Hans Oeschger (2 April 1927, Ottenbach – 25 December 1998, Bern) was a Swiss climatologist.
The Oeschger counter, developed by his team, was a leading instrument for measuring the activity of naturally occurring radioisotopes (3H, 14C, 26Al, 37Ar, 39Ar, 81Kr, 85Kr).
He was a pioneer in ice core research, and in collaboration with his colleagues, he was the first to measure the glacial-interglacial changes in atmospheric CO2.
Along with Chester C. Langway and Willi Dansgaard, Oeschger documented a series of abrupt climate changes in the Greenland ice cores, now known as Dansgaard–Oeschger events.
Oeschger expressed concerns about the potential increase in the greenhouse effect due to rising CO2 levels.