The Great Mystery of the Little Ice Age

This past winter has been an especially cold and snowy one in the northern US and there is a tendency to think that this is about as cold as it gets. Never mind the fact that the winter of 2012 was similar, it is hard to imagine the climate or weather being much colder. Yet it was. We aren’t talking about many thousands of years ago, we are talking about much more recently in history. This was the period called the Little Ice Age.

When the little ice age was

First, we need to define what the little ice age was, and when it was. Keep in mind that it is very difficult to say when it started or when it ended, however, we do have enough knowledge to approximate this.

Sometime around the middle of the 1600’s, temperatures dropped worldwide. There is little doubt that this was a worldwide phenomenon considering the core samples and written accounts that have come from all over the globe, including south of the equator, in Australia, as well as in North America, Asia, and Europe. Some scientists believe that the little ice age actually began in the 1300’s and didn’t end until the mid-1800’s. Still, the major drop in global temperatures occurred in the mid-1600’s.

Gradual and sudden changes

The change didn’t occur suddenly but was spread over time, which is one reason that it is so hard to determine when it actually started. It clearly had nothing to do with the last glacial period of around 11,000 years ago, but the temperatures dropped precipitously in many places so that summers were cooler and shorter, and winters were much colder than normal, throughout the globe. This might bring to mind much more recent winters, but the change was even more profound and spread out over a much longer period of time.

At its peak, the temperatures were so extreme that in London, England, they held yearly festivals on the thick ice that formed over the Thames River. It would have been possible at that time to walk from what is now New Jersey to what is now Manhattan, over the ice. Around the world, lakes that never froze in the recorded past did so in regularity. It snowed in Australia. Crops in many areas failed. People died from the frigid temperatures of winter, in places that were normally mild, year around.

Mysterious causes

What caused it is a bigger mystery. Some scientists have proposed that it was caused by volcanic activity that blocked the rays of the sun. There is a distinct problem with that idea. Major volcanic eruptions have been occurring since then and they were occurring before then as well. On average, there are 11 to 13 volcanoes erupting somewhere in the world at any given time. This hasn’t changed appreciably.

Yet neither before nor after the little ice age in recorded history has there been such a drastic drop in global temperature, though there have been many major volcanic eruptions around the world. There isn’t a way for us to determine if there was a similar change prior to the last ice age since it wasn’t recorded.

Others have suggested that ocean currents changed greatly. The ocean is the temperature thermostat of the planet. Their thoughts are that this caused the change. Yet there is absolutely no evidence that supports such a tremendous change in ocean currents. All evidence is that the currents have remained fairly constant.

Even El Nino is a naturally occurring change, but one that would have been incapable of causing such a drastic global change. There have been very powerful La Nina currents along the west coast of the Americas and while this brings more moisture in over the US, there doesn’t seem to be a huge connection with the abrupt cold we have seen. Both El Nino and La Nina are not only naturally occurring, they don’t last for more than a couple of years before the currents again change.

Best theory

The best theory is still missing some major pieces. During the worst part of the little ice age, it was observed that the Sun had no sunspots. We now know that sunspots are caused by magnetic vortices or vortexes on the sun’s surface. But we have no idea how the lack of sunspots could cause a much lower earth wide temperature, even though we do understand that our climate comes from the sun.

Still, this idea is compelling, because the sun normally goes through an 11-year cycle, from lots of sunspots, to very few. We don’t know what could have caused it to suddenly not have any sunspots for 70 years. Again, we don’t even know if this had anything to do with the little ice age, but the coincidence that this time of little solar activity matches with the coldest period of the little ice age almost exactly is too much to ignore.

The effects of the little ice age

The effects of the little ice age are more documented. We do know that many successive crops failed during that time. The great famine of Ireland happened during the little ice age. Scientists are still not totally sure about the connection between the lower temperatures and the fungus that destroyed the Irish potato crop.

It was also during this period that the thriving Viking colonies on Greenland, which had survived for a thousand years, failed in a relatively short amount of time. It is likely that this was related to the abruptly much harsher temperatures and weather of the little ice age. The impact of those times are still felt in Greenland, which is still not nearly as warm as it was at the peak of the Viking activity. In fact, on the ground observations showed that the Greenland icepack grew faster and larger in the winter of 2014 – 2015 than in the previous 25 years.  It is likely that the drop in temperatures and increase in snow and ice has little to do with the little ice age, but we don’t know for sure. We also don’t know if the same mechanism is in play, though there are some indications that the output of energy from the sun may be a little less than it has been.

The cause of the little ice age is still much in contention. Yet we do know that it happened, and it happened when there was an unusual lack of sunspots. Could there be a connection? In time, we may learn the answer to this. For now, let’s just say that there is a very good possibility. The future may hold the ultimate answer.