As the world has warmed, species distributions have moved polewards in latitude, upwards in elevation and deeper in depth. This global redistribution calls on ecologists to apply long-standing hypotheses about the factors that limit species distributions. Here I present macrophysiological analyses showing that marine and terrestrial ectotherms differ in the extent to which they are physiologically limited within their distributional range. I use records of species’ range shifts to further elucidate the relative roles of species traits and ecological interactions in mediating range shifts in a warming world. From this and other work, I review emerging generalities on the ecology and mechanics of climate range shifts.