Michael McElroy grew up in Belfast and earned a Ph. D. in applied mathematics from Queen’s University, where he famously solved ten test problems instead of the required three. His curiosity pushed him from planetary studies during the space race to deep investigations of Earth’s atmosphere.

At Kitt Peak National Observatory he created a theory describing upper atmospheres, earning the 1968 James B. Macelwane Medal for early career researchers. He then joined Harvard at age 31, becoming one of its youngest tenured professors.

McElroy’s work on ozone depletion linked bromine and nitrous oxide to the rapid formation of Antarctica’s ozone hole. This research helped shape the Montreal Protocol, a global treaty that phased out harmful chemicals.

He also warned in 1971 that rising carbon dioxide could trigger a runaway greenhouse effect, using Venus as an analog. His forward‑thinking ideas predated widespread concern about climate change.

McElroy collaborated with politicians, including Al Gore, and led a task force that used intelligence data to study climate‑related security risks. He founded Harvard’s Environmental Science and Public Policy concentration and the Harvard–China Project on Energy, Economy and Environment.

In 2024 he received the American Geophysical Union’s William Bowie Medal for lifetime contributions to Earth and space science. He retired from teaching in 2024 but continued his work with the Harvard–China Project, bringing scholars worldwide to study climate issues.

His legacy lives on through students, colleagues, and the policies he helped shape. He died of cancer at 86, leaving a family and a world that owes him much for his relentless pursuit of knowledge.

A Scientist Who Challenged the Skies

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