COSMIC RAYS, CLOUDS, AND CLIMATE
- From Scienceweek earlier this week and excerpt from Science, 2002,
3. COSMIC RAYS, CLOUDS, AND CLIMATE
The following points are made by K. S. Carslaw et al (Science 2002
1) The correlation between cosmic rays and Earth's cloud cover over
a solar cycle, first reported by Svensmark and Friis- Christensen in
1997, was hailed by some as the missing piece in the puzzle of
understanding how the Sun could influence climate change. The
intensity of cosmic rays varies globally by about 15% over a solar
cycle because of changes in the strength of the solar wind, which
carries a weak magnetic field into the heliosphere, partially
shielding Earth from low-energy galactic charged particles. Although
long suspected of having some influence on atmospheric processes,
the correlation between cosmic rays and global cloudiness was to
some researchers the clearest indication that such a link might
2) Changes in cloud cover are important because clouds exert a
strong control over Earth's radiative balance. Since the original
observation, improved satellite data have become available and the
cosmic ray-cloud effect seems to be present in low-altitude clouds.
Because low clouds exert a large net cooling effect on the climate,
this determines the sign of the possible cosmic ray- cloud effect:
More cosmic rays are associated with more low clouds and lower
temperatures. The observed variation of low clouds by about 1.7%
absolute corresponds to a change in Earth's radiation budget of
about 1 Wm^(-2) between solar maximum and minimum. This change in
energy input to the lower atmosphere is highly significant when
compared, for example, with the estimated radiative forcing of 1.4
Wm^(-2) from anthropogenic CO2 emissions.
3) In summary: It has been proposed that Earth's climate could be
affected by changes in cloudiness caused by variations in the
intensity of galactic cosmic rays in the atmosphere. This proposal
stems from an observed correlation between cosmic ray intensity and
Earth's average cloud cover over the course of one solar cycle. Some
scientists question the reliability of the observations, whereas
others, who accept them as reliable, suggest that the correlation
may be caused by other physical phenomena with decadal periods or by
a response to volcanic activity or El Nino. Nevertheless, the
observation has raised the intriguing possibility that a cosmic ray-
cloud interaction may help explain how a relatively small change in
solar output can produce much larger changes in Earth's climate.
Physical mechanisms have been proposed to explain how cosmic rays
could affect clouds, but they need to be investigated further if the
observation is to become more than just another correlation among
ON COSMIC RAYS
Radio, X-ray and gamma-ray astronomy have resulted in many
discoveries which can only be interpreted in terms of the presence
of large fluxes of relativistic particles in galaxies. In parallel
with these developments, cosmic ray studies opened up new areas of
astrophysical importance through direct observation of high energy
particles at the top of the atmosphere and in the environment of the
Earth from satellites and, for the very highest energy cosmic rays,
from the surface of the Earth by the large air-shower arrays.
Cosmic radiation (what we would now call cosmic rays) was discovered
as long ago as 1912 by Victor Hess (1883-1964), but the
astrophysical understanding of the origin and propagation of these
particles had to await the 1960s when cosmic ray particle detectors
were flown in satellites. These observations established many
crucial facts about the particles detected in the cosmic radiation.
First of all, the energy spectra of the particles are almost exactly
the same as the typical spectrum of high-energy articles inferred to
be present in both Galactic and extragalactic nonthermal radio
sources. Observations indicate that the cosmic ray particles
observed at the top of the atmosphere are only part of a population
of high-energy particles pervading the whole Galaxy.
Subsequent satellite observatories have determined the chemical
composition and detailed energy spectra of cosmic ray nuclei.
Remarkably, the chemical composition of the cosmic rays is similar
to the abundances of the elements in the Sun, although there are
some variations in the abundances at the higher energies. These
observations provide evidence on the chemical composition of the
cosmic rays as they left their sources and also about the
modifications which could have taken place during propagation from
their sources to the Earth. These observations are very important
for high energy astrophysics because they are the only particles
which we can detect which have traversed a considerable distance
through the interstellar medium and which were accelerated in events
such as supernovae and possibly pulsars in the relatively recent
past, probably within the last 10^(7) years.
At the very highest energies, cosmic rays are detected by large air-
shower arrays on the surface of the Earth. The arrival rate of the
most energetic particles is very low indeed, but particles with
energies up to about 10^(20) eV have been detected. One important
puzzle is the origin of these very high energy particles. Their
arrival directions seem to be reasonably isotropic and, at these
very high energies, these should not be significantly influenced by
the magnetic field in our own Galaxy.
Adapted from: Paul Davies (Ed.): The New Physics. Cambridge
University Press 1989.
What ISN'T discussed here is how the biosphere MODULATES this
chaotic input--and the biosphere's ability to modulate its chemistry
and temperature by EMFs on MUCH faster timescales than w/ CO2 as a
green house gas. The electrical feedbacks are largely instantanious.
This gets to the major criticisms of Gaia discussed in the 1970s and
1980s when Lovelock wrote many of his ideas and repeated those of
NONE of the climatologists who claim to be "skeptics" have EMF and
bio backgrounds. NONE of them.