101-1 Evidence From Past Mass Extinctions: Managing the Current Extinction Crisis

Abstract:

Extinction requires knowing about the past.  Understanding the concept of extinction was through discovery of fossil mosasaurs, mammoths, and mastodons.  We are currently in what has been called the sixth mass extinction, caused by human activities.  The sixth mass extinction has progressed through several stages, with the earlier stages largely involving hunting and the last stage involving global warming due to burning of fossil fuels.  Two of the Big 5 mass extinctions known from the fossil record were primarily due to geological warming caused by unusual volcanic outpourings.  What can we learn from them to help understand and manage the global warming phase of the current mass extinction, particularly for marine environments which cover ~70% of the modern Earth?  For example, the Siberian traps are one of these extensive episodes of volcanism and they led to the largest of the Big 5, the end-Permian mass extinction, ~252 million years ago.  Among many effects this end-Permian warming caused much of life to migrate towards the poles, so that equatorial regions are considered to have been "dead zones".  Another big effect of this mass extinction was to greatly diminish reefs in the oceans.  Effects of this extinction also caused the sizes of many organisms to decrease and for several small shelly invertebrates to proliferate in shallow marine systems, so-called "disaster taxa". Therefore, the record of the end-Permian mass extinction and its Early Triassic recovery is about more than increased extinction and includes detailed evidence on variability of the extinction and recovery from a variety of viewpoints.  This provides the opportunity to produce useful information for us to understand and manage the effects of the current mass extinction in modern oceans. These studies tell us that we need to prepare for a world with not only increased extinction but also including oceans that have dead zones, disaster taxa, significant size reduction of animals, and loss of reefs produced by animals like corals.  The pace of environmental change seems to be going faster that we had thought it would.  Therefore, it seems imperative that studying our biggest ancient mass extinction and associated recovery in a detailed fashion, in the context of helping to manage the current mass extinction, is an increasingly compelling course of action.

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