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Methane is a relatively potent greenhouse gas with a high global warming potential (i.e., warming effect compared to carbon dioxide). When averaged over 100 years each kg of CH4 warms the Earth 25 times as much as the same mass of CO2. The total warming effect of CH4 is smaller than that of CO2, since there is approximately 220 times as much CO2 in the Earth's atmosphere as methane.
On Earth, the major natural greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect (not including clouds); carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone, which causes 3–7%
This sounded strange to me given that attention seems to be focused on CO2.Thank you!
According to:http://www.epa.gov/methane/sources.htmlThe top three producers of methane in the USA are, in order, landfills, natural gas (which is methane, and any leaks are just pushing methane straight into the atmosphere), and livestock farming.
Assuming wikipedia is correct, and going back to part of the original question. Why do we hear so much about C02, and what we should be doing to combat those emissions?One possible answer is that as an individual there is little you can do about the methane emissions, afterall you have no control over landfill, methane leakage and livestock. But, you can control or reduce your own C02 output.
I am still unconvinced about the 4x figure that my orginal calculation produced!
This means that a 1 tonne methane emission will have 25 times the impact on temperature of a 1 tonne carbon dioxide emission during the following 100 years. Methane has a large effect for a brief period (about 10 years), whereas carbon dioxide has a small effect for a long period (over 100 years).
The methane concentration has increased by about 150% since 1750
From 1832 to 2004, the atmospheric CO2 concentration increased from 284 ppmv to 377 ppmv, or about 33%, with most of the change occurring since 1970.
So what's the situation with regard water vapour? Am I right in assuming they are talking about clouds? If so, then surely we're up that proverbial creek without a paddle.
Back to methane. I remember a couple of years back the New Zealand government tried to take measures to reduce CH4 emissions from cows. Did anything ever come of that? And would it really have made a difference? Or, again, was it a purely political move?If cows are anything like my horses with regard potent methane farts then it's a serious issue!
Morning Edition, June 19, 2007 · Most of the industrialized nations of the world have agreed to reduce the amount of greenhouse gases coming from power plants and factories. But in New Zealand, one-third of these warming gases come from animals, in the form of methane. So researchers are trying something unique to lower New Zealand's greenhouse-gas hoofprint: They want to change what goes on inside the stomachs of millions of sheep and cows. Just outside the town of Palmerston North is the Taraua Wind Farm, where hundreds of turbines sit on a ridge overlooking the city. The wind farm is a solution to some of New Zealand's problems with greenhouse gases. But the real problem is right underneath the turbines: the sheep and cows that produce methane. Harry Clark, an animal scientist for AgResearch, is working on a project that tries to reduce methane emissions from ruminant animals. Clark spends much of his time in a shed among a few dozen cows and sheep at Massey University. These animals don't know it, but they have a gas problem.Methane warms the planet 20 times more than carbon dioxide. A ruminant animal creates methane when it digests food in its rumen — a part of its digestive system that works like a fermentation tank. The rumen is overrun with about 400 kinds of microbes, which break down whatever the animal eats. One of these microbes specializes in making methane. "And that methane, then, is either burped out or it gets absorbed into the bloodstream, and then breathed out through the lungs," Clark explains.Ninety-five percent of the methane comes out of the animal's mouth, going up into the atmosphere, and warming the climate. Scientists suggest that putting a stop to the gas problem could be as simple as getting rid of the microbes. Harry Clark's colleague, Ron Reimus, says they can't see any reason to keep those methane microbes. "We feel that because they're not absolutely required for survival, that you could get rid of them," Reimus says. One strategy used is to genetically engineer the microbes so they won't make methane. Another is to give the sheep and cows some type of feed that the bugs won't like. Graeme Maybey runs a 500-acre dairy farm of 350 cows in Woodville, located along the north island of New Zealand. Maybey says farmers in New Zealand are aware that methane can warm the planet, and they're not against altering livestock to do something about that methane. "If we can reduce the release of methane in our cattle, as long as it's not going to affect production of milk and meat, then yeah, we're all for it," Maybey says.Clark's team attempts to achieve this balance between high productivity and low methane emissions. The team measures everything the livestock eat, how much milk they give and how much they weigh. Most importantly, Clark says, they measure how much methane is coming out of them with a special type of halter. The plastic contraption partially covers the animal's nose, and through a pipe, it carries breath exhalations through a tube and then to a collector. Clark and his team measure changes in methane when they alter the microbes in a cow's stomach, or when they give the cow a new kind of feed.Clark hopes that once the methane-making microbes are gone, the energy they consume will stay in the cow or sheep, and help it produce more milk or meat. "New Zealand relies on the agricultural sector for its livelihood, and so we can't do anything to stop methane," says Clark. "It's got to get done without detriment to the productivity of the animal, that's a given."The scientists at Massey University aren't there yet, but if they can figure out how to cut livestock's methane emissions, many countries in the world might be willing to pay New Zealand to
Quote from: DoctorBeaver on 21/07/2007 09:17:17So what's the situation with regard water vapour? Am I right in assuming they are talking about clouds? If so, then surely we're up that proverbial creek without a paddle.I think so, Doc. Again, this is something that i think is not made too much of a fuss of (in the media) because we as individuals can do nothing to combat it. But what can governments do about it either?Again too much information only (no pun intended) clouds the issue.