"Contaminated data"

See the piece by Ross McKitrick here.

Excerpt:

...we have confirmed, on new and stronger grounds, that the IPCC's global surface-temperature data is exaggerated, with a large warming bias. Claims about the amount of surface warming since 1980, and its attribution to anthropogenic greenhouse-gas emissions, should be reassessed using uncontaminated data. And governments that rely on the IPCC for advice should begin asking why it was allowed to suppress earlier evidence of this problem.