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Earth's climate is warming rapidly at rates which, by some estimates, exceed those of climatic niche evolution among vertebrate animals by >10,000fold (Quintero & Wiens, 2013). Assessing this ubiquitous threat to biodiversity requires a variety of robust approaches to predict organismal responses to future climates. In this issue, Briscoe et al. (2022) provide a road map for using species' functional traits (morphological, physiological, and behavioral) and localized and global climate data to inform biophysical models that estimate the effects of specific climate scenarios on the energy balance and water economy of animals in the wild. Biophysical modelling approaches predict relationships between heat exchange, body temperature and behavior over wide ranges of environmental temperature from functional traits. Many of the direct impacts of climate change are consequences of supplyanddemand mismatches involving water or energy, the currencies of life. Biophysical modelling is uniquely wellsuited for predicting these impacts and evaluating adaptation strategies available to conservationists, managers and policymakers. Biophysical models have long been of interest to physiological ecologists for understanding the responses of humans and animals to challenges imposed by their physical environments, and constraints on those responses (Winslow et al., 1937). One of the earliest and most influential animal models used a climate space and energy budget analysis approach to characterize the environment within which an animal can survive— a space bounded by air temperature, radiation, wind speed and humidity (Porter & Gates, 1969). Biophysical models use functional traits, (e.g., body size, plumage thickness, metabolic/evaporative responses to temperature, critical thermal tolerances, etc.) and climate/microclimate data to examine constraints on animal performance. These models are versatile enough to examine individual limits on performance via estimates of energy or water fluxes under specific climate scenarios for endotherms such as mammals or birds or produce body temperature estimates in ectotherms such as reptiles and amphibians. When mapped onto current and projected future climate data, wellparameterized biophysical models provide robust predictors of future species abundance and distributions. Briscoe et al.'s (2022) goal is to introduce and increase the accessibility of the biophysical modelling approach to the broader global change research community. They start by introducing mechanistic biophysical models, which use animal functional traits as their bases and compare these to statistical or phenomenological models that correlate species distributions with predictor variables. The authors highlight how biophysical models can describe spatial and temporal variability and account for complexity such as changes in environmental constraints across lifehistory stages. They then provide examples of how biophysical modelling can be applied to both ectotherms and endotherms. For ectotherms— such as reptiles, amphibians and arthropods— biophysical models and species' functional traits can be used to predict thermal constraints on offspring sex, the viability of developing eggs, and limits on daily activity and energy acquisition under any climate scenario. For endotherms, such as mammals and birds, the costs of maintaining a high stable body temperature can be quantified in terms of water and energy fluxes. High rates of energy and water exchange define endotherms and limit their performance and distribution, making limits on distributions intimately tied to species' traits associated with diet and energy as well as to water availability in the environment. Biophysical models have provided insights into individual performance and limits of species distributions, allowing researchers to identify functional bottlenecks or limits of species persistence. Briscoe et al. (2022) present a vision for tackling global change problems that includes a new cohort of global change researchers proficient in biophysical modelling approaches with access to functional trait databases. As physiological ecologists, we suggest that limited access to taxonspecific functional trait data and a lack of indepth knowledge of many organisms' natural history will continue to create a bottleneck in expanding the value and implementation of biophysical modeling approaches. As the authors note, however, the collection of empirical speciesspecific physiological data remains Blair O. Wolf and Andrew E. McKechnie joint first authors.