Earth Science News  





. The Milky Way Shaped Life On Earth

Cosmic radiation penetrating the atmosphere promotes the formation of clouds which have a cooling effect on Earth's climate.
by Staff Writers
Copenhagen, Denmark (SPX) Nov 15, 2006
Frenzied star-making in the Milky Way Galaxy starting about 2400 million years ago had extraordinary effects on life on Earth. Harvests of bacteria in the sea soared and crashed in a succession of booms and busts, with an instability not seen before or since. According to new results published by Dr. Henrik Svensmark of the Danish National Space Center in the journal Astronomische Nachrichten, the variability in the productivity of life is closely linked to the cosmic rays, the atomic bullets that rain down on the Earth from exploded stars.

They were most intense during a baby boom of stars, many of which blew up.

'The odds are 10,000 to 1 against this unexpected link between cosmic rays and the variable state of the biosphere being just a coincidence, and it offers a new perspective on the connection between the evolution of the Milky Way and the entire history of life over the last 4 billion years,' Dr Svensmark comments.

Dr Svensmark looked at the long record of life's bounty given by counts of heavy carbon atoms, carbon-13, in sedimentary rocks. When bacteria and algae in the ocean grow by taking in carbon dioxide, they prefer the ordinary carbon-12 atoms. As a result, the sea becomes enriched in carbon-13, which is acceptable to sea creatures building their carbonate shells. Variations in carbon-13 therefore record how much photosynthetic growth was in progress when the shell-makers were alive - in other words, how productive the biosphere was at that time.

To his surprise, Dr Svensmark noticed that the biggest fluctuations in productivity coincided with high star formation rates and cool periods in Earth's climate. Conversely, during a billion years when star formation was slow, cosmic rays were less intense and Earth's climate was warmer, the biosphere was almost unchanging in its productivity.

This reveals a link more subtle than any straightforward idea of, say, a warm climate being life-friendly or a cold climate deadly. The record shows that in all icy epochs the biosphere kept lurching between exceptionally low and exceptionally high productivity. The suggested reason is that, although ice is unfriendly to life, winds are stronger when the world is cold. By stirring the oceans, they improve the supply of nutrients in the surface waters so much that productivity can be higher than in a warm climate. And this, in effect, enlarges the fluctuations in biological productivity.

Most likely, the variations in cosmic radiation affected biological productivity through their influence on cloud formation. Hence, the stellar baby boom 2.4 billion years ago, which resulted in an extraordinarily large number of supernova explosions, had a chilling effect on Earth probably by increasing the cloud cover.

This is one of a number of new perspectives on climate change arising from the discovery that cosmic rays promote the formation of clouds, which have a cooling effect on the surface temperature of Earth. Recent experiments on how the cosmic rays influence cloud formation were reported in DNSC press release 3 October 2006.

Related Links
Danish National Space Center
Darwin Today At TerraDaily.com

Elephants Herd Electrocuted In India
Guwahati (AFP) India, Nov 13, 2006
Three wild elephants were electrocuted after apparently wandering into a high-tension electricity line in India's northeastern state of Assam, a wildlife official said Monday. The three were part of a herd of about 35 elephants that had strayed into the Behali tea plantation, about 230 kilometres (142 miles) north of Guwahati, Assam's main city.

.
Get Our Free Newsletters Via Email
  



  • Joining Forces To Predict Tsunamis
  • Indian Disaster Warning System To Be Ready By 2007 Says Space Agency
  • Japan Probes Damage From Killer Twister
  • Developing Models To Predict Organizational Response To Extreme Events

  • Global Warming Threatens Canada Hydro Power, Oil Exports
  • Stakes Rise At UN Climate Poker Game Amid Hopes For A US Shift
  • US, Saudi, China Rank Among Worst On Climate Change
  • Opposition To Usurp Canadian Position At Kyoto Talks

  • SciSys Wins Software Role For CryoSat-2 Mission
  • Next Generation Imaging Detectors Could Enhance Space Missions
  • SSTL Signs Contract With Federal Republic Of Nigeria For Supply Of EO Satellite
  • NASA Snow Data Helps Maintain Largest And Oldest Bison Herd

  • Russia To Raise Gas Prices For CIS States
  • Rand Study Says Renewable Energy Could Play Larger Role Under Right Conditions
  • Developing Uses For Sugar-Cane Bagasse: Biotechnology Applied To The Paper Industry
  • BAE Systems Selected To Participate In Fuel Cell Bus Program

  • 26,000 Russians Contracted HIV Since Start Of Year
  • Next Flu Pandemic: What To Do Until The Vaccine Arrives
  • Industrial Chemicals Are Impairing The Brain Development Of Children Worldwide
  • Indonesia Given A Hand In Bird Flu Fight

  • The Milky Way Shaped Life On Earth
  • Elephants Herd Electrocuted In India
  • Tracing A Metal Link
  • Scientists Find New Way To Search For Origin Of Life

  • Silicon Valley Trying To Lead By Green Example
  • Zanzibar Plastic Bag Ban Takes Effect As Environment Woes Mount
  • OECD Says China Must Step Up Environmental Efforts
  • Dilovasi, Symbol Of Savage Industrialization And An Embarrassement For Turkey

  • Buffet for Early Human Relatives Two Million Years Ago
  • Unraveling Where Chimp And Human Brains Diverge
  • Researchers Discover How Brain Protein Might Control Memory
  • SimCity For Real

  • 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