Climate Change Won't Spare Global Ocean: No Corner Untouched by 2100

Climate change is impacting our Earth in new and unforeseen ways. Yet how is it affecting our oceans? Scientists have conducted an ambitious new study that describes the full chain of events that we might be able to expect from excess greenhouse gas entering the ocean--and it doesn't look good. It turns out that no corner of the world ocean will be untouched by climate change by 2100.

"When you look at the world ocean, there are few places that will be free of changes; most will suffer the simultaneous effects of warming, acidification and reductions in oxygen and productivity," said Camilo Mora, the lead author of the new study, in a news release. "The consequences of these co-occurring changes are massive--everything from species survival, to abundance, to range size, to body size, to species richness, to ecosystem functioning are affected by changes in ocean biogeochemistry."

In order to examine how climate change will affect the ocean, the researchers used the most recent and robust models of projected climate change developed for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). They quantified the extent of co-occurrence of changes in temperature, pH, oxygen and primary productivity based on two scenarios: business-as-usual and a less extreme scenario where concentrations of CO2 only reach 550 ppm by 2100.

So what will happen to our oceans? The world's ocean surface will simultaneously be impacted by varying intensities of ocean warming, acidification, oxygen depletion or shortfalls of productivity. Only a very small fraction of these waters, mainly in the polar regions, will face the opposing effects of increases in oxygen or productivity. Nowhere will there be cooling or pH increase.

By 2100, global averages for the upper layer of the ocean could experience a temperature increase of 1.2 to 2.6 degrees Celsius. In addition, the seafloor could also experience changes, albeit smaller ones that those found of the surface. The ecosystems that are liable to experiences the largest absolute changes will be coral reefs, seagrass beds and shall soft-bottom benthic habitats.

"The impacts of climate change will be felt from the ocean surface to the seafloor. It is truly scary to consider how vast these impacts will be," said Andrew K. Sweetman, co-author of the new study, in a news release. "This is one legacy that we as humans should not be allowed to ignore."

The findings are published in the journal PLOS Biology.