Carbon time bomb ticking away, beneath the ocean

May 22nd, 2008 - 3:33 pm ICT by admin  

Washington, May 22 (IANS) Scientists have sounded a grim warning over how global warming could destabilise vast carbon reserves beneath the ocean floor and unleash a catastrophic threat. These carbon reserves exist as clathrates, ice lattices and continental permafrost and are found even under freshwater lakes like Lake Baikal in Siberia. These ice structures may hold trillions of tonnes of methane.

“We are extremely concerned that clathrates are the largest single source of greenhouse gases that could be added to the atmosphere. If you raise temperatures even slightly, they could be released,” said Robert Hazen of Carnegie Institution.

Ronald Cohen of Carnegie Institution also warned that natural warming caused large releases of methane around 55 million years ago.

Carbon is also locked away down in the earth’s crust: in magma and old carbonate rocks buried by plate tectonics, in fossil fuels like coal and oil.

This realisation could have profound implications for our climate, argued Hazen, who organised the meeting at the institution’s Geophysical Laboratory in Washington, DC.

“We may be on the verge of a transformational moment… a glimpse of new, unexplored scientific territory,” he said.

Though the deep carbon cycle could theoretically absorb human-made emissions, Hazen points out that this would take millions of years. Catastrophic methane emissions could happen over just a few decades.

Natural processes such as volcanism are also known to bring carbon to the surface, but there may be other mechanisms to release buried carbon that have not been considered by mainstream climate science.

For example, there is growing evidence that microbes living deep in the crust may be converting carbon into forms that can migrate to the surface - notably methane.

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