The author of that article is a bonehead. The 97 % figure comes from multiple studies, surveys, polls and examination of the literature. Not from some "amalgamation" of the two things mentioned. Honestly toe, if you can't see the bias in this article right from the first paragraph, I can see how you are so confused. Pure propaganda.
A survey of 3146 earth scientists asked the question "Do you think human activity is a significant contributing factor in changing mean global temperatures?" (Doran 2009
97.5% of climatologists who actively publish research on climate change responded yes.
This overwhelming consensus among climate experts is confirmed by an independent study that surveys all climate scientists who have publicly signed declarations supporting or rejecting the consensus. They find between 97% to 98% of climate experts support the consensus (Anderegg 2010).
Powell examined nearly 14,000 abstracts, searching for explicit rejections of human-caused global warming, finding only 24
we found that just over 4,000 papers expressed a position on the cause of global warming, 97.1% of which endorsed human-caused global warming. In the self-ratings, nearly 1,400 papers were rated as taking a position, 97.2% of which endorsed human-caused global warming.
We found that about two-thirds of papers didn't express a position on the subject in the abstract, which confirms that we were conservative in our initial abstract ratings. This result isn't surprising for two reasons: 1) most journals have strict word limits for their abstracts, and 2) frankly, every scientist doing climate research knows humans are causing global warming. There's no longer a need to state something so obvious. For example, would you expect every geological paper to note in its abstract that the Earth is a spherical body that orbits the sun?
This result was also predicted by Oreskes (2007), which noted that scientists
"...generally focus their discussions on questions that are still disputed or unanswered rather than on matters about which everyone agrees"
However, according to the author self-ratings, nearly two-thirds of the papers in our survey do express a position on the subject somewhere in the paper.
We also found that the consensus has strengthened gradually over time. The slow rate reflects that there has been little room to grow, because the consensus on human-caused global warming has generally always been over 90% since 1991. Nevertheless, in both the abstract ratings and self-ratings, we found that the consensus has grown to about 98% as of 2011.
http://www.skepticalscience.com/global-warming-scientific-consensus-advanced.htm