8 February 2010

An inconvenient truth about the IPCC

It is one of the most critical and frequently cited findings of the IPCC and has been used to justify action to reduce greenhouse gas emissions by governments around the world:

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.

In the IPCC Fourth Assessment Report, the words very likely specifically mean a probability greater than 90%.

While this figure has been treated as definitive in our understanding and response to global warming, it is not based on science as most people would believe. The figure was determined via a show of hands from representatives from each country. It was the result of a political process that did not involve climate scientists.

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