Sunday, 2 September 2012

Another "chimera" to frighten us - Antarctic methane

"Antarctic researchers found as much as 400 billion metric tons of carbon hidden under the ice sheets, with the potential to seep out as methane and accelerate global warming." wails Bloomberg reporter Alex Morales. How did they "find" all that methane? Drilling through the ice? Well no, the "Antarctic researchers" haven't actually found anything under the ice, least of all methane. That sentence is straight out of Morales fertile imagination. The "Antarctic researchers" have deduced that "The Antarctic Ice Sheet could be an overlooked but important source of methane". according to the press release on the University of Bristol website.
The new study demonstrates that old organic matter in sedimentary basins located beneath the Antarctic Ice Sheet may have been converted to methane by micro-organisms living under oxygen-deprived conditions. The methane could be released to the atmosphere if the ice sheet shrinks and exposes these old sedimentary basins.
"May have been converted", "could be released", "if the ice sheet shrinks" - doesn't sound like the certainty or near-certainty expressed in the Bloomberg and other press and blog reports. Surprisingly, HuffPo has a balanced and surprisingly accurate (I'm a biased naysayer  of course, but credit where credit's due) report "Antarctic Methane: A New Factor in the Climate Equation" by Climate Central writer Michael D. Lemonick.
Wadham and her colleagues didn’t actually detect the Antarctic methane directly. What they did do was to prove that the frozen continent has all the right conditions in place to make methane deposits a very likely bet.
Thank you Michael, for that antidote to the exaggerated and factually inaccurate (is a factual inaccuracy a lie?) of the mainstream media doomsayers. he continues
The first link in their chain of reasoning is the fact that Antarctica was largely ice-free millions of years ago, sporting lush forests that eventually decomposed to form soil rich in organic matter. Parts of West Antarctica were open water, where marine life created similarly rich sediments at the bottom of the sea — sediments that are up to eight miles thick in some places, with thousands of feet of ice on top of them.
In principle, bacteria should have decomposed some of these vast storehouses of organic matter into methane. The methane should bubble up to the undersides of the ice sheets. Once there, the freezing cold and high pressure of the overlying ice should have transformed them into deposits known as methane hydrates, the same formations scientists know are trapped on the continental shelves of the Arctic Ocean.
Morales waffles on in his total misunderstanding of both the research and what the researchers actually said.
The carbon stored under Antarctic ice is on par with the amount held in the northern hemisphere’s frozen permafrost soils and the lower end of estimates for methane trapped under the Arctic Ocean, according to Jemma Wadham, professor of Glaciology at the U.K.’s University of Bristol and lead author of a study in the journal Nature yesterday.
"Is on par"? The Bristol Uni press release says
They also calculated that the potential amount of methane hydrate and free methane gas beneath the Antarctic Ice Sheet could be up to 400 billion tonnes (that is, 400 Pg of carbon), a similar order of magnitude to some estimates made for Arctic permafrost.
"Could be......a similar order of magnitude to some estimates made for Arctic permafrost" - Morales should stick to his reports on wind and solar power, wherein he swallows figures for installed capacity and equates them with delivered energy.

The final word from the Nature abstract "Potential methane reservoirs beneath Antarctica"
We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage.
Fair enough.

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