Arctic Ocean Stores 58 Megatons of Carbon Each Year--As Long as It's Not Too Warm

It turns out that while we may be pouring out carbon dioxide, there's one place on Earth that's preventing this gas from reaching our atmosphere. The Arctic Ocean is slowly becoming more of a carbon sink, soaking up carbon before it can impact our climate. These findings have important implications for future climate models and the health of the Arctic ecosystem.

As our climate warms, Arctic ice is melting--particularly during the summer months. Sunlight penetrates surface waters and there, large blooms of phytoplankton are encouraged to grow by these favorable conditions. When the phytoplankton die, a small portion of their carbon sinks to the deep ocean, creating a reservoir of carbon beneath the waves.

In order to actually assess how much carbon the Arctic Ocean has been taking up over the years, though, the researchers took a closer look. They developed a model to trace the flow of carbon in the Arctic, looking at conditions in which carbon was either stored or released from the ocean. They also modeled the changing Arctic between 1996 and 2007 in order to see how it was developing over time.

"People have suggested that the Arctic is having higher productivity, and therefore higher uptake of carbon," said Stephanie Dutkiewicz, one of the researchers, in a news release. "What's nice about this study is, it says that's not the whole story. We've begun to pull apart the actual bits and pieces that are going on."

So what is going on exactly? It turns out that at least between 1996 and 2007, the Arctic stored an average of about 58 megatons of carbon each year. What was more interesting was the fact that the Arctic seemed to store increasing amounts, rising by about 1 megaton each year. While this confirms the fact that the Arctic is becoming more productive with melting sea ice, though, the scientists also made other discoveries.

It turns out that when the waters were the warmest, less carbon was taken up. For example, the Arctic waters absorbed less carbon in 2007 than in 2005. The year of 2007 experienced one of the most severe periods of ice shrinkage ever recorded. This phenomenon in particular can be attributed to the fact that certain conditions need to be met for optimal biological activity. If waters are too warm, there's a point where less carbon is stored.

"The Arctic is special in that it's certainly a place where we see changes happening faster than anywhere else," said Dutkiewicz in a news release. "Because of that, there are bigger changes in the sea ice and biology, and therefore possibly to the carbon sink."

The findings are published in the journal Global Biogeochemical Cycles.