The history of life on Earth has been marked five times by events of mass biodiversity extinction caused by extreme natural phenomena. Today, many experts warn that a Sixth Mass Extinction crisis is underway, this time entirely caused by human activities.
A comprehensive assessment of evidence of this ongoing extinction event was published recently in the journal Biological Reviews by biologists from the University of Hawai'i at Mānoa and the Muséum National d'Histoire Naturelle in Paris, France. "Drastically increased rates of species extinctions and declining abundances of many animal and plant populations are well documented, yet some deny that these phenomena amount to mass extinction," said Robert Cowie, lead author of the study and research professor at the UH Mānoa Pacific Biosciences Research Center in the School of Ocean and Earth Science and Technology (SOEST). "This denial is based on a biased view of the crisis which focuses on mammals and birds and ignores invertebrates, which of course constitute the great majority of biodiversity." By extrapolating from estimates obtained for land snails and slugs, Cowie and co-authors estimated that since the year 1500, Earth could already have lost between 7.5 and 13% of the two million known species on Earth—a staggering 150,000 to 260,000 species. "Including invertebrates was key to confirming that we are indeed witnessing the onset of the Sixth Mass Extinction in Earth's history," said Cowie. Read more...
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