Air conditioning
In 1902, the first modern electrical air conditioning unit was invented by Willis Carrier in Buffalo, New York. After graduating from Cornell University, Carrier found a job at the Buffalo Forge Company. There, he began experimenting with air conditioning as a way to solve an application problem for the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York. The first air conditioner, designed and built in Buffalo by Carrier, began working on 17 July 1902.
Guy Stewart Callendar
Guy Stewart Callendar (; February 1898 – October 1964) was an English steam engineer and inventor. His main contribution to knowledge was developing the theory that linked rising carbon dioxide concentrations in the atmosphere to global temperature. This theory, earlier proposed by Svante Arrhenius, has been called the Callendar effect. Callendar thought this warming would be beneficial, delaying a "return of the deadly glaciers."