Carbon dioxide emissions have been altering the climate since the Industrial Revolution, some 200 years ago, though it took us a while to figure that out. NASA scientist James Hansen first warned Congress about the dangers of greenhouse gases in 1988.
But an earlier climate warning came five decades previous, way back in 1938. That's when Guy Stewart Callendar, an engineer specializing in steam and power generation, published a paper that theorized that carbon dioxide emissions from industrial activity could have a greenhouse effect. His prescient paper appeared in the quarterly journal of the Royal Meteorological Society.