Arctic Sea Ice Removes CO2 from the Atmosphere with Delicate Frost Flowers

As our climate changes and as temperatures warm, the Arctic is being altered in unprecedented ways. In fact, the extent of sea ice has decreased by about 30 percent in summer and in winter, sea ice is getting thinner. Now, scientists have found that sea ice actually removes CO2 from the atmosphere with the help of frost flowers and as it retreats, more gas may be released.

"If our results are representative, then sea ice plays a greater role than expected, and we should take this into account in future global OC2 budgets," said Dorte Haubjerg Sogaard, one of the researchers, in a news release.

In order to better understand the role Arctic sea ice plays when it comes to the planet's CO2 balance, the researchers examined sea ice in Greenland. They found that sea ice may have a major impact on the global carbon cycle and that chemical processes have a much greater impact on sea ice's ability to remove CO2 than biological processes. More specifically, when winter flower-like ice formations end up forming on the surface of newly formed sea ice, these frost flowers hold extremely high concentrations of calcium carbonate. The flowers can have a significant impact on the potential CO2 uptake in the Arctic.

"The chemical removal of CO2 in sea ice occurs in two phases," said Sogaard. "First crystals of calcium carbonate are formed in sea ice in winter. During this formation CO2 splits off and is dissolved in a heavy cold brine, which gets squeezed out of the ice and sinks into the deeper parts of the ocean. Calcium carbonate cannot move as freely as CO2 and therefore it stays in the sea ice. In summer, when the sea ice melts, calcium carbonate dissolves, and CO2 is needed for this process. Thus, CO2 gets drawn from the atmosphere into the ocean-and therefore CO2 gets removed from the atmosphere."

The findings reveal that sea ice in the Arctic draws large amounts of CO2 from the atmosphere into the ocean. The fact that this ice is melting, therefore, will likely has large impacts on atmospheric CO2 in the future.