Yes he is. But seems nowadays if you get some fancy title that confers you know something it makes your opinion worth more than other scientists with credentials equal to or exceeding them mute. The IPCC is a UN funded organization with a vested interest in controlling world affairs. Also funny this is same guy who told skeptics to "rub their faces with asbestos", what a great scientist and human being. Most of the members of the touted mainstay for human caused climate change (ie IPCC) have less credentials than those that signed posted petition.