In his commencement speech last week to graduating students at Boston College, John Kerry warned of the “crippling consequences” of climate change. The figure he used to back up his dire predictions was “97% of the world scientists.” In the WSJ, Joseph Bast, president of the Heartland Institute, and Roy Spencer, principal research scientist for the University of Alabama, ask, where did Mr. Kerry get the 97% figure? Perhaps, Mr. Bast and Dr. Spencer suggest, from Kerry’s boss, Barack Obama, who tweeted on May 16 that “Ninety-seven percent of scientists agree: #climate change is real, man-made and dangerous.”
But as Mr. Bast and Dr. Spencer point out here, rigorous international surveys conclude that there is no basis for the claim that 97% of scientists believe that man-made climate change is a dangerous problem. Most climate scientists disagree with the consensus on key issues as to the reliability of climate data and computer modes.
Last week Secretary of State John Kerry warned graduating students at Boston College of the “crippling consequences” of climate change. “Ninety-seven percent of the world’s scientists,” he added, “tell us this is urgent.”
Where did Mr. Kerry get the 97% figure? Perhaps from his boss, President Obama, who tweeted on May 16 that “Ninety-seven percent of scientists agree: #climate change is real, man-made and dangerous.” Or maybe from NASA, which posted (in more measured language) on its website, “Ninety-seven percent of climate scientists agree that climate-warming trends over the past century are very likely due to human activities.”
Yet the assertion that 97% of scientists believe that climate change is a man-made, urgent problem is a fiction. The so-called consensus comes from a handful of surveys and abstract-counting exercises that have been contradicted by more reliable research.
One frequently cited source for the consensus is a 2004 opinion essay published in Science magazine by Naomi Oreskes, a science historian now at Harvard. She claimed to have examined abstracts of 928 articles published in scientific journals between 1993 and 2003, and found that 75% supported the view that human activities are responsible for most of the observed warming over the previous 50 years while none directly dissented.
Ms. Oreskes’s definition of consensus covered “man-made” but left out “dangerous”—and scores of articles by prominent scientists such as Richard Lindzen, John Christy, Sherwood Idso and Patrick Michaels, who question the consensus, were excluded. The methodology is also flawed. A study published earlier this year in Nature noted that abstracts of academic papers often contain claims that aren’t substantiated in the papers.