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Global Warming?Common or Rare?

Scientists now know that past global warming events were triggered by a gigantic release of methane from the oceans. They want to know where exactly this methane is stored and what causes its release?in case it could happen again.

Julianna Kettlewell writes in bbcnews.com that researchers have found a series of vents in the Nordic Seas that may have released enough methane 55 million years ago to have caused massive global warming. When the methane hit the atmosphere, it was converted into carbon dioxide, triggering a sudden temperature rise of about 40 degrees, in one of the largest global warming events ever discovered.

But before it was released, where was all this methane stored? Norwegian scientists think it came from trapped organic matter in the ocean floor that was heated so intensely by lava from underwater volcanoes that it broke down into methane and forced its way to the surface through these vents. Bjorn Jamtveit says, "We believe these hydrothermal vents are a likely explanation for the gases that caused the climatic change."

There's only one problem: the carbon dioxide released at that time contained a lot of the isotope carbon-12, but the carbon produced when organic matter is heated intensely by lava contains a greater proportion of carbon-13. Mark Maslin says, "The problem is that the carbon released is the wrong sort of carbon."

This could have happened if such enormous amounts of gas were produced that the small proportion of carbon-12 was enough to leave a mark in the fossil record. "It is a bit like having a swimming pool filled with white paint," says Gerald Dickens. "If you want to turn that swimming pool pink, you can either add a little red paint or a lot of pink paint."

And there was enough CO2 for that to happen. Jamtveit says, "When we calculate the amount of gas that can be released by this process it is enormous. It corresponds to the amount of gas in the petroleum resources in the whole Earth today."

We have to hope the Nordic vents theory is accurate, because lava events like the one that occurred over 50 million years ago are rare. The other theory about the methane release says that hydrates, a frozen mixture of water and methane produced by microbes, are locked inside sediments on the ocean floor. If the sea warms up enough, these hydrates could melt, releasing large amounts of methane, and this could happen any time. Maslin says, "We've got global warming occurring?and if we keep it up will all the gas hydrate be released to cause super global warming? Unfortunately I think the answer to that is 'yes.'"

Want to see global warming in action? Don't miss The Day After Tomorrow, and read the book too! What was it like to attend the premiere??ask Anne Strieber.

Photo credit: http://www.freeimages.co.uk/

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