What climate change deniers get totally wrong about the Little Ice Age

When we typically think of an ice age, the first thing that comes to mind is often prehistoric humans hunting woolly mammoths or battling saber-toothed tigers. Technically, an ice age is a prolonged period of colder climates when polar and mountain ice sheets are unusually extensive across the earth's surface and on geological timescales, they happen regularly. During the last ice age, some 16,000 ago, Earth's northern hemisphere was blanketed in ice about two miles thick.

But during the Little Ice Age — a period of regional cooling beginning around 700 years ago, especially in the North Atlantic region — things were a lot less intense. During long stretches of the Little Ice Age, seasonal winters would be unusually cold and the following summers were merely mild instead of hot. And while the recent rash of record-breaking heatwaves might make an ice age sound nice right about now, the period was marked by bitter winters, deadly plagues and brutal famines, including one that killed about 10 percent of Europe's population. Strangely, this little interval in Earth's history is often used to deny the realities of climate change.

Ever since the 2000s, climate change deniers have been forcefully peddling their pseudoscience to the political mainstream, an astonishing feat given the irrefutable evidence for ecosystem collapse all around us. Many of these deniers are either motivated by political partisanship or are actually being paid by fossil fuel companies, employing a wide-range of tactics to sow doubt about human-driven global warming.

Ultimately, their goal is to convince the world that humans do not need to stop burning fossil fuels, emitting greenhouse gases into the atmosphere, thereby changing our atmosphere's composition and unnaturally heating the planet.

Climate change deniers often uphold the Little Ice Age, which lasted roughly from the early 14th century through the mid-19th century, as evidence that climatologists are lying. Scientists disagree on the exact length of this event, as well as when its intensity got better or worse, but few dispute that it happened. Yet climate change deniers argue that this proves fluctuations in climate are not caused by humans, as indeed this period predates the industrial revolution.

In reality, the Little Ice Age actually demonstrates just how fragile the Earth's climate is — and, by extension, just how easily human beings (or anything else) can radically change it. Additionally, it demonstrates how superstition prevailed in that era in ways not intellectually or emotionally dissimilar from the denialism seen today.

"During the onset of the Little Ice Age, intriguing historical records reveal that European populations attributed magical beliefs to weather manipulation," Francois Lapointe, a postdoctoral associate in the University of Massachusetts' Department of Earth, Geographic, and Climate Sciences, told Salon by email. Lapointe added that the written archives reveal that medieval Europeans believed mystical practices controlled the weather, which they noticed was getting colder during their own lifetimes.

"It is noteworthy that periods of intensified volcanic eruptions, which contributed to the cooling during the Little Ice Age, coincided with peaks of persecution against individuals accused of witchcraft," Lapointe added. "These unfortunate 'witches' were often blamed for causing disastrous weather conditions and crop failures. The correlation between increased volcanic activity and the rise in witch persecutions suggests that climate-induced hardships during the Little Ice Age fueled fears and superstitions about supposed weather manipulation."

From there Lapointe pivoted to the climate change deniers of today, who he argued are "impeding efforts to address this urgent global crisis and inflicting severe consequences on our planet. Climate change denial, perpetuated by certain groups and individuals, fosters doubt and confusion, undermining public understanding and hindering collective action on this critical issue."

Yet what actually happened during the Little Ice Age? The short answer is that there were a number of complex causes, and as such scientists today do not know for sure. Yet when speaking with Salon, Mark C. Serreze — the director of the National Snow and Ice Data Center (NSIDC) — offered a fascinating breakdown of the ingredients that led to the lengthy cold weather snap known as the Little Ice Age.

"There is no single reason for it," Serreze told Salon, adding that this was not a single monolithic era but rather "a long period where there were several cold air cold periods, separated by somewhat warmer intervals."

Yet despite the lack of any "clear resolution" regarding its exact cause, scientists know some of the various elements that played a role. Among these are solar output.

"We know that when sunspot activity is low, we tend to have less solar radiation coming through, and so that seems to be part of it," Serreze explained. "But other things were going on as well. There's very strong evidence that there was an extended period of volcanic activity. And we know that an individual big volcanic eruption — say Mount Pinatubo in 1991 — actually had a signal in global cooling."

Based on what we know from ice cores and other scientific evidence, we can deduce that there was "an extended period of volcanic activity," one that — like emitting greenhouse gases from fossil fuels — "put all kinds of stuff up on the stratosphere, stratospheric aerosols and that initiated some cooling."

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Nor were reduced sunspot activity and increased volcanic activity alone in causing the Little Ice Age. In the early 20th century, Serbian scientist Milutin Milankovitch speculated that as Earth's position relative to the Sun changes, there are long-term and cumulative effects that alter Earth's climate. This is now known as the Milankovitch Effect.

"What happened is that, if you look back at Earth's history over the past 2000 years, we were in a period where because of changes in Earth's tilt, there was an overall global cooling going on," Serreze observed. "And that turned around right around the mid-to-end of the 19th century to the warming that we see today."

Yet there is also a fourth factor that Serreze lists in addition to solar activity, volcanic activity and changes in the Earth's orbital geometry. It all comes down to the Atlantic Meridional Overturning Circulation, or AMOC for short. This system of ocean currents — which is also being destabilized by climate change — includes one "belt" of ocean water that flows north and is warm, so that upon reaching the northern Atlantic it cools and evaporates. While that happens, AMOC causes the water in that region to become saltier and therefore both colder and heavier, sinking and flowing south to create a second belt. These two currents are connected by other oceanic features in the Labrador Sea, the Nordic Sea and the Southern Ocean.

In terms of modern climate change, the ongoing concern is that if AMOC slows down too much or stops entirely, temperatures in Europe will plummet to Little Ice Age levels and the number of extreme storms all over the world will increase. As for the Little Ice Age, "there is evidence from ocean cores and things like this that that overturning circulation may have been disrupted somehow so that it wasn't bringing the warmth into Northern Europe that it normally would."

Lapointe also added a new interesting hypothesis to understanding what exacerbated the Little Ice Age — namely, that Western colonization of the American continents played a significant role.

"On a more speculative yet interesting hypothesis is the 'Great Dying' of the Americas," Lapointe argued. "In 1492, Christopher Columbus reached the Americas, initiating a significant period of European exploration and colonization. Over the ensuing decades, Europeans encountered Indigenous American populations, leading to conflicts, violence and the introduction of deadly diseases. Among the most devastating diseases brought by Europeans was smallpox, which resulted in the deaths of millions of Indigenous Americans, causing immeasurable tragedy and loss of life."

The hypothesis, Lapointe asserted, is that in addition to the horrors of the Western genocide against indigenous peoples, "the colonization process may have had unintended ecological ramifications with potential climate implications. Many Indigenous American communities were skilled farmers who practiced land cultivation and clearance for agricultural purposes. The arrival of European colonists disrupted these established farming practices, leading to depopulation in certain regions."

Since the forests were left untended, the hypothesis holds that "the reforestation following the decline of Indigenous American populations might have resulted in a temporary drawdown of carbon dioxide from the atmosphere. The increased forest cover could have absorbed CO2 through photosynthesis, thus contributing to a cooling effect on the planet," Lapointe said.

If there is one consistent lesson that can be drawn from what science tells humans about the Little Ice Age, it is that the climate is a delicate combination of elements that can be dramatically changed by outside variables. Perhaps the logical fallacy committed by those who sincerely believe that the Little Ice Age disproves climate change is that, because humans were not responsible on that particular occasion, they assume this means they could not be responsible today. Yet that mindset is inherently unscientific, according to anthropologist Brian Fagan, who wrote a 2000 book called "The Little Ice Age" and is professor emeritus of Anthropology at the University of California, Santa Barbara.

"Natural climate change has been with us since humans first evolved on earth. It is constant and will continue to challenge us," Fagan wrote to Salon. "The data that documents this from a wide variety of scientific and historical sources is beyond question. So is the firm scientific evidence for climate change caused by human activity, which is accumulating very rapidly and on a scale that is now beyond question."

Fagan added, "If you wish to deny that the evidence for this exists, then you are challenging the basic tenets of science — and that is delusional. It's the same old mix of conspiracy theories, tired, outmoded ideologies and long discredited scientific theories that hold even less water than they did a century ago. We are living in a climatically very different world, manipulated in considerable part by human activity. Climate change denial is delusional with a capital D. It's a waste of everyone's time."