Table 4. Example quotations (coding units) expressing (left) acknowledgment and (right) doubt that AGW is serious. For each document category, two examples are given: the first typifies a relatively ‘strong’ quotation, the second a relatively ‘mild’ one. Substantiating quotations for all documents are provided in section S7, supplementary information. Doubt AGW is serious (IP3) 1982 ‘ . . . there are some potentially catastrophic events that must be considered. For example, if the Antarctic ice 1981 ‘ . . . it has not yet been proven that the increases in atmospheric CO2 constitute a serious problem that [83] [111] requires immediate action.’ sheet[,] which is anchored on land should melt, then this could cause a rise in sea level on the order of 5 meters. Such a rise would cause flooding on much of the US East Coast, including the State of Florida and Washington, DC.’ 1982 ‘There is unanimous agreement in the scientific community that a temperature increase of this magnitude [(3.0 1989 ‘We also know that the modeled projections are far from certain: potential impacts could be small and [99] ± 1.5) °C] would bring about significant changes in the earth’s climate, including rainfall distribution and [113] manageable or they could be profound and irreversible.’ alterations in the biosphere.’ PEER- 2002 ‘Atmospheric CO2 has increased from ∼275 to ∼370 parts per million (ppm). Unchecked, it will pass 550 ppm 2000 ‘ . . . science cannot yet provide reliable guidance on what, if any, levels of greenhouse gas concentrations might REVIEWED [108] this century. Climate models and paleoclimate data indicate that 550 ppm, if sustained, could eventually [114] be judged “dangerous,” . . . .’ produce global warming comparable in magnitude but opposite in sign to the global cooling of the last Ice Age . . . Atmospheric CO2 stabilization targets as low as 450 ppm could be needed to forestall coral reef bleaching, thermohaline circulation shutdown, and sea level rise from disintegration of the West Antarctic Ice Sheet.’ 1994 ‘The rate of the climate change is thought to exert stress on ecosystems. While changes in, for example, 1995 ‘Among the options that might become necessary to deploy at some time in the future, should climate change [109] precipitation or infrequent events such as droughts or storms may be more directly related to this stress, there [86] 10 remains great uncertainty in estimating these characteristics of climate.’ prove to be serious, are those that involve geoengineering techniques to control greenhouse gas concentrations or to limit potential impacts.’ NON-PEER- 1984 ‘Clearly, there is vast opportunity for [global] conflict. For example, it is more than a little disconcerting the 1996 ‘Is global warming good or bad? Let’s say human activity does contribute to warming the planet . . . warming REVIEWED [115] few maps showing the likely effects of global warming seem to reveal the two superpowers losing much of the [116] that occurs mostly during the winter would reduce extreme cold, increase cloud cover and moderate rainfall, with the rest of the world seemingly benefitting.’ temperature fluctuations. This sort of warming is more likely to raise soil moisture levels than to produce severe droughts . . . [T]he indications are that a warmer world would be far more benign than many imagine . . . [M]oderate warming would reduce mortality rates in the US, so a slightly warmer climate would be more healthful . . . We are faced with more questions than answers on almost every aspect of this issue, including whether possible changes could be both good and bad.’ 1980 ‘Findings. 1. While CO2-induced changes in global climate may have certain beneficial effects, it is believed that 1998 ‘Fortunately, all indications are that climate change is a very long-term phenomenon . . . Do we need an [117] the net consequences of these changes will be adverse to the stability of human and natural communities.’ [118] insurance policy? Some people argue that the world needs to take out an insurance policy against the possibility of global warming just in case . . . Because of the scientific uncertainties, we don’t have a clear understanding of the risks involved. The Kyoto agreement makes the cost of the policy high. No one can tell us with certainty what benefit we will gain. Thus, it doesn’t seem to be a good time to buy the policy.’ ADVERTORIALS 2002 ‘The risk of climate change and its potential impacts on society and the ecosystem are widely recognized. Doing 1995 Title: ‘The sky is not falling.’ By-line: ‘The environment . . . better than you think.’ [119] nothing is neither prudent nor responsible.’ [112] ‘Good news: The end of the Earth as we know it is not imminent . . . [M]ore than 30 years have passed since the environmental movement began. They made their point. There is no longer a need for alarmists . . . [T]o those who think industry and nature cannot coexist, we say show a little respect for Mother Nature. She is one strong lady, resilient and capable of rejuvenation. The environment recovers well from both natural and manmade disasters . . . Does this justify or lessen the impact of industrial pollution? Of course not. Our point is that nature, over the millennia, has learned to cope. Mother Nature is pretty successful in taking on human nature.’ 2004 ‘ . . . research has highlighted the risks to society and ecosystems resulting from the buildup of greenhouse 2000 ‘Just as changeable as your local weather forecast, views on the climate change debate range from seeing the [120] gases.’ [121] issue as serious or trivial, and from seeing the possible future impacts as harmful or beneficial.’ Environ. Res. Lett. 12 (2017) 084019 INTERNAL Acknowledge AGW is serious (IP1)