Additional info from the Union of Concerned Scientists
One critical strategy the IPCC uses to ensure the scientific credibility and political legitimacy of its reports is to represent the range of scientific opinion on climate change fairly. To this end, the IPCC provides several channels for input from experts along the entire spectrum of opinion, even global warming contrarians.
First, accredited NGOs from all sides of the issue are welcome as observers at the opening plenary session and some other sessions over the course of the report production cycle. In addition, well-known contrarians can and do become contributing authors by submitting material to lead authors, and play advisory roles for their governments by working with government representatives to revise and approve the final SPMs.
The presence of climate change experts from industry and environmental organizations in the assessment process also illustrates the IPCC’s desire to seek input from outside traditional research institutions. Industry examples have included representatives from the Electric Power Research Institute and ExxonMobil. Environmental examples have included representatives from Environmental Defense, the Natural Resources Defense Council, and others all over the world.
Given the many stages at which experts from across the political and scientific spectrum are included in the process, it is difficult to accept the contrarian claim that the IPCC produces biased reports (PDF).
Adapted from © Union of Concerned Scientists