UPDATE: Local copy of paper added.
Earth has been bombarded with radiation from stellar events as the solar system travels through the Milky Way. This is linked to Earth’s paleo history.
“Research by a Danish physicist suggests that the explosion of massive stars – supernovae – near the Solar System has strongly influenced the development of life. Prof. Henrik Svensmark of the Technical University of Denmark (DTU) sets out his novel work in a paper in the journal Monthly Notices of the Royal Astronomical Society.”
From Royal Astronomical Society press release
Evidence of nearby supernovae affecting life on Earth (link to PDF, no paywall)
National Space Institute, Technical University of Denmark,
22 April 2012
Observations of open star clusters in the solar neighborhood are used to calculate local supernova (SN) rates for the past 510 million years (Myr). Peaks in the SN rates match passages of the Sun through periods of locally increased cluster formation which could be caused by spiral arms of the Galaxy. A statistical analysis indicates that the Solar System has experienced many large short-term increases in the flux of Galactic cosmic rays (GCR) from nearby supernovae. The hypothesis that a high GCR flux should coincide with cold conditions on the Earth is borne out by comparing the general geological record of climate over the past 510 million years with the fluctuating local SN rates. Surprisingly a simple combination of tectonics (long-term changes in sea level) and astrophysical activity (SN rates) largely accounts for the observed variations in marine biodiversity over the past 510 Myr. An inverse
correspondence between SN rates and carbon dioxide (CO2) levels is discussed in terms of a possible drawdown of CO2by enhanced bioproductivity in oceans that are better fertilized in cold conditions – a hypothesis that is not contradicted by data on the relative abundance of the heavy isotope of carbon,13C.”
“The author also thanks the many geoscientists who have provided data and helpful comments, and Nigel Calder for general discussions regarding this work.” Nigel Calder’s web site is in our blog roll to the left.
The general idea is not new; Svensmark has extended the scope in time and fields of evidence, critically stating WHY there is a link, radiation.
In the comments Michele Casati gives a link to a 2005 paper “ICE AGE EPOCHS AND THE SUN’S PATH THROUGH THE GALAXY
D. R. Gies and J. W. Helsel”.
Below is Fig 1 which provides a different and perhaps easier graphic for a layperson.
Post by Tim Channon, co-moderator.