Subscribe to our free daily newsletters
. Earth Science News .

Subscribe to our free daily newsletters

Natural Climate Change Periodically Wipes Out Mammal Species

Extintion... it's a way of life...
by Staff Writers
Paris (AFP) Oct 11, 2006
Climate change, naturally induced by tiny shifts in Earth's rotational axis and orbit, periodically wipes out species of mammals, a study published on Thursday says. Palaeontologists have long puzzled over fossil records that, remarkably, suggest mammal species tend to last around two and a half million years before becoming extinct.

Climate experts and biologists led by Jan van Dam at the University of Utrecht in the Netherlands, overlaid a picture of species emergence and extinction with changes that occur in Earth's orbit and axis.

The Earth's orbit is not a perfect circle: it is slightly elliptical, and the ellipticality itself goes through cycles of change that span roughly 100,000 and 400,000 years.

Its axis, likewise, is not perfectly perpendicular but has a slight wobble, rather like a poorly-balanced child's top, which goes through cycles of 21,000 years.

In addition, the axis, as schoolbooks tell us, is also tilted, and this tilt also varies in a cycle of 41,000 years.

These three shifts in Earth's pattern of movement are relatively minor compared with those of other planets.

But they can greatly influence the amount of radiation -- heat and light -- which Earth receives from the Sun. The effect can be amplified, causing global cooling, affecting precipitation patterns and even creating Ice Ages in higher latitudes, when two or all the cycles peak together.

Van Dam's team looked at 132 species of mammal fossils recovered from three sites in Spain, in layers of soil that dated from 24.5 million years ago to 2.5 million years ago.

What they looked for was the fossilised teeth of rodents, mainly because these could be spotted and identified much quicker than the remains of other animals.

They found that rodent species bit the dust in two regular waves.

One wave of extinction was roughly every 2.4 million years or so and the other was about every million years or so, coinciding with extremes in the cycles of ellipticality, wobble and tilt.

These were not swift, massive die-outs of the kind that famously wiped out the dinosaurs 65 million years ago, but rather a fadeout of species which could not cope with habitat loss or competition, especially when Ice Ages kicked in.

As they became extinct, other species emerged.

"At any given time, there would be around 15 (rodent) species in residence," van Dam told AFP. "During the extinction waves, about five or six species would disappear over a period of about 100,000 years or so."

The paper, which appears on Thursday in the British journal Nature, is confident that the species turnover among rodents also happened to other mammals and possibly other biological groups too.

Astronomical impact "provides a crucial missing piece in the puzzle" of regular species turnover, it says.

Previous research has also established that Earth's climate system can be affected by massive volcanic eruptions or the impact of an asteroid or comet. These can kick up so much dust that the planet receives less sunlight, and in turn plant species suffer.

In addition to natural factors, the world's climate system and its biodiversity are also being affected by the burning of fossil fuels.

Oil, gas and coal, and to a lesser degree agriculture, release carbon gases into the atmosphere, creating a "greenhouse effect" that traps solar radiation and causes Earth's surface temperature to warm.

Source: Agence France-Presse

Related Links
University of Utrecht
Darwin Today At

Asia-Pacific Faces Global Warming Disaster
Sydney (AFP) Oct 10, 2006
Millions of people in the Asia-Pacific region could be forced from their homes and suffer increasing disease, cyclones and floods caused by global warming, scientists warned Monday. Climate change will seriously threaten regional human security and national economies this century, according to a report by the Australian government's Commonwealth Scientific and Research Organisation (CSIRO).

  • North Korea Braces For Sanctions
  • Inter-Korean Projects In Jeopardy
  • British Experts Smoke Out Hi-Tech Help For Fire Rescue
  • Year Of 'Quake Jihad' For Pakistan Militants

  • Natural Climate Change Periodically Wipes Out Mammal Species
  • Asia-Pacific Faces Global Warming Disaster
  • Global Warming Will Alter Character Of The Northeast
  • Arctic Sea Ice Declines Again In 2006

  • Deimos And Surrey Satellite Technology Contract For Spanish Imaging Mission
  • NASA Satellite Data Helps Assess the Health of Florida's Coral Reef
  • Alcatel Alenia Space To Build SIRAL-2 Radar Altimeter For CryoSat-2
  • Earth from Space: The French Frigate Shoals

  • Harvesting Machine Driving Mesquite-to-Ethanol Potential
  • Russian Export Blend Could Replace Urals Crude As Main Index Setter
  • Russia-Germany Energy Cooperation Could Be Extended
  • Can Colorado Oil Shale Ease America Energy Woes

  • West Java Goes Own Way On Avian Flu Management
  • A Biocontrol Agent Which Doesn't Trigger Antibiotic Resistance
  • US, Australian Scientists Develop Vaccine Against Deadly Viruses
  • 'Killer' B Cells Provide New Link In The Evolution Of Immunity

  • Giant Insects Might Reign If Only There Was More Oxygen In The Air
  • Composting May Be Alternative In Wake Of Horse Slaughter Bill
  • Bacteria Do Not Have Species
  • Grant Awarded To Study Interaction Of Ecology And Evolution

  • Canadin Prime Minister Says New Clean Air Act Coming
  • Monitoring Contaminants In Water Systems In Real Time
  • EU Lawmakers Uphold Environmentalist Approach On Chemicals
  • Manganese Can Keep Toxic Hydrogen Sulfide Zones In Check In Aquatic Systems

  • Rapid Rise In The Arctic Ocean May Alter Views Of Human Migration
  • Democrat Push For Wellness Agency
  • More Than Meets The Human Eye
  • Chinese Oldest Academy Celebrates 1,030 Years

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement