we have evidence to suggest that changes in the ocean will be comprehensive."

That doesn't mean the oceans will be lifeless come 2100. But the ecosystems will likely have changed. That means fish will migrate to and from different areas, coral reefs will die out, and invasive species will likely take over certain ecosystems.

"Some people will take it as this will be the end of the world, and that's not right," Mora said. "Many species will still be there, some will stay and adapt. But the reality is that the ecosystems are going to change, including ours. We have a comfort zone and climate change is going to change that comfort zone to another place."

Here's the estimates they are running on. By 2100, Mora predicts there will be a worldwide ocean temperature increase of between 1.2 and 2.6 degrees C, up to a 4 percent reduction in dissolved oxygen content, oceans will be more acidic by about .3 on the pH scale, and phytoplankton will be up to 10 percent less productive.

It's hard to talk specifics when it comes to consequences for these changes, Mora said, but in general terms, the impacts will be greatest in areas surrounding developing countries. That's more fuel for the fire that people already living in poverty will be most affected by climate change. They estimate that between 400 and 800 million people will lose their jobs, revenue, or source of food. Those drops include decreases in fish catches and declines in tourism as endemic species (and coral reefs) die out or migrate.

"We know that there are species that have survived these sorts of changes, but predicting which ones will respond in the future, we don't know," he said. "Imagine you're climbing a ladder and you fall from the top. You don't know which bones you might break, but you know it won't be good. All we can tell you is that you should avoid falling from that ladder."