Warming mean temperatures have shifted distributions, altered phenologies, and increased extinction risks of diverse organisms, and have impacted human agriculture and health. However, knowledge of mean temperatures alone does not provide a complete understanding either of changes in climate itself or of how changing climate will affect organisms. Temporal temperature variation, primarily driven by daily and annual temperature cycles, has profound effects on organism physiology and ecology, yet changes in temperature cycling are still poorly understood. Further, pronounced temperature differences at small spatial scales are rarely considered but may strongly alter predicted impacts of changing climates. From analyses of large climate data sets, we find stronger increases in daily temperature cycling relative to changes in annual temperature cycling in temperate and polar regions such that, with respect to diurnal and annual cycling, the world is flattening as temperate and polar regions converge on tropical temperature cycling profiles. I will also discuss our recent work using individual-based models of ectotherm behavior to explore how spatial temperature variation influences biological impacts of changing climate.