Friday » February 9 » 2007
Will the sun cool us?
The Deniers -- Part VII
Financial Post
Friday, February 02, 2007
January 12, 2007
The science is settled" on climate change, say most scientists in the
field. They believe that man-made emissions of greenhouse gases are heating the
globe to dangerous levels and that, in the coming decades, steadily increasing
temperatures will melt the polar ice caps and flood the world's low-lying
coastal areas.
Don't tell that to Nigel Weiss, Professor Emeritus at the Department of Applied
Mathematics and Theoretical Physics at the
Dr. Weiss believes that man-made greenhouse gases have recently had a role in
warming the earth, although the extent of that role, he says, cannot yet be
known. What is known, however, is that throughout earth's history climate
change has been driven by factors other than man: "Variable behaviour of
the sun is an obvious explanation," says Dr. Weiss, "and there is
increasing evidence that Earth's climate responds to changing patterns of solar
magnetic activity."
The sun's most obvious magnetic features are sunspots,
formed as magnetic fields rip through the sun's surface. A magnetically active
sun boosts the number of sunspots, indicating that vast amounts of energy are
being released from deep within.
Typically, sunspots flare up and settle down in cycles of about 11 years. In
the last 50 years, we haven't been living in typical times: "If you look
back into the sun's past, you find that we live in a period of abnormally high
solar activity," Dr. Weiss states.
These hyperactive periods do not last long, "perhaps 50 to 100 years, then
you get a crash," says Dr. Weiss. 'It's a boom-bust system, and I would expect
a crash soon."
In addition to the 11-year cycle, sunspots almost entirely "crash,"
or die out, every 200 years or so as solar activity diminishes. When the crash
occurs, the Earth can cool dramatically. Dr. Weiss knows because these
phenomenon, known as "Grand minima," have recurred over the past
10,000 years, if not longer.
"The deeper the crash, the longer it will last," Dr. Weiss explains.
In the 17th century, sunspots almost completely disappeared for 70 years. That
was the coldest interval of the Little Ice Age, when
The previous cooling period lasted 150 years while a minor crash at the
beginning of the 19th century was accompanied by a cooling period that lasted
only 30 years.
In contrast, when the sun is very active, such as the period we're now in, the
Earth can warm dramatically. This was the case during the Medieval Warm Period,
when the Vikings first colonized Greenland and when
No one knows precisely when a crash will occur but some expect it soon, because
the sun's polar field is now at its weakest since measurements began in the
early 1950s. Some predict the crash within five years, and many speculate about
its effect on global warming. A mild crash could be beneficial, in giving us
Earthlings the decades needed to reverse our greenhouse gas producing ways.
Others speculate that the recent global warming may be a blessing in disguise,
big-time, by moderating the negative consequences of what might otherwise be a
deep chill following a deep crash. During the Little Ice Age, scientists
estimate, global temperatures on average may have dropped by less than 1 degree
Celsius, showing the potential consequences of even an apparently small
decline.
Dr. Weiss prefers not to speculate. He sees the coming crash as an opportunity
to obtain the knowledge necessary to make informed decisions on climate change,
and the extent to which man-made emissions have been a factor.
"Having a crash would certainly allow us to pin down the sun's true level
of influence on the Earth's climate," concludes Dr. Weiss. Then we will be
able to act on fact, rather than from fear.
Lawrence Solomon is executive director of Urban Renaissance Institute and
Consumer Policy Institute, divisions of Energy Probe Research Foundation.
CV OF A DENIER:
Nigel Weiss, professor emeritus of mathematical astrophysics in the University
of Cambridge, discovered the process of "flux expulsion" by which a
conducting fluid undergoing rotating motion acts to expel the magnetic flux
from the region of motion, a process now known to occur in the photosphere of
the sun and other stars. He is also distinguished for his work on the theory of
convection, and for precise numerical experiments on the behaviour of
complicated non-linear differential equations. Nigel Weiss is a recipient of a
Royal Society Citation, he is a past President of the Royal Astronomical
Society, and a past Chairman of Cambridge's