Phenology is a key component of life on earth. Many birds time their nesting so that eggs hatch when insects are available to feed nestlings. Likewise,
insect emergence is often synchronized with leaf out in host plants. For people, earlier flowering means earlier allergies. Farmers and gardeners need
to know the schedule of plant and insect development to decide when to apply fertilizers and pesticides and when to plant to avoid frosts. Phenology
influences the abundance and distribution of organisms, ecosystem services, food webs, and global cycles of water and carbon. In turn, phenology may
be altered by changes in temperature and precipitation.
Changes in phenological events like flowering and animal migration are among the most sensitive biological responses to climate change. Across the world,
many spring events are occurring earlier—and fall events are happening later—than they did in the past. However, not all species are changing
at the same rate or direction, leading to mismatches. How plants and animals respond can help us predict whether their populations will grow or shrink
– making phenology a “leading indicator” of climate change impacts.