Human activities contribute to climate change by causing changes in Earth’s atmosphere in the amounts of greenhouse gases, aerosols (small particles), and cloudiness. The largest known contribution comes from the burning of fossil fuels, which releases carbon dioxide gas to the atmosphere.

Frequently Asked Questions 2.1: How do Human Activities Contribute to Climate Change and How do They Compare with Natural Influences? (pg. 100)

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-faqs.pdf

It’s interesting that not only do you fail to provide a quote supporting your own position – even the article you cited in this post refutes it.

No it’s not. According to the article you cite the EPA recognizes CO2 as the largest source of greenhouse gas emissions:

Advocates of EPA regulation want to target the largest sources of emissions, such as automobiles and coal-fired power plants.

Also, according to the IPCC the global mean concentration of CO2 in 2005 was 379 parts per million (ppm). Global mean concentration of CH4 (methane) in 2005 was 1,777 parts per billion (ppb). Over the past two decades, CH4 growth rates in the atmosphere have generally decreased.

IPCC Fourth Assessment Report Working Group I: The Physical Science Basis, Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing, page 131

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf

Yes methane is 21 more times effective at trapping heat than CO2, but there is far less of it in the atmosphere because less is emitted and methane’s atmospheric lifetime is 12 years versus between 50 and 200 years for carbon dioxide.