Costello says double-counting elsewhere could reduce the real number of known species from the current figure of 1.9 million overall to 1.5 million. See Answer See Answer See Answer done loading Since 1970, then, the size of animal populations for which data is available have declined by 69%, on average. His writing has appeared in The Washington Post, Reader's Digest, CBS.com, the Richard Dawkins Foundation website and other outlets. PopEd is a program of Population Connection. Calculating the background extinction rate is a laborious task that entails combing through whole databases' worth of . When a meteor struck the Earth some 65 million years ago, killing the dinosaurs, a fireball incinerated the Earths forests, and it took about 10 million years for the planet to recover any semblance of continuous forest cover, Hubbell said. Population Education uses cookies to improve your experience on our site and help us understand how our site is being used. If they go extinct, so will the animals that depend on them. To make comparisons of present-day extinction rates conservative, assume that the normal rate is just one extinction per million species per year. The background extinction rate is often measured for a specific classification and over a particular period of time. Human life spans provide a useful analogy to the foregoing. Bethesda, MD 20894, Web Policies A commonly cited indicator that a modern mass extinction is underway is the estimate that contemporary rates of global extinction are 100-1000 times greater than the average global background rate of extinction gleaned from the past (Pimm et al. Population Education is a program of Population Connection. By FredPearce PMC To discern the effect of modern human activity on the loss of species requires determining how fast species disappeared in the absence of that activity. Because some threatened species will survive through good luck and others by good management of them, estimates of future extinction rates that do not account for these factors will be too high. A few days earlier, Claire Regnier, of the National Museum of Natural History in Paris, had put the spotlight on invertebrates, which make up the majority of known species but which, she said, currently languish in the shadows.. [1], Background extinction rates have not remained constant, although changes are measured over geological time, covering millions of years.
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