So far climate scientists haven’t abolished the Little Ice Age. Instead they sort of agree it happened, though many insist that while it was cooler than something that happened right before it, that thing certainly wasn’t any stinking Medieval Warm Period, and while the cooling of the LIA was a meteorological, agricultural and medical disaster warmth is bad too. The settled science also isn’t quite sure of the dates except that it ended in the early 1800s. Which means at least some of the warming we’re currently living through is a natural rebound from an unusual cooling event. But now they have a theory about what caused the cooling: Warming. Specifically, a burst of warm tropical ocean water riding the Gulf Stream to Northern Europe in the late 1300s met the Arctic waters around Greenland and Scandinavia and began flushing a lot of ice into the North Atlantic then melting it. The resulting release of freshwater both cooled and desalinated the North Atlantic, slowing down the “Atlantic Meridional Overturning Circulation” ocean conveyor belt that ultimately controls the Gulf Stream, leading to 600 years of cold weather. It’s a clever hypothesis. But could it happen again? Apparently “Climate models do not capture these events reliably” so um nobody knows and they should get more money to discover whether we’re all doomed this way or some other way.
The idea that warming could cause the Gulf Stream to shut down and plunge Europe into a cold epoch isn’t new. In the wrong hands it has even led to some comical results, as we showed in our Crystal Ball video on the Pentagon’s Climate Report. So maybe this is more of the same, except in this case the Little Ice Age really happened and something caused it.
The new study goes further than just pointing to the Gulf Stream. It reasons that the right conditions in the atmosphere to support accelerated ice melt also had to arise, namely a persistent high pressure ridge over Greenland. They think they have evidence of such a phenomenon from the records of solar activity encoded in tree rings (yes the tree rings are not just thermometers, they’re also solar panels apparently). Just possibly the sun got brighter and volcanic activity was at a minimum in the late 1300s which led to warming and high pressure over Greenland, and that meant extra ice melting.
As for today, the authors believe there is less Arctic ice available now than there was in the 1300s so it’s less likely the ocean conveyor belt could get interrupted. But then again... apparently there’s been a buildup of freshwater in the Beaufort Sea and it might someday get released into the North Atlantic, weighing down the conveyor belt and kickstarting another little Ice Age.
Which will be one more thing to blame on global warming. Or, for the denialists out there, one more piece of evidence that climate is incredibly complicated, with unpredictable feedback loops that make modeling a mug’s game.