Meet Harold S. Johnston

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Harold S. Johnston was a prominent American chemist who made several significant contributions to the field of atmospheric chemistry. 

Some of his greatest contributions and notable achievements include:

Johnston, together with A.O. Nier and H.M. Rosenstock, developed the mass spectrometer, an instrument used to measure the composition and abundance of chemical elements and isotopes in atmospheric samples.

Johnston and his colleagues conducted the first in-situ measurements of stratospheric ozone, which led to the discovery of the Antarctic ozone hole in the 1980s.

Johnston and his team developed the first reliable method for measuring atmospheric carbon dioxide levels, which helped establish the link between fossil fuel combustion and climate change.

Johnston authored a paper recognizing for the first time that exhaust from aircraft flying in the stratosphere could destroy the global ozone layer. 

He was awarded the Tyler Prize for Environmental Achievement.