19 December 2016
New research finds local temperatures may play an important role in whether people believe in climate change. The study, published in the Proceedings of the National Academy of Sciences (PNAS), found that of the Americans surveyed, their belief that the earth is warming related to the frequency of record-high and record-low temperatures they had experienced themselves. The research carried out by Boston University, George Washington University, Utah State University, and the University of Oxford concludes that many Americans only perceive global warming as a worldwide phenomenon that is happening if they have experienced local warming in their climate and this sets up a challenge for how scientists reduce climate scepticism, particularly if their own weather seems inconsistent with global warming.
‘A belief in global climate change seems to be influenced by whether they have experienced record high temperatures themselves, and recent record low temperatures can counteract this belief,’ says Dr Felix Pretis, co-author on the study and fellow at the Programme for Economic Modelling at the Oxford Martin School at the University of Oxford. ‘This evidence shows us there is a problem in communicating climate change which happens over many years. On the basis of this research, we suggest that in addition to monthly temperature anomalies, agencies could report the number of new record high and low temperatures in that month as well.’
The study finds that local variations in US climate lead some people to experience a locally cooling climate even though global warming is occurring. Researchers found people who experienced this local cooling are less likely to believe in global warming. This result is based on a measure for local climate change that compares the number of days in the year for which the record high temperature is more recent than the record low temperature. This measure indicates that climate has warmed along the US east and west coasts and there, large fractions of county populations believe that the Earth is warming based on survey data (published in 2015 from the Yale Project on Climate Change Communication and George Mason Center for Climate Change Communication, conducted between 2008 and 2013). Along the southern portions of the Ohio and Mississippi Rivers where record low temperatures are more recent, a smaller percentage believes that the Earth is warming even after taking other factors like social background and age into account. Moreover, recent experiences of record low temperatures over the last five years were found to offset the effect of a long period of warming on people’s beliefs.
The study notes that part of this dichotomy may be because of the early terminology used to describe climate change that suggested the earth was simply warming – not changing in other innumerable but measurable ways as well. This might have led residents living in areas that experienced an unusually cold winter to doubt that climate change is occurring.
‘Who do Americans trust on the issue of climate change; scientists or themselves?,’ asks Robert Kaufmann, professor in the Department of Geography and the Center for Energy & Environmental Studies at Boston University and lead author of the paper. ‘For many Americans, the answer seems to be themselves.’
The results highlight the difficulties in communicating climate changes to the public and the paper suggests possible ways of improving this communication, according to the authors. It notes the importance of differentiating between weather, the temperatures of a relatively short period of time such as a season, and climate, which is more long-term: the average temperatures over a period of 25 or 30 years. Emphasising the difference between weather and climate, as well as highlighting local changes may help scientists more effectively communicate about climate change, concludes the study.
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Notes for Editors:
The paper, ‘Spatial heterogeneity of climate change as an experiential basis for scepticism’, is published in the Proceedings of the National Academy of Sciences (PNAS).