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review article

Ecological responses to recent climate change
Gian-Reto Walther*, Eric Post², Peter Convey³, Annette Menzel§, Camille Parmesank, Trevor J. C. Beebee¶, Jean-Marc Fromentin#, Ove Hoegh-GuldbergI & Franz Bairlein**
* Institute of Geobotany, University of Hannover, Nienburger Str. 17, 30167 Hannover, Germany ² Department of Biology, The Pennsylvania State University, 208 MuellerLab, University Park, Pennsylvania 16802, USA ³ British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK § Department of Ecology, Technical University Munich, Am Hochanger 13, 85354 Freising, Germany k Integrative Biology, Patterson Labs 141, University of Texas, Austin, Texas 78712, USA ¶ School of Biological Sciences, University of Sussex,Falmer, Brighton BN1 9QG, UK Â Â Á # IFREMER, Centre Halieutique Mediterraneen et Tropical, Bvld Jean Monnet, BP 171, 34203 Sete Cedex, France I Centre for Marine Studies, University of Queensland, St Lucia, 4072 Queensland, Australia ** Institute for Avian Research `Vogelwarte Helgoland', An der Vogelwarte 21, 26386 Wilhelmshaven, Germany............................................................................................................................................................................................................................................................................

There is now ample evidence of the ecological impacts of recent climate change, from polar terrestrial to tropical marine environments. The responses of both ¯ora and fauna span anarray of ecosystems and organizational hierarchies, from the species to the community levels. Despite continued uncertainty as to community and ecosystem trajectories under global change, our review exposes a coherent pattern of ecological change across systems. Although we are only at an early stage in the projected trends of global warming, ecological responses to recent climate change are alreadyclearly visible.

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he Earth's climate has warmed by approximately 0.6 8C over the past 100 years with two main periods of warming, between 1910 and 1945 and from 1976 onwards. The rate of warming during the latter period has been approximately double that of the ®rst and, thus, greater than at any other time during the last 1,000 years1. Organisms, populations and ecological communities donot, however, respond to approximated global averages. Rather, regional changes, which are highly spatially heterogeneous (Fig. 1), are more relevant in the context of ecological response to climatic change. In many regions there is an asymmetry in the warming that undoubtedly will contribute to heterogeneity in ecological dynamics across systems. Diurnal temperature ranges have decreased becauseminimum temperatures are increasing at about twice the rate of maximum temperatures. As a consequence, the freeze-free periods in most mid- and high-latitude regions are lengthening and satellite data reveal a 10% decrease in snow cover and ice extent since the late 1960s. Changes in the precipitation regime have also been neither spatially nor temporally uniform (Fig. 1). In the mid- and highlatitudes of the Northern Hemisphere a decadal increase of 0.5±1% mostly occurs in autumn and winter whereas, in the sub-tropics, precipitation generally decreases by about 0.3% per decade1. There is now ample evidence that these recent climatic changes have affected a broad range of organisms with diverse geographical distributions2±6. We assess these observations using a processoriented approachand present an integrated synopsis across the major taxonomic groups, covering most of the biomes on Earth. We focus on the consequences of thirty years of warming at the end of the twentieth century, and review the responses in (1) the phenology and physiology of organisms, (2) the range and distribution of species, (3) the composition of and interactions within communities, and (4) the structure...