How do you arrive at the 97% figure?
Unless Betsy has a new source, she is probably referring to the 2009 Doron/Zimmerman survey that came up with the 97% figure. The details of how that survey was conducted are quite fascinating.
According to Ambler's [peer] review of the Doron/Zimmerman data, 10,257 scientists were contacted, 3,146 responded. That's less than 31%. Of that group "only 5% described themselves as climate scientists, numbering 157. The authors reduced that by half by only counting those who they classed as "specialists."
Ambler further dissects the consensus: "In our survey, the most specialized and knowledgeable respondents (with regard to climate change) are those who listed climate science as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change (79 individuals in total). Of these specialists, 96.2% (76 of 79) answered "risen" to question 1 and 97.4% (75 of 77) answered yes to question 2."
http://voices.yahoo.com/only-76-scientists-97-agree-cagw-11314412.html?cat=3