The article, which is among the first to be written by environmental historians in the journal Nature, critiques previous scholarship of this field and provides guidance for how our society today can address climate change by studying the past through a new research framework. 

“By building on previous scholarship by archaeologists, historians, geographers, linguists, and paleoclimatologists, we found that many societies and communities were resilient in the face of climate change, meaning that they responded in ways that maintained their essential structure, function and identity,” says Degroot. “Our research reveals that many societies effectively responded to the modest climate changes that preceded today’s global warming, suggesting that, with sufficient political will, effective adaptation will be possible for us, too.”

Building a Team

The team of 18 researchers, led by environmental historian , came up with the term HCS as a way to describe the field of research that examines the past impacts of climate change on society through different disciplines including archaeology, genetics, geography, history, linguistics and paleoclimatology. 

“Until recently, many HCS scholars have worked largely within their own disciplines, without joining forces in interdisciplinary teams,” says Degroot. “We found that a lack of communication between disciplines contributed to biases in HCS research that encouraged scholars to focus on societies that endured crises or even collapsed as climate changed. We draw attention to examples of resilience and adaptation that have too often been systematically ignored.”

To find these examples, Degroot used a Georgetown Environment Initiative (GEI) grant to convene a truly multidisciplinary team of scholars. 

The group, first assembled in 2018, includes Kathryn de Luna, Provost’s Distinguished Associate Professor of history; Timothy Newfield, assistant professor in history and biology;  Naresh Neupane, assistant research professor of biology;  and Ph.D. students Jakob Burnham (G’23) and Emma Moesswilde (G’24).

A key collaborator was leading tree ring scientist Kevin Anchukaitis (SFS ‘98), a former Georgetown undergraduate student and now an associate professor in the School of Geography and Development at the University of Arizona. Contributing historians included Martin Bauch from the Leibniz Institute for the History and Culture of Eastern Europe, Fred Carnegy from the University ������̳ London, Heli Huhtamaa from Heidelberg University, Adam Izdebski from the Max Planck Institute for the Science of Human History, Katrin Kleemann from the Ludwig Maximilian University of Munich, and Natale Zappia from California State University. 

George Hambrect, an anthropologist from the University of ������̳ Park Maryland, was also instrumental, as were sociologist Piotr Guzowski from Bialystok University, geographers Jianxin Cui from Shaanxi Normal University and Qing Pei from the University of Hong Kong, and paleoclimatologist Elena Xoplaki from the Justus-Liebig University of Giessen. 

Methods and Malleability

With GEI funding, the founding members of the team met at Georgetown to develop a new research framework for HCS scholarship. They eventually drafted a step-by-step process that HCS researchers can follow to more effectively link changes in global climate, local environments, and human societies. 

They used this framework to learn how societies endured the largest natural climate changes of the past two millennia: periods of climatic cooling that were caused, in part, by volcanic eruptions. The team found that there were numerous instances in the past where societies were able to adapt to moderate climate change without losing core aspects of their structure.

“We uncovered five characteristics that allowed societies to endure or exploit climate change, including trade networks, governments that learned from mistakes, and the ability to be mobile,” says Degroot. “Our case studies show that human adaptations to modest climate changes were creative and diverse. They also show that during the last two thousand years there was no single, global trajectory of climate’s impacts on human history.  Societies did not inevitably collapse or suffer when the climate changed.” 

Planning for the Planet

While the findings of this research may provide hope for the future of humanity, it is also important to note that these case studies examine instances where societies in the past were forced to adapt to only moderate forms of climatic cooling. Climate models agree that global warming in the twenty-first century will be far more extreme.  

Degroot explains that in general, the greater the climate change, the more difficult it is for societies to adjust and maintain resilience. 

“While our technological societies may have capacities for adaptation that pre-industrial societies lacked, the warming our greenhouse gas emissions has caused is already much greater in magnitude than the cooling of the Little Ice Ages,” says Degroot. “Our study does not prove that humanity can adapt to the extreme climate changes associated with high or even middle-range emissions scenarios. It is still imperative that we urgently reduce greenhouse gas emissions – while adapting to the warming we can’t avoid.”

He also notes due to unequal distributions of wealth in society, some social groups will be more severely impacted than others by climate change – just as they were in the past. 

“The capacity for resilience is often – but not inevitably – distributed according to the power, influence and access of unequal social groups. The resilience of one social group – and indeed of one society – may come at the expense of another,” he explains. “ It is urgently necessary for policymakers on every level both to implement effective adaptation programs and to ensure that the benefits are broadly shared.”

Her findings, , reveal previously unknown facts about avian behavior and could contribute to a greater understanding of why species are in decline. 

Mapping Migration

Stanley began working on this research in 2019 with Peter Marra, director of the Georgetown Environmental Initiative. The pair decided to study yellow-billed cuckoos due to their large population declines and ability to easily carry the weighter satellite tracking tags. 

“When we first started tracking the cuckoos we only had a vague understanding of where they went, so we coordinated with partners in Western, Eastern, Southern and Midwestern sites in the United States to determine the birds’ migration patterns,” says Stanley. “After we tagged the birds, we found that they actually spend the majority of the year in the area of South America known as Gran Chaco, which is currently an area that is under heavy developmental pressure.”

Gran Chaco is a region that comprises Argentina, Paraguay, and Bolivia, which is currently undergoing heavy deforestation. Stanley hopes to use Argos system satellite data to compare the declining number of cuckoos to increasing levels of habitat loss. 

This is important as migratory birds are a great indicator for ecologists and conservation biologists of the impact of environmental changes on wildlife. 

“Migratory birds can tell you a lot because they exist in so many different places and rely on a variety of habitats,” says Stanley. “They are key insights that provide answers to the main question our work is centered around: how can we protect species?”

In North America, the migratory bird population is dropping rapidly. According to a study published by Marra in Science, over 3 billion birds have been lost in the past 50 years, but it is currently unknown exactly why this is happening. Stanley explains that prior to advancements in tracking technologies, scientists have known very little about migration patterns in most species, not just birds.

“Being able to track birds and other animals is crucial for us to understand their full annual cycle and therefore pinpoint what and where the stress points are for them,” she explains. “Without tracking technology we never would have known about their migration or movement behavior. The yellow-billed cuckoo for example is moving the majority of the time.”

ICARUS Initiative

This project is part of a growing body of research to track many different species of animals across the globe. The International Cooperation for Animal Research Using Space, or ICARUS project, in a multi-decade project that will collect data about the migration patterns of a variety of species from different countries. Though Stanley is using a different data model, her research will contribute to this greater field of understanding. 

In his interview with The New York Times, Marra says that ICARUS will be an “incredibly powerful tool to address enormously vexing problems in conservation biology.” 

Emily Williams, a Ph.D. candidate in the Department of Biology hopes to use the smallest ICARUS tags to track the migration of American robins next year.  

“Though an extremely common backyard bird in the United States, very little is known about the migration patterns of the American robins and how it varies across their range from fully sedentary populations to partially migratory populations to fully migratory populations,” says Stanley. 

While Stanley and Williams will not be directly working together, their collective research will help scientists better understand bird migration and necessary conservation efforts to protect bird species in the future.

“Welcome to Climate History”

Degroot started the Climate History podcast as an extension of his popular website , and the , an organization of some 200 scholars that he co-founded with environmental historian Sam White. Both provide resources on the history of climate change: not only recent, human-caused global warming but also the less severe, natural changes that preceded it. 

Degroot, who stresses the human consequences of those changes on the site, noticed that this work was gaining a large following. As viewership increased at HistoricalClimatology.com, he wanted to create a new way to connect with audiences. 

“Podcasts are one of the most common ways that people consume information today, and I think they’re becoming more important in some ways than writing” Degroot says. “Academic papers may only have a few hundred views if that. But our podcast has over 31,000 plays on SoundCloud alone.”

Eager to further develop this resource for people interested in climate change past and present, Degroot created his podcast in 2015. His first episode featured Geoffrey Parker, author of Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century. Trump’s election, medieval climate change and Frankenstein’s monster were some of the issues discussed with guest speakers in later episodes.

Though the podcast was gaining traction on the website, Degroot said that the project fell by the wayside until Emma Moesswilde began her Ph.D. program at Georgetown.

Creating a Better Podcast

Moesswilde, who is studying the intersection of agricultural and climate history, began her Ph.D. program under Degroot’s mentorship in Fall of 2019. That same semester, the two re-launched the ad-free Climate History podcast as co-hosts through the help of the (GEI), a university-wide initiative to advance the multidisciplinary study of the environment and sustainability. 

“GEI has been offering Impact Awards to seed or stimulate research, education and outreach around environmental issues and activities,” says director Peter Marra. “This podcast is a perfect example of the sort of activity we have been able to support.”

Since relaunching in September 2019, seven new episodes with guest speakers have helped create both an entertaining podcast and a collaborative space for academic work.

“In a variety of capacities, we have had speakers come to Georgetown from other universities to speak as guests and in this way, the podcast becomes a broader piece of intellectual exchange,” says Moesswilde. 

Degroot is also conscious of reaching out to speakers with whom he feels undergraduate students will be able to engage. Recently, the professor invited two guest lecturers from his HyperHistory course, Valeria Trouet and Amy Hessl to be featured on the podcast.

“Undergraduate students are influential in terms of inspiring topics and guests,” says Degroot. “I have assigned episodes for students to listen to in my class and my class has helped me think of whom to invite.”

The Importance of Being Diverse

To Degroot and Moesswilde, diversity is one of the most important aspects of inviting guest speakers, and of the podcast as a whole.

“Historically the most visible figures in climate change activism and scholarship have been white men, but that is changing rapidly, so we are really trying to have more diverse guests,” says Degroot. “But diversity goes beyond individual identity. The study of climate history has always been about combining different disciplines. You need science to figure out how climate changed, and you need history or archaeology to uncover how those changes affected people.”

Degroot and Moesswilde’s podcast, like their work, is therefore multidisciplinary, combining approaches in for example climate modeling, paleoclimatology, archaeology, and environmental history to uncover how societies responded to climate change. Since they believe the past can help us better understand our present and anticipate our future, they hope to use their podcast to introduce history to as many people as possible. 

“Scholarship is a tool that should be for the public good, which is something that I think we really stress at Georgetown,” Degroot says. “When we research, we do it for the world. That was why I started this podcast and our other online resources: so that we can connect with individuals by clearly explaining the work researchers are doing and why it is important.”

Moesswilde said that the idea of shared learning is why she was excited to come to Georgetown and that she is excited to be a part of a project that works collaboratively for the public good.

“It is unique to have a podcast that is rigorous enough to have academics get something out of it, but also appeal to a number of different audiences like students and the general public,” says Moesswilde. 

COVID-19 Episode

The podcast’s latest episode discusses COVID-19 and its implications for how we perceive not only our present and future, but our past. Instead of interviewing a guest speaker, Degroot and Moesswilde have a frank conversation about living through two significant crises: the COVID-19 pandemic and human-caused climate change. 

“We’ve read a lot of articles that attempt to interpret the present moment in light of the past, by comparing it to very different pandemics for example,” says Degroot. “Yet those comparisons usually seem a little forced to me. Emma and I wanted to have a broader discussion of how this moment is altering how we think and feel as environmental historians – and especially as historians of climate change.”

More about the Podcast

Degroot and Moesswilde, along with a team of graduate students, run the podcast and the Historical Climatology website in their spare time. 

“There has been a shift in the role of the graduate students from just being a student to being a junior colleague,” says Degroot. “None of this would be possible without them.”