It comes as no surprise that Arctic sea ice melt has a range of ecological and economic consequences, from hastening sea level rise to disrupting food chains. Polar bears, for instance, are having to change their diets from seals, their preferred prey source, to other options like snow geese, while ice melt is unlocking trillions of frozen microplastics into the marine environment. Now, new research shows that the consequences of melting sea ice don’t stop there: Sea ice melt may just affect the global carbon budget more than thought.
Scientists have long known that oceans absorb atmospheric carbon dioxide (CO2), but new research on sea ice in Greenland shows that Arctic sea ice also plays a role in harvesting this greenhouse gas. The authors found that vastly retreating sea ice, as what’s been observed in the Arctic during summer months, as well as thinner ice observed in winter months, means Arctic ice is absorbing less CO2 over time.
“We have long known that the Earth’s oceans are able to absorb huge amounts of CO2. But we also thought that this did not apply to ocean areas covered by ice, because the ice was considered impenetrable,” researcher Dorte Haubjerg Søgaard said in a press release. “However, this is not true: New research shows that sea ice in the Arctic draws large amounts of CO2 from the atmosphere into the ocean.”
The researchers also gained insight into the mechanisms behind CO2 absorption in Arctic ice. They found that chemical processes, like calcium carbonate crystals that form in winter months, are more effective at removing CO2 than biological processes. They also found that “frost flowers,” ice formations that form on newly formed sea ice each winter, are also important for removing CO2.
Recent data from the NASA-supported National Snow and Ice Data Center (NSIDC) revealed that 2014 Arctic sea ice coverage was at its sixth-lowest extent since record keeping began in 1979. NSIDC warned that changing winds could even push the ice extent lower this season.
“If our results are representative, then sea ice plays a greater role than expected, and we should take this into account in future global CO2 budgets,” Søgaard said in the press release.