We’ve known for years that global warming could lead to a new ice age. Why is no one doing anything?

Previously published at WGBH News.

Call it a cascade of calamitous events.

According to scientists, a “cold blob” of water has formed south of Greenland. The blob’s origins can be traced to rapidly melting glaciers, which in turn is the consequence of global warming. The blob could impede the flow of the Gulf Stream, which carries warm water north. And if that happens, the temperature in Europe may drop steeply, hurricanes may become more intense, and sea levels on the East Coast of the United States may rise even more rapidly than they are already.

“We’re all wishing it’s not true,” Peter de Menocal, a scientist at the Woods Hole Oceanographic Institution, told The New York Times earlier this month. “Because if that happens, it’s just a monstrous change.”

A monstrous change indeed — and one that we’ve known about for decades. The possibility that climate change could flip and, in just a matter of years, plunge part of the world into a new ice age is something that has occasionally made its way into the media. Yet the world has done very little about it. Massive amounts of greenhouse gases are still being pumped into the atmosphere. The climate is getting warmer and weirder.

So let’s turn the wayback machine to January 1998. That’s when The Atlantic, known then as The Atlantic Monthly, published a cover story called “The Great Climate Flip-Flop” by William H. Calvin, a theoretical neurophysiologist based at the University of Washington in Seattle.

Calvin’s article made an indelible impression on me — so much so that I’ve been storing it somewhere in the back of my head for all these years. After the Times published its recent story on the cold blob, I dug up Calvin’s article from a library database so I could see how they compared. The match was chilling, so to speak.

“Of this much we’re sure: Global climate flip-flops have frequently happened in the past, and they’re likely to happen again,” Calvin wrote. “It’s also clear that sufficient global warming could trigger an abrupt cooling in at least two ways — by increasing high-latitude rainfall or by melting Greenland’s ice, both of which could put enough fresh water into the ocean surface to suppress flushing.” (“Flushing” is a reference to the process by which the Gulf Stream carries warm water to the north, sinks to the bottom of the ocean, and returns as cold water to the south.)

Calvin’s article is filled with frightening details, including evidence that natural global warming in millenia past triggered ice ages in exactly the same way he was warning us about. Of course, those previous warm spells were not accelerated by human activity. Calvin also suggested that the flip-flop would not be gradual; once under way, it could wreak its havoc in just a few years.

As for what would happen in the aftermath, Calvin foresaw starvation, a population crash, and powerful countries invading poorer ones in order to commandeer their food supplies. “The effects of an abrupt cold last for centuries,” he wrote. “They might not be the end of Homo sapiens — written knowledge and elementary education might well endure — but the world after such a population crash would certainly be full of despotic governments that hated their neighbors because of recent atrocities. Recovery would be very slow.”

Unfortunately, the effect Calvin’s article had on me did not extend to anyone with the power and influence to do something about it.

For instance, consider the reaction of the late Michael Kelly, who took over as The Atlantic’s editor about a year after Calvin’s story was published. Kelly threw a party at the magazine’s headquarters in Boston — can we agree that it never should have been moved to Washington? — and I brought up Calvin’s work, perhaps hoping that Kelly was as energized as I was by it and was planning to run some follow-ups.

“Interesting if true” is how I recall his semi-dismissive reaction. He was hardly alone, of course.

So now scientists are actually taking measurements of what’s happening with the Gulf Stream, and the Times is taking notice. Its story was accompanied by a vibrant multimedia treatment, but the message was muddled. Data show that Europe might actually get warmer rather than colder. Or maybe Europe will get colder, but that “might ultimately be muted or possibly canceled out by continued global heating.”

This is good, careful reporting, reflecting the work and words of scientists who are by nature cautious. And yet all of it seems insufficient given the cataclysmic events we may be facing.

The Times does manage to bring on the drama by quoting from a story it published in 1998, around the same time that Calvin’s article appeared in The Atlantic. That’s when the Times profiled Wallace S. Broecker, whom it described in its headline as the “Iconoclastic Guru Of The Climate Debate.”

“The climate system is an angry beast, and we are poking it with sticks,” Broecker said.

We should have listened to Broecker. We should have listened to Calvin. We now need to take drastic measures as quickly as possible. Let’s just hope that they don’t have to be quite as drastic as some of Calvin’s more extreme ideas, like bombing the fjords of Greenland to stop the flow of fresh water into the ocean.

Re-entering the Paris climate agreement is nice, and was a necessary first step. But it’s not going to do much to prevent a new ice age — or the unimaginable human suffering that would come with it.