Relationship between sea ice and gas exchange more complex than current theories suggest

SIMBA Principal Investigator Steve Ackley admits he’s not an expert when it comes to the ocean processes of absorbing carbon dioxide, a key greenhouse gas that contributes to global warning.

But he does know a few things about the physics of sea ice. The traditional theory holds that sea ice cover seals off the ocean from exchanging gas with the atmosphere.

“From this trip and other work, we’re finding that’s not true,” he said following the two-month cruise in the Bellingshausen Sea. In fact, he said, gas exchange can be prolific when the ice cover warms up slightly.

“I think we’re really plowing new ground as far as what’s happening with CO₂ in the Southern Ocean and its relationship to the sea ice cover,” he said.

Ackley said the findings from the SIMBA cruise might further shake up the paradigms on CO₂ exchanges between the ocean, ice and atmosphere. The picture still lacks details from the winter, when the sea ice is most extensive, he noted.

“This trip is probably one of the first times we’ve actually measured CO₂ fluxes at the same time that you’re measuring meteorological conditions [and] the ice properties, and trying to relate these and look at them in a time series way,” he said.

In an unrelated international study published in the journal Science in May, researchers reported that the Southern Ocean’s ability to absorb carbon dioxide has weakened by about 15 percent per decade since 1981, and will be less efficient in the future. 

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