<human>:  Who was the first person to propose the idea that the earth was warming?
<bot>: The first person to propose the idea that the earth was warming was Svante Arrhenius in 1896. Arrhenius was a Swedish chemist who was the first to describe the concept of greenhouse gases and the effect they have on the atmosphere. He also proposed that the warming of the planet was caused by the increase in greenhouse gases in the atmosphere.