When the World Was Cold: Five Questions for Dagomar Degroot


Compared with the climate change we’re experiencing now, the Little Ice Age — which chilled the globe from the 13th to the 19th century — was modest. “The world has already warmed more, relative to mid-20th-century temperature averages, than it cooled in the chilliest stretches of the Little Ice Age,” says Dagomar Degroot, a historian at Georgetown University. “And there is much more warming to come.”

Visual: Courtesy of Dagomar Degroot

Yet in his new book, “The Frigid Golden Age,” Degroot argues that the Little Ice Age has a lot to teach present-day societies about coping with climate change.

In particular, the Dutch Republic managed to thrive during a time of cooling that caused great suffering elsewhere. Degroot, himself born in the Netherlands, explores what made the Dutch so resilient.

For this installment of the Undark Five, I interviewed him by email about the book and about the history of climate change in general. Our conversation has been edited for length and clarity.

UNDARK — We see climate change as something modern, but you point out that it’s happened many times.

DAGOMAR DEGROOT — When most people refer to “climate change,” they really mean anthropogenic — or human-caused — global warming. That is indeed something new: a consequence of the modern production and consumption of fossil fuels on a totally unprecedented scale. “Climate change,” however, can also refer to any long-term change in regional or global weather patterns. By that definition, climate change is as old as the Earth itself.

Our species, Homo sapiens, is around 300,000 years old. [In that time], different natural forces have cooled or warmed the Earth, and thereby changed its patterns of oceanic and atmospheric circulation. The alternating ice ages and warm interglacial periods of the Pleistocene likely drove hominids to migrate, evolve, and speciate. In the wake of the last great ice age, warming trends repeatedly interrupted by abrupt cooling episodes may have encouraged hunter-gatherers in the Levant to experiment with agriculture.

In the Holocene, the geological epoch that succeeded the Pleistocene, state societies that emerged from cereal cultivation thrived in periods of modest warming and abundant precipitation. The Roman Empire, for example, reached its height during a warm climate, the so-called Roman Climatic Optimum. By contrast, many societies suffered when even modest climatic cooling shortened growing seasons, or when changing patterns of atmospheric circulation provoked either torrential rains or catastrophic droughts.

Still, cutting-edge research shows that climatic trends or events did not “shape” societies, but rather expanded or contracted the range of possible — or convenient — human activities.

UD — What was the Little Ice Age and what effects did it have on societies around the globe?

DD —The Little Ice Age was a period of modest cooling — roughly one degree Celsius in the coldest decades — that affected most of the globe between the 13th and 19th centuries. The cooling came in a series of waves — “very little ice ages,” as I’ve called them — that each lasted for less than a century. All but one followed from a confluence of major volcanic eruptions and low solar activity. Two of the coldest waves of the Little Ice Age, the Grindelwald Fluctuation and Maunder Minimum, framed the 17th century, which was accordingly the chilliest of the period across much of the world.

Cooling helped cause shifts in atmospheric circulation, altering winds, ocean currents, precipitation, and sea ice extent from region to region. Brief warm periods also interrupted every cold wave, so that the Little Ice Age was perhaps above all a period of unpredictable, unstable weather.

Many climate historians have found that periods of climatic cooling set off a “fatal synergy” — as Geoffrey Parker put it — between harvest failures, outbreaks of epidemic disease, and conflict in the agricultural empires that dominated the premodern world. Most climate histories therefore focus on societal disasters. Yet climate historians have increasingly found examples of societies that seem to have been resilient, even adaptive, in the face of climatic shocks. Perhaps the best example is that of the Dutch Republic, which enjoyed a so-called Golden Age during the 17th century.

UD — Why did the Dutch manage to prosper during this Little Ice Age?

DD — The coastal regions of the Dutch Republic were somewhat of an anomaly in the 17th-century world. They relied heavily on waterborne trade and industry — rather than the meager surpluses produced by contemporary agriculture — and participated in a capitalist economy that lent itself to high levels of urbanization. European harvest failures allowed Dutch merchants to exploit their control of the Baltic grain trades to export food into desperate markets.

Weather associated with climatic cooling did occasionally imperil Dutch lives and livelihoods, but Dutch entrepreneurs often found ways to adapt. They developed technologies that helped them fight urban fires, often kindled in storms or amid cold winters, and profit from icebreaking.

The Dutch were always at war in the 17th century, often in watery environments that responded dramatically to climate change. Usually, these responses either benefited Dutch campaigns or could be exploited by Dutch commanders. Torrential rains repeatedly increased the effectiveness of deliberate flooding of the countryside, which literally washed away Spanish sieges in the 80 Years’ War that gave rise to the Dutch Republic.

Still, the Dutch did not manage to prosper in the 17th century solely because they coped so well with climate change. Their resilience is just one part of the Dutch Golden Age, one that historians had, for the most part, not yet explored.

UD —What lessons can we learn from the Dutch in adapting to present-day climate change?

DD — The world has already warmed more, relative to mid-20th-century temperature averages, than it cooled in the chilliest stretches of the Little Ice Age. And there is much more warming to come. To avoid the disruptions climate historians have detected in the 17th century — or worse — we must act now to reduce carbon emissions and adapt vulnerable communities to new environmental realities. This is, I think, the first lesson of the Little Ice Age.

The second is that climate change has had, and probably will have, very unequal consequences for different groups of people. We often assume that developed societies will fare better in a warmer future than the developing world. Yet the Dutch thrived in the 17th century not simply because their republic was rich, but because much of its wealth derived from activities that benefited from climate change.

Today, we can learn from the republic by strengthening social safety nets, investing in technologies that exploit or reduce climate change, and thinking proactively about how we will adapt to the planet of our future. It just so happens that much of the federal government in the United States is abandoning these policies, but there are more optimistic stories at the state and municipal levels, and there is exciting news coming out of China and India.

UD — As a teacher, why do you think teaching climate history is important?

DD — I have personally found the greatest satisfaction in helping my students become part of the solution. This year, I asked students to use accessible, online climate change reconstruction and projection tools to write jargon-free articles that describe the impacts of past, present, and future climate changes on local communities. We hope that they will resolve a troubling paradox in climate surveys: the tendency for people to believe that climate change will harm people in the United States, but not in their community.

Overall, the most important thing that teachers can do right now is to teach courses about climate change. Surveys have found that most people — even in America — believe that Earth’s climate is changing, but few talk about that belief with friends and family. There is a veil of silence that seems to surround the issue, and teachers have a responsibility to tear it apart. At Georgetown, we teach about climate change in just about every discipline, from theology to physics. We have found that every teacher and professor in every field can incorporate climate change into their courses.

Tom Cassauwers is a Belgian journalist who writes about technology and politics. His English-language articles have appeared in Ozy Magazine, Nieman Journalism Lab, and Atlas Obscura.