The response of beetles to climate change during the Quaternary Period is reviewed for the purpose of evaluating their future response to global warming. Beetles responded to Quaternary climatic changes mostly by dispersal, which ultimately led to large-scale changes in geographic distribution. Fragmentation and isolation of populations associated with climate change did not result in either higher rates of speciation or extinction, although local extinctions occurred when dispersal routes were blocked by barriers. Studies from archaeological and late Holocene sites indicate that the fragmentation of the natural landscape by human activities had as great an impact on the local diversity of beetle populations as did climate change. Habitat reduction and fragmentation continue today and are making species increasingly vulnerable to extinction. The major difference between the future and past responses of beetles to climate change is that extinction rates are expected to be much higher, independent of whether the causes of climate change are natural or anthropogenic. The question of determining whether global warming has natural or anthropogenic causes is important because of the ethical implications of extinction.
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Access A Broad Range of Paleoclimatic Studies. Current debates regarding potential man-induced modification of climate make this volume especially timely. Introductory sections address the major and minor physical controls, or drivers, that affect Earth's climate. Several chapters describe the naturally occurring range of variation of climatic conditions and illustrate past changes in global temperatures. Case studies show how ancient temperature conditions are determined, as well as new techniques that have significant potential as proxies for assessing paleoclimates. Several chapters demonstrate the magnitude and length of duration of numerous temperature variations, which occurred during geologic time periods.