Wallace Smith Broecker, a renowned scientist who raised early alarms about climate change and popularized the term “global warming” has died at the age of 87. The longtime Columbia University professor and researcher died at New York City hospital. Broecker had been ailing in recent months.

Broecker brought “global warming” into common use with a 1975 article that correctly predicted rising carbon dioxide levels in the atmosphere would lead to pronounced warming. He later became the first person to recognize what he called the Ocean Conveyor Belt, a global network of currents affecting everything from air temperature to rain patterns.

He was known in science circles as the ‘Grandfather of Climate Science’ and the ‘Dean of Climate Scientists.’ Broecker received the National Medal of Science in 1996 and was a member of the National Academy of Science.