It might seem strange to say it, but I am a global warming skeptic because of Carl Sagan. This might seem strange because Sagan was an early promoter of the theory that man-made emissions of carbon dioxide are going to fry the globe. But it’s not so strange when you consider the larger message that made Sagan famous. As with many people my age, Sagan’s 1980 series “Cosmos,†which aired on public television when I was eleven years old, was my introduction to science, and it changed my life. “Cosmos&88221; shared the latest developments in the sciences of evolution, astronomy,...