Deep beneath the ocean waves near Antarctica, mid-depth seawater is mixed. For years, though, scientists have puzzled over exactly what causes this mixing--a crucial part of understanding how our climate is regulated. Now, they've discovered undersea mountains in the Drake Passage, a channel between the southern tip of South America and the Antarctic continent, which explains this mixing.

Learning about ocean mixing is crucial for developing climate models and, in consequence, providing accurate long-term climate projections. As our climate and as temperatures change, creating these models is more important than ever. Until now, though, this ocean mixing component has been missing.

That's why scientists decided to take to the field in order to find out the information they needed. The researchers journeyed to the Southern Ocean and then released tiny quantities of an inert chemical tracer into the Southeast Pacific. They then tracked the tracer for several years as it traveled through the Drake Passage in order to find out exactly how quickly the ocean mixed.

So what did they find? It turns out that the tracer showed almost no vertical mixing in the Pacific. As the water passed over the mountainous ocean floor in the narrow continental gap, though, this water began to mix dramatically.

"A thorough understanding of the process of ocean mixing is crucial to our understanding of the overall climate system," said Andrew Watson, one of the researchers, in a news release. "Our study indicates that virtually all the mixing in the Southern Ocean occurs in the Drake Passage and at a few other undersea mountain locations. Our study will provide climate scientists with the detailed information about the oceans that they currently lack."

The new findings could especially help researchers understand how carbon dioxide is being mixed with ocean waters. As CO2 continues to increase in our atmosphere, this factor is especially important when developing models. This mixing also impacts climate since it determines how much heat is being transferred toward both poles.

The findings are published in the journal Nature.