In September 1933, American meteorologist Joseph Kincer asked a simple question: is the climate changing? So began the effort to understand the scope of humanity’s interference with the climate.
By examining trends in measured temperatures at many different locations around the world, Kincer concluded that the world was getting warmer, but did not suggest a reason. A few years later in 1938, British engineer Guy Callendar showed that Earth’s land temperatures had warmed by about 0.3°C in the previous 50 years.
