When the ice covering the Arctic Ocean retreated to a record low in summer 2007, what remained held a revelation for Wei-Jun Cai. Aware that the re-shaped environment could affect levels of greenhouse gas CO2 in the atmosphere as well as be affected by it, the following summer the University of Georgia marine scientist embarked on a mission to study exactly how. Together with his co-workers aboard Chinese research vessel Xue Long – which means “Snow Dragon” – Cai sought to discover just how much CO2 the uncovered water could absorb. “It was widely accepted in the scientific community that once the ice was removed, there would be a huge amount of CO2 going into the basin,” he explained.
Over 90 percent of the world’s CO2 is absorbed by the ocean. The first step in that process is simply dissolving the gas in the water in a similar way to, but in lower amounts than, it would be in a fizzy drink. Algae living in the water can then breathe in the CO2, like any plant does, bringing the amount of the gas in the ocean back down. As the algae grows, feeding on other nutrients as it does so, the carbon stays locked within its cells. “In the Arctic, in the marginal areas, we have nutrients coming in from the Pacific, so that promotes biological fixation into algae,” Cai explained. “Previously, people only measured the ocean margin areas, and the Arctic basin when it was completely covered by ice. In those cases, you see very low CO2 levels in the ocean margins, and that’s still the same, we measured very low CO2 levels in the margins.” Scientists had therefore begun to assume that if more of the Arctic was uncovered this would help balance the CO2 emitted into the atmosphere by burning fossil fuels. Read the rest of this entry »