Printer Friendly
The Free Library
4,539,202 articles and books
Member login
User name  
Password 
 
Join us Forgot password?

Warm spell did little for Eocene flora. (Earth Science: from Boston, at the annual meeting of the Geological Society of America).


Global warming kicked off the Eocene epoch Eocene epoch (ē`əsēn'), second epoch of the Tertiary period in the Cenozoic era of geologic time, from approximately 54.9 to 38 million years ago. about 55 million years ago, but new research shows that this greenhouse phase did little for North America's plants. In contrast, warming that began 18,000 years ago caused glaciers to retreat and brought rapid shifts in the continent's flora and fauna.

The transition from the Paleocene epoch Paleocene epoch (pā`lēəsēn'), first epoch of the Tertiary period in the Cenozoic era of geologic time (see geologic timescale) between 60 to 66 million years ago. In W North America, the uplift of the Rocky Mts. to the Eocene was marked by a rise in average temperatures of 4 [degrees] to 8 [degrees] C in just 10,000 to 20,000 years. That initiated the so-called Paleocene-Eocene Thermal Maximum (PETM PETM - Paleocene Eocene Thermal Maximum), which lasted 200,000 years.

North America's menagerie changed dramatically during the PETM, yet plant life during the Paleocene and Eocene remained similar. However, a gap in the floral record during the PETM has left open the possibility that a transient greenhouse effect greenhouse effect: see global warming. introduced a dramatic but short-lived flux in plant life.

New data on prehistoric plant diversity at Powder River Basin, Wyo., fill key blanks in the missing interval--and suggest it doesn't hide any surprises. Although the relative abundance of different plants shifted somewhat, the local array of flora changed minimally during the PETM, reports Scott L. Wing, a paleobiologist at the National Museum of Natural History in Washington, D.C. From fossilized leaves and pollen, he and his colleagues have determined that the only new plants known to have migrated into the region appeared after the PETM.

During the PETM, Wing suggests, expansive forest cover may have inhibited the immigration of plants. In contrast, he notes, the glacial retreat that accompanied the warming that began 18,000 years ago opened up virgin ground that plants colonized quickly.

--B.H.
COPYRIGHT 2001 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2001, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

 Reader Opinion

Title:

Comment:



 

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:effects of global warming
Publication:Science News
Article Type:Brief Article
Date:Nov 24, 2001
Words:270
Previous Article:Genomes of dangerous bacteria exposed. (Biomedicine).(Salmonella enterica; Yersinia pestis)(Brief Article)
Next Article:Coral-killing army recruits human bugs. (Earth Science: from Boston, at the annual meeting of the Geological Society of America).(source of...
Topics:



Related Articles
Global warming underfoot: holes in the ground hold untapped climate riches.
Warming raises sea level off California. (cause for warming unclear) (Brief Article)
Hot air in Berlin.(conference on regulation of carbon dioxide emissions)(Column)
Warmth in north pushes spring forward. (increased plant growth may be due to global warming)(Earth Science)(Brief Article)
Climate's Long-Lost Twin.(geological evidence of elevated sea levels during stage 11 interglacial period)
Global Warming.
Ocean Warming Studies Bolster Evidence of Human Hand in Climate Change. (Update).(research)(Brief Article)(Illustration)(Statistical Data Included)
The global warming crisis.
Science fiction about global warming.(Correction, Please!)
Global warming too hot or not? The theory of global warming proposes that man's activities are causing the Earth to heat up, but there is compelling...

Terms of use | Copyright © 2008 Farlex, Inc. | Feedback | For webmasters | Submit articles