Committee on the Science of Climate Change, US National Research Council (2001). "Summary". Climate Change Science: An Analysis of Some Key Questions. Washington, D.C., US: National Academies Press. pp. 1–3. doi:10.17226/10139. ISBN0-309-07574-2. Archived from the original on 5 June 2011. Retrieved 20 May 2011. "The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue" (page 3).
Committee on the Science of Climate Change, US National Research Council (2001). "Summary". Climate Change Science: An Analysis of Some Key Questions. Washington, D.C., US: National Academies Press. pp. 1–3. doi:10.17226/10139. ISBN0-309-07574-2. Archived from the original on 5 June 2011. Retrieved 20 May 2011. "The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue" (page 3).
Committee on the Science of Climate Change, US National Research Council (2001). "Summary". Climate Change Science: An Analysis of Some Key Questions. Washington, D.C., US: National Academies Press. pp. 1–3. doi:10.17226/10139. ISBN0-309-07574-2. Archived from the original on 5 June 2011. Retrieved 20 May 2011. "The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue" (page 3).