Humans have always developed societies around climate patterns — after all, the climate guides what we eat, what we wear, and how we interact with the world.

For the past several thousand years, regional climate patterns have stayed relatively stable and communities have been able to plan for the future. But every now and then a major environmental event would occur — such as a volcanic eruption — that would abruptly change the cadences of life.

Suddenly, an area would experience extraordinary flooding, a harsh cold spell, or severe droughts, upending the normal order of things and forcing deep restructuring.

Now, a growing field of climate historians are looking back at these earlier events to better understand how societies adapted, or failed to adapt, to environmental disruption. While the scale of the current climate crisis is unique, historians have been able to draw important lessons from past adaptation efforts that can help shape climate action today.

“When do societies start to fall apart? When do populations really suffer? It’s often when there’s a very high amount of social and economic inequality,” Dagomar Degroot, associate professor of environmental history at Georgetown University, told Global Citizen. “Because who suffers the most? It's usually the poorest people without access to resources, people who are just barely getting by, maybe relying on just one kind of crop so they are vulnerable when that crop fails.

“We found that societies that were most resilient had robust traditions of civic charity, or very little social and economic inequality,” he said. “Reducing inequality is one way of adapting to climate change and building resilience.” 

Global Citizen spoke with Degroot to learn more about the field of environmental history, what past societies can teach us about climate change, and what he thinks will happen in the years ahead

Global Citizen: Why did you decide to study the history of climate change and what are some of the historic examples that you’ve focused on? 

Dagomar Degroot: When you study the past, there are different approaches to it. There’s simple curiosity, where you're just interested in what has already happened. I wanted to study history to find what seemed most important for the present and the future and I thought climate change would be the biggest issue of the 21st century. What could I contribute as a historian? What would be my unique take and what knowledge could I generate? It had its origins in the desire to be useful.

So I started looking at the Dutch Republic. It was quite exceptional because it seemed to thrive in a period of profound cooling when other countries around the world did much more poorly. It seemed to me that eventually I could write a book that was more focused on resilience and adaptation in the face of climate change rather than just failure and catastrophe, which had characterized the scholarship at first.

More broadly, I had already been interested in science before history, so the interdisciplinary nature of the field really interested me — you need archaeology, anthropology, climate modeling, paleoclimatology, genetics, linguistics.

What we’re trying to do is reconstruct how the climate has changed by identifying the causes if possible, identifying how global or hemispheric climate change happened at the local level, and determining social responses.

Do past climate shocks compare to what’s happening today in terms of scale and severity?

Yes and no. In the history of complex human civilization, which is the Holocene phenomenon, the current geologic epoch, there is nothing comparable to what’s happening now. Not just climate change to date, but where we’re heading as well. 

The Pleistocene, the epoch associated with ice ages, the shifts between cooling and warming events could be abrupt and the magnitude of change could be shocking. On the last glacial maximum, it was 6 degrees Celsius cooler than the late 20th [century] average.

But in terms of the current magnitude of heating, we haven’t seen anything like this in the history of humanity. What’s happening now is quite different. Climate change is just one part of what we call the Anthropocene, which is characterized by the human burden on Earth’s environment, how humanity has become one of the greatest forces of nature. When you think about the range of whether a species can evolve or stay intact, climate change may not even be the most important force they face. It may be habitat loss or pesticides. Climate change is part of an even larger alteration of the earth’s environment

What are some of the key lessons we can learn from how past societies adapted to climate change?

One of the most important things, and there’s a whole bunch of them, is the necessity of adaptation. Adaptation is just as important as mitigation. The amount that you have to adapt is directly related to the amount that you can mitigate. You don’t have to adapt as much if you can limit warming to 1.5 degrees Celsius.

Adaptation as something absolutely urgent, something governments should undertake yesterday, is something we learned in our research. You have all these examples of societies of the past that have adapted, societies armed with rudimentary technology and no way of understanding what’s happening globally. 

That’s the kind of message we keep hammering home — that small global climate changes can have profound impacts on local weather, but absent adaptation, populations can be very vulnerable to that extreme weather.

Adaptation globally, and in the US in particular, is in its infancy. We have not devoted nearly enough investment in adaptation measures. Now we’re kind of playing catch-up.

The other question is, "What is adaptation?" That seems to be just as important. Adaptation is not just about building sea walls. It goes much deeper than that. Policies like the Green New Deal really get it. Adaptation is really about building equality. 

When do societies start to fall apart? When do populations really suffer? It’s often when there’s a very high amount of social and economic inequality. Because who suffers the most? It's usually the poorest people without access to resources, people who are just barely getting by, maybe on just one kind of crop, they are vulnerable when that crop fails.

Societies that were most resilient had robust traditions of civic charity, or very little social and economic inequality. Reducing inequality is one way of adapting to climate and building resilience. 

It seems we need immediate transformation throughout societies to effectively mitigate the climate crisis —  is it possible for a society to rapidly change?

Those examples do exist, but the question is how much do those past populations have in common with us today. We live in a very different world. Historically, migration has been the most important response to climate change. If there’s a mega drought what do past populations do? They migrated. Can we move 40 million people from California to the Midwest? Well, that’s gonna be very difficult but it does show that we might have to normalize migration in the warmer future.

Right now, the opposite is happening. There’s been this movement to crack down on refugees and migration. Migration has to be normalized and there has to be ways to accommodate refugees. That is one way you can normalize quick changes.

But reducing emissions, that is still the most important thing, and in my opinion, we really have to find ways of scaling up solutions to draw greenhouse gas emissions out of the atmosphere. This can get politically problematic, there’s no sort of way around that, but we’re already in a dangerous climate at this point, and our goal should not just be limiting to 1.5, but going back to where we were in the 20th century. 

When it comes to climate adaptation, do major societal shifts tend to happen at the grassroots level or top-down?

It really depends on the polity. We’re talking about every different kind of governmental organization and government type.

We do have societies that successfully imposed top-down solutions. There are plenty of good solutions in early modern Europe from France to the Holy Roman Empire to Britain in the 18th century. Japan is probably the best example in the 17th century. They imposed top-down solutions in order to free grain supplies to store more grains, so in lean years there would be more to go around.

Societies with grassroots solutions including many Indigenous polities are highly adaptive and responsive in the face of climate changes. These were relatively egalitarian societies, where grassroots were more common, so it’s difficult to say if one type is more common than the other. 

In some parts of the world, societies that depended on capital intensive investments to regulate their affairs and regulate nature, they seemed to be more brittle rather than smaller societies that could flexibly harvest diverse resources and migrate.

I think structural changes are the most important by far, and I think the COVID-19 pandemic epidemic provides a good example of that, where individual action is just not enough to ultimately end the pandemic. Even now in the US, we’re talking about vaccine and mask mandates. 

Climate change is much more the case. You cannot alter entire industries on the time scales needed without top-down action. How do you drive it? You might be able to with grassroots political action. There’s a kind of symbiosis that’s possible there, but ultimately you need big governments that impose effective regulations that force industries to change. How are you going to build the adaptation that you need and smooth out the inequalities that exist without top down solutions?

That doesn't mean it’s either/or. We can each take steps to alter our lifestyles, figure out our carbon budget, alter the kinds of cars we buy, our diets, how we get power in our neighborhoods, particularly for those who have more money and means. Often they are the biggest polluters and they have the most freedom to change. The more money you have, the more freedom you have, the more obligation you have to change your lifestyle. But that will never be a substitute for structural changes. 

Do societies tend to adapt before or after the climate becomes excessively inhospitable?

The kind of climate knowledge we have now, where we understand climate systems as a network of different pressure and circulation systems and we understand not only what’s happening with them across the atmosphere and oceans, that is a 20th century invention. And the ability to monitor how climate changes and to predict how it changes, that’s really an invention of the late 20th century. So none of that existed prior to the 20th century, and there was no good way of predicting what would happen in the future. 

This predictive work we have now and the ability to look forward, there’s very little evidence of that in the past. Populations only adapted when things got bad enough, whether that means migrating, freeing up trade supplies, making new trade networks and transportation networks. Usually we see that after a flurry of extreme events.

There were efforts to understand whether people would be in a new sort of reality by looking at the past, by accessing people’s memories and written reports to determine whether weather was different 50 years ago. Efforts to do that usually took the form of whether extreme conditions were less common in the past then they were in the present. Then you can adapt to that, by, for example in the Dutch Republic, developing new technologies. 

Sometimes you’re resilient when climate change hits, and it has nothing to do with whether you adapted. There’s this blend of resilient communities and communities that adapted only after disasters struck, this development of greater resilience because you know bad things are going to happen. 

Even though we have all this predictive power and understand the scope of the climate crisis, countries have largely failed to act. What accounts for this?

It goes back to social and economic inequality and, more broadly, the functioning of democracies.

In the US, the issue is unique. There’s still more resistance to climate action than there is in many other places. What’s happening is the will of the population is no longer translating into who’s getting elected and that’s a result of the sheer amount of money in politics, and gerrymandering, and voter disenfranchisement. You have widespread public support for climate action, even regulating greenhouse gases as pollutants. You poll people on the individual components of the Green New Deal, almost all of them turn out to be popular. Why wouldn’t it be implemented when it’s going to make the economy richer? Well, it’s because you have all these politicians in Washington who oppose it and who do not reflect the overall will of the people. 

Another part of it, almost obviously, is there’s clearly been a concentrated disinformation campaign going all the way back to the 1980s in order to convince people that there’s scientific uncertainty whether it’s happening and raising people’s fears about the costs of action, saying that it will gut the economy and cost people their jobs. Fossil fuel companies have poured millions into this campaign.

With all that you know about how societies have adapted in the past and considering the scale of the current climate crisis, are you optimistic about our ability to manage the decades ahead?

Yes and no — I think we’ve already seen some pretty exciting developments just in the last five years. Where we are now is probably not where people expected. One thing is that we have made the worst case outcomes, the really apocalyptic scenarios where it warms 4, 5, 6 degrees Celsius, we have made those outcomes a lot less likely, partly because of the plummeting cost of renewable energy.

That has been a hugely positive outcome, and governments seem to be developing serious climate policies that will contribute to further reductions in warming, I think you’ll see more and more of that when the extreme impacts become more evident. So if you ask me how much warming do you think we’ll have, I think it’s likely we’ll have less than 3 degrees by 2100.

At the same time, we’re now realizing that computer models have difficulty signaling how global trends will create local anomalies. What we can expect is that the rate of warming will have a big impact on the likelihood and magnitude of extreme weather at the local level. The local and regional impact of even modest warming is going to be greater than expected

The local and regional impacts of climate change seem to be greater than what some scientists have predicted. There are these long tail risks. For example, very extreme sea level rise by 2100 was not properly spelled out in past reports. 

Two things seem to be happening. There's more action on reducing emissions than people realize, but the impacts seem to be greater. It’s my assumption that by 2100 we will have taken concrete action to sharply reduce warming, maybe we’ll even have capped warming. 

I'm hopeful we can keep to that 2 degrees target, but warming of that magnitude degrades the Earth, making it less habitable. The planet will be diminished and more dangerous. Some societies may falter, the world will be a worse place to live in and a lot of the biodiversity, an unacceptable amount, will be lost. That’s what I would expect 

It's also a question of implementation. Can we limit warming to 1.5 degrees Celsius? In order to do that you have to develop the technologies, test them, and then implement them on a massive scale. The time horizon is short. The politics around negative emissions is fraught because it’s like ‘oh it allows the fossil fuel companies to continue polluting.” The same with adaptation. But it’s now clear we need all of it.

This interview has been edited and condensed for clarity.

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