Feldman: When did your work in solar-terrestrial science begin; in what area were you working; what led you to choose this field?
Schatten: As a graduate student at Berkeley, I turned away from particle and nuclear physics, because the field seemed to be involved with a mass production of science with little room for individuality. This is exemplified by numerous papers with massive numbers of scientists on the authorship list, etc. The young field of solar terrestrial physics had a lot of new, interesting, yet poorly understood phenomena which to study. They excited my interest to study this developing field of science. I also did not buy the standard particle physicist's view in the supremacy of the "reductionist" philosophy - ie. That if we only understand the basic case of something, we can understand the whole as a sum of its parts. This is a little bit like saying we can understand human beings or society, by only understanding elementary particles. The whole is greater than the sum of its parts. When we understand non-linear phenomena, we can now understand that sometimes understanding the parts provides virtually no help in understanding the whole!
Feldman: At what point did you shift towards the question of solar variability and climate change? Did the publication of Eddy's paper play a role? At that point in time, what were the field's strengths and weaknesses? How convincing was the case for a solar influence on climate change? What impact did Eddy's publications have on the field?
Schatten: I would say my move towards solar variability and its influence on climate was motivated by factors beyond Eddy's work. Jack Eddy did have a major influence on the field. His work with the Maunder Minimum and the "little ice age" certainly captivated interest in the field. Nevertheless, the work of Willson and Hudson, which first showed the "solar constant" (the light output of the Sun observed at Earth) was varying, played an equal role in motivating me personally into the field. Two areas of research, which I engaged in stand out to me. 1) With Sabatino Sofia and Ludwig Oster, we developed equations to show that the brightness effects of faculae were comparable to the diminished light output from sunspots. Later we showed that the effects of active regions at high solar latitudes would be quite different from the effects near the solar equator where the Earth predominantly resides. 2) Secondly with Hans Mayr, I investigaed why some solar magnetic fields form sunspots, and are dark, and others form faculae, and are bright. Although sometimes sunspots had been popularly known as solar hurricanes, we actually showed that there is a scientific basis to this view. We calculated the enormous amount of solar convective energy flowing into a sunspot. This torrent of energy could be quenched through an inflow and downflow of neutral hydrogen originating near the cool solar surface and flowing into the interior of the Sun below the sunspot. In this way, the latent energy of ionization would offset the eddy heat transport, and make a sunspot an "inverse Ion-Hurricane." Such flows are only now being detected through helioseismology.
Feldman: What did the Boulder conference of 1978 contribute to the field; what motivated calling the conference at that particular time? What role did you play in the conference?
Schatten: To me, a few conferences stand out, that I attended. One was an early conference in the early 70's in Pasadina, where the effects of faculae, and "energy balance" in active regions were discussed. There were a number of conferences in Boulder. The one run by Donnelly on solar predictions was, to me, pivotal. Notable was the work by the Russian geophysicist, Ohl, from which the modern methods of solar activity forecasting that I, and others engage in was presented. Additionally, at that conference, I chaired the session on Sun-Weather connections. A key paper, which had political ramifications, and some actually preferred not be considered so prominently, was a small study by Schaffer and Volland. It showed that many Sun-Weather effects could be explained by the enhancement of statistical correlations associated with common periodicities and persistencies in both the terrestrial and solar "weather" systems. This can lead to a breakdown in the statistical assumption of data independence, which the unwary scientist fails to realize when s/he applies standard statistical formulae. I have seen and reviewed numerous papers with this error in it. Feldman: What purpose did you have in mind for the book you co-authored with Doug Hoyt, Solar Variability and Climate Change (1997)? Has the book been successful?
Schatten: I can't really speak for Doug. My feeling that there is some "Sun-Climate" influences that are not well understood, but that it does not explain the recent global warming trend, which likely is anthropogenic. Nevertheless, I really wanted to move away from an advocacy presentation ( pro or con ) and move towards presenting a balanced picture. This would then capture both the views of the zealous researchers for solar influences, as well as the criticisms of the staunch detractors. Both sides have much to say, and I felt the book would be interesting if it captured the flavor and excitement of the field. I tried to ensure that the book really be balanced. Additionally, I also felt that solar influences are not physically understood; that solar energy may do more than simply "add energy," which is how many climate models treat solar influences. I had some personal views on how solar activity may act as a Greenhouse agent, by adding energy into the Earth's stratosphere, and this may, through chemical and structural changes in the atmosphere, allow changes in the opacity to occur, which are unmodeled in climate models. Yet, I felt that to even discuss my personal views would be to present a slanted view, so this aspect was not included in the book, to ensure the book was as objective as we could make it. Nevertheless, we did focus on the solar irradiance as the main driver of solar influences, as opposed to the particle inputs into the terrestrial system, however, most researchers in the field, feel similarly, because the energies are so disparate (factor of 10 **5 to 10 ** 6), and the solar irradiance affects the average stratosphere and troposphere, whereas the particle influences generally are further out, except for the cosmic radiation.