At the request of The Associated Press, eight climate and biological scientists graded for scientific accuracy what a dozen top candidates said in debates, interviews and tweets, using a 0 to 100 scale.

To try to eliminate possible bias, the candidates’ comments were stripped of names and given randomly generated numbers, so the professors would not know who made each statement they were grading. Also, the scientists who did the grading were chosen by professional scientific societies.
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Vermont Sen. Bernie Sanders, with an 87, had the lowest score among the Democrats, dinged for an exaggeration when he said global warming could make Earth uninhabitable. Former Florida Gov. Jeb Bush scored the highest among Republicans, 64, but one grader gave him a perfect 100. Bush was the only Republican candidate who got a passing grade on climate in the exercise.

Below Clinton’s 94 were O’Malley with 91; Sanders, 87; Bush, 64; Christie, 54; Ohio Gov. John Kasich, 47; Kentucky Sen. Rand Paul, 38; Fiorina, 28; Florida Sen. Marco Rubio, 21; businessman Donald Trump, 15; retired neurosurgeon Ben Carson, 13; and Cruz with 6.

http://www.pbs.org/newshour/rundown/fact-checking-the-presidential-candidates-on-climate-science/