Climate variability and change can have profound impacts on cycles, human activities, and the biosphere itself. Changes in regional climates can instigate larger climate shifts in other areas across the globe, and changes in the overall global climate can lead to local shifts in patterns of rainfall or temperature. Local changes in average rainfall or temperature may cause ecosystems to alter or an agricultural crop to fail. Invisible though climate changes may be, they have a profound impact here on Earth's surface. To explore the broad topic of climate change and variability, look below at some key topics and questions.