Baliunas received her M.A. (1975) and Ph.D. (1980) degrees in Astrophysics from Harvard University. Her scientific awards include the Newton Lacy Pierce Prize in Astronomy from the American Astronomical Society, awarded in 1988. She also received the Derek Bok Public Service Prize from Harvard University. In 1991 Discover magazine profiled her as one of America's outstanding women scientists.
She has also received a political award, the Petr Beckmann Award for Scientific Freedom from Doctors for Disaster Preparedness, a body associated with the Oregon Institute of Science and Medicine in recognition of her work criticising the theory of global warming.
Baliunas's main focus is on astrophysical research. She studies visible and ultraviolet spectroscopy of stars; structure, variations, and activity in cool stars; evolution of stellar angular momentum; solar variability and global change; adaptive optics; exoplanets of Sun-like stars.
In 1992, Baliunas was third author on a Nature paper that used observed variations in sun-like stars as an analogue of possible past variations in the Sun. The paper says that
More recently she has moved into the global warming area as a skeptic. The work of Willie Soon and Baliunas, suggesting that solar variability is more strongly correlated with variations in air temperature than any other factor, even carbon dioxide levels, has been widely publicized by lobby groups including the Marshall Institute and Tech Central Station, and mentioned in the popular press. However, her viewpoint — that solar variation accounts for most of the recent climate change — is not widely accepted among climate scientists.
Baliunas is a strong disbeliever in a connection between CO2 rise and climate change, saying in a 2001 essay with Willie Soon:
The claim that atmospheric data showed no warming trend was incorrect, as the published satellite and balloon data at that time showed a warming trend (see satellite temperature record). In later statements Baliunas acknowledged the measured warming in the satellite and balloon records, though she disputed that the observed warming reflected human influence.
Baliunas contends that findings of human influence on climate change are motivated by financial considerations: "If scientists and researchers were coming out releasing reports that global warming has little to do with man, and most to do with just how the planet works, there wouldn't be as much money to study it. Baliunas' own research is funded in part by NASA, the Air Force Office of Scientific Research, the National Oceanic and Atmospheric Administration, and the American Petroleum Institute.
In 2003, Baliunas and Astrophysicist Willie Soon published a review paper on historical climatology which concluded that "the 20th century is probably not the warmest nor a uniquely extreme climatic period of the last millennium." With Soon, Baliunas investigated the correlation between solar variation and temperatures of the earth's atmosphere. When there are more sunspots, the total solar output increases, and when there are fewer sunspots, it decreases. Soon and Baliunas attribute the Medieval warm period to such an increase in solar output, and believe that decreases in solar output led to the Little Ice Age, a period of cooling from which the earth has been recovering since 1890.
Shortly thereafter, 13 of the authors of papers cited by Baliunas and Soon refuted her interpretation of their work. There were three main objections: Soon and Baliunas used data reflective of changes in moisture, rather than temperature; they failed to distinguish between regional and hemispheric temperature anomalies; and they reconstructed past temperatures from proxy evidence not capable of resolving decadal trends. More recently, Osborn and Briffa repeated the Baliunas and Soon study but restricted themselves to records that were validated as temperature proxies, and came to a different result.
Half of the editorial board of Climate Research, the journal that published the paper, resigned in protest against what they felt was a failure of the peer review process on the part of the journal. Otto Kinne, managing director of the journal's parent company, stated that "CR [Climate Research] should have been more careful and insisted on solid evidence and cautious formulations before publication" and that "CR should have requested appropriate revisions of the manuscript prior to publication.
Baliunas earlier adopted a skeptical position regarding the hypothesis that CFCs were damaging to the ozone layer. The originators of the hypothesis, Paul Crutzen, Mario Molina and Frank Sherwood Rowland, were awarded the Nobel Prize for Chemistry in 1995. Her arguments on this issue were presented at Congressional hearings held in 1995 (but before the Nobel prize announcement).
Although Baliunas never publicly retracted her criticism of the ozone depletion hypothesis, an article by Baliunas and Soon written for the Heartland Institute in 2000 promoted the idea that ozone depletion rather than CO2 emissions could explain atmospheric warming.