Claim: In a paper published online this week in the Journal of Geophysical Research-Atmosphere, economics professor Ross McKitrick says the resulting discrepancies may be leading to an overstatement of the role of greenhouse gases in the atmosphere.

Relevance (1 = gold evidence, 0 = mined hard negative): 1
Passage: The 2007 Fourth Assessment Report compiled by the IPCC (AR4) noted that "changes in atmospheric concentrations of greenhouse gases and aerosols, land cover and solar radiation alter the energy balance of the climate system", and concluded that "increases in anthropogenic greenhouse gas concentrations is very likely to have caused most of the increases in global average temperatures since the mid-20th century".

Relevance (1 = gold evidence, 0 = mined hard negative): 1
Passage: The executive summary of the WG I Summary for Policymakers report says they are certain that emissions resulting from human activities are substantially increasing the atmospheric concentrations of the greenhouse gases, resulting on average in an additional warming of the Earth's surface.

Relevance (1 = gold evidence, 0 = mined hard negative): 1
Passage: A retired journalist for The New York Times, William K. Stevens wrote: "The Intergovernmental Panel on Climate Change said the likelihood was 90 percent to 99 percent that emissions of heat-trapping greenhouse gases like carbon dioxide, spewed from tailpipes and smokestacks, were the dominant cause of the observed warming of the last 50 years.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: A 2011 study by noted climate research scientist, Tom Wigley, found that while carbon dioxide () emissions from fossil fuel combustion may be reduced by using natural gas rather than coal to produce energy, it also found that additional methane (CH4) from leakage adds to the radiative forcing of the climate system, offsetting the reduction in forcing that accompanies the transition from coal to gas.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: European Science Foundation in a 2007 position paper states: There is now convincing evidence that since the industrial revolution, human activities, resulting in increasing concentrations of greenhouse gases have become a major agent of climate change ... On-going and increased efforts to mitigate climate change through reduction in greenhouse gases are therefore crucial.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: Greenhouse gases are not the only emissions of energy production and consumption.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: In 2008, Spencer and William Braswell published a paper in the Journal of Climate which suggests that natural variations in how clouds form could actually be causing temperature changes, rather than the other way around, and could also lead to overestimates of how sensitive the Earth's climate is to greenhouse gas emissions.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: US National Academy of Sciences: "In the judgment of most climate scientists, Earth's warming in recent decades has been caused primarily by human activities that have increased the amount of greenhouse gases in the atmosphere.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: Human activities, primarily the burning of fossil fuels (coal, oil, and natural gas), and secondarily the clearing of land, have increased the concentration of carbon dioxide, methane, and other heat-trapping ("greenhouse") gases in the atmosphere...There is international scientific consensus that most of the warming observed over the last 50 years is attributable to human activities.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: There are a number of anthropogenic greenhouse gases.

Relevance (1 = gold evidence, 0 = mined hard negative): 0
Passage: Rennie 2009: "Claim 1: Anthropogenic CO2 can't be changing climate, because CO2 is only a trace gas in the atmosphere and the amount produced by humans is dwarfed by the amount from volcanoes and other natural sources.