The US Senate is considering an act to repeal with prejudice an Obama anti-methane regulation. The story from activist source Climate Central is
Senate Mulls ‘Kill Switch’ for Obama Methane Rule
The U.S. Senate is expected to vote soon on whether to use the Congressional Review Act to kill an Obama administration climate regulation that cuts methane emissions from oil and gas wells on federal land. The rule was designed to reduce oil and gas wells’ contribution to climate change and to stop energy companies from wasting natural gas.
The Congressional Review Act is rarely invoked. It was used this month to reverse a regulation for the first time in 16 years and it’s a particularly lethal way to kill a regulation as it would take an act of Congress to approve a similar regulation. Federal agencies cannot propose similar regulations on their own.
The Claim Against Methane
Now some Republican senators are hesitant to take this step because of claims like this one in the article:
Methane is 86 times more potent as a greenhouse gas than carbon dioxide over a period of 20 years and is a significant contributor to climate change. It warms the climate much more than other greenhouse gases over a period of decades before eventually losing its potency. Atmospheric carbon dioxide remains a potent greenhouse gas for thousands of years.
Essentially the journalist is saying: As afraid as you are about CO2, you should be 86 times more afraid of methane. Which also means, if CO2 is not a warming problem, your fear of methane is 86 times zero. The thousands of years claim is also bogus, but that is beside the point of this post, which is Methane.
IPCC Methane Scare
The article helpfully provides a link referring to Chapter 8 of IPCC AR5 report by Working Group 1 Anthropogenic and Natural Radiative Forcing.
The document is full of sophistry and creative accounting in order to produce as scary a number as possible. Table 8.7 provides the number for CH4 potency of 86 times that of CO2. They note they were able to increase the Global Warming Potential (GWP) of CH4 by 20% over the estimate in AR4. The increase comes from adding in more indirect effects and feedbacks, as well as from increased concentration in the atmosphere.
In the details are some qualifying notes like these:
Uncertainties related to the climate–carbon feedback are large, comparable in magnitude to the strength of the feedback for a single gas.
For CH4 GWP we estimate an uncertainty of ±30% and ±40% for 20- and 100-year time horizons, respectively (for 5 to 95% uncertainty range).
Methane Facts from the Real World
From Sea Friends (here):
Methane is natural gas CH4 which burns cleanly to carbon dioxide and water. Methane is eagerly sought after as fuel for electric power plants because of its ease of transport and because it produces the least carbon dioxide for the most power. Also cars can be powered with compressed natural gas (CNG) for short distances.
In many countries CNG has been widely distributed as the main home heating fuel. As a consequence, methane has leaked to the atmosphere in large quantities, now firmly controlled. Grazing animals also produce methane in their complicated stomachs and methane escapes from rice paddies and peat bogs like the Siberian permafrost.
It is thought that methane is a very potent greenhouse gas because it absorbs some infrared wavelengths 7 times more effectively than CO2, molecule for molecule, and by weight even 20 times. As we have seen previously, this also means that within a distance of metres, its effect has saturated, and further transmission of heat occurs by convection and conduction rather than by radiation.
Note that when H20 is present in the lower troposphere, there are few photons left for CH4 to absorb:
Even if the IPCC radiative greenhouse theory were true, methane occurs only in minute quantities in air, 1.8ppm versus CO2 of 390ppm. By weight, CH4 is only 5.24Gt versus CO2 3140Gt (on this assumption). If it truly were twenty times more potent, it would amount to an equivalent of 105Gt CO2 or one thirtieth that of CO2. A doubling in methane would thus have no noticeable effect on world temperature.
However, the factor of 20 is entirely misleading because absorption is proportional to the number of molecules (=volume), so the factor of 7 (7.3) is correct and 20 is wrong. With this in mind, the perceived threat from methane becomes even less.
Further still, methane has been rising from 1.6ppm to 1.8ppm in 30 years (1980-2010), assuming that it has not stopped rising, this amounts to a doubling in 2-3 centuries. In other words, methane can never have any measurable effect on temperature, even if the IPCC radiative cooling theory were right.
Because only a small fraction in the rise of methane in air can be attributed to farm animals, it is ludicrous to worry about this aspect or to try to farm with smaller emissions of methane, or to tax it or to trade credits.
The fact that methane in air has been leveling off in the past two decades, even though we do not know why, implies that it plays absolutely no role as a greenhouse gas.
More information at THE METHANE MISCONCEPTIONS by Dr Wilson Flood (UK) here
Natural Gas (75% methane) burns the cleanest with the least CO2 for the energy produced.
Leakage of methane is already addressed by efficiency improvements for its economic recovery, and will apparently be subject to even more regulations.
The atmosphere is a methane sink where the compound is oxidized through a series of reactions producing 1 CO2 and 2H20 after a few years.
GWP (Global Warming Potential) is CO2 equivalent heat trapping based on laboratory, not real world effects.
Any IR absorption by methane is limited by H2O absorbing in the same low energy LW bands.
There is no danger this century from natural or man-made methane emissions.
Senators and the public are being bamboozled by opaque scientific bafflegab. The plain truth is much different. The atmosphere is a methane sink in which CH4 is oxidized in the first few meters. The amount of CH4 available in the air is miniscule, even compared to the trace gas CO2, and it is not accelerating. Methane is the obvious choice to signal virtue on the climate issue since governmental actions will not make a bit of difference anyway, except perhaps to do some economic harm.
Give a daisy a break (h/t Derek here)
For a more thorough and realistic description of atmospheric warming see: