When it comes to cows, a key point missed in many of these superficial debates is that the US population of cattle is around 100 million – one cow per every three Americans – and we fatten them on subsidized ADM corn in CAFOs (Confined Animal Feeding Operations), not on grass. This is entirely unnatural for cattle; corn is much harder for cattle to digest than the grasses on which they are naturally adapted to ruminate. This causes them to “eructate” a lot more methane than cows grazed on grass. Here’s a recent article on cows and GHGs:
http://www.sciam.com/article.cfm?id=the-greenhouse-hamburger
Fattening cattle on corn instead of grass also gives them acid indigestion, promoting growth of dangerous e-coli, requiring lots of antibiotics not needed for grass-fed cows, greatly increasing the risk of antibiotic resistant strains. Some of these really nasty e-coli find their way into our food supply, leading to food poisonings and mass recalls. This is documented in detail in the compelling bestseller _The Omnivore’s Dilemma_ by Michael Pollan – highly recommended reading!
But getting back to climate change, methane is indeed the #2 greenhouse gas (pardon the expression) after CO2. Concentrated feedlots can’t recycle the volumes of manure they yield, so it stews in manure “ponds” (devastating if they spill into waterways, as seen recently) where it ferments into yet more methane.
Rice farming, landfill garbage, and leaks from natural gas pipelines are other significant human sources of excess methane; wetlands and peat bogs are natural sources. Thawing of permafrost in the tundra is expected to add lots more methane as the climate warms (a big temperature-to-greenhouse-effect positive feedback.)
One methane molecule has some 21 times the greenhouse warming effect of one CO2 molecule; it takes around eight to ten years for methane in the atmosphere to oxidize into CO2 (adding yet one more CO2 molecule that will persist for on average 100 years).
Methane concentrations today are almost triple their pre-industrial levels. While those in denial about climate used to crow about a recent “plateau” in this very elevated level, there is recent evidence of levels starting to rise again, such as here:
http://earthobservatory.nasa.gov/Newsroom/view.php?id=35856

Anyway, it’s clear that Boehner did not want to answer George’s persistent questions (props to George for focusing on the real issue). Boehner kept jumping ahead to “we shouldn’t act if China won’t” – which completely fails to answer the question about CO2!
I believe this illustrates the problem we are up against: many conservatives have already decided that capping CO2 will be too costly, will push jobs overseas, etc. From that point, they work backwards to choose talking points that cast doubt on the science.

Carbon Credit indulgences buy a stairway to heaven, guarded by arbitrageur-priests like Al Gore. Can God make a collection plate so vast that even He cannot fill it? Sure! ALL OF THEM.