Sun & Global warming
An interview with Dr Sallie Baliunas of the Harvard Smithsonian Center for Astrophysics
(This interview is recorded on several other web sites including

Here Comes the Sun to Further Cloud Global Warming Theory

Debate on the causes of predicted global warming usually revolves around climate models scientists construct. But can those models account for all the variables the universe has to offer? Not really, according to Dr. Sallie Baliunas of the Harvard Smithsonian Center for Astrophysics, who puts forth the sun as a variable not to forget.

ďThe science altogether is unsettled, but we know for sure that the models that make the predictions into the future are exaggerating the warmth,Ē Dr. Sallie Baliunas tells TechCentralStation Host James Glassman.

Baliunas points out that increases in magnetism at the center of our solar system correlate quite strongly with temperature rises here on Earth. She also notes the difficulty of this scientific enterprise saying, ďThere are something like 5 million parameters that have to go into a good climate model, and it has to compute for a time longer than the age of the universe if we wanted to know something.Ē

She and Glassman recently talked in Boston about the science, the uncertainty, and the sunís perhaps overlooked influence on climate change.

James K. Glassman: Dr. Baliunas, weíve heard that temperatures have increased on Earth over the last century. Now, is our assumption essentially that they had been stable before that?

Sallie Baliunas: The temperature of the Earth has increased over the last 100 years. We have instruments Ė thermometers -- at the surface of the Earth that tell us that. The warming began early in the 20th century, late in the 19th century. But before that, there was a very long, protracted cooling that began in the 14th century that continued to the mid 19th century -- a 500-year relative cold spell called the Little Ice Age. Before that, 800 or 1,000 years ago -- the early part of the second millennium -- the temperature was even higher than today, worldwide.

Glassman: So youíre saying there was global warming before the 20th and 21st centuries?

Baliunas: Yes.

Glassman: Well, they didnít have SUVs then?

Baliunas: No.

Glassman: Why was the Earth heating up?

Baliunas: One property of climate is change. The temperature of the Earth has changed dramatically in some cases. And itís changed relatively greatly in the last 1,000 years even.

Glassman: How can you tell?

Baliunas: The thermometers go back only about 100 years or so over some substantial portion of the Earth. Then we have to rely on other records, things that help us reconstruct the climate. For example, growth of tree rings is usually retarded during cold times or more advanced during warm times. So by boring into trees scientists can tell where there have been milder periods or cooler periods. And then there are many other indicators. Glaciers advance and retreat: mountain glaciers, polar glaciers. Coral growth rings tell us about the temperature of the ocean. There are many such indicators that go back thousands of years.

Glassman: So if there was global warming way back, way before the 20th century, and it wasnít the result of spewing gasses into the air, that is to say man-made global warming, then what caused it?

Baliunas: Thatís the big question. We need to answer the question: What are all the causes of climate change, natural climate change, that is, non man-made? Look back in time, before the time when most of the carbon dioxide had been put in the air, you still see natural changes of a degree or so over decades or centuries, which is on the order of what the 20th centuryís warming has been.

Now to answer your question: weíve been looking at changes in the sunís energy output, and we can estimate changes in the sunís energy output going back as far as 10,000 years by looking at tree rings, interestingly enough. And when we do that, we see the ups and downs of the climate of the last 1,000 years and even of the 20th Century match very well with the changes of temperature.

Glassman: In other words, what youíre saying is that because of activity on the surface of the sun, the Earth is warming up?

Baliunas: Right. When the sunís magnetism is strong, the sunís energy output is higher and the Earth is warmer. We see that as a fact. We measured that carefully over the last 20 years with satellites from the Earth, and we measured it indirectly going back 400 years, 1,000 years, and 10,000 years.

Glassman: So in effect there are times when the sun is warmer than at other times?

Baliunas: Yes, and that warmth means the climate of the Earth warms.

Glassman: Now, have you actually correlated the activity of the sun with this magnetism that youíre talking about, with the rise of temperatures on Earth?

Baliunas: Yes, the correlation is very strong. For the temperature records going back on Earth, we can reconstruct the northern hemisphere about 250 years or so. And the ups and downs of temperature match almost exactly the up and downs and change in magnetism, and so, the energy output of the sun. As the sun warms or cools, the Earthís temperature is responding. And it doesnít take much of a change of the sun either -- only about a few tenths of a percent of its energy output -- to cause these temperature swings.

Glassman: So, for example in the 1300s was there a period of global warming, climate change with temperatures rising? Was there solar activity then?

Baliunas: With records going back 1,000 years of solar magnetism, and the warm period certainly was in effect from about the years 1000 to 1200, maybe 1300 was about the edge of it, then there started a cooling. That 200- or 300-year period, the sun was much more active, magnetically, and we think, therefore, much brighter energetically than it is today. And then the magnetism declined into a long period of very low magnetism, lower energy output, and in step with these major changes in the Earthís climate over the last thousand years.

Glassman: Has there been solar activity over the last hundred years that would correlate with the temperature on Earth?

Baliunas: Yes, it correlates almost exactly with the temperature on Earth. The sun is as magnetically active as itís been in our direct telescope records of the sun since the days of Galileo. So the magnetism of the sun has been rising gradually, and it was especially sharp early in the 20th century, coincident with this rise in temperature on the Earth.

Glassman: Now there were declining temperatures from the 1940s through the mid-70s. Was there a lack of magnetism?

Baliunas: Yes, from about the 1930s, the 1940s the sunís magnetism waned a little bit and has since picked up a little bit.

Glassman: What youíre saying is that solar activity is causing global warming?

Baliunas: We are looking to find all the causes of natural change of the climate of the Earth, the sun being one of them. That way we can subtract out the natural changes and look for the human signal. We see, essentially, no signal of human activity.

Most of the changes that we see line up with the changes in the sun. Now thereís some uncertainty, so there may be a human signal. But if there is, itís quite tiny.

Glassman: What do your colleagues think of this idea?

Baliunas: Itís very interesting. Many of the climate models now try to incorporate the effect of the sun on them. Our next stumbling block is what exactly is the mechanism for change on the sun, and how does the Earth respond to that?

We think first of changes in the total energy output of the sun, but thatís not the only way the sun changes. Different wavelengths of light are changing, and there are also high energy particles coming out of the sun, changing in step with magnetic changes. Some scientists have thought that those particles, for example, produce changes in cloud cover on Earth and change the temperature. We have to understand that before we can make a good estimate of what the sunís impact is. Right now everyone is struggling with the causes.

Glassman: Your colleagues, fellow astrophysicists, donít say, ďOh, this is some sort of silly ideaĒ?

Baliunas: No, astronomers know the sun is a variable star.

Glassman: But, apparently, a lot of journalists or a lot of people who politicize this issue donít understand that?

Baliunas: They donít understand it, yeah. But itíll take time for their education.

Glassman: Let me ask you about ice at the North Pole. According to the global warming theory, it should be melting rapidly. But you say that ice isnít cooperating with that theory?

Baliunas: No, neither ice nor temperature is cooperating with the model predictions. Youíre so right that the models, the computer output say that the North Pole should be warming dramatically and rapidly. It hasnít been. Itís really been cooling. Ice packs have been growing. Thereís just been no evidence that the Poles have been warmer. And to go look at, say, cracks in the ice or the calving of an iceberg and then to work backwards from that and say that has a human cause, thatís just bad logic.

Glassman: I have read articles in the New York Times and elsewhere about the observation of some icebreakers saying, ďWow, thereís doesnít seem to be as much ice up here.Ē Youíre saying that thatís not a very good way to look at it.

Baliunas: No, those observations have been overturned. Thereís just been a paper published about sea ice thickness in the North Pole and temperatures. If the issue is temperature, looking at the ice is a proxy for temperature. But ice can change for reasons other than temperature. It can change because precipitationís changed. Some of the models, in fact, say that sea ice should be growing as the polar regions warm a little bit because itís so cold at the North Pole that a little warming drives more precipitation.

Glassman: As a scientist, how do you react to journalistic coverage of this issue?

Baliunas: I try to read it all because people want to know the answer. But thereís a sociology to journalism that I donít subscribe to, and so Iím not a journalist. That sociology is that scary stuff sells newspapers.

Glassman: And youíre a scientist, so you want to find out whatís really going on?

Baliunas: Scientists have to go by the facts.

Glassman: How much warming have we actually seen in the last 100 years?

Baliunas: Thereís been about a half a degree centigrade or a degree Fahrenheit warming. Most of that warming occurred early in the century, before the greenhouse gasses by human activities were added to the atmosphere.

Glassman: And is this the first time weíve ever seen warming on this planet?

Baliunas: Oh no. (laughs) No. There have been times -- the warming in the late 19th century, especially in the high polar regions -- that canít be caused by the human-induced greenhouse gasses. That was much stronger than any warming weíve seen in recent decades. Now with ice core records -- drilled in the high latitudes and polar regions to pull up a hundred thousand, two hundred thousand years of ice core layers that tell the temperature Ė thereís some warmings and coolings there over decades that are astonishing: several degrees. Not man-made.

Glassman: And when you say every decade, youíre talking about thousands of years ago or hundreds of years ago?

Baliunas: Some of these episodes during the Little Ice Age, for example, were just several hundred years ago.

Glassman: If there is an increase in temperature, and as you say it has been a half a degree over the past century, people are worried that maybe that is the beginning of a big acceleration of temperature. Do you think the science is settled at this point about whether weíll have any more global warming?

Baliunas: I think the science is settled that the predictions are exaggerated. There is maybe some human-made warming, but itís going to be so small that itís going to be lost in the natural variability. And thatís the conclusion from science.

The acid test of all this is the last 22 years of satellite measurements made of the lower layer of air of the Earth. That layer of air should be warming quite rapidly. Itís where the carbon dioxide greenhouse effect should be taking place. That layer there has not seen a big warming trend. Itís seen ups and downs but thereís been no net trend. That layer of air has to warm first according to the models. Then it, in turn, warms the surface. Now weíve seen a little bit of warming of the surface, but it canít be caused by that carbon dioxide effect in that atmospheric layer, which shows no warming. You canít bypass the lower layer of air and warm the surface by carbon dioxide effect. So the satellite measurements, which are precise and validated by independent balloon measurements everyday, say that there has been no effect that we can see and, therefore, the future effect is going to be minimal.

Glassman: As far as the causes of this one-half degree increase are concerned, do scientists in your field, really the climate scientists, have a settled conclusion as to why thatís occurred?

Baliunas: No. I think right now everyoneís looking at the sun as one reason, but there are issues of the ocean, ocean circulation, ocean changes on time scales of decades to centuries. And we donít understand that. We donít understand the mechanism for the sun. Thereís still many surprises left.

Glassman: Would you say, in general, that at this point the science is unsettled?

Baliunas: The science altogether is unsettled, but we know for sure that the models that make the predictions into the future are exaggerating the warmth.

Glassman: If we could somehow find a way to reduce CO2 in the atmosphere without slowing our economy, which is a big if, are we certain that that would actually help us in terms of reducing global warming?

Baliunas: Thatís an interesting question. There certainly is a technology that is easy and affordable, itís just not politically palatable. And that is nuclear power. Nuclear power produces no carbon dioxide. We know how to build nuclear power plants, it just seems to me culturally and politically unforeseeable in the future. So, that would do it without wrecking the economy while still having growth in energy use.

The other question is much more important. If you put all these resources into mitigating a problem, what other problems are you taking those resources from? Since we canít see a human-made carbon dioxide signal where there should be one, it means that the carbon dioxide effect from human activities must be quite small.

Glassman: Letís say everyone stopped emitting any greenhouse gas. All human greenhouse gasses were just halted. Do you think that itís still possible to have global warming?

Baliunas: Yes. If the causes of global warming are not owing to human activities, then the climate will continue on its course of change. It may be solar, it may be related to the oceans, it may be internal to the Earthís climate. So the fact that we stop emitting carbon dioxide will do nothing to change the course of the climate. Thereís one interesting related issue, which is carbon dioxide in the air in recent decades has produced a tremendous agricultural boon. There have been estimates of at least a 10 percent efficiency increase. So plants have been growing quicker, better, greener. Crops have been growing better. This has been for free, essentially. So cutting carbon dioxide means we lose that increase in efficiency that weíve gained.

Glassman: But back in 1100, 1200 we saw a rise in the temperature of the Earth, even though, I guess we can assume there werenít a lot of greenhouse gasses being emitted by people in the Middle Ages.

Baliunas: Thatís right, absolutely. In the 10th, 11th century, it looks to me like the sunís energy output rose and thatís really what caused the warming back then. If youíre a student of history, youíll know that was a great time of expansion in Europe: town building, city building, university building, church building, trade, because the climate was really benign.
Glassman: How long do you think it will be until weíll actually be able to say, in a conclusive way, what has caused the warming thatís occurred in the last century?

Baliunas: Thatís a very hard question and I really, I really donít know. Every few years everyone says that another 10 years of research and weíll know. But weíve been saying that for 10 or 20 years now.

Glassman: Has anyone brought forth any evidence that says, ďDr. Baliunas says thereís a correlation between magnetic activity of the sun and the rise of temperature on Earth, but this, that and the other disproves thatĒ?

Baliunas: I donít see how you canít disprove the correlation. The next step is for us to find the mechanism for that correlation. The correlation is only the starting point. It may be that itís a coincidence that these two things have changed together.

Glassman: But that would be quite a coincidence?

Baliunas: It seems odd because we have some mechanisms that look like they might explain it. We now have to prove that.

Glassman: Iíve read a lot about how humans are going to be causing a dramatic warming. A recent summary of a UN report forecast possible floods and extreme weather and outbreaks of malaria -- incredible predictions.

Baliunas: Theyíre not credible, as the scientific report states. To get an estimate of what climate is going to be by region is not possible region by region. And you canít look at those outcomes like floods and storms. Models have no ability to sees storm fronts, for example. So they canít predict storminess. It even brings up the point about how credible the average temperatures are, globally -- those that are often quoted. Global averages are made out of region-by-region averages, which are admittedly incorrect -- wrong in some cases by 11 degrees centigrade over portions of the United States. Rainfall is wrong by 200 percent in some areas. So averaging out all of those mistakes canít possibly give you anything reliable, even in the global average.

Glassman: We know how difficult it is to predict the weather for tomorrow; so, how are we going to predict the climate 100 years from now?

Baliunas: Thatís exactly the problem. Predicting the weather is done on a very small scale. We have to try to do that globally, but we canít do that because the computer power isnít available. We also donít have the knowledge of what changes in the climate. So we have to make some assumptions and guesses. There are something like 5 million parameters that have to go into a good climate model, and it has to compute for a time longer than the age of the universe if we wanted to know something. So we canít. We have to make simplified assumptions. We know those assumptions are wrong. We know the outcome doesnít match up with reality.

Glassman: Frequently we hear the press and politicians jump on an issue that relates to science and blow it all out of proportion. The recent Y2K crisis was a good example. But I think weíve seen something else related to climate. About 25 years ago, werenít people talking about something else happening in the climate?

Baliunas: Weather and climate are important issues for humans. Near the 1940s, the temperature reached a maximum and then began to decline. And by the 1970s, it looked like it might be a crisis. So there were scientists saying that the ice age was coming, in part aggravated by soot and smokestack emissions that were also being looked at around that time.

Glassman: So these smokestack emissions were supposedly blocking the sun? Is that right?

Baliunas: Right. The smokestack emissions, the soot causes a shading effect of sunlight. So it was thought that they may be producing that 1970s cooling. This probably isnít so. Nonetheless, there was a huge cry that, perhaps, the next major glaciation was occurring -- which really would be serious.

Glassman: Whatever happened to those people who were talking about global cooling?

Baliunas: Oh, they then looked at their models, added carbon dioxideís effect and then began to talk about global warming.

Glassman: So they went from global cooling to global warming in a very short period of time?

Baliunas: Many of them did, yes.

Glassman: Looking back at the global cooling scare, I guess itís good we didnít try to fix that one?

Baliunas: No, I donít know how youÖ we could not have fixed that problem. And Iím not sure we can fix the carbon dioxide problem, whose evidence canít be seen.

Glassman: Now, isnít it also true that some leaders of the global warming movement were also highly active with the global cooling movement?

Baliunas: I guess for some people you just canít lose.