The polar bear is native to the arctic circle and depends on sea ice for hunting its main prey, seals. They are: snow cover, glacier volume, sea ice area, greater variability in weather conditions and more frequent extreme weather events are also predicted, as global warming proceeds, it modifies temperature-dependent biological phenomena. Climate envelope: climatic conditions under which a particular species can persist (climatic niche") Species with longer lifespans and generation times will not evolve rapidly and will be more dependent on their capacity for phenotypic plasticity: ex. caterpillar could evolve rapidly in response to temp, bird will have a slower response. Spatial shifts in the range of organisms: animals and plants will move towards the poles or upward in elevation. Speckled wood butterfly: data looking at where the species occurs at different time intervals: distribution has been shifting over the 1900s, black and red southern end, blue more northern as time progresses.