Ecology in Action

Climate change has already profoundly changed the ecological world on all levels of the biological hierarchy. Comparing the past with the present allows researchers to document that changes have happened, and to understand why some groups (e. g. birds vs. mammals in the Mojave Desert) respond differently than others. Climate change has already changed population phenology, and researchers can estimate the speed of phenological change. Population range shifts may occur on two fronts: leading-edge expansion and trailing-edge contraction. Both of these processes are influenced by biotic and abiotic factors. Climate change can also influence the genetic structure and sex ratio of populations – in extreme cases leading to extinction. Changes to the timing of migration or to the emergence of plants and insects can cause phenological mismatch of exploitative or competitive interactions. Prey species are likely to benefit, while predators or herbivores may suffer from lack of food. On a larger scale, both terrestrial and aquatic ecosystems are showing the effects of climate change, even in tropical biomes where warming and drying are not as prominent as they are in more temperate or polar biomes. Though immune to drought, marine biomes are suffering from acidification and from low oxygen levels.