Our understanding of climate – like the climate itself – has evolved over the course of history, slowly developing into the science we use today. Working out the relation between human agency and climate has been central to this development: are civilizational changes driven by changes in climate? Or do we instigate changes in climate? In addition, studying the climate has always meant looking at the past. Our measurements of climate variables such as temperature and rainfall cover only a fraction of the Earth’s history. Consequently, scientists rely on proxy records to reconstruct the past. Identifying such records, and deciphering what they can tell us about climate and its ties to humanity, is an art. Charenko’s Climate by Proxy masterfully tells the story of how scientists developed this skill.
Charenko shines a spotlight on key proxies – from tree rings to sloth dung to ice cores – that shaped our ideas about climate. As different types of proxy were identified at different times and in different places, scientists proposed diverging models shaped by the material nature of those proxies. Proxies with varied spatial or temporal ranges and resolutions pointed towards diverse facets of climate, revealing cycles and patterns over different scales and time spans that lead to seemingly contradictory ideas about how climate behaves as a whole.
Climate by Proxy builds its exploration of the use of proxies around the standing narrative of how human agency came to be linked to climate (see, for example, Hulme’s Reducing the Future to Climate: A Story of Climate Determinism and Reductionism (2011)), and the book is a useful and detailed resource that both presents this story and adds depth to it. From as early as classical antiquity up until the nineteenth century, human nature was largely viewed by Western cultures as determined by fixed climatic conditions. Following the mounting evidence for climatic shifts, such as ice ages, climate was identified as a potential cause of changes in human civilizations, such as migration and civilization collapse. Eventually, the deterministic view came to be replaced with one of mutual interaction. Events such as the Dust Bowl and debates around whether humans caused the Pleistocene extinction cultivated a sense of agency over local climate; questions about control and adaptation emerged. Today a new, reductionist, form of determinism has taken hold. The future of humanity seems dictated by the global climate change that we ourselves have initiated, which is close to being out of our control.
Charenko succeeds in adding a new layer to this story, foregrounding how the discovery of different material proxies prompted these shifts in understanding. Plant macrofossils and geoarchaeological evidence such as rock striations from glacier movement were the first clues that suggested that climates had not always been the same, and had even changed in recent history (Chapter 1). Tree rings and pollen deposits in peat bogs were analysed to identify both slow shifts and periodic cycles at different scales (Chapter 2). The onset of the American Dust Bowl spurred scientists to try to use these models to predict how the crisis would unfold and develop appropriate mitigation strategies. The question of the human–climate relationship, and the potential predictive value of climate science, were now at the forefront (Chapter 3). The use of sloth dung and packrat middens to analyse causes of the Pleistocene extinction of large mammals pushed this question further and suggested humans’ potential to be a destructive force (Chapter 4).
The book concludes with a call to examine more closely how our contemporary understanding of climate is shaped – and potentially limited – by our use of proxy evidence to test our models (Chapter 5 and the conclusion). Charenko examines how proxies such as ice cores, which provide a high-resolution record of the relationship between temperature and carbon dioxide, have encouraged an atmospheric and planetary-scale conception of climate. In this more exploratory part of the book, Charenko calls attention to concerns that this conception of climate can create a ‘doomerist’ sense of a reductionism. Focusing on the way proxy evidence privileges certain ranges and scales, as Charenko does, might prove an interesting way out of this reductive attitude. Here Charenko is tentative in her suggestions, providing more of a starting point than an expansive argument. What might an alternative conception of climate science look like, and how might we adapt our use of proxy records to its development? Charenko gestures to models of local ecosystems and human societies, which are comparatively poorly understood but more relevant to human agency. But ultimately this is left open.
Climate by Proxy concentrates on one angle: the relation between the history of mainstream Western science and the material properties of different proxy records. But the book also deals throughout with the question of how colonialist understandings of climate have been tied to eugenicist beliefs and weaponized against indigenous communities. It also points out how Western science has privileged its reconstruction of past events from physical proxy records over conflicting reconstructions that could be made from oral records provided by indigenous communities. Although Charenko does not delve more deeply into alternative indigenous scientific frameworks or alternative conceptions of climate (which might have been relevant to the final call to explore alternative ways of modelling climate), this book nonetheless offers a useful complement to this literature.
Climate by Proxy has much to recommend it to a wide audience, presenting both the relevant science and the historical context in an accessible manner with a clear and engaging style. The novel contributions regarding the role of proxy records in this history, and the drawbacks of our current science, offer a compelling narrative with intriguing implications that are deserving of future analysis. For a philosophical readership, the book illustrates the fascinating interrelation between theories and physical evidence. Climate science’s reliance on reconstructions of the past from proxies provides a fascinating case study of how limits on observation impact science – in this case, limits set by what records happen to be preserved rather than by our experimental capacities.
