Waters of the World

by Sarah Dry

  The Bretherton diagram—and the fledgling discipline of Earth system science that produced it—today speaks poignantly of both the hubris of thinking it might be possible to “solve” the earth system and the humility that comes from confronting the scope of the problem. “The study of the Earth is on the verge of a profound transformation,” proclaimed Bretherton’s report, but so, too, was the planet itself: “human activity is now causing significant changes on a global scale within the span of a few human generations.”49 The implicit question raised by the report was whether human beings could catch up with themselves before it was too late.

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  CONCLUSION

  Arriving at the Bretherton diagram after spending time in the company of the scientists I have profiled, it is possible to see it as an amalgam rather than a singular thing. In a quite literal sense, one can locate within it (and its accompanying text) much of the work with which this book has been concerned. Here, for example, is the Tropical Rainfall Measuring Mission, NASA’s first mission to measure rainfall on Earth, which Joanne Simpson was recruited to run in 1986, the same year that the diagram itself was published. Here too is a mention of the World Ocean Circulation Experiment (WOCE), the global project for which Henry Stommel had laid the conceptual foundation and about which he was deeply ambivalent. Also present is Gilbert Walker’s Southern Oscillation, whose erratic occurrences were still, in 1986, unpredictable (and remain so today), and which exemplifies the importance of studying climatic processes on a global scale. Less explicitly but perhaps more fundamentally, the climatic roles played by clouds and water vapor remain a subject of pressing mystery in the Bretherton diagram just as they did for Charles Piazzi Smyth. And here too is the need to understand the way ice moves and changes shape: whether, as Tyndall had also wondered, it slides on liquid water at its base, and how, in a warming world, its motions might lead to the detachment and melting of the massive West Antarctic ice sheet.

  The lives and work of John Tyndall, Charles Piazzi Smyth, Gilbert Walker, Joanne Simpson, Henry Stommel, and Willi Dansgaard were lived, as we live our own lives, in a stream of constantly shifting desire, intention, and chance. As Tyndall felt so acutely, a misplaced step in the Alps could have brought him tumbling down. Piazzi Smyth’s life might have been very different if he hadn’t rashly resigned from the Royal Society. Gilbert Walker had a nervous breakdown from which he recovered, but what if he hadn’t? These counterfactual stories are useful as reminders that the contingency of individual lives has influenced the creation of what might otherwise seem to be a natural object—the system of the earth, the vision of the globe.

  Both Tyndall and Piazzi Smyth demonstrated that it was possible and sometimes necessary to make knowledge about the planet alone. The nature of that knowledge, and what it meant to be alone, was negotiable. When he was on top of Tenerife, Piazzi Smyth was imaginatively supervised by a congregation of his scientific peers. Tyndall often climbed “alone” in the Alps in the presence of guides. Making reliable knowledge out of an amalgam of field and laboratory work was never straightforward. Gilbert Walker, in many ways a useful anomaly here, sat at the center of a web of imperially enabled statistics like a calculating spider. His failure to predict the monsoon is less significant than his success at showing how certain powerful modes of calculation depend on unimaginably large networks of observations, networks which are today even more important, and arguably even less visible, than they were for Walker. Understanding how such hidden numbers produce highly visible and influential knowledge—such as the global temperature index—is critically important.

  A full history of our understanding of the planet cannot be told solely from the perspective of individuals. Indeed, since World War II the sciences of climate have become bigger and bigger, and the role played by any one individual smaller and smaller. This was the change that Stommel foresaw and lamented. As he saw it, it entailed the loss of freedom that he considered necessary for solving the big conceptual problems. Joanne Simpson encountered the same paradox when she sought to build alliances with government funding bodies in order to do the science she really wanted to do. Cloud modification, much less hurricane modification, was never going to be a solitary endeavor. Similarly, no ice cores get drilled without serious money being expended. Willi Dansgaard had to find a way to harness the budgetary and logistical might of national governments. Piazzi Smyth and Walker, too, both relied on extensive networks to provide them with the necessary equipment and authority to do their work. Realizing that individuals cannot function alone does not mean that individual lives no longer matter to the telling of history. By looking at the interaction between individuals and institutions—between energy at different scales of the system—we come closest to understanding how the system works.

  The tools with which scientists study—and then describe—the planet in global terms are influential. They generate knowledge that contains within it both assumptions about who gets to know—who has the training and skill, the moral authority, and therefore the trust to do so—and what that knowledge is good for. This book has conveyed the stories of how scientists have created tools for global knowledge and what was consequential about those tools. While my protagonists are almost all English speakers and nearly all men, they belong to different times, different places and, perhaps most challengingly, different disciplinary histories. I have chosen to do this deliberately, as I wished to show how the thing we today refer to quite casually as climate science is an amalgam of different ways of knowing the earth. This is, in one sense, a good thing, a source of resilience, in that it offers multiple pathways for generating knowledge. For decades, calls for the need for interdisciplinarity have been common, sometimes more strident than others. Despite this, truly interdisciplinary working remains elusive across the natural and social sciences. A recent meta-analysis of twenty scientific assessments of global climate science noted that “only a fifth of the case studies analysed attempt to integrate practical elements [or] consider socio-economic and geophysical aspects across spatial scales.”1 And yet, as this book makes clear, climate science was always interdisciplinary. For better or worse, there never really was a singular discipline of climate science.

  Global visions are necessarily made up of unglobal things—individuals, places, moments in time. This is, in itself, neither a bad nor a good thing, but it is a fact about which it is important to be aware. The concept of global knowledge is a powerful one. It may be one that we feel we need today, but this does not make it either neutral or natural. All our global visions are, like the visions described in this book, the products of individual minds working in particular places at particular times—histories that might have turned out differently. Put differently, the same Earth is there for all of us, but, to use a phrase Tyndall might have appreciated, it wears many veils. The tools with which we pull back the veils go, in this book, by the names of the various scientific disciplines into which humans have divided the study of the planet: geology, physics, astrophysics, cosmic physics, atmospheric physics, meteorology, oceanography, paleoclimatology, climate science. Those disciplines organize the methods for thinking and doing science, and in this way they, too, determine what can be known by the people who work within them. There are circles within circles of structure and chance, of painstaking preparation and the unpredictable contingencies of the day. Together, it adds up first to individual lives and the knowledge thereby produced, then to disciplinary consolidation of knowledge, and finally to something like the Bretherton diagram, a synthesis of not just the entire planet but multiple ways of knowing the planet.

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  Interdisciplinarity can take many forms. The Bretherton diagram represented the integration of knowledge from across many scientific disciplines. It also gestured toward the need for integrating the social sciences as a means of modeling the role of human factors in the system. The awareness of planetary change that prompted the series of workshops out of which the diagram
emerged also prompted a call for another flavor of interdisciplinarity, this time for bringing the science of climate and the traditional discipline of history together.

  This awareness was prompted directly by ice cores. Thanks to the magic of isotope chemistry and Dansgaard’s “one really good idea,” ice cores became frozen annals. The earth, it turned out, not only had a history but had kept its own, remarkably detailed, archive. Ice cores, just one member of a remarkable family of paleo-proxies, stand out for their ability to register very long time spans with remarkably high resolution. Indeed, it is possible in some ice cores to read the earth’s history on an annual basis, as a historian might read a church register. This special feature of ice cores made it possible to align human history and climate history in a way never before possible. The earth now had a history that could be directly calibrated to human history. This raised questions, foremost among them how climate affected human history. It was precisely to “evaluate the effects of climate and weather on human affairs in the past” that a 1979 conference on “Climate and History” held at the Climatic Research Unit at UEA brought together 250 researchers from across the sciences, social sciences, and humanities.2

  At the conference, several things were clear. One was that the question of influence was a complex, multidimensional one. Different human cultures had responded very differently to changes in climate in different times and places. There was no longer any case for the anyway often-derided species of environmental determinism espoused most prominently by Ellsworth Huntington. Also clear was the need for humans to better understand climatic changes in order to prepare for the future. Less clear was whether humans had themselves also influenced climate. In 1979 at UEA, there was no mention of human-induced climate change. The arrow of influence seemed to point decisively from climate to humans, even as scholars emphasized the contingent nature of that influence. There was no room either for environmental determinism or a possible link between human activity and changes in climate. Such a state of affairs did not last long. Increasing evidence about the effects of human activity on rising carbon dioxide in the atmosphere and new indications that global temperatures were rising made the arrow pointing from humans to climate harder to ignore. But in 1979, at the UEA, such concerns could be, and were, pushed to the side.

  Ice cores generated a felt need for communication across the aisle that famously separated the two cultures. “‘Climate and history,’ as a field of study is located at the point of intersection of many different disciplines,” asserted the editors of the conference proceedings, “and progress in the field demands interdisciplinary cooperation.” History here was a term laden with meanings. “Our approach,” explained the editors disingenuously, “is simply to study the history of climate itself, to attempt to reconstruct the pattern of climatic changes and fluctuations over past centuries and millennia.”3 The history of climate, in this sense, could be and often was considered an almost purely scientific endeavor then (save, the editor’s note, for a few special historians, Le Roy Ladurie chief among them, who addressed the question of climatic influences on human history).

  In asserting that the history of climate was self-evidently scientific, the editors were stating what they believed was an anodyne truth, a mere cliché. But assertions of self-evidence often betray deep uncertainties. Despite the claim to the contrary, there was nothing natural (in the sense of necessary) about the historical nature of climate as represented by these twentieth-century researchers. It was, instead, the product of its own disciplinary history, as contingent and as un-self-evident as any product of humanity.

  Geologists like Charles Lyell and James Hutton discovered the earth’s “deep time” in the late eighteenth century. But, as Martin Rudwick has convincingly shown, perhaps even more important than the discovery of deep time was the simultaneous creation of a new way of thinking about the earth’s past, a new form of historical consciousness that Rudwick calls Earth’s “deep history.” Much more important for our understanding of the planet than a merely expanded amount of time (what geologist James Hutton famously described as having “no vestige of a beginning and no prospect of an end”), argues Rudwick, was a new sense of “the historicalness or historicity of nature.”4 The Bible, with its complex and contingent histories, provided early geologists with a ready model for how change happens over time. From scripture, they borrowed the presiding assumption that the unfolding of the geological history of the earth was a set of contingent events that resembled human history much more than it did the unchanging orbits of the planets described by Isaac Newton.5 This borrowing from scriptural models of history was itself far from accidental. The sense that at every point events could have turned out differently was, argues Rudwick, “deliberately and knowingly transposed into the world of nature” from that of human culture and human history. Among other things, Rudwick’s argument gives lie to the simple conflict stories of science and religion. Far from obstructing the discovery of a deep history of the planet, scriptural understanding “positively facilitated it,” argues Rudwick. Though the editors of the UEA conference volume reduced the historicity of climate to something self-evident (“simply . . . the history of climate itself”), geology was “born” historical in a richer and more meaningful sense. Geology was, from its very beginnings, a science built self-consciously on the model of the most human of all histories, that of the Bible.

  Climate science today, inasmuch as it has been built partially on the foundations of geology, contains within it some of this historicity, this contingency. But it also contains a different approach to history, one closer in spirit to Newton than to Hutton. The Newtonian time of planetary objects—history that unfolded in precise cycles rather than stories with surprising turns—has always also been a part of what we can now, retrospectively, label climate science. It informed the calculations by which men like James Thomson estimated the melting of ice under pressure. These physical methods gave rise to the kind of thinking that enabled Broecker and others to start working out the global mechanisms responsible for the rapid transformations in the ice records. This work helped create a new way of thinking about the internal history of climate that came to be called climate dynamics.6 Climate dynamics did not draw explicitly upon traditional historical methods or seek collaboration, as the scientists at the 1979 UEA conference did, with traditional historians in building time lines. Nevertheless, it was a new way of thinking about the climate. Unlike those geologically indebted disciplines which were more or less content to simply describe the unfolding of climate history (for example, classical climatology and many aspects of meteorology and oceanography before the postwar period), scientists interested in physical dynamics wanted to generate a causal understanding of how the pieces of a system connected and how those connections generated phenomena that could be measured. Doing climate history here entailed understanding the causal relations between physical phenomena rather than “merely” describing them. According to this way of thinking, the movements of water, air, or ice had histories that could be generated not through observation and description alone but through the correct application of physical principles. Henry Stommel’s paper on the westward intensification of boundary currents is the locus classicus for this sort of thinking within oceanography. It not only captured the drive toward understanding physical phenomena that lay at the heart of this kind of climate history, but demonstrated the value of simplicity in this new arena.

  In this sense, scientists who studied the dynamics of climate were also self-consciously historical. While there was always uncertainty about the precise path that the climate system followed—a real sense that things could easily have unfolded differently—the science of climate dynamics emphasized not this uncertainty, but the links between elements of the system. In other words, they were more concerned with what could be explained causally, in terms of physical dynamics, and less with what was—at least theoretically—fundamentally unpredictable. In that sense, it seem
s fair to consider them to be historical in their approach, different as it was from the chronological descriptive framework of the classical climatologists. When the uncertainty became more than noise, new theories to account for it had to be developed. Chief among these was the meteorologist Ed Lorenz’s description of the chaotic features of certain systems, atmospheric ones in particular. Chaos, as Lorenz understood it, was a way to introduce unpredictability into a system without descending into randomness, “mere” contingency. Chaotic systems are far from random. Instead, they circle around certain stable states while never setting into a fixed rut. But they are unpredictable, confounding the physicist’s ambition to make good on the Newtonian promise of perfect knowledge predicated on a keen enough knowledge of initial conditions. Lorenz showed that in chaotic systems, initial conditions could never have been fine enough to preclude the possibility for uncertain outcomes. In exchange for some knowledge, perfect knowledge was ceded.