Climate change experts come in all shapes and colors. The Earth system is very complex and the climate on this planet is influences and can be understood from various perspectives. To get the whole picture we have to combine many different Earth science disciplines.
One of the best talks I've heard in a very long time was given by Prof. emeritus Terrence Gerlach from USGS and the Cascades Volcanic Observatory presented his work: Volcanic Versus Anthropogenic CO2: An Example of the Importance of Geoscience Evidence
http://www.agu.org/pubs/pdf/2011EO240001.pdf
And for the record - I decided his talk was excellent long before I learned his mother was Norwegian. Although I'd really like to give credit to his Norwegian genes when it comes to his coolness. I mean, he knew - without ever having been to Norway - that there is no such thing as bad weather, only bad clothing.
