Results of a survey of a scientists on U.S. Republican presidential candidates' statements on climate change. When it comes to climate science, two of the three Democratic presidential candidates are 'A' students, while most of the Republican contenders are flunking. Graphic: Associated Press Survey

By Seth Borenstein
23 November 2015 WASHINGTON (Associated Press) – When it comes to climate science, two of the three Democratic presidential candidates are ‘A’ students, while most of the Republican contenders are flunking, according to a panel of scientists who reviewed candidates’ comments. 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. […] “This individual understands less about science (and climate change) than the average kindergartner,” Michael Mann, a Pennsylvania State University meteorology professor, wrote of Cruz’s statements. “That sort of ignorance would be dangerous in a doorman, let alone a president.” […] For the Republicans, climate change came up more in interviews than in their four debates. But Rubio did confront the issue in the 16 September 2015 debate in a way that earned him bad grades from some scientists. “We are not going to make America a harder place to create jobs in order to pursue policies that will do absolutely nothing, nothing, to change our climate, to change our weather, because America is a lot of things, the greatest country in the world, absolutely,” Rubio said. “But America is not a planet. And we are not even the largest carbon producer anymore. China is. And they’re drilling a hole and digging anywhere in the world that they can get ahold of.” Scientists dispute Rubio’s argument that because China is now the top emitter, the U.S. can do little to change the future climate. The U.S. spews about 17 percent of the world’s carbon dioxide emissions, “so big cuts here would still make a big difference globally,” said geochemist Louisa Bradtmiller at Macalester College in St. Paul, Minnesota. Rubio’s inference that China is not doing much about global warming “is out of date. The Chinese are implementing a cap-and-trade system in their country to reduce emissions,” said Andrew Dessler, a climate scientist at Texas A&M University. At an August event In California’s Orange County, Cruz told an interviewer, “If you look at satellite data for the last 18 years, there’s been zero warming. … The satellite says it ain’t happening.” Florida State University’s James Elsner said ground data show every decade has been warmer than the last since the middle of the 20th century and satellite data-based observations “show continued warming over the past several decades.” […]

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“What We Know” on climate science by the American Association for the Advancement of Science on climate science: http://bit.ly/ZxACVI “Climate Change: Evidence and Causes” by the U.S. National Academy of Sciences and Royal Society of United Kingdom: http://bit.ly/1pufueQ [more]

AP FACT CHECK: On climate science, most GOP candidates fail