Incorporating human behaviour into Earth system modelling.

Climate change and other challenges to the stability and functioning of natural and managed environmental systems are driven by increasing anthropogenic domination of the Earth. Models to forecast the trajectory of climate change and to identify pathways to sustainability require representation of human behaviour and its feedbacks with the climate system. Social climate models (SCMs) are an emerging class of models that embed human behaviour in climate models. We survey existing SCMs and make recommendations for how to integrate models of human behaviour and climate. We suggest a framework for representing human behaviour that consists of cognition, contagion and a behavioural response. Cognition represents the human processing of information around climate change; contagion represents the spread of information, beliefs and behaviour through social networks; and response is the resultant behaviour or action. This framework allows for biases, habituation and other cognitive processes that shape human perception of climate change as well as the influence of social norms, social learning and other social processes on the spread of information and factors that shape decision-making and behaviour. SCMs move beyond the inclusion of human activities in climate models to the representation of human behaviour that determines the magnitude, sign and character of these activities. The development of SCMs is a challenging but important next step in the evolution of Earth system models.

Determinants of emissions pathways in the coupled climate-social system.

The ambition and effectiveness of climate policies will be essential in determining greenhouse gas emissions and, as a consequence, the scale of climate change impacts1,2. However, the socio-politico-technical processes that will determine climate policy and emissions trajectories are treated as exogenous in almost all climate change modelling3,4. Here we identify relevant feedback processes documented across a range of disciplines and connect them in a stylized model of the climate-social system. An analysis of model behaviour reveals the potential for nonlinearities and tipping points that are particularly associated with connections across the individual, community, national and global scales represented. These connections can be decisive for determining policy and emissions outcomes. After partly constraining the model parameter space using observations, we simulate 100,000 possible future policy and emissions trajectories. These fall into 5 clusters with warming in 2100 ranging between 1.8 °C and 3.6 °C above the 1880-1910 average. Public perceptions of climate change, the future cost and effectiveness of mitigation technologies, and the responsiveness of political institutions emerge as important in explaining variation in emissions pathways and therefore the constraints on warming over the twenty-first century.

Recreational users' perceptions of coastal water quality in Rhode Island (USA): Implications for policy development and management.

Stakeholders' understanding of water quality influences how they approach water policy problems and their support for potential solutions. This study explores how resource policy in the United States accounts for different water quality meanings held by recreational users. In-person surveys were conducted along the shoreline in Rhode Island (USA) to examine how recreational users make sense of coastal water quality. Findings indicate that recreational users' understanding of water quality is constructed from an array of environmental conditions (e.g., chl a, phosphates) and attitudinal factors (e.g., perceived problems associated with sewage, algae, or trash), and the meanings ascribed to water quality extend beyond the biophysical indicators typically employed by water resource managers. Potential management strategies based on these findings include expanding current definitions of water quality and monitoring a broader suite of factors, conducting research that captures nuanced meanings of water quality held by different users, and developing outreach programs that clarify the potential impacts of water quality components on human health and well-being.

Conformity to masculine norms predicts US men's decision-making regarding a new male contraceptive.

Health decision-making is often explained by affective and cognitive processes, but this processing is rarely explored in relation to gender norms. We investigated how conformity to specific masculine norms is linked to the affective and cognitive processes that lead to US men's decisions regarding a new male contraceptive. US male college students (N = 151) completed an online survey. They read a description of a long-acting reversible contraceptive, then completed questionnaires measuring their affective and cognitive responses, their information-seeking and willingness-to-try the contraceptive, and their conformity to masculine norms. Participants reported less willingness-to-try the contraceptive when they endorsed masculine norms regarding men's Power Over Women and concern with Heterosexual Self-Presentation, and these effects were consistently mediated by beliefs about its negative impact on sex. Positive emotions predicted willingness-to-try and information-seeking but were unrelated to masculine norms. This broadens our understanding of how conformity to specific gender norms impacts health decision-making processes.