Effective responses to global environmental problems necessitate collective action, significantly influenced by citizen preferences. Public acceptability is crucial for policy implementation in democracies, and policymakers often try to align actions with constituent preferences. However, in the United States, environmental attitudes and policy preferences have become increasingly polarized since the early 1990s. While Republicans are generally less environmentally concerned and supportive of related policies than Democrats, the nature of this polarization—symmetrical (equal movement away from the median) or asymmetrical (unequal movement)—remained unclear. This study aimed to address this gap by analyzing harmonized data from four distinct surveys spanning five decades (1973-2022), focusing on seven dimensions of environmental and climate change attitudes to determine the pattern of polarization (symmetrical or asymmetrical), its temporal changes, and its variation across different attitudinal measures.

Existing research highlights the increasing ideological divergence between the Democratic and Republican parties in the US, evident at both elite and citizen levels. Studies suggest both symmetrical and asymmetrical polarization in public opinion. Some show an equal divergence of both parties from the median, while others point towards the disproportionate shift of Republicans towards more conservative stances across various issues. Regarding environmental attitudes, political polarization is a key driver, with party affiliation strongly predicting environmental attitudes and policy support. The mechanisms driving this polarization include group-level factors (elite cues from party leaders) and individual-level factors (social identity and in-group conformity). Previous research, while noting increasing anti-environmental attitudes among Republicans, lacked a comprehensive analysis across multiple surveys and attitudinal measures to determine whether the process is symmetrical or asymmetrical. This study aims to address this gap by combining data from multiple long-term surveys.

This study utilized pooled cross-sectional data from four sources: the General Social Survey (GSS, 1973-2021), two Pew Research Center surveys on climate change attitudes (2001-2020 and 2009-2019), and the Gallup Poll Social Series (GPSS, 1989-2021). These data encompass nearly five decades of information and cover seven distinct measures of environmental and climate change attitudes: support for environmental spending, confidence in the scientific community, climate change worry, beliefs about when climate change will happen, the seriousness of climate change, whether climate change is a major threat, and whether climate change is a top priority. A total of 110,237 individual respondents are included. Cross-classified random effect models (CCREM) were employed to analyze the data, controlling for age, gender, education, and race. Predicted probabilities were calculated to aid in the interpretation of the results, allowing for the assessment of symmetrical versus asymmetrical polarization.

The analysis revealed that contemporary environmental and climate change attitudes show symmetrical polarization, with Democrats and Republicans exhibiting equally divergent attitudes from the median. However, historical trends reveal asymmetric patterns. For environmental attitudes (support for environmental spending and confidence in scientists), Republicans showed a significant decrease in pro-environmental attitudes starting in the early 1990s, while Democrats displayed a substantial increase from the mid-2010s. For climate change beliefs (worry, beliefs about when climate change will occur, and whether it's exaggerated), symmetrical polarization was observed, with both parties moving away from the median since the mid-1990s. In climate change attitudes (climate change as a top priority and a major threat), the research found evidence of two distinct periods of asymmetric polarization: a decline in Republican support starting in the mid-1990s and an increase in Democratic support from the mid-2010s. Robustness checks, including exploring cohort effects and comparing different model estimation techniques, supported these findings. The increase in pro-environmental attitudes among Democrats resulted in a 10-20% increase in the overall mean of pro-environmental and climate change attitudes in the US population.

The findings confirm previous research on the decline in pro-environmental attitudes among Republicans, largely attributed to the influence of conservative think tanks, media, and lobbying efforts from fossil fuel industries. The more recent upward trend in pro-environmental attitudes among Democrats requires further investigation. Several potential explanations include increased acceptance of the scientific consensus on anthropogenic climate change, shifting political coalitions (more women and highly educated individuals identifying as Democrats), changes in social norms within the Democratic party, and responses to shifting elite cues. While the study found limited evidence for a 'rising green generation', exploratory analysis suggests that younger Democrats are becoming increasingly pro-environmental. However, the increase in pro-environmental attitudes among Democrats seems consistent across age groups.

This study demonstrates both symmetrical and asymmetrical polarization in environmental and climate change attitudes in the US. While contemporary attitudes are symmetrically polarized, historical trends reveal distinct patterns of asymmetric polarization, particularly the decline of pro-environmental attitudes among Republicans and the recent rise among Democrats. These shifts have implications for collective action and coalition-building on climate change. Future research should focus on the factors driving the increased pro-environmental attitudes among Democrats, explore polarization in other areas of environmental policy, and further investigate age-related trends.

The study relies on broad attitudinal measures, potentially susceptible to partisan responding. Future research should utilize more nuanced measures. The analysis focuses on national trends and may not fully capture regional variations. The recent shift among Democrats needs further investigation with additional data.