Climate History, the History of Science, and the Climate Crisis

Global temperature anomalies over the last 2,019 years. Ed Hawkins using data from PAGES2k and HadCRUT4.6.

This is the second post in the series Historians Confront the Climate Emergency, hosted by ActiveHistory.ca, NiCHE (Network in Canadian History & Environment), Historical Climatology, and Climate History Network.

By Dagomar Degroot

Historians have always concerned themselves as much with the present as the past. Some do so explicitly, their work guided by a conscious desire to provide context for a matter of present concern. Others do so implicitly. They may study the past because it makes them curious, but that curiosity is inevitably shaped by their day-to-day lives. One way or another, history as a discipline is the outcome of the history historians must live through.  

Today no challenge seems more daunting than the climate crisis. Earth’s average temperature has warmed by over one degree Celsius since the nineteenth century, and it is likely – though not inevitable – that much more warming is on its way. Global temperature changes of this magnitude, with this speed, profoundly alter both the local likelihood and severity of extreme weather. Human-caused heating will reverberate through the Earth for millennia – by slowly melting ice sheets and raising sea levels, for example. 

Our lives and livelihoods will be – in many cases, are already – shaped by this crisis. No surprise, then, that ever more historians now think urgently and seriously about the implications of climate change for their scholarship. Forecasts of the warmer future are still dominated by economics and climate science, but few now deny that scholars of the past – including historians – can offer unique perspectives on how we entered this crisis, where it might be taking us, and how we can avoid its greatest dangers.   

As this series reveals, historians grapple with climate change in increasingly diverse ways, and here it is again useful to draw a distinction between implicit and explicit approaches. In a sense, just about every kind of history has relevance to the present crisis, because climate affects every aspect of the human experience. Climate change alters the environments that sustain and shape our lives, shifting the basic conditions that channel our actions and thoughts. The climate crisis is therefore as much about the transformation of the planet as it is about the reshaping of human relationships. Any history that deals with those relationships – all history, by definition – implicitly tells us something about climate change and its social consequences. If you are a historian, your work is about global warming.  

The editors of this series, however, asked me to describe how scholars of the past explicitly engage with the climate crisis. Arguably, the most influential and numerous publications have originated in both the history of science and the related fields of climate history and historical climatology. A quick and necessarily incomplete overview of just these two kinds of scholarship reveals the value and diversity of historical approaches to climate change.  

Historians of science initially concentrated on how global warming was discovered and understood by scientists with increasing certainty. While it is simplistic to conclude that scientists “knew” about global warming for many decades, or even over a century – as is often stated in popular media and occasionally in scholarship – historians of science nevertheless revealed the deep roots of today’s scientific understanding of global warming. Led by Naomi Oreskes, they also found that serious debate among climate scientists over the existence of human-caused global warming ended in the 1990s, or perhaps even earlier. Although a majority of the public doesn’t know it, just about every climate scientist understands that humans are today responsible for the rapid heating of the planet. 

Confirming the scientific consensus on global warming led some historians of science to argue that fossil fuel companies and far-right scientists cynically promoted climate denial in order to serve their regressive political or economic interests. This was – and remains – perhaps the most influential and politically potent argument proposed by historians about the climate crisis. Climate scientists, in this narrative, bravely announced their inconvenient truths but could not overcome the falsehoods propagated by their more media-savvy antagonists. 

Nevertheless, other historians soon pointed out that climate science has long involved more than the apolitical discovery and communication of truth. Historians of science revealed for example how models and simulations came to dominate climate science – rather than other ways of knowing – and argued that climate scientists themselves failed to choose communications strategies that could mobilize grassroots, local action. 

Historians have long traced the emergence of ideas about climate from antiquity through the present. Recently, historians of science have revealed that the climate ideas most view as characteristically modern in fact have deep roots. They have shown, for example, that legends of ancient climate changes caused by human sin or shortsightedness helped influence the development of early modern science, and – with new practices in forestry and agriculture –contributed to the emergence of what we might now call sustainability thinking. 

Climate historians and historical climatologists take an entirely different approach to the climate crisis. Historians active in historical climatology search for human records – usually documents – that either describe past weather or activities that must have been strongly influenced by weather. By finding enough of these records – by scouring what they call the “archives of society” – historical climatologists uncover how climate changed over decades or even centuries. Working with those who uncover evidence for past weather in the “archives of nature” – tree rings, ice cores, or lakebed sediments, for example – they can develop remarkably precise “reconstructions” that reveal the existence of substantial climatic fluctuations even before the onset of today’s extreme warming. 

The antecedents of this work date back to the nineteenth century, but it was really only in the 1970s that Christian Pfister and other pioneers proposed ranking qualitative accounts of weather on simple ordinal scales. These scales allowed for the closer integration of the archives of society with the archives of nature, especially in Europe, but historical climatologists studying different parts of the world continued to use distinct methods for quantifying historical evidence. Only now are they working towards developing a common approach. 

In any case, reconstructions permit histories of human responses to past climate changes. While these climate changes have been relatively modest in global scale – the Little Ice Age, the most studied period of preindustrial climate change, only cooled the Earth by several tenths of a degree Celsius between the fifteenth and eighteenth centuries – some were nevertheless sufficient to dramatically alter local environments. Archaeologists, economists, geneticists, geographers, linguists, literary scholars, and paleoscientists have all used distinct methods and sources to uncover how these alterations shaped the history of human populations. 

Yet few disciplines have contributed more to this scholarship – recently coined the “History of Climate and Society” – than history. Historians have in recent years increasingly avoided making simple connections between climate changes, harvest failures, and demographic disasters: a chain of events that scholars of past climate have long emphasized. New climate histories instead uncover wellsprings of both vulnerability and resilience within communities, and they increasingly consider the full range of possible relationships between climate change and human history across the entire world and into the twentieth century.

Together, historians of science and climate historians have done much more than add a little climate to historians’ understanding of the past. Histories of climate science help uncover why governments and corporations have not responded quickly or adequately to the climate crisis. They also reveal how the crisis might be communicated more effectively, or how more diverse ways of knowing could be incorporated within climate science. They show us why we should nevertheless believe the forecasts of climate science – and how we can best act on that belief. 

Historical climatology helps reveal the baselines against which human emissions are changing Earth’s climate today, and helps uncover the likely response of local environments to global warming. Climate historians can suggest what strategies may succeed or fail when climates change, and add complexity to forecasts of the future that too often assume simple social responses to shifting environmental conditions. Many tell stories about the influence of climate on human affairs that capture public attention more vividly than frightening statistics ever could. 

Yet both climate history and historical climatology also demonstrate the fundamental discontinuity between climates present and past. The speed, magnitude, and cause of present-day warming simply has no parallel in the history of human civilization. History is a guide to climate action, but it also warns us that to a large extent we are in uncharted waters. 

Two very different future emissions scenarios.

Ten years ago, I wrote my first article on this website, and back then my message was something like: believe me, history helps us understand global warming! I could not have imagined that, in just ten years, climate change would be widely recognized as a serious subject for historical study – or that historians such as Ruth Morgan would earn a seat in a working group of the Intergovernmental Panel on Climate Change. In some ways, the sea change in the historical discipline has mirrored a broader transformation in social attitudes towards climate change: a transformation driven in part by the courage of young activists, but also by the growing severity of the climate crisis. Climate scholarship in history is now more numerous and more diverse – in its topics and authorship – than it ever has been, a shift that also echoes developments in climate activism.  

I expect these trends to continue. When future historians write about our time, you can be sure that climate change will play a central role in the story. As we live through that history, our scholarship will be climate scholarship – whether we see it that way or not. 

Dagomar Degroot is an associate professor of environmental history at Georgetown University, co-director of the Climate History Network and HistoricalClimatology.com, and co-host of the podcast Climate History.