Earlier today, while at brunch, I got to visiting about the remarkably warm winter and now spring that is upon us. I recounted to my bruncheoneers the story of how the Siberian tundra was beginning to thaw and that this so called positive feedback loop might really have serious effects on the acceleration rate of the change in our climate.
My friends pretty much rejected the use of positive feedback for a such a dire mechanism.
I guess they do have a point.
So, Here is a another negative positive feedback story from Planet Save.
New scientific theory, hydrate hypothesis,
suggests global warming catastrophe
by Brad Arnold
Friday, 24 February 2006
A recent scientific theory called the "hydrate hypothesis" says that historical global warming cycles have been caused by a feedback loop, where melting permafrost methane clathrates (also known as "hydrates") spur local global warming, leading to further melting of clathrates and bacterial growth.
Now that most scientists agree human activity is causing the Earth to warm, the central debate has shifted to when we will pass the tipping point and be helpless to stop the runaway global warming.
There are enormous quantities of methane trapped in permafrost and under the oceans in ice-like structures called clathrates. The methane in Arctic permafrost clathrates is estimated at 400 billion tons.
Methane is more than 20 times as strong a greenhouse gas as CO2, and the atmosphere currently contains about 3.5 billion tons of the gas.
The highest temperature increase from global warming is occurring in the arctic regions-an area rich in these unstable clathrates. Simulations from the National Center for Atmospheric Research (NCAR) show that over half the permafrost will thaw by 2050, and as much as 90 percent by 2100.
Peat deposits may be a comparable methane source to melting permafrost. When peat that has been frozen for thousands of years thaws, it still contains viable populations of bacteria that begin to convert the peat into methane and CO2.
Western Siberia is heating up faster than anywhere else in the world, having experienced a rise of some 3C in the past 40 years. The west Siberian peat bog could hold some 70 billion tonnes of methane. Local atmospheric levels of methane on the Siberian shelf are now 25 times higher than global concentrations.
By the way, warmer temperatures and longer growing seasons have caused microbial activity to increase dramatically in the soil around the world. This, in turn, means that much of the carbon long stored in the soil is now being released into the atmosphere.
Releases of methane from melting oceanic clathrates have caused severe environmental impacts in the past. The methane in oceanic clathrates has been estimated at 10,000 billion tons.
55 million years ago a global warming chain reaction (probably started by volcanic activity) melted oceanic clathrates. It was one of the most rapid and extreme global warming events in geologic history.
Humans appear to be capable of emitting CO2 in quantities comparable to the volcanic activity that started these chain reactions. According to the U.S. Geological Survey, burning fossil fuels releases more than 150 times the amount of CO2 emitted by volcanoes.
Methane in the atmosphere does not remain long, persisting for about 10 years before being oxidized to CO2 (a greenhouse gas that lasts for hundreds of thousands of years). Chronic methane releases oxidizing into CO2 contribute as much to warming as does the transient methane concentrations.
To summarize, human activity is causing the Earth to warm. Bacteria converts carbon in the soil into greenhouse gasses, and enormous quantities are trapped in unstable clathrates. As the earth continues to warm, permafrost clathrates will thaw; peat and soil microbial activity will dramatically increase; and, finally, vast oceanic clathrates will melt. "
At lunch last week, I shared with one of my environmentalist friends that the IPCC's new report has a new high on its estimates of the top range of the temperature change that they can reasonably predict.
Some computer models predict that it is 11 degrees C.
To survive that, we will need to
live in the oceans,
or in great caverns under the earth,
or under great domes,
or under energy shields,
or in the atmosphere,
or on the poles.
Or maybe we could go screw some other planet up.
This is rapidly becoming one of those B movies,
where the good guys keep trying to do the right thing,
and the bad guys keep doing the wrong thing.
At the end, the bad guys melt.
Hopefully before the rest of us.
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art courtesy of Christopher Bailey