[Arragonis]

The origin of the 97% figure.

This number will prove a new embarrassment to the pundits and press who use it. The number stems from a 2008 master’s thesis by student Maggie Kendall Zimmerman at the University of Illinois, under the guidance of Peter Doran, an associate professor of Earth and environmental sciences. The two researchers obtained their results by conducting a survey of 10,257 Earth scientists. The survey results must have deeply disappointed the researchers — in the end, they chose to highlight the views of a subgroup of just 77 scientists, 75 of whom thought humans contributed to climate change. The ratio 75/77 produces the 97% figure that pundits now tout...

... answered the two key questions on the survey:

1 When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?

2 Do you think human activity is a significant contributing factor in changing mean global temperatures?

The questions posed to the Earth scientists were actually non-questions. From my discussions with literally hundreds of skeptical scientists over the past few years, I know of none who claims the planet hasn’t warmed since the 1700s, and almost none who think humans haven’t contributed in some way to the recent warming — quite apart from carbon dioxide emissions, few would doubt that the creation of cities and the clearing of forests for agricultural lands have affected the climate. When pressed for a figure, global warming skeptics might say humans are responsible for 10% or 15% of the warming; some skeptics place the upper bound of man’s contribution at 35%.