MEXICO: Carbon dioxide released from the depths of the ocean helped end the last ice age over 12,000 years ago, according to research from Australian scientists.
Scientists at the Australian National University (ANU), in conjunction with a team of British researchers, concluded that carbon exchange between the ocean and the atmosphere was responsible for ending the ice age, and that carbon levels in the air have more than doubled since the last big freeze.
“Atmospheric carbon dioxide levels fluctuate from around 185 parts per million (ppm) during the most recent ice age, to 280 ppm during warmer periods such as the last millennium. Since 1850 carbon dioxide levels have risen to nearly 400 ppm,” said joint lead researcher, Dr Gianluca Marino, from the ANU’s Research School of Earth Sciences.
The research revealed that carbon dioxide levels present in organisms living close to the surface of the water spiked at the conclusion of the ice age, suggesting that the sudden release into the atmosphere was partly responsible.
“This suggests the ocean was releasing carbon dioxide into the atmosphere that had been stored deep in the ocean for the period of the ice age,” said joint lead author, Dr Miguel Martinez-Boti from the UK’s University of Southampton.
Scientists found the Southern Ocean was primarily responsible for that major re-release of carbon into the atmosphere, but Dr Gavin Foster from the University of Southampton said oceans may also have played a role in warming the planet.
“Our results support a primary role for the Southern Ocean, but we don’t yet know the full story,” he said.
“The new data confirms that natural variations in atmospheric carbon dioxide are linked to carbon stored in the oceans.”
