A scientist who raised early alarms about climate change and popularised the term “global warming” has died.
Columbia University professor and researcher Wallace Smith Broecker died on Monday aged 87 at a New York City hospital, according to a spokesman for the institution’s Lamont-Doherty Earth Observatory.
Prof 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 temperature rises.
He later became the first person to recognise what he called the Ocean Conveyor Belt, a global network of currents affecting everything from air temperature to rain patterns.
“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 11C (20F) or more and London feeling more like Spitsbergen, Norway, which is 600 miles north of the Arctic Circle.
Prof 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.
Prof Broecker 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 popularised the notion that this could lead to a dramatic climate change ‘tipping point’ and, more generally, Broecker helped communicate to the public and policymakers the potential for abrupt climate changes and unwelcome ‘surprises’ as a result of climate change,” said Penn State professor Michael Mann.
“We live in a climate system that can jump abruptly from one state to another,” Prof 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.
Prof Broecker received the National Medal of Science in 1996 and was a member of the National Academy of Science.
He also served a stint as the research coordinator for Biosphere 2, an experimental living environment turned research lab.
Prof Broecker was born in Chicago in 1931 and grew up in suburban Oak Park.
He joined Columbia’s faculty in 1959, spending most of his time at the university’s laboratory in Palisades, New York.
He was known in science circles as the “Grandfather of Climate Science” and the “Dean of Climate Scientists”.
“His discoveries were fundamental to interpreting Earth’s climate history,” said Prof Oppenheimer.
“No scientist was more stimulating to engage with; he was an instigator in a good way, willing to press unpopular ideas, like lofting particles to offset climate change. But it was always a two-way conversation, never dull, always educational. I’ll miss him.”