The Paleocene-Eocene Thermal Maximum

Credit: Ashok Boghani, FlickrCC

The Paleocene-Eocene Thermal Maximum (PETM), was an interval of high temperature during the late Paleocene and early Eocene epochs (roughly 55 million years ago).  It lasted for 100,000 years.  The onset was rapid with the global temperature increasing by more than 5 degrees Celsius within a few thousand years.  The ecological consequences were large, with widespread extinctions in both marine and terrestrial ecosystems.

To get some perspective on the situation we now face, the global temperature has increased by over 1 degree C in the past sixty years and is expected to increase by another three to four degrees by the end of the century.  This temperature change is occurring twenty times faster than that of the transition to the PETM which, nevertheless, resulted in widespread extinctions.

Not surprisingly, scientists estimate that the current extinction rate of species is hundreds to thousands of times faster than the normal background rate. Global warming, ocean acidification, and the destruction of natural habitat are all involved. Human activity is having the impact of a slow-motion asteroid strike.  Instead of seconds, it is taking decades, and we have a front row seat to the show.