Environmental indicators of climate change: Phenological aspects

Abstract

Recent climate change has caused an increase in mean temperature on earth by 0.8� °C during the last century with spatially heterogeneous change. Patterns of precipitation, wind and extreme weather have likewise changed considerably. These changes have prompted an enormous interest in the potential impact of climate change (and other components of global change) on all living beings. Environmental indicators of climate change should be easy to apply, consistent over time and space, reliable, and informative. The biological impact of climate change has been assessed with the help of environmental indicators such as change in phenology and change in distribution. Indicators of change in phenology include advanced spring arrival date of migratory birds, advanced first date of singing by birds and advanced first flowering date of plants in response to change in temperature. Indicators of change in distribution include change in the northernmost range limit of butterflies and birds. While there is a huge literature on responses to climate change, there is little assessment of the indicator ability of different biological responses to climate change. Here I briefly review environmental indicators of climate change; rank the response of different species in terms of their indicator ability; test for consistency in indicator ability over time; and test for consistency in indicator ability among indicators. Finally, I provide a list of research areas in need of further development.