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1. The Climate Action Simulation

   https://doi.org/10.1177/1046878119890643  

   Rooney-Varga, Juliette N.; Kapmeier, Florian; Sterman, John D.; Jones, Andrew P.; Putko, Michele; Rath, Kenneth (December 2019, Simulation & Gaming)

   Background. We describe and provide an initial evaluation of the Climate Action Simulation, a simulation-based role-playing game that enables participants to learn for themselves about the response of the climate-energy system to potential policies and actions. Participants gain an understanding of the scale and urgency of climate action, the impact of different policies and actions, and the dynamics and interactions of different policy choices. Intervention. The Climate Action Simulation combines an interactive computer model, En-ROADS, with a role-play in which participants make decisions about energy and climate policy. They learn about the dynamics of the climate and energy systems as they discover how En-ROADS responds to their own climate-energy decisions. Methods. We evaluated learning outcomes from the Climate Action Simulation using pre- and post-simulation surveys as well as a focus group. Results. Analysis of survey results showed that the Climate Action Simulation increases participants’ knowledge about the scale of emissions reductions and policies and actions needed to address climate change. Their personal and emotional engagement with climate change also grew. Focus group participants were overwhelmingly positive about the Climate Action Simulation, saying it left them feeling empowered to make a positive difference in addressing the climate challenge. Discussion and Conclusions. Initial evaluation results indicate that the Climate Action Simulation offers an engaging experience that delivers gains in knowledge about the climate and energy systems, while also opening affective and social learning pathways. 

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2. Estimating Transient Climate Response in a Large‐Ensemble Global Climate Model Simulation

   https://doi.org/10.1029/2018GL080714  

   Adams, B. K.; Dessler, A. E. (January 2019, Geophysical Research Letters)

   Abstract The transient climate response (TCR), defined to be the warming in near‐surface air temperature after 70 years of a 1% per year increase in CO₂, can be estimated from observed warming over the nineteenth and twentieth centuries. Such analyses yield lower values than TCR estimated from global climate models (GCMs). This disagreement has been used to suggest that GCMs' climate may be too sensitive to increases in CO₂. Here we critically evaluate the methodology of the comparison using a large ensemble of a fully coupled GCM simulating the historical period, 1850–2005. We find that TCR estimated from model simulations of the historical period can be much lower than the model's true TCR, replicating the disagreement seen between observations and GCM estimates of TCR. This suggests that the disagreement could be explained entirely by the methodology of the comparison and undercuts the suggestions that GCMs overestimate TCR. 

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3. Building Consensus for Ambitious Climate Action Through the World Climate Simulation

   https://doi.org/10.1029/2021EF002283  

   Rooney‐Varga, Juliette N.; Hensel, Margaret; McCarthy, Carolyn; McNeal, Karen; Norfles, Nicole; Rath, Kenneth; Schnell, Audrey H.; Sterman, John D. (November 2021, Earth's Future)

   Abstract Sociopolitical values are an important driver of climate change beliefs, attitudes, and policy preferences. People with “individualist‐hierarchical” values favor individual freedom, competition, and clearly defined social hierarchies, while “communitarian‐egalitarians” value interdependence and equality across gender, age, heritage, and ethnicity. In the US, individualist‐hierarchs generally perceive less risk from climate change and express lower support for actions to mitigate it than communitarian‐egalitarians. Exposure to scientific information does little to change these views. Here, we ask if a widely used experiential simulation,World Climate,can help overcome these barriers.World Climatecombines an engaging role‐play with an interactive computer model of the climate system. We examine pre‐ and post‐World Climatesurvey responses from 2,080 participants in the US and use a general linear mixed model approach to analyze interactions among participants' sociopolitical values and gains in climate change knowledge, affect, and intent to take action. As expected, prior to the simulation, participants holding individualist‐hierarchical values had lower levels of climate change knowledge, felt less urgency, and expressed lower intent to act than those holding communitarian‐egalitarian values. However, individualist‐hierarchs made significantly larger gains across all constructs, particularly urgency, than communitarian‐egalitarians. Participants' sociopolitical values also shifted: those with individualistic‐hierarchical values before the simulation showed a substantial, statistically significant shift toward a communitarian‐egalitarian worldview. Simulation‐based experiences likeWorld Climatemay help reduce polarization and build consensus towards science‐based climate action. 

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4. Optimizing Topographic Boundary Conditions for East Pacific Climate Simulation

   https://doi.org/10.1175/JCLI-D-24-0316.1  

   Meegan-Kumar, Dervla; Elsaesser, Gregory S; Battisti, David S; Colose, Christopher M; Wu, Jingbo; Sexton, Jared; Baldwin, Jane W (June 2025, Journal of Climate)

   Abstract Overly smooth topography in general circulation models (GCMs) underestimates the blocking effect of the steep mountain ranges flanking the eastern Pacific. We explore the impact of this bias on common biases in Pacific climate simulation [i.e., the unrealistic cross-equatorial symmetry of near-surface winds, sea surface temperatures (SSTs), and precipitation] through sensitivity experiments with modified Central and/or South American topography in an atmosphere–ocean coupled GCM. Quantifying orographic blocking potential via the Froude number, we determine that an envelope topographic interpolation scheme best captures observed blocking patterns. Implementing envelope topography only in Central America reduced model biases as greater blocking of the trade winds warmed SST and enhanced convergence in the northeastern Pacific. Doing so additionally over the Andes improved the simulation of South Pacific circulation and the South Pacific convergence zone as stronger deflection of the westerlies intensified the South Pacific anticyclone. This mitigated convection biases in the southeast Pacific by increasing subsidence and cooling SST. However, remote impacts of the Andes exacerbated the dry bias in the northeast tropical Pacific, resulting in negligible improvement in the East Pacific double-ITCZ. We find that, due to the significant role of large-scale convergence in driving precipitation patterns, other model biases, such as cloud-radiative biases, may modulate the impact of altering topography. Our results highlight the importance of considering alternate methods for calculating model topographic boundary conditions, though the optimal interpolation scheme will vary with model resolution and the impact of topography on GCM biases can be sensitive to choices made in formulating parameterizations. Significance StatementIn this study, we explore how the mountain ranges spanning Central and South America shape the climate of the Pacific by blocking large-scale midlatitude and tropical winds. We show that the height of these mountains is typically too low in climate models and that elevating them can improve patterns of rainfall, surface ocean temperatures, and near-surface winds in the Pacific. This is important because model biases in the Pacific climate limit their utility for understanding current and future climate variability. Improving the representation of blocking by mountains can thus be a simple method for reducing uncertainties in future climate projections. 

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5. Hurricane Simulation and Nonstationary Extremal Analysis for a Changing Climate

   https://doi.org/10.1175/JAMC-D-22-0003.1  

   Carney, Meagan; Kantz, Holger; Nicol, Matthew (November 2022, Journal of Applied Meteorology and Climatology)

   Abstract Particularly important to hurricane risk assessment for coastal regions is finding accurate approximations of return probabilities of maximum wind speeds. Since extremes in maximum wind speed have a direct relationship with minima in the central pressure, accurate wind speed return estimates rely heavily on proper modeling of the central pressure minima. Using the HURDAT2 database, we show that the central pressure minima of hurricane events can be appropriately modeled by a nonstationary extreme value distribution. We also provide and validate a Poisson distribution with a nonstationary rate parameter to model returns of hurricane events. Using our nonstationary models and numerical simulation techniques from established literature, we perform a simulation study to model returns of maximum wind speeds of hurricane events along the North Atlantic coast. We show that our revised model agrees with current data and results in an expectation of higher maximum wind speeds for all regions along the coast, with the highest maximum wind speeds occurring along the northeast seaboard. 

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