Ghost of past climate haunts modern research
This Eocene tooth belonged to a shark that lived nearly 50 million years ago. The creature may have witnessed a slice of that period's warming trend. (Mike Timberlake)
Earth is warming today, and it has warmed rapidly and dramatically before.
Richard Norris of Scripps Institution of Oceanography studies a warming event from 55 million years ago.
Richard Norris: We believe that the temperatures rose dramatically, over a relatively short period of time, because of a massive injection of greenhouse gases into the atmosphere and the ocean. And that is, of course, the same kind of process that is going on today.
In this Paleocene Eocene event, as it’s called, Earth’s temperatures are thought to have risen up to 7 degrees Centigrade – as high as 13 degrees Farenheit – in perhaps two hundred years. During that time, Earth changed. Wet places got wetter, dry places got drier, plants and animals expanded their northern ranges.
Sea level rose. Some species went extinct. Norris told Earth & Sky that we today can learn from this ancient climate event. For one thing, he said, after the sudden Paleocene Eocene event, warmer conditions persisted for nearly 200,000 years.
Richard Norris: We’re not talking about making quick and dirty and reversible changes to the atmosphere and the ocean today. We’re talking about making really quite permanent changes at least from a human standpoint.
Thanks today to NASA: explore, discover, understand.
Exactly why the greenhouse gases were released into the atmosphere during the Paleocene Eocene event is under debate. One theory says that volcanic activity in the North Atlantic triggered the release of methane frozen under the deep seafloor. On the other hand, the warming that’s happening today is caused by our burning of fossil fuels.
The main relationship between this ancient event and what we see today is this rapid rate of temperature rise.
Richard Norris said, “I am an optimist, in the sense that I think that it will take a monumental change for us to really come to grips with this problem. But it’s not insoluable. We know about a lot of the technologies already that would get us out of this sort of problem. It’s sort of a matter of will – and of economics.”
For more, see History’s Warning. An ancient global warming episode drastically changed the planet. Life on Earth needed 200,000 years to recover. What we’re headed for in the next century could be even bigger.
Our thanks to:
Richard Norris
Scripps Institution of Oceanography
Additional Teacher Resources
NASA: Earth Observatory – NASA Study Finds World Warmth Edging Ancient Levels
Scientists have concluded in a recent study that because of a rapid warming trend over the past 30 years, the Earth is now reaching and passing through the warmest levels in the current interglacial period, which has lasted nearly 12,000 years. This warming is forcing a migration of plant and animal species toward the poles. This article includes graphics, images, and an explanation of the greenhouse effect.
NASA: Evidence for Global Warming
A detailed tutorial on global warming, including graphs, images, and maps.
