How was global warming discovered?

There was no one discoverer of global warming as such. As is common in science there was a gradual accumulation of evidence by many scientists.

Early discoveries about climate change (American Institute of Physics - the discovery of global warming)

1824

Jean-Baptiste Fourier calculates that the Earth would be far colder if it lacked an atmosphere.

1859

John Tyndall discovers that some gases block infrared radiation. He suggests that changes in the concentration of the gases could bring climate change.

1896

Svante August Arrhenius publishes first calculation of global warming from human emissions of CO2

1897

Thomas Chrowder Chamberlin produces a model for global carbon exchange including feedbacks.

1930s

Global warming trend since late 19th century reported.

Milankovitch proposes orbital changes as the cause of ice ages.

1938

Guy Stuart Callendar argues that CO2 greenhouse global warming is underway reviving interest in the question.

First warnings about climate change (Directgov - a history of climate change)

From the late 1950s, carbon dioxide (CO2) measurements were made on a mountain top in Hawaii. Over the next decade, these measurements confirmed that levels of CO2 in the atmosphere were rising year on year. In 1967, an early computer simulation suggested that global temperatures might increase by more than 4 degrees Fahrenheit, depending on CO2 levels.

Improved climate models developed over the next 20 years confirmed the link between CO2 emissions and global warming. Then an ice core from Antarctica first revealed a link between carbon dioxide levels and temperature going back more than 100,000 years. Warnings like these encouraged international action on climate change.

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The individual that is considered to be the founder of global warming is Doctor Hansen from the GISS. Prior to his claim of the planet's warming in 1984, the common consensus in the science community was that the planet was steadily cooling. From 1934 until the late eighties, the planet had steady and consistent cooling for the entire period. This ran is stark contrast to the past 10,200 years of steady warming since the last ice age. Total warming before man strted burning his first piece of coal was over eleven degrees C. From 1934 until 1978 we saw almost 0.5 degrees of cooling. This was coupled with our increased use of fossil fuel and the fact that CO2 always follows temperature to provide "proof that man's use of fuel was cooling the planet.