How human activities have influenced “energy flow” in the environment

A collection of fossilized owl pellets in Utah suggests that when the Earth went through a period of rapid warming about 13,000 years ago, the small mammal community was stable and resilient, even as individual species changed along with the habitat and landscape. By contrast, human-caused changes to the environment since the late 1800s have caused an enormous drop in biomass and “energy flow” in this same community, researchers reported today in Proceedings of the National Academy of Sciences.