A well-known Canadian climate-denialist, Tim Ball (above), appears on a list of about 24 people asked to block the release of a new documentary film. The award-winning website, Inside Climate News, has exposed secret e-mails from another denialist, Fred Singer, an American. In them, Singer seeks advice from a group of pundits and scientists, including Ball, on how to keep the film “Merchants of Doubt,” from being shown to the public. The film shows how these individuals go about trying to convince government and the public that climate science is not real and that human activity is not the driving force behind climate change. Ball argues on his blog, for example, that water vapour, not carbon dioxide, is the most important greenhouse gas. It is not known whether Ball supplied the kind of advice to Singer that he asked for. Singer has ties to both the fossil fuel and tobacco industries.