Sallie Baliunas

About the author: Sallie Baliunas is an astrophysicist at the Harvard-Smithsonian Center for Astrophysics and deputy director of the Mount Wilson Observatory. She is also chair of the Science Advisory Board at the George C. Marshall Institute in Washington, D.C.

Humanity's use of fossil fuels, which produces heat-absorbing gases such as carbon dioxide and methane, does not significantly contribute to global warming. Most of the global warming during the twentieth century occurred before 1940, even though the levels of human-produced carbon dioxide increased greatly after 1940. Moreover, climate forecasts drawn from computer simulations— which tend to predict an acceleration of global warming for the future —are highly unreliable. For example, no warming of the lower troposphere (the atmosphere between 5,000 and 28,000 feet) has been recorded, even though climate simulators indicated that tropospheric warming should have already...