The vast Southern Ocean in Antarctica soaks up billions of tons of CO2 from the atmosphere annually, and a new study shows that we may have vastly underestimated its ability to do so. According to a report from Nature, the findings confirmed the suspicions of scientists who believed that as carbon emissions rose, so would the amount sequestered by the ocean.

The study gathers millions of readings from the field to provide a clearer picture of the way the Southern Ocean captures carbon dioxide from the atmosphere, providing a buffer against climate change. The findings were published today in the journal Science.

It found that in 2011, the Southern Ocean absorbed 4.4 gigatons of CO2, which is more than 10 percent of the carbon emitted by humans at that time. It was nearly twice the amount absorbed ten years prior.

But what is behind the sudden increase in absorption rates? Unfortunately, the Southern Ocean didn’t change much over time. The amount of CO2 emitted, however, did. The ocean has a large capacity to absorb carbon dioxide, and will continue to absorb as much is present in the atmosphere until it reaches a saturation point.

While it’s good news that we know where some of the carbon emitted by human activity is going, the discovery is not without its downsides. CO2 in the ocean makes the water more acidic, which has far reaching environmental effects on species with calcium built into their body structures, like corals, crustaceans, and mollusks.