After naming global warming the top science story of 2004, Discover received numerous questions from readers about the science. Glaciologists Waleed Abdalati and Jay Zwally of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, answer two of them.
Not long ago scientists were worrying about another ice age. What happened?
The idea that we might be entering another ice age was put forward in the 1970s by some scientists who noted a cooling trend in global temperatures from the 1940s to the 1970s. At that time, scientists were gaining a better understanding of climate cycles that occur because of slow changes in the shape and orientation of Earth’s orbit with respect to the sun. Scientists knew about the warming effects of greenhouse gases, but proponents of global cooling argued that greenhouse warming would be more than offset by Earth’s orbital changes. Some also argued that the effects of aerosols and ...
