The climate scientist who popularized the term "global warming" has died. Wallace Smith Broecker was 87.

Columbia University said the longtime professor and researcher died Monday at a New York City hospital. A spokesperson for the university's Lamont-Doherty Earth Observatory said Broecker had been ailing in recent months.

Broecker brought the term "global warming" into common use with a 1975 paper that correctly predicted rising carbon dioxide levels in the atmosphere would lead to pronounced warming.

Broecker was also first to recognize what he called the Ocean Conveyor Belt, a global system of ocean currents circulating water and nutrients.

"Wally was unique, brilliant and combative," said Princeton University professor Michael Oppenheimer. "He wasn't fooled by the cooling of the 1970s. He saw clearly the unprecedented warming now playing out and made his views clear, even when few were willing to listen."

In the Ocean Conveyor Belt, cold, salty water in the North Atlantic sinks, working like a plunger to drive an ocean current from near North America to Europe. Warm surface waters borne by this current help keep Europe's climate mild.

Otherwise, he said, Europe would be a deep freeze, with average winter temperatures dropping by about 11 degrees or more and London feeling more like Spitsbergen, Norway, which is nearly 1,000 km north of the Arctic Circle.

Broecker said in 1997 that by dumping huge amounts of greenhouse gases into the atmosphere, 'we are conducting an experiment that could have devastating effects.' (Gregorio Borgia/Associated Press)

Broecker said his studies suggested that the conveyor is the "Achilles heel of the climate system" and a fragile phenomenon that can change rapidly for reasons not understood. It would take only a slight rise in temperature to keep water from sinking in the North Atlantic, he said, and that would bring the conveyor to a halt. He said it is possible that warming caused by the buildup of greenhouse gases could be enough to affect the ocean currents dramatically.

"Broecker single-handedly popularized the notion that this could lead to a dramatic climate change 'tipping point' and, more generally, Broecker helped communicate to the public and policy-makers the potential for abrupt climate changes and unwelcome 'surprises' as a result of climate change," said Penn State professor Michael Mann.

'Playing with an angry beast'

"We live in a climate system that can jump abruptly from one state to another," Broecker told The Associated Press in 1997. By dumping into the atmosphere huge amounts of greenhouse gases, such as carbon dioxide from the burning of fossil fuels, "we are conducting an experiment that could have devastating effects."

"We're playing with an angry beast — a climate system that has been shown to be very sensitive," he said.

Broecker was born in Chicago in 1931 and grew up in suburban Oak Park.

He joined Columbia's faculty in 1959 and was known in science circles as the "grandfather of climate science."

He was presented with the National Medal of Science by former U.S. president Bill Clinton in 1996 and the Tyler Prize for Environmental Achievement in 2002.