A NASA Scientist Explains Greenhouse Effect (1990)

This PBS NewsHour report about the greenhouse effect provides a useful window into the state of scientific inquiry and public discourse about climate change in 1990. The report includes footage of congressional testimony from NASA scientist James Hansen, who was among the early figures sounding the alarm about climate change, and includes a helpful, if slightly simplified, explanation of the greenhouse effect. Also indicative of the time period are the focus on chlorofluorocarbons from aerosol sprays (CFCs became a much smaller concern after their use was sharply limited in the 1990s) and the identification of methane as a relatively unimportant greenhouse gas (methane is now considered a quite significant factor driving climate change). The report states that Hansen’s claims caused “controversy,” and that “most climatologists felt” he had “jumped the gun.” But by the 21st century, Hansen’s argument that the greenhouse effect was resulting in global temperature change represented the overwhelming scientific consensus.

The MacNeil/Lehrer NewsHour | NewsHour Productions | April 17, 1990 This video clip and associated transcript appear from 11:18 - 14:06 in the full record.