Two meta-analyses examining more than 100 studies and over 1,000 species have shown that more than 80% of range and phenology shifts have been in the direction expected from climate change, giving us a very high confidence that global climate change is already impacting biodiversity.
Many individual studies have examined the evidence for recent biological changes in relation to measured climatic changes. These have mostly concentrated on a limited set of taxa, or been restricted to particular countries or regions. However, two meta-analyses combine a broad spectrum of results to test whether a coherent pattern exists across regions and for a diverse array of species. One analysis examined the results of 143 studies on a wide spectrum of species, totalling 1,473 organisms from all regions of the world. Of the 587 species showing significant temperature-related changes (in distribution, abundance, phenology, morphology or genetic frequencies), 82% had shifted in the direction expected from climate change (e.g. distributions moving towards higher latitudes or altitudes; Root et al. 2003). The timing of spring events, such as egg-laying by birds, spawning by amphibians and flowering by plants, was shown (by 61 studies) to have shifted earlier by 5.1 days per decade on average over the last half-century, with changes being most pronounced at higher latitudes (Root et al. 2003). The second analysis reviewed studies of over 1,700 species, and found similar results: 87% of phenology shifts and 81% of range shifts were in the direction expected from climate change (see figure; Parmesan and Yohe 2003). These studies give us a very high confidence that global climate change is already impacting biodiversity.
BirdLife International (2004) There is strong evidence that climate change is impacting a wide range of organisms. Presented as part of the BirdLife State of the world's birds website. Available from: http://birdlife.org/datazone/sowb/casestudy/169. Checked: 01/08/2014
|Key message: Climate change is already affecting birds in diverse ways|