From reason.com
Stars in Her Eyes
Astronomer Sallie Baliunas on sunspots, global
warming, and the benefits of privately funded
science
An astronomer at the Harvard-Smithsonian Center
for Astrophysics in Massachusetts, Baliunas is
also the deputy director of the Mount Wilson
Institute in the San Gabriel Mountains north of
Pasadena, California. She spends about a week a
month on the West Coast, using Mount Wilson's
historic 100-inch telescope to study "sun-like
stars." Baliunas came to the observatory as a
graduate student in 1977.
.......
Sallie Baliunas: I'm interested in why the sun
has a regular cycle of magnetism. There's a
clock, so to speak. Sunspots come and go every 11
years, and the sun's energy output changes in
step with those changes in magnetism. The sun
also changes on longer time scales. That has an
influence on the earth's environment. So the
question is, Why does the sun do that? There is
no good basic theory that says why the sun would
have a magnetic clock.
Reason: So you look at other stars to try to
figure out what's going on with the sun?
Baliunas: Right. Here's an analogy. You're an
extraterrestrial and you come to Earth, and you
have 24 hours and you want to study the life
cycle of a human. You can do one of two things.
You can sit and follow one human for 24 hours and
watch tiny microscopic changes in that human, or
you can gather together a whole town and take
information and look at the commonality. You can
say, here's an infant and he needs to be taken
care of, and here's a kid, and here's a young
adult, and put together a picture of the human
life span that way. I look at what I call
"sun-like stars" at different phases of long-term
evolution. It's a great deal quicker than waiting
around for the sun to do something.
Reason: Have you gotten any interesting results?
Baliunas: It depends what time scale one is
talking about. The sun brightens and fades over
the sunspot cycle, the 11-year cycle. But also
the intensity of the 11-year cycles has been
building over the centuries.
Reason: What do you mean by "intensity"?
Baliunas: Looking back several hundred years, the
sun's magnetism is at an all-time high. The last
four peaks have been quite high.
Reason: Do these fluctuations produce a big
effect?
Baliunas: It's relatively small from cycle to
cycle, but we estimate that from the 17th century
to now it could have been four or five tenths of
a percent of the sun's energy output. Run that
through a climate model, and that's enough to
explain the temperature change.
Reason: Using the current models...
Baliunas: Using the current models...
Reason: Which you're not sure are right anyway...
Baliunas: Nobody's sure--all models have similar
problems.
We're saying [with] a few tenths percent change,
which we don't think is unreasonable for the sun,
you can explain everything. Now that's not the
only mechanism. That's the first one, which one
might think of as brightness change. There's some
new work coming out of Europe on clouds. The
amount of cloud coverage on the earth is changing
by a few percent every 11 years --it's
anti-phased with the cycle. The latest idea is
that it's the sun modulating the cosmic rays that
are coming in making nuclei of clouds.
So after looking at all these vast unknowns, I
then saw the key problem for the greenhouse
extremists. We always read about how the
temperature has warmed about a degree
Fahrenheit--a half degree centigrade--in the last
100 years. But if you look at the temperature
records, it's quite clear: All the warming occurs
early in the century. But most of the greenhouse
gases are put in the atmosphere after World War
II, in the last 50 years. So they can't cause
most of the warming of the last 100 years.
Something else had to. The sun's changes fit that
very well. That just may be a coincidence, but
that's what we're pursuing.
Reason: What has the sun's effect since 1940
been?
Baliunas: That's a harder question because we
consider changes of the sun on time scales of
several decades or more. So asking me what has
gone on since 1940 is almost at the limit of what
I'm looking at. If you want to look back over the
last 100, 200, or 300 years, it's a little easier
for me to talk about it.
Reason: Would this solar variability research say
anything about what would happen if we were
really to increase greenhouse gases in the
atmosphere a lot?
Baliunas: That experiment has been done. We've
increased the amount of greenhouse gases by an
equivalent of going halfway to a doubling of
carbon dioxide--and doubling is the benchmark
that everyone talks about. And then you look at
how the earth's temperature has responded, and it
has not warmed more than a tenth or two-tenths of
a degree. So a simple back-of-the-envelope
calculation says a doubling is a few tenths of a
degree. That's not significant, because it's not
noticeable above the natural background changes.
The real test of this is the last 20 years, with
very precise satellite measures of the earth's
temperature made globally. The global average
temperature of the atmosphere, just above the
surface of the earth, has not warmed at all.
There's been no warming trend in the past 20
years, and the models all say that there should
have been a warming of several tenths of a degree
centigrade in that time.
Reason: And the atmosphere has warmed at certain
levels.
Baliunas: No. There's been no warming in the
satellite data. There's been a cooling in the
lower stratosphere, and no warming in the lower
troposphere. And at the surface, I should mention
that the continental U.S. has very good
measurements over the last 100 years and there's
been no net warming there either.
Reason: How does this fit in with your solar
explanations?
Baliunas: We're trying to subtract the sun's
influence [from climate fluctuations caused by
other sources]. The sun is particularly good at
explaining this early 20th-century warming, which
can't have been caused by the greenhouse gases.
If we had a good prediction for what the sun
would do next, given the past calibrations that
we've done, we then could make a prediction. But
we're not at the point where we can predict what
the sun will do 50 years from now.
Reason: There was an International Panel on
Climate Change, whose results have been widely
disseminated. What do you think about the IPCC
report?
Baliunas: The IPCC report actually is very
careful to say that the models have not been
validated. That tells you that you can't make a
prediction with them. The executive summary says
that there's a discernible human influence, but
the information in the chapter on which that
conclusion was based has been overturned by the
scientific process. The report is obsolete.
Reason: What overturned it?
Baliunas: The executive summary's conclusion was
based on the results of new climate simulations
that made predictions both in three dimensions
and time. That's the way to go: Global warming
won't be uniform over the globe--certain areas or
different levels of the atmosphere will warm more
than others. So you look at the regions that are
supposed to warm first--for example, the Arctic
or, in the case of that report, a region of the
lower atmosphere over the southern hemisphere
oceans. And in the report, it was claimed that
there was good agreement between the theory and
the observations. But when that underlying paper
was published, it was very quickly overturned by
a longer stretch of data.
Reason: By whom?
Baliunas: One paper is by Pat Michaels and Chip
Knappenberger. That was published in Nature.
There had been a short uptick in the temperature
of that region, but when looking at a longer
temperature record that was both earlier and
later, it was seen that that uptick was just part
of a long-term null trend. So the models had
predicted wrongly. There had been no increase in
that area.
I have only cut small sections of the interview.
tom watson tosiwmee |
