A widely misunderstood research paper says
the sun's behaviour and the Earth's position in the galaxy, not CO2
build-up, are at the root of global warming
A widely misunderstood research paper says the sun's behaviour and
the Earth's position in the galaxy, not CO2 build-up, are at the root
of global warming
On July 1, the prestigious Geological Society of America (GSA)
released a blockbuster scientific paper that fundamentally challenges
the view that carbon dioxide is the principal driver of climate change.
Apart from its scientific importance, it has political implications as
well, since it pulls the rug out from under the Kyoto accord.
Co-authored by University of Ottawa geology professor Dr. Jan Veizer
and University of Toronto-trained astrophysicist Dr. Nir J. Shaviv,
this study shows that changes in atmospheric carbon dioxide (CO2), the
gas most targeted by Kyoto, has had little effect on Earth's long-term
temperature variations compared to natural causes.
In a unique cross-disciplinary study, Veizer and Shaviv combined
their perspectives of Earth sciences and astrophysics to show the
primary driver of Earth's major climate swings over the past
half-billion years almost certainly originates with the most violent
natural phenomenon known -- supernovas, the cataclysmic explosions that
end the normal life of the galaxy's largest stars.
At first glance, such an announcement sounds like sensational fodder
for Canadian newspaper editorial pages and TV and radio talk shows.
Yet, because of the complexity of the science involved, most media,
particularly the CBC, which focused instead on a simpler but less
significant pro-Kyoto announcement from Geneva, merely ignored the
story. Those in the press who sensed correctly that the GSA paper was
crucially relevant to today's climate-change debate were faced with the
impossible task of quickly understanding and immediately reporting upon
a scientific discovery that would take someone trained in the field
many hours to properly interpret. Not surprisingly, the few media
reports that did come out on the issue left readers more perplexed than
informed. Like the brilliant but short-lived supernovas it references,
the study was briefly described in confused articles on several
newspaper front pages and then virtually disappeared.
For experts frustrated with the continual dumbing-down of climate
science in the Kyoto debate, the media's treatment of the Veizer paper
is all too familiar. Without a TV scientist like David Suzuki to
simplify and "interpret" the study, tragically few Canadians will give
the paper a second thought. Of course, this is partly due to the strong
bias against announcements that run counter to the familiar script in
the Kyoto debate -- "We must stop disastrous climate change by reducing
our emissions of greenhouse gases" has become the international mantra
of environmentalists and politicians alike.
But it is also due to the fact that climate is arguably the most
complex phenomenon science has ever tackled -- indeed, we are still
deeply uncertain about the causes of climate change. Unfortunately for
news anchors, politicians and environmentalists dressed in polar bear
suits, there are no cheat sheets or one-minute tutorials to help them
quickly learn to speak meaningfully about climate change. Canadian
professors Chris Essex and Ross McKitrick sum up the situation
perfectly in their award-winning book, Taken by Storm: "Non-scientists
should stop looking for shortcuts around the hard work of learning the
Environment Minister David Anderson has often said he must proceed
on the basis of the best science available. Well, luckily for him,
science has just advanced again and the potentially revolutionary
implications could save us billions. So lets follow Essex and
McKitrick's advice and take a closer look at the Veizer/Shaviv paper in
an effort to understand how it relates to today's climate-change debate.
Although there is a superficial correlation between rising
atmospheric CO2 concentrations and recent temperature records,
scientists have also observed a consistent trend linking variations in
the output of the sun with terrestrial climate. Like most stars, our
sun experiences regular and predictable changes in brightness driven by
variations in its speed of rotation, its magnetic field, the incidence
of sunspots and the gravitational effect of the major planets.
Independent European and Chinese records clearly show significant
climactic effects on the Earth when the sun is unusually bright or dim.
Throughout the 20th century, the sun continued to brighten and so,
not surprisingly, the Earth warmed. This direct heating effect may be
responsible for about a third of the warming observed in the past 100
years. Scientists who have argued that greenhouse gases are causing
climate change acknowledge that the sun plays a role, but still insist
the majority of the warming has been caused by greenhouse gas increases.
But the computer models used by the Intergovernmental Panel on
Climate Change (IPCC) to support the need for Kyoto are weak at
modelling changes in cloud cover. This matters acutely because
low-lying clouds cool the Earth by reflecting much of the incoming
sunlight back into space, while wispy, high clouds tend to trap heat.
Overall, clouds are likely a cooling influence, so anything that
diminishes cloud cover in general will indirectly warm the Earth,
especially if the reduction is mostly in lower clouds. Surprisingly,
increases in solar activity tend to reduce cloud cover, so solar
effects may be far more important than indicated by direct heating
To begin to appreciate the significance of the Veizer paper, it is
important to first understand how increases in the sun's activity
diminish cloud cover.
Clouds form more readily when tiny particles in our atmosphere,
known as aerosols, pick up electric charges and so act as more
effective nuclei for the collection of water droplets. Recent
theoretical and experimental studies demonstrate that galactic cosmic
rays -- high-energy particles that originate in deep space -- are one
of the sources that act to charge aerosols and thereby create more
low-lying clouds. So anything that reduces galactic cosmic rays hitting
the Earth will indirectly warm the planet.
This is where the sun comes in. When our star is more active, not
only does it give off more radiant energy that warms us, but it also
emits more solar wind -- a continuous stream of very high-speed charged
particles. These particles act to deflect the galactic cosmic rays that
would ordinarily hit the Earth, leading to less cloud formation and a
diminished cooling effect. In other words, the reduction in cloud cover
amplifies direct solar heating, so most of the past century's warming
may be completely natural and attributable to changes in the activity
of our sun. This would imply that carbon dioxide emissions have had
little effect, and will consequently have little impact in the future.
When the IPCC report was being written, specialists in the field
knew there was good evidence this natural amplification of the direct
heating effect of the sun could explain recent warming. However, the
IPCC left the idea aside under the label "Very Low Scientific
Understanding," partly because of the short length of time for which
good data existed. Even though the solar-cosmic ray climate link
appeared to many experts to be more meaningful than the CO2 climate
connection, skeptics of the cosmic ray theory have argued we are unable
to differentiate between the impact of CO2 and solar activity when the
only data we have was during a period when both were increasing in
Thanks to Veizer and Shaviv, the missing data now has been provided.
By analyzing the fossilized remains of seashells, Veizer has been
able to reconstruct the Earth's temperature record for the past
half-billion years, the period during which there have been
hard-shelled sea creatures. Surprisingly, this record displays a
repeating cycle of temperature increases and decreases every 135
million years, a period that corresponds with no known terrestrial
phenomena. Independently, Shaviv had determined galactic cosmic rays
striking the Earth have been varying with about the same periodicity
over an even longer time frame. Once Veizer and Shaviv made the
connection, they wondered whether they were looking at a reflection of
some sort of regular celestial phenomenon in the climate history of the
Indeed, it appears they were. Our solar system passes through the
bright arms of the Milky Way Galaxy with approximately the same
regularity as the long-term temperature changes Veizer had discovered.
And because interstellar matter bunches up in the galaxy's arms, we see
the birth of large, very bright, but short-lived stars that end their
lives as supernovas while still inside the arms, giving off powerful
bursts of galactic cosmic rays.
The changes in galactic cosmic ray intensity due to our passage
through the arms of the Milky Way are much larger than those caused by
variations in the output of our sun. Consequently, the corresponding
temperature variations were significant enough for Veizer to see in his
"seashell thermometers" even though they occurred hundreds of millions
of years ago.
So the process works like this:
- When we are in the bright arms of the galaxy, we are relatively
close to more supernovas, the galactic cosmic ray intensity is
consequently high, we therefore have more cooling clouds, and so we see
colder periods on the Earth;
- When we are out of the arms and galactic cosmic ray strength is low, there are less clouds and the Earth is warmer.
Veizer and Shaviv conclude that 75% of the temperature variability
in the last half-billion years is explained by cosmic ray changes as we
move in and out of galactic spiral arms.
Yet, over the same time frame, the geologic record shows essentially
no correlation between CO2 levels and temperature even though CO2
levels have been up to 18 times higher than today. In fact, CO2
concentration was more than 10 times higher than current levels during
the Ordovician glaciation, about 440 million years ago.
Veizer and Shaviv use their study results to conclude that a
doubling of today's CO2 levels would result in a change in low-latitude
sea temperatures of about 0.5C. This translates into a global
temperature rise of only about 0.75C instead of the 1.5-to-5.5C global
warming predicted by the IPCC. This new forecast compares favourably
with other predictions (e.g. MIT's Richard Lindzen, 1997) and matches
the rate of change observed by weather satellites over the past 22
Of course, all of this is fabulous news for normal Canadians and the
environment. This study, as well as many others that have come out
recently, support the contention that the IPCC's conclusions are
obsolete and the scientific rationale for Kyoto has evaporated. While
reducing the air pollution that threatens our health and damages the
natural world continues to be important, no sensible person wants to
throw billions down the drain fighting climate change if humanity has
essentially no impact.
Unfortunately, as Essex and McKitrick point out, the global-warming
"stage is populated by many people whose desire to save the world is
deemed an acceptable, even preferable, substitute for technical
This is no longer good enough. Parliamentarians, the media and
indeed all Canadians who want to play a role in the debate must quickly
learn more of the relevant science. Only then will we have a chance of
developing environmental policy that actually protects the environment
while sustaining human progress.
Dr. Tim Patterson, a professor in the Department of Earth Sciences at Carleton University, specializes in Paleoclimatology.