Deep-sea volcanoes play key climate role
A vast network of under-sea volcanoes pumping out nutrient-rich water in the Southern Ocean plays a key role in soaking up large amounts of carbon dioxide, acting as a brake on climate change, scientists say.
A group of Australian and French scientists have shown for the first time that the volcanoes are a major source of iron that single-celled plants called phytoplankton need to bloom and in the process soak up CO2, the main greenhouse gas.
Oceans absorb about a quarter of mankind's CO2 from burning fossil fuels and deforestation, with the Southern Ocean between Australia and Antarctica among the largest ocean "carbon sinks."
Phytoplankton underpin the ocean's food chain. When they die or are eaten, they carry large amounts of carbon that they absorb to the bottom of the ocean, locking up the carbon for centuries.
There have been a number of studies showing iron is released from deep-sea volcanoes, said Andrew Bowie, a senior research scientist with the Antarctic Climate & Ecosystems Cooperative Research Center in Hobart, Tasmania.
"But no study has considered that on a global level and considered its importance on Southern Ocean carbon storage," Bowie, one of the authors, told Reuters.
The volcanoes are dotted along deep ocean ridges that mark major plate boundaries of the earth's crust and the study is based in part on measurements of how much iron there is in the Southern Ocean at depths of up to four kilometres (nearly three miles).
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