It was one of the greatest calamities of all time: Something turned up Earth's thermostat, touching off a monstrous heat wave that killed many animals and drove others far from their homes to seek cooler climes.
This catastrophe occurred 55 million years ago, after the age of the dinosaurs and long before humans appeared. But scientists warn that today's global warming means that it could be happening again.
The ancient hot spell, which lasted 50,000 to 100,000 years, goes by the unwieldy name of Paleocene-Eocene Thermal Maximum (PETM). It was caused by a sudden -- in geological terms -- doubling or tripling of carbon dioxide and other greenhouse gases in the atmosphere. Climate scientists say the result was an increase of 10 to 12 degrees Fahrenheit -- even higher near the poles -- above the prevailing temperature.
"In certain regards, the PETM is very similar to what is happening right now," said Gerald Dickens, an earth scientist at Rice University in Houston. "Just like now, a huge amount of carbon rapidly entered the ocean or atmosphere. The most notable difference is the rate. Things are happening much faster now than during the PETM."
Most scientists attribute much of today's global warming to the burning of carbon-rich fossil fuels. If the trend continues, Dickens said, the world will add as much carbon to the atmosphere in 500 years -- from 1800 to 2300 -- as the PETM did over 10,000 years.
The long-ago heat wave "shows without a doubt that if you pump a bunch of greenhouse gases into the atmosphere, the planet warms," Matthew Huber, an earth scientist at Purdue University in West Lafayette, Ind., wrote in the June 1 edition of the journal Nature.
Scientists realized the speed and extent of the prehistoric carbon explosion only recently.
A blizzard of scientific papers "reflects the community's excitement at discovering an extraordinary perturbation in biogeochemical systems that was unimaginable 10 years ago," James Zachos, an earth scientist at the University of California, Santa Cruz, declared on his website....
Many species of mammals arose during the PETM and spread to new areas of the world, altering the course of evolution.
But the unusual warmth also caused the loss of many deep-sea species. "It was the most severe extinction in the last 90 million years," said Gabriel Bowen, another Purdue geologist.
What is there to say?
We are going to have all of this knowledge and yet no more wisdom. :(