CERN's cosmic cloudmaker cranks up (Register)
Eric Gisin
May solve climate mystery, Thermageddon scare
By Andrew Orlowski . Get more from this author
Posted in Environment, 16th November 2009 14:13 GMT
While CERN's vast Large Hadron Collider accelerator gathers all the headlines - allowing humble
hacks to become Hollywood blockbuster scriptwriters - an ancient piece of atom hardware is
beginning experiments that may prove to be of significance.
CERN's much-anticipated CLOUD experiment has begun, the atom lab says. Using the 50-year-old Proton
Synchrotron, the experiment simulates cosmic rays passing through the earth's atmosphere, and hopes
to reveal the extent to which the constant background drizzle of charged particles plays a role in
cloud formation. Earlier experiments have suggested that ionisation causes clouds to "seed" - and
that ionisation is influenced by the type and quantity of cosmic rays that reach the earth.
Both the sun and the earth's magnetic fields act as umbrellas, protecting the surface from the high
energy particles, although two particles still reach the surface per second. But small changes in
the cosmic ray flux produce significant changes in cloud cover. When fewer cosmic rays reach earth,
the planet's climate is warmer, when more reach earth, the climate cools.
"So marked is the response to relatively small variations in the total ionization, we suspect that
a large fraction of Earth's clouds could be controlled by ionisation," noted Danish scientist
Henrik Svesmark this summer. Svensmark has pioneered the research using smaller experiments, but
has waited over a decade to see it tested on such a scale.
Much of the recent interest comes from climate watchers. Clouds are one of the biggest factors in
determining global surface temperature, but the UN's IPCC admits the level of scientific
understanding of them is poor.
The cosmic ray effect - a factor of the background CBR bombardment itself, and the relative
strength of the earth and the Sun's magnetic shields - shows a strong correlation between
temperature, CBR and is extraordinary. Here's the relationship over the short term - around 2,000
years.
[graphs: 1000 years]
And here's the correlation into deep time, with CO2 as a comparison.
[graph: 500M years]
In addition, "deep freezes" in the Earth's temperatures have coincided with short-lived but intense
bursts of cosmic ray activity. Modulation is thought to reflect the Sun's passage through spiral
arms of the Milky Way, and also the Sun's oscillation in relation to the plane of the galaxy. The
Sun bobs up and down 2.7 times per orbit.
CERN became involved when a visiting lecture by former New Scientist editor Nigel Calder was
attended by Jason Kirkby - CLOUD's project leader. It's taken 12 years to fire up the particles for
this major test. CERN has an interview with Kirby here. �
James
Most of Earth's biggest extinctions occurred when the solar system was at its most northerly point in its cycle, which stretches about 230 light years above the galactic plane.