New research has implications for global warming mitigation strategies
By Summit Voice
SUMMIT COUNTY — Researchers studying Antarctic sediment cores say a huge carbon dioxide “burp” from the Southern Ocean helped end the last ice age. The research re-affirms earlier findings that oceans are large and dynamic carbon pools and may help determine whether the idea of pumping carbon dioxide into the oceans to mitigate global warming is feasible.
Working with marine sediment core samples, University of Cambridge scientists measured the amount of carbon in the shells of bottom-dwelling marine creatures to establish ocean carbon levels during the ice age. The findings suggest that carbon dioxide was locked away in the ocean during the ice age.
“Our results show that during the last ice age, around 20,000 years ago, carbon dioxide dissolved in the deep water circulating around Antarctica was locked away for much longer than today,” said Dr. Luke Skinner. “If enough of the deep ocean behaved in the same way, this could help to explain how ocean mixing processes lock up more carbon dioxide during glacial periods.”
As background the scientists explained that, while ice age cycles appear to be paced by slight changes in the Earth’s orbit around the sun. internal feedback loops involving carbon turn the solar nudge into a significant global energy imbalance.
With oceans acting as large, dynamic reservoirs of carbon, scientists have speculated that changes in ocean circulation play a large role in spurring changes in atmospheric carbon dioxide. The Southern Ocean around Antarctica may be a key player in this cycle, as deep water is lifted to the surface, where it can exhale carbon dioxide to the atmosphere.
The Cambridge research indicates that more carbon dioxide was locked up in the deep ocean during ice ages, and that, as pulses of the gas were released, it helped trigger global thaws every 100,000 years or so. Each of those pulses was about equivalent to the change in atmospheric carbon dioxide levels since the start of the industrial revolution.
The research also shows how the ocean circulation can change significantly over a relatively short space of time.
“Our findings underline the fact that the ocean is a large and dynamic carbon pool. This has implications for proposals to pump carbon dioxide into the deep sea as a way of tackling climate change, for example,” Dr. Skinner said. Such carbon dioxide would eventually come back up to the surface, and the question of how long it would take would depend on the state of the ocean circulation, as illustrated by the last deglaciation,” says Dr Skinner.
The results of the study were published May 27 in Science.