John C. Briggs

• Biodiversity Journal, 5 (4): 447–452

  John C. Briggs
  Global biodiversity gain is concurrent with declining population sizes

  ABSTRACT
  Many authorities believe that the world’s foremost conservation problem is biodiversity loss caused by the extinctions of thousands of species per year. Estimates of huge losses are based on indirect evidence such as the amount of habitat destroyed, pollution, or overexploitation. But, we now have documented records of species extinctions that provide direct instead of indirect information about diversity loss. By using extinction records for well-known animal groups plus surrogate data, I show there is no evidence for an unusually high rate of extinction, a mass extinction is not yet underway, and there are indications of a continued biodiversity gain. On the other hand, there is ample evidence to demonstrate the persistence of numerous small populations that are the remnants of once widespread and productive species. These populations represent an extinction debt that will be paid unless they are rescued through present day conservation activity. They constitute the world’s true biodiversity problem.

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