Calvin’s thesis, simply put, was that global warming could disrupt the northward flow of the Gulf Stream and thus, paradoxically, kick off a new ice age in Northern Europe — which is, after all, at approximately the same latitude as Labrador.
Now a new scientific study, reported in the journal Nature, finds that it may already be happening, according to this New York Times story.
Here’s an excerpt from the Nature press release:
Failures of the Atlantic Ocean’s circulation system are thought to have been responsible for abrupt and extreme climate changes during the ice age that lasted from 110,000 to 23,000 years ago. More recently, a fictional shutdown of the Gulf Stream inspired the 2004 Hollywood blockbuster The Day after Tomorrow.
The climate shifts depicted in the movie, in which New York is engulfed by an instant ice age, are mere fancy. But scientists are worried about the real changes measured in the North Atlantic. Both salinity and water density, which influence the transport of warm waters, have previously been found to be decreasing.
Global warming is often thought to be a gradual process. But, as Calvin noted in the Atlantic, the effects of it could come in catastrophic waves, as tipping points are reached and then breached. This isn’t alarmism — it’s realism.