Your contention is that the overwhelming consensus in the scientific community is that warming is anthropogenic. That is not borne out by the study:

"We emailed 8547 authors an invitation to rate their own papers and received 1200 responses (a 14% response rate). After excluding papers that were not peer-reviewed, not climate-related or had no abstract, 2142 papers received self-ratings from 1189 authors. The self-rated levels of endorsement are shown in table 4. Among self-rated papers that stated a position on AGW, 97.2% endorsed the consensus. Among self-rated papers not expressing a position on AGW in the abstract, 53.8% were self-rated as endorsing the consensus. Among respondents who authored a paper expressing a view on AGW, 96.4% endorsed the consensus."

Assuming that all scientists agree with AGW based on this study would be fallacious. The only claim you can make is that those who write about AGW overwhelmingly agree with the AGW consensus. Approximately half of the papers that took no position on AGW agree that warming is anthropogenic. If the email survey is reliable, we can extrapolate that 70% of published paper authors agree with the consensus on AGW while 29% do not. But study never makes that claim. The only result the study endorses is that nearly all of papers about AGW agree that warming is anthropogenic. It never makes the claim that scientists who took no position in AGW agree with the consensus on AGW.