Activity summary sheet the anthropocene human impact on environments

Oreskes, Naomi, 2007, “The scientific consensus on climate change: How do we know we’re not wrong?” Climate Change: What It Means for Us, Our Children, and Our Grandchildren, edited by Joseph F. C. DiMento and Pamela Doughman, MIT Press, pp. 65-99. 4 The Scientific Consensus on Climate Change: How Do We Know We’re Not Wrong? Naomi Oreskes In December 2004, Discover magazine ran an article on the top science stories of the year. One of these was climate change, and the story was the emergence of a scientific consensus over the reality of global warming. National Geographic similarly declared 2004 the year that global warming ‘‘got respect’’ (Roach 2004). Many scientists felt that respect was overdue: as early as 1995, the Intergovernmental Panel on Climate Change (IPCC) had concluded that there was strong scientific evidence that human activities were affecting global climate. By 2001, the IPCC’s Third Assessment Report stated unequivocally that human activities are having detectable effects on the earth’s atmosphere and bodies of water (Houghton et al. 2001). Prominent scientists and major scientific organizations have all ratified the IPCC conclusion. Today, all but a tiny handful of climate scientists are convinced that earth’s climate is heating up and that human activities are a significant cause. Yet many Americans continue to wonder. A recent poll report in Time magazine (Americans see a climate problem 2006) found that only just over half (56 percent) of Americans think that average global temperatures have risen despite the fact that virtually all climate scientists think that they have.1 Oreskes, Naomi, 2007, “The scientific consensus on climate change: How do we know we’re not wrong?” Climate Change: What It Means for Us, Our Children, and Our Grandchildren, edited by Joseph F. C. DiMento and Pamela Doughman, MIT Press, pp. 65-99. 66 Naomi Oreskes More startlingly, a majority of Americans believe that scientists are still divided about the issue. In some quarters, these doubts have been invoked to justify the American refusal to join the rest of the world in addressing the problem. This book deals with the question of climate change and its future impacts, and by definition predictions are uncertain. People may wonder why we should spend time, effort, and money addressing a problem that may not affect us for years or decades to come. Several chapters in this book address that question—explaining how some harmful affects are already occurring, how we can assess the likely extent of future harms, and why it is reasonable to act now to prevent a worst-case scenario from coming true. This chapter addresses a different question: might the scientific consensus be wrong? If the history of science teaches anything, it’s humility. There are numerous historical examples where expert opinion turned out to be wrong. At the start of the twentieth century, Max Planck was advised not to go into physics because all the important questions had been answered, medical doctors prescribed arsenic for stomach ailments, and geophysicists were confident that continents could not drift. Moreover, in any scientific community there are always some individuals who depart from generally accepted views, and occasionally they turn out to be right. At present, there is a scientific consensus on global warming, but how do we know it’s not wrong? The Scientific Consensus on Climate Change Let’s start with a simple question: What is the scientific consensus on climate change, and how do we know it exists? Scientists do not vote on contested issues, and most scientific Oreskes, Naomi, 2007, “The scientific consensus on climate change: How do we know we’re not wrong?” Climate Change: What It Means for Us, Our Children, and Our Grandchildren, edited by Joseph F. C. DiMento and Pamela Doughman, MIT Press, pp. 65-99. The Scientific Consensus on Climate Change 67 questions are far too complex to be answered by a simple yes or no, so how does anyone know what scientists think about global warming? Scientists glean their colleagues’ conclusions by reading their results in published scientific literature, listening to presentations at scientific conferences, and discussing data and ideas in the hallways of conference centers, university departments, research institutes, and government agencies. For outsiders, this information is difficult to access: scientific papers and conferences are by experts for experts and are difficult for outsiders to understand.