AEI also reportedly offered additional payments, and to reimburse travel expenses.

The report, due to be released Friday in Paris by the UN's Intergovernmental Panel for Climate Change (IPCC), is likely to give a bleak assessment of the damage to the future of the environment.

It is the culmination of four days of debate between more then 500 scientists at a closed-door meeting in Paris, who have been poring over the first review of the scientific evidence for global warming in six years.

AEI's letters characterise the IPCC report as "resistant to reasonable criticism and dissent and prone to summary conclusions that are poorly supported by the analytical work" and request articles that "thoughtfully explore the limitations of climate model outputs," The Guardian said.

Kenneth Green, the AEI visiting scholar who sent the letters, confirmed to The Guardian that the thinktank had approached scientists and analysts to pen essays that would be compiled into an independent review of the IPCC's report.

"Right now, the whole debate is polarised," Green was quoted as saying by the newspaper.

"One group says that anyone with any doubts whatsoever are deniers and the other group is saying that anyone who wants to take action is alarmist. We don't think that approach has a lot of utility for intelligent policy."

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