Research has led to broad agreement among scientists that anthropogenic climate change is happening now and likely to worsen. In contrast to scientific agreement, US public views remain deeply divided, largely along ideological lines. Science communication has been neutralised in some arenas by intense counter-messaging, but as adverse climate impacts become manifest they might intervene more persuasively in local perceptions. We look for evidence of this occurring with regard to realities and perceptions of flooding in the northeastern US state of New Hampshire. Although precipitation and flood damage have increased, with ample news coverage, most residents do not see a trend. Nor do perceptions about past and future local flooding correlate with regional impacts or vulnerability. Instead, such perceptions follow ideological patterns resembling those of global climate change. That information about the physical world can be substantially filtered by ideology is a common finding from sociological environment/society research.

Discussion At global and multi-decade timescales, climate change poses risks so broad, varied and potentially catastrophic that mitigation by reducing greenhouse emissions must be a core point of discussion. At local and shorter time scales, however, mitigation becomes almost symbolic, while adaptation demands immediate attention. But adaptation too requires a sense of how the system is changing, which even at local levels can trigger ideological resistance. Perceptions and realities of New Hampshire flooding are one case in point. Anthropogenic climate change raises the probability of heavy-precipitation events and coastal flooding. Development expanding the area of impervious cover, or building up vulnerable areas, raises the likelihood of flood damage even without climate change, and would exacerbate problems as change occurs. Conversely, a suite of strategies could help to avoid, manage or reduce the consequences, as could projects designed to lessen the magnitude of floods. Adaptation efforts would enhance community resilience to floods and other climate change risks (Lopez-Marrero and Tschakert, 2011; Moser and Boykoff, 2013; Nelson, 2011). Positive actions are not costless, however. They need support based on a realistic assessment of changing risks and vulnerability, which is why public perceptions about future floods matter. Proximity of recent floods should, in principle, raise awareness that floods have been increasing, and that scientists project higher risks in the future. This hypothesis led us to expect certain geographical patterns in flood perceptions, but such patterns are not evident in our data. Instead we find that ideology remains the most consistent predictor of perceptions about local flooding. A post-political, physical framing of New Hampshire flood perceptions succeeds no better than its counterparts for perceptions about global climate change. While physical events undoubtedly can impact perceptions, in this instance such impacts appear mild and contingent compared with those of ideology. More immediate, severe or prolonged physical events might have greater impacts. Learning that worse disasters can change opinions would be un-reassuring, however, from the standpoint of averting crises or irreversible change before it is too late. More research is needed on effective ways that science communication about local impacts can counter media-reinforced biased assimilation even without looming disasters. Understanding relationships between environmental and social change calls for interdisciplinary research, including designs where dependent variables are social, and the independent variables include environmental as well as social factors. Such designs effectively import natural-science data and knowledge into social-science analytical frameworks. They can address different questions, and admit more social complexity, than the complementary efforts to incorporate ‘human dimensions’ within basically natural-science frameworks. One recurring result from social-science based interdisciplinary research, exemplified here, is that among some individuals, information about the physical world is substantially filtered by ideology. Environmentally-driven models, or politics-free data, may overlook this important constraint. Ideology remains the elephant in the room, even when researchers would rather talk about other things.

Acknowledgements The University of New Hampshire Survey Center conducted all telephone interviews for CERA, CAFOR and the Granite State Poll. The Carsey School of Public Policy provided logistical and administrative support.

Funding

Climate questions on the Granite State Poll have been supported by grants from the National Science Foundation (New Hampshire EPSCoR EPS-1101245; The Living Bridge IIP-1230460), and by the Carsey School of Public Policy and Sustainability Institute at the University of New Hampshire. CERA and CAFOR surveys were supported by grants from the US Department of Agriculture National Institute of Food and Agriculture (2010-67023-21705, 2014-68002-21782), Environmental Protection Agency, National Oceanographic and Atmospheric Administration (AB-133F-11-SE-0724), Ford Foundation, Neil and Louise Tillotson Fund, and at the University of New Hampshire the Carsey School of Public Policy, Sustainability Institute and the College of Liberal Arts.