Spatial and temporal heterogeneity in climate change limits species' dispersal capabilities and adaptive potential

Global climate change has already caused local declines and extinctions. These losses are generally thought to occur because climate change is progressing too rapidly for populations to keep pace. Based on this hypothesis, numerous predictive frameworks have been developed to project future range shifts and changes in population dynamics resulting from global climate change. However, recent empirical work has demonstrated that seasonally asynchronous climate change regimes - when a region is warming during some parts of the year, but cooling in others - are constraining species' responses to climate change more strongly than rapid warming, leading to intra-specific variation in responses to climate change and local population declines. Here, we couple a review of the literature related to asynchronous climate change regimes with meta-population simulations and an analysis of long-term North American climate trends to show that seasonally asynchronous regimes are occurring throughout most of North America and that their current spatial distribution may be a strong barrier to dispersal and gene flow across many species' ranges. Thus, even though adaptation to climate change may potentially be more common and rapid than previously thought, species whose ranges overlap with asynchronous regimes will likely succumb to local declines that may be difficult to mitigate via dispersal. Future climate-related predictive frameworks should therefore incorporate asynchronous regimes as well as more traditional measures of climate velocity in order to fully capture the array of potential future climate change scenarios.