For nearly a century, interdisciplinary scholars have gradually reconstructed the existence of a so-called “Little Ice Age.” Their research is ongoing, but most now believe that average global temperatures declined by about one degree Celsius between the thirteenth and the twentieth centuries. The extent, meteorological consequences, and timetable of cooling varied from region to region, but sorting through these statistical complexities still yields an unmistakable downward trend in planetary temperatures.
Or does it? Economic historians Morgan Kelly and Cormac Ó Gráda of University College Dublin challenge the existence of a Little Ice Age (LIA) in a special issue of The Journal of Interdisciplinary History (JIH). Kelly and Ó Gráda examine recent reconstructions of European winter and summer temperatures from the medieval period to the twentieth century, but find “no statistical evidence of any major breaks, trends or cycles in European weather of the sort that one could associate with an LIA.” Kelly and Ó Gráda concede the existence of decades marked by extreme cold – the 1690s, for instance, or the 1810s – but to them these are mere blips in the statistical noise. They believe that climate historians have danced around this problem by changing the parameters of the LIA: some have identified its origins in the thirteenth centuries, and others in the sixteenth century, for example.
Kelly and Ó Gráda also challenge the “tenacious” idea that human history is driven by the direct influence of climate change. However, their argument is undermined by their use of long-term indices of wheat prices to supposedly correct the climatic reconstructions compiled by historical climatologists. Food prices are determined by more than the weather, even in preindustrial societies. A historian of past climates would more carefully tease out the complicated relationships between cultural structures, economic trends, environmental conditions and wheat prices, because the determinism dismissed by Kelly and Ó Gráda has all but vanished from serious scholarship on the LIA.
Hendrick Avercamp, Winter Scene on a Canal, ca. 1605.
The article published by Kelly and Ó Gráda fits neatly into a long pattern – a statistical trend! – of scholars in statistically rigorous disciplines challenging the conclusions of (historical) climatologists. In Merchants of Doubt, Naomi Oreskes and Erik Conway reveal how a cabal of right-wing physicists set out to undermine the science of global warming in the 1980s and 90s. Kelly and Ó Gráda certainly do not have such nefarious motivations, and they present some interesting correctives to popular narratives of the LIA. Still, their arguments against reconstructions of past climates are similarly problematic.
Fortunately, in its special issue on the Little Ice Age, the JIH provided space for rebuttals and further analysis. Perhaps the most compelling response was written by environmental historian Sam White, my co-founder at the Climate History Network. His article is well worth reading in its entirety, but its central point is simple: “Kelly and Ó Gráda have not detected a novel snag that somehow evaded hundreds of climate scientists.” Historical climatologists work with more than just records of grain prices. By employing a diverse mix of ice cores, tree ring records, historical sources and many other natural or documentary data that respond to weather, scholars have written thousands of articles that identify the LIA as the most significant climatic event for the 8,000 years prior to the onset of global warming. Of course, many of these articles were written outside of Europe, about regions other than Europe. White goes beyond the Eurocentric focus of Kelly and Ó Gráda to summarize the latest international, interdisciplinary research, which confirms that “the first four centuries of the last millennium (1000 to 1400) were warmer than the following four centuries (1400 to 1800).”
All the same, White concedes that Kelly and Ó Gráda are right to highlight the frequently inconsistent definitions of the Little Ice Age. To answer their objection, White presents three overlapping but compatible definitions of the Little Ice Age. According to the first, the world cooled between approximately 1400 and 1850, when the first influence of human greenhouse gas emissions ushered in the age of anthropogenic global warming. Under the second definition, the LIA was an “age of extremes” that lingered from the 1310s to the 1810s. Fluctuations – not general cooling trends – are paramount in this conception of the period. Finally, the third definition zeroes in on the coldest phase of the LIA, between 1580 and 1710, which coincided with a global socioeconomic “general crisis” in the seventeenth century.
Ultimately, White argues that serious scholars of the Little Ice Age have moved far beyond the straw man arguments that Kelly and Ó Gráda attempt to undermine. All the same, the kinds of objections presented by the economic historians are useful reminders that scholarship of past climates must be clear, consistent, and aware of the many influences that shape human history. The latest issue of The Journal of Interdisciplinary History reveals once again that otherwise problematic articles can be extremely useful for the conversations they inspire.
Established in 1988 by the UN and the World Meteorological Organization, the Intergovernmental Panel on Climate Change (IPCC) is a scientific body that periodically summarizes the scholarly understanding of the world’s climate. In 2007, the panel’s fourth assessment report outlined in stark terms the likelihood of anthropogenic global warming. Since then, severe storms and drought have ravaged North America, Australia and Africa, yet unusually wet, cold conditions have accompanied some European winters. Through it all carbon emissions have continued to rise, now driven largely by developing nations. Today, the IPCC’s highly anticipated summary for policymakers was finally released, in lieu of its fifth assessment report that will be published later this year. In this article, I explore this landmark report and the responses it has inspired from the perspective of a climate historian.
Initially, the most striking aspect of the IPCC’s new summary for policymakers was not its content but the media reaction. The banner at CNN is currently: “A town that’s melting.” Its subheading: “climate change already happening in Alaska town.” Additional titles announce: “climate change: it’s us,” and “Miama’s rising water,” while an opinion calls for “common sense.” Not surprisingly, among major news networks the BBC has provided the most informative analysis of the IPCC’s report, and its banner, while not as large as CNN’s, nevertheless reads: “UN ‘95% sure’ humans cause warming.” Of course, the Fox News headline is in substantially smaller font, and its conclusion is characteristically fair and balanced: “Hockey Schtick: UN report ignores global warming pause.” Worse still is coverage given by the Times of India, which features only a link in diminutive font buried at the bottom of its website. Meanwhile the homepage for CCTV, a major Chinese broadcaster, contains no reference at all to the report. Taken together, headlines at the big media outlets confirm the enduring importance of partisan divisions in the global warming discussion. They also suggest that scholars, journalists, the IPCC, and indeed the UN must do more to raise awareness of global warming in countries that will be most affected by its consequences. Still, the banner headlines on many centrist news outlets in the West are encouraging.For those who have paid heed to the relentless debate about global warming, much of the action in the IPCC's fifth summary for policymakers happens in the first few pages. In previous days and weeks, so-called climate “skeptics” flooded the airwaves, encouraging rampant speculation about whether the alleged “pause” in global warming would feature prominently in the IPCC's new report. In fact, in its second page the IPCC's summary actually confirms that:
The IPCC affirmed that average global temperatures at sea and on land have risen by 0.85 degrees Celsius since 1880, although that will come as no surprise. What does impress, however, is the IPCC's explicit repudiation of the false narrative of the "pause." Climate historians know better than most that climatic reconstructions can be manipulated with ease. Start your graph of annual temperatures with a year of anomalous warmth, and you're bound to discover long-term cooling. Begin with an unusually cold year, and you'll find just the opposite. That is precisely why scholars must set their temporal and geographic parameters before reconstructing past climates. What region are we examining? For what time, and why? With what sources? What are the limitations of those sources? These questions are essential for the accurate reconstruction of past climates, and the answer can never be: "because of the expected result." Moreover, to unravel why variations in temperature occur, we must also seek the stimulus - the "forcing" - for cooling or warming. Is a volcanic eruption responsible for a few unusually cold years? Is an intense El Niño to blame for a really hot year? Neither event need contribute to a long-term climatic trend.
Not surprisingly, skeptics eager to discredit the scientific consensus around global warming have ignored these questions. Instead, they have arbitrarily started their climatic reconstructions at 1998, a year of extreme warmth, in order to highlight supposed cooling since then. Unfortunately for them, the scholars of the IPCC have included this paragraph:
In other words, the presence of short-term fluctuations in climate does not throw into doubt the existence of long-term climatic trends. If anything, the impact of strong El Niño in 1998 reveals what can happen when an entirely natural event that stimulates warming compounds the the influence of anthropogenic greenhouse gases. Still, the IPCC's fifth summary did include these passages:
Those paragraphs will probably be manipulated by skeptics and misinterpreted by many journalists. While they seem to suggest that there has been a pause in the warming trend, the context matters. The surrounding passages confirm that model accuracy has improved, further strengthening projections of future warming. However, in 10 or 15-year intervals, natural signals can mask the anthropogenic warming trend. In other words, volcanic eruptions can stimulate short-term cooling, but, again, that hardly rules out long-term warming. In short intervals some natural influences will surprise scientists and confound models, because we are still learning more about the intricacies of our world's climate. Nevertheless, the big conclusions are still the same: the earth is warming, we're to blame.
The IPCC's summary for policymakers also addresses climates in the more distant past. Another argument frequently advanced by skeptics holds that the Medieval Climate Anomaly - previously known as the Medieval Warm Period - was actually accompanied by hotter temperatures than we face today. Their conclusion is that modern warming isn't a big deal, and falls within natural variability. Of course, the cause of current warming is more important to climate scientists than the scale of warming to date, because it is precisely that cause which will trigger future warming far beyond anything humanity has encountered. Nevertheless, the IPCC's report also discredits the idea that medieval warmth exceeded or matched modern temperatures:
In subsequent pages, the IPCC's report describes the worrying findings presented in thousands of scientific papers during the past six years. Oceans are warming, polar ice caps are shrinking and sea levels are rising, while the atmospheric concentration of carbon dioxide, methane, and nitrous oxide have risen to levels unseen in over 800,000 years. In its most important conclusion, the panel's report reveals that greenhouse gases emitted by human activity are now 95% certain to have caused recent warming. These emissions have affected carbon cycle processes, stimulating further warming from natural sources (for example, methane hidden under melting permafrost). Meanwhile, the ocean has absorbed 30% of anthropogenic carbon dioxide, causing dangerous ocean acidification.
The IPCC's fifth summary concludes that warming in the coming century will likely fall between 1.5-4 degrees Celsius. Moreover, it is more likely that warming will exceed a catastrophic 6 degrees Celsius than fall beneath 1 degrees Celsius. The lower range of this estimate is 0.5 degrees Celsius lower than it was in the IPCC's fourth assessment in 2007, owing in part to the slight divergence between model projections and climatic trends in the past decade. It is possible that the range will be adjusted upward in the IPCC's next report, as model simulations and average global warming converge again. Either way, our best guess for the future hasn't changed much: we probably face warming of approximately 3 degrees Celsius worldwide by the end of the century.
Social and environmental vulnerability to climate change, from low (pale green) to high (purple).
Of course, a 3 degree Celsius rise in average global temperatures does not mean each day will be three degrees warmer, no matter where we are. In many regions, warming will be expressed in extremes: a doubling, or tripling, of days accompanied by severe heat, along with far more dangerous storms and flooding. Moreover, warming in some countries will far outstrip the global average, and demographic, social or environmental conditions already increase the vulnerability of many of these countries to climate change. In 2011, scholars at Maplecroft, a global risk analytics company
, created the above map of global climate change vulnerability by analyzing 42 social, economic and environmental variables. News outlets in China and India take note: it is precisely the countries that increasingly contribute most to warming that have the most to lose. In that context, let us hope that the dire projections in the IPCC's fifth summary help moderates bridge the partisan divide to inspire concrete responses to climate change in the developed west.
~Dagomar DegrootFurther reading: Climate scientist Michael Mann, author of The Hockey Stick and the Climate Wars, measures claims by climate skeptics in light of the IPCC's fifth summary for policymakers.
On September 28th, the scientists of the International Geosphere-Biosphere Programme respond to the IPCC's fifth summary.
Contributing Author: Benoit S. LecavalierAugust 18th, 2013 marked the start of a two week long workshop called the Advanced Climate Dynamics Course (ACDC). The venue was located in a former fishing village in the Vesterålen islands of Arctic Norway, a little place called Nyksund with a population of slightly over a dozen permanent residents. We were there for more than just hiking through the great outdoors, eating the local food, and performing local outreach. We were there to discuss what many call small talk: the climate. Organized by European and North American Universities, this event attracted internationally renowned researchers and graduate students, gathered there to discuss the climate dynamics of the last deglaciation. Twenty thousand years ago, during the last glacial maximum, the climate was cooler, the Greenland and Antarctic ice sheet were larger, and gargantuan bodies of ice rested across North America, the British Isles, and Scandinavia. Consequently, the sea-level was lower than it is today by over 120 meters. The emphasis of the workshop was to discuss how the climate system transitioned from glacial to present interglacial conditions. The seminars began by summarizing our present understanding of climate on time-scales of thousands of years. The driver, often referred to as the pacemaker for the ice ages, is the changes in the Earth’s orbit around the sun. These gradual changes in the Earth’s orbit affect incoming solar radiation at the Earth’s surface, which can either facilitate the growth of an ice sheet or deter it. However, countless feedbacks within the climate system render the situation complex. For example, ice sheet’s reflective nature deflects radiation back into space affecting the available energy at the surface. In addition ice sheets, which can rival mountain ranges in size, affect atmospheric jet streams and deflect storm tracks as well as precipitation patterns. To understand these feedbacks within the climate system we have to look at paleoclimate records: terrestrial and marine records of past climate.
The following days were spent going over climate proxies, which preserve physical characteristics of past climatic conditions. These tell us about past temperatures on land and in the ocean, how vigorously the oceans circulated, and past sea-levels, among many other things. After being presented with collections of paleoclimate records, we could speculate on the role of the atmosphere and ocean during the deglaciation. The question that came came to mind: if the ice ages are driven by slow gradual changes in the Earth’s orbit around the sun, what processes, feedbacks, and mechanisms could punctuate the system with such abrupt and rapid climate change?
Evening in Nyksund.
We reviewed the literature to investigate the consensus on what is currently understood and what observations lack a proper explanation. Our review emphasized the necessary role of geophysical modeling of the climate system to understand how all these complex processes are intertwined. State-of-the-art atmosphere-ocean general circulation models tell us about the state of the atmosphere and ocean, while glacial system models reveal the response of ice sheet to past climate change and the resulting change in sea-level. Atmosphere-Ocean models are predominantly applied for the past and future 100 years, so the question remains: what were the climatic conditions over the ice sheets thousands of years ago? What climate forcing led to ice sheet instabilities, causing the flow of iceberg armadas in the North Atlantic? To which extent did the fresh water from these icebergs affect the circulation of the Ocean? How have these changes in circulation affected global heat transport and the carbon cycle? What about global temperatures? Fortunately, we are beginning to answer these questions thanks to international cross-disciplinary collaborations, which are often initiated by workshops such as the ACDC.
Many atmosphere-ocean modelers take an interest in simulating the deglacial climate, with help from the glaciological community who provide past ice sheet reconstructions. These scientists have discovered that massive ice sheets show the potential to deflect atmospheric stationary waves. The ice sheets respond to climatic shifts, and in warmer conditions they can change dynamically by releasing icebergs into the ocean. Fresh water melting from those icebergs produces density differences in the Atlantic Ocean which slows down the formation of heavy deep water, affecting global circulation. This change in ocean heat transport cools the North Atlantic, while the Southern Oceans warm in a compensating fashion. The models simulate these dramatic climate events, hinting at underlying mechanisms and illuminating the observations found in paleoclimate records. This goes a long way towards explaining how the Earth as a whole warmed out of the glaciation and why records in the North Atlantic reflect quick warming with subsequent rapid and prolonged cool period before finally stabilizing to present conditions.
However, the story is far from understood, for every answer brings new questions. The workshop got everyone thinking about possible avenues of research which will have to be investigated to address our questions. That is why we gathered there in that little Norwegian village. It was to exchange ideas, data and model predictions, to work together and form collaborations, and to piece together a story that shaped humanity and still affects us today.
Researchers at the Advanced Climate Dynamics Course, 2013.
A week ago I returned from what was, surprisingly, my first trip to Germany. This year the European Society for Environmental History convened its biannual conference in Munich, a city I’ll remember for its beautiful architecture, sensible public transit and delicious beer. No fewer than fifteen climate history panels were part of the conference, and despite my best attempts I couldn't attend them all. Still, I decided to share some of what I learned (or remembered) while listening to papers that were good enough to keep me from exploring Munich. Note that for the purposes of this little article, the terms “climate history” and “historical climatology” are synonymous.
1. Climate history must be inclusive to be effective.
There is only limited value in mining one kind of documentary source for evidence of past weather and, in turn, past climate change. Of course, the value of such work fluctuates with the source under investigation: registers of past events called chronicles are notoriously prone to exaggeration, for example, while ship logbooks provide standardized, easily quantifiable and remarkably reliable weather observations. Still, a reconstruction of past climate that makes any claim to accuracy must, where possible, employ a wide variety of documentary evidence compiled by many authors. These reconstructions are strengthened when meteorological information contained in some documentary sources can be verified using the data contained in other documents. They gain even more credibility alongside scientific evidence like model simulations, or statistics developed using natural archives (ice cores or tree rings, for example). Good climatic reconstructions are necessarily interdisciplinary, and we should think carefully about what we are really saying when we discuss observations written by a single author, in a single source. Are we reconstructing the climate of a vast region across the decades, or are we engaging in literary criticism?
If interdisciplinary work is essential to historical climatology, interactions between sub-disciplines are just as important. Climate history is often considered a sub-discipline of environmental history, which, in turn, is one genre in the broader field of history. Agricultural history, forest history and energy history are all among the sub-disciplines that together constitute environmental history. Like climate history, they lose significance when divorced from one another. Reconstructions of past climates are fascinating, but historians can also incorporate the many different sub-disciplines and genres of their profession to do something scientists can’t: weave the history of climate into the history of humanity. The narratives we get can be as valuable as the models developed by scientists as we struggle to understand our plight on a warming planet.
Beautiful Munich: the perfect city for a conference.
2. We're only scratching the surface of relevant documentary evidence.
Chronicles and weather diaries have long formed the backbone of the documentary evidence used to reconstruct past climates. Questions of interpretation hound both sources, however, and these days, correspondence and ship logbooks are increasingly in vogue. In Munich I heard scholars like Rudolf Brázdil describe how correspondence related to the collection of taxes can yield strikingly detailed climatic reconstructions. Tax records can be placed alongside court documents, toll accounts and maintenance registers as largely quantitative sources that can yield rich climatic data if interpreted using qualitative evidence. New sources – and new methods of source interpretation - can provide data about wind patterns, hailstorms, and other previously unexamined meteorological conditions, deepening our understanding of climate change.
3. We need new ways of conceptualizing the relationship between climate change and human history.
Fernand Braudel, perhaps the greatest historian of the twentieth century, introduced a revolutionary way of conceptualizing time. According to his notion of “total history,” different kinds of historical change transpire differently across time and space. Environmental or economic transformation at a vast scale spanned the centuries, yet the historical “event” was immediate. Understanding the past from this perspective allowed him to gather the entire Mediterranean world into a single narrative using the huge, lumbering structures of history.
Braudel's conception of historical change. Source: http://goo.gl/MSqC4U
The problem for historical climatologists – and indeed, all environmental historians – is that Braudel was wrong. Interdisciplinary research has revealed that many historical structures can be brittle; they can break quickly with immediate yet regionally specific ramifications. For example, climate change influenced by volcanic eruptions and the subsequent expansion of polar ice could alter prevailing weather patterns over the North Sea in one cruel winter. However, the same processes behind routinely cold winters in northern Europe could bring not frost but rather drought to the Mediterranean.
So different kinds of historical change can occur across many scales of time and space, and that complicates our attempt to conceptualize connections between past environments and historical events. Human history cannot be modeled – we simply lack all of the necessary variables – but in recent years environmental historians have made great progress going beyond the problematic concepts like footprint metaphor or social metabolism in their efforts to conceptualize the connections between nature and society. In this effort historical climatologists lag behind their peers, and for that reason climate histories can devolve into lists in which weather events likely stimulated by a climatic shift cause environmental changes that contribute to one event after another in the history of a particular region. Historians need to work with colleagues across many disciplines to develop ways of understanding relationships between climate, weather and human history. These ways of understanding might not completely explain the past, but they might help us conceive of historical change more clearly, with insights applicable for our future on a warming planet.
Note: originally posted on The Otter, blog of the Network in Canadian History and Environment (NiCHE).
On February 10th I embarked on the first leg of a long voyage from Toronto to Goa, a former Portuguese enclave nestled among the beaches of western India. After enduring the concrete monolith that is Frankfurt’s international airport, I finally boarded my second flight and flew south through Turkey, past Syria, across Iran and down towards Mumbai. I left the plane at an hour past midnight. Mosquitos swarming through the airport quickly prompted me to take the malaria medication that would later give me incredibly vivid dreams. Hours later the shock of a violent landing in Goa was nothing compared to the culture shock that followed. As I left the airport and stepped onto the rust-coloured soil I saw signs promoting European luxury vehicles or American cologne towering over slums and endless trash amid lush tropical beauty. After three sunrises and two sunsets without sleep I finally arrived at my hotel, ignoring for the moment the hand-sized spider dangling near my door.
For those planning to attend next month’s ASEH conference, Toronto does not look like this.
With the help of funding generously provided by Network in Canadian History and Environment (NiCHE), I had travelled nearly 13,000 kilometers to attend the fourth Open Science Meeting (OSM) organized by the Past Global Changes (PAGES) initiative. A core project of the International Geosphere-Biosphere Programme, PAGES has over 5000 subscribing scientists across more than 100 countries. Because research supported by PAGES explores past environments to create a roadmap for the future, the initiative is especially concerned with climate change. Every four years its Open Science Meeting is held in a new location, and in case the Olympic parallels were not obvious enough a “PAGES lamp” was lit at the opening ceremonies. It may not have resembled London’s burning torch, but it did avoid the mishap that embarrassed my fellow Canadians at the Vancouver Olympics.
It’s easy for historians to forget that we don’t have a monopoly over the interpretation of the past. There’s nothing like a scientific conference to remind us that we can only access a tiny sliver of the very recent past, that other disciplines can find voices which speak to the present in sources beyond the documents we hold sacred. Many of the scientists at the OSM reconstructed past climates to measure the significance of modern warming, to unravel how climatic shifts influence different environments, and to provide a clearer picture of the world’s natural history.
In papers and posters scientists presented results derived from the exhaustive analysis of, for example, changes in the growth of trees, the thickness of permanent ice cover and the scope of lakebed deposits. Conclusions were compared with other data that measured shifts in animal ranges, tree lines or glacial extent, all of which can be used to reconstruct changes in regional temperature or precipitation. Evidence from these so-called “proxies” was weighed against a range of sophisticated models, enabling projections of climates past that move seamlessly into the present and future.
Not surprisingly, correlating fluctuations in diverse proxy records and tying them to climatic trends is hardly straightforward. Physicist Ashoka Kumar Sinhvi gave an opening keynote address that exposed the frequently overlooked complexity of linking different kinds of data between different environments at different scales, revealing the limitations of our understanding of past and future climates. Later in the day that concept was echoed by André Berger, who explained how the intricate constellation of influences that shapes the global climate is never stable, complicating the attempt to find historical analogues for our present condition. Sinhvi, Berger and others helped frame the rich data presented in the papers and posters that followed by demonstrating yet again that in science, as in history, the past is opaque, unstable, and forever subject to interpretation.
Of course, that never stops us from seeking more information and, in turn, greater clarity. Some particularly fascinating papers explored past Antarctic climates at a time when the Antarctic Peninsula is warming at a rate of 5.3° C per century. Michael Weber presented findings that reveal how the Antarctic ice sheet is much more reactive to atmospheric Carbon Dioxide than previously believed. Robert Mulvaney then described how the rate of Antarctic melting, unprecedented in the past millennium, likely had analogues in the distant past when ice shelves were entirely absent. Medieval warmth and early modern cooling, familiar to historians of climates past, apparently were not felt in Antarctica. On the other hand, Guillaume Leduc presented exhaustive findings that, while skewed towards the Atlantic region, nevertheless suggested that the “Little Ice Age” between the fourteenth and nineteenth centuries strongly affected global sea surface temperatures. Those results may have critical implications for the nascent field of marine environmental history, which until now has not adequately considered climatic fluctuation.
High times in the Low Countries during the “Little Ice Age.”
To unravel histories that bridge culture and nature, environmental historians require some scientific literacy, yet I wasn’t sure what to expect as I prepared to give at a talk at a conference where formulas were ubiquitous and historiography unheard of. I argued that documentary evidence can improve the accuracy of reconstructions of temperature or precipitation, giving us a way of testing meteorological patterns recorded by the kinds of sources unearthed by scientists. Accustomed to the critical analysis of diverse documents, historians are ideally situated to filter documents through the kind of methodology that lets us quantify past weather observations and, in turn, reconstruct the climatic past. Moreover, while tree rings or ice cores rarely provide much more than seasonal resolution, surviving documents can record weather with far greater temporal precision, and some even chart hourly changes.
Most importantly, documentary evidence grants us access to past wind intensity or direction, weather conditions that are less easily measureable through the analysis of scientific proxy data. For centuries it was necessary for European mariners to estimate longitude by calculating a ship’s speed, direction and any leeway in its course, for which the most important influence was wind. Hence many logbooks kept aboard ships abound with reliable and quantifiable meteorological information taken several times on virtually every day of the vessel’s journey. The bulk of my talk presented results from English and Dutch ship logbooks, which suggest that easterly winds increased in the late seventeenth century as the climate cooled across the North Sea.
I was relieved and delighted by the reception I received from the scientists in the audience. More importantly, it was heartening to see the importance of interdisciplinary cooperation in the new “Future Earth” project spearheaded by the International Geosphere-Biosphere Programme. Still, many scholars in both the sciences and the humanities continue to take a passive approach to building connections between disciplines. Conferences like the PAGES OSM have existed for decades, yet many historians fail to realize that their insights are needed and desired. Similarly, most presenters at the upcoming ASEH conference are historians, and scientists or engineers remain underrepresented. Establishing connections between institutions like NiCHE, the ASEH, PAGES and the Climate History Network (CHN) can help move us forward, but what’s even more valuable is feedback from those who have benefitted from conferences in another discipline.
Slums bordering a wealthy part of Mumbai. Though poorly represented in this picture, the smog was overwhelming.
After the conference in Goa I spent a few days in the vast metropolis of Mumbai. My plane was delayed, and as it finally approached the city our pilot was forced to circle the airport for a few minutes before we could land. The slums in Mumbai are so vast that their full extent can only be grasped from the air. As I shifted in my leather seat I glimpsed the innumerable shanties, clustered around open sewage, barely visible through the purple smog. The impoverished people far below, and countless millions like them, will suffer most as our planet continues to warm, yet their voices are never heard in academic or political conferences. The quest to understand climate change must become more inclusive, not just of other academic disciplines, but of all voices, past and present, learned and “unlearned,” rich and poor.
For reasons both occasionally justified and frequently questionable, many academics have been slow to adopt the kinds of media that have changed how most people process information. Presentation software like PowerPoint is still approached with trepidation by some scholars, while the potential of social media for quickly sharing information across disciplines has only been realized by a small (but growing) minority.
Comic books are, of course, far older than the internet and, if loosely defined, may in some form predate writing itself. Infographics like the one I've posted below are influenced by the spectacularly successful style in which modern comic books portray the exploits of their heroes and villains. The information is dense, communicated in equal parts through writing and flashy visuals, and flows smoothly across a page. Might such infographics suggest new possibilities for academic posters? In fact, should we have paper posters at all, when digital equivalents can be so much more accessible?
Regardless, this infographic from LearnStuff.com succinctly summarizes a great deal of information about the past century of climate change, its environmental consequences, and what it may tell us about the future. Some interesting questions are raised by the determinism of statements in which, for example, mass mortality is directly linked to future climate change. Should we dispense with the kind of nuance that perceives climatic fluctuation as one influence among many when we try to warn policymakers and the public about the impending catastrophe of global warming? Or should we explore the full complexity of relationships between climate change and (future) societies, because our insights are valuable, and after all it is simplification that gives openings for global warming skeptics?
There is no easy answer, but in the meantime attempts to communicate the urgency of our plight are always valuable.
Note: created by Learnstuff.com. Thanks to Josh MacFayden of the Network in Canadian History and Environment (NiCHE) for bringing this to my attention.
For those interested in climates past and present, trees do more than absorb carbon dioxide. Seasonal changes in cellular growth near the bark of a tree leave rings buried in its wood. The size of those records is tied to the growth of the tree; a good year will imprint a thick ring, while hard times leave mere slivers. Anyone who's ever owned a plant will understand that most trees need abundant sun, moderate temperatures and sufficient water. Of course, gardeners are aware that different plants - from weeds to trees - respond to different conditions. By researching the peculiar tastes of various tree species climatologists can use tree trunks to reconstruct yearly fluctuations in temperature and precipitation, sometimes over hundreds of years.
The resulting reconstructions have been featured on this site ("Does tree ring data reflect global cooling? July 9, 2012"). With good reason: tree rings enable reliable climatic reconstruction for most parts of the world, especially in temperate regions where the contrast between seasons usually yields more discernible rings. However, most sources useful for the reconstruction of past climates have their shortcomings, and these inevitably stimulate controversy. Tree rings are no exception. Sulphur released into the atmosphere by volcanic eruptions of sufficient size at the right locations can cool the world's average temperature. Strangely that global cooling, while recorded by other sources and climate models, is not represented to the same extent in tree ring data. A new study by Michael Mann, Jose Fuentes and Scott Rutherford in the journal Nature Geoscience has suggested that trees in some altitudes simply stop growing when temperatures plummet below a certain threshold. Many trees would survive, and for those trees the next tree ring would therefore record growth only after temperatures had rebounded above that threshold. It is possible, therefore, that climatic reconstructions compiled using tree rings are less accurate than previously thought.
No fewer than twenty-three scientists responded to these claims, and the subsequent debate is nicely summarized by Scott Johnson at Ars Technica. Whatever its resolution, the controversy highlights the weaknesses of climatic reconstructions that use just one kind of source. The most reliable reconstructions of past climates and, for that matter, human history are generally those that incorporate a wide-ranging and diverse selection of evidence. For some weather conditions, in some places, for some time, evidence useful for climatic reconstruction can include all manner of sources, involving not only tree rings, plankton deposits, ice cores and other records accessible by scientists, but also surviving documentary records from literate cultures.
Logbook kept aboard the vessel "Wapen van Hoorn," sailing from Holland to Asia in 1627.
The cross-disciplinary dialogue encouraged by this diversity of sources can break down, however, when scholars broaden their focus. Changes in weather conditions like wind direction that may be associated with climatic fluctuation aren't easily reflected in scientific data. Reconstructions therefore rely heavily on, for example, logbooks kept aboard ships that record daily weather. On the other hand, past cultures that communicated information orally have left us few sources useful for climatic reconstruction, and when piecing together the climatic shifts that affected such civilizations we must depend on, for example, tree ring data. As our interest enters the distant past we leave behind both documentary sources and tree ring data, and our reconstructions must increasingly rely on ice cores. Beyond 1.5 million years into the past we must turn to sediments and consider increasingly indirect consequences of climatic fluctuation, as our reconstructions diminish in accuracy.
Ultimately we cannot measure or understand global warming without reference to the past; after all, the world must be warming relative to what came before. Moreover, our best guess of what may happen in the future can come through an analysis of warmer (and colder) periods in our past. For that reason it is critical that we grasp the limitations of the sources that we use to reconstruct the climates of that past. Ultimately the best answers are always found through diversity: diversity of sources, methodologies, and perspectives.
Note: I will be discussing some of these themes next week at the PAGES Open Science Meeting
in Goa, India.
Whether consciously or unconsciously, most scholars study something important to their societies. The walls of the ivory tower are, in fact, quite porous. It's no surprise that the genre of history that deals with environmental issues - environmental history - grew out of the debates surrounding the use of DDT. No surprise, either, that academics within disciplines from anthropology to economics are increasingly considering the influence of climate change just as the effects of global warming are becoming painfully obvious. Now more than ever, research into past climates is not just for scientists. If environmental history grew steadily in the decades since its conception, so too did its semi-autonomous, interdisciplinary cousin: climate history, or historical climatology. This site regularly describes some of the more interesting work published by historical climatologists, before considering how it can reframe today's environmental issues. Equally striking, however, is what's not (yet) published, but spoken. Testament to the growing importance of climate history within environmental history, interviews about past climates have aired this year on two of the major audio resources in the discipline: Nature's Past and Environmental History Resources. Moreover, last year the growing diversity of climate history was well represented at the major conference for the North American branch of environmental history. In Madison, Wisconsin, papers explored how a shifting climate influenced issues ranging from nineteenth century famines in the far north to the construction of the St. Petersburg ice palace during the frigid winter of 1740. Even more topics are on this year's agenda. In Toronto climate change will be connected to cold war national security, the history of Lake Superior, Alberta's fossil fuel economy, the hydrology of central Mexico, warfare down the Danube, early modern transportation, and much more.
As the study of past climate change claims an increasingly important place within environmental history, it has also entered the mainstream of the historical profession. At this year's meeting for the American Historical Association - the largest conference in the discipline - climate history was featured in three back-to-back sessions. As described by Sam White of the Climate History Network, historians unraveled how past climatic variability influenced hurricanes in New Orleans, agricultural sustainability, and human history across many thousands of years. Rising interest in climate change within history and other non-scientific disciplines is obvious in published scholarly literature. It is equally apparent online and at conferences, where the insights described and discussed have equal relevance for our struggle to make sense of a warming planet.
As this is published, so-called "Frankenstorm" hurricane Sandy is merging with a winter gale and bearing down on the American east coast. The deaths of sixty people in the Caribbean will likely represent this historic storm's most direct and poignant toll. However, as panic spreads through the most densely populated region of the United States it is the hurricane's potential to influence the American election and, possibly, the shape of the world in years to come that has most captured the world's attention. Whether the worst fears of meteorologists come to pass or not, Sandy presents a unique "teachable moment" for historical climatologists, many of whom study the interactions between past weather and historical events.
The most fundamental lesson we can glean from the impending catastrophe is simply that weather affects history. Most historical narratives still focus on events within purely human spheres, describing changes in relationships between classes, for example, or cultural trends. The rise of post-modernism in particular has left some historians suspicious of attempts to describe environmental influences and, ultimately, "what really happened." Of course, there are the limits - both practical and conceptual - that cloud our ability to reconstruct the past and make sense of relationships between human histories and, for example, severe weather events. Nevertheless, hurricane Sandy reveals that many histories are little more than interesting stories unless they at least attempt to address environmental influences.
New York: possibly facing the worst storm in its history. Reuters.
A second lesson that will become increasingly evident in coming days, weeks and years is similarly simple: some of hurricane Sandy's most important influences will be counter-intuitive. We may find, for example, that widespread fear drove many people to vote early, paradoxically increasing voter turnout. As I charted how weather patterns influenced by past climatic shifts affected Dutch East India Company ship journeys, for example, I expected to find that more frequent storms in colder climates proved devastating to the Company and its sailors. Instead, because East Indiamen were gigantic, solidly-built ships, many storms actually benefited crews by pushing their ships forward more quickly with their high winds. Because so many sailors died of disease while at sea, shortened journeys, influenced by storms, probably saved lives. Environmental influences are rarely straightforward, and historical climatologists know this better than most.
In the aftermath of hurricane Sandy's landfall, it's likely that many will describe how the storm "caused" devastation along the East Coast and, in turn, altered the election. The third and final lesson, then, is that weather events are but one influence among many. Natural disasters occur at the intersection of human and environmental histories; indeed, while "natural" usually refers to stimuli that, at least until recently, have largely existed beyond human influence, there is no "disaster" without human settlement. Teasing out how exactly hurricane Sandy affected the East Coast, how it helped change the election, and what social structures were especially vulnerable will be a painstaking task. Luckily, there is an entire field of study devoted to unraveling those relationships.
Article originally posted on ActiveHistory.ca. In recent weeks widespread outrage over the publication of Kate Middleton’s topless photos has existed in strange parallel with a decidedly muted response to a shocking acceleration of Arctic melting. While every day brought new stories of royal indignation and litigation to the front pages of major newspapers, concern over the plight of our increasingly topless planet was tucked away in corners of the internet, where many comments were, as ever, skeptical at best. Nevertheless, our destruction or, at least, transformation of the planet’s environment continues despite our apathy and cynicism. This summer Arctic ice cover fell to 3.41 square kilometers, a decline by an area the size of Texas against the previous minimum and some 50% lower than the average between 1979 and 2000. The reasons for enduring public skepticism of climate science and global warming have been examined at length – most eloquently in Naomi Oreskes’ and Eric Conway’s Merchants of Doubt – but the causes for the apathy of believers are less clear.
Upon encountering present-day mysteries our natural inclination as “active” historians is to sift through the past for context and, perhaps, answers. This article proceeds along similar lines, and it is the fourth in a series that explores how historians can shed light on global warming and its consequences. My research unravels relationships between early modern climatic fluctuations and the commercial, military and cultural histories of the Dutch Republic in the seventeenth century. Although those climatic fluctuations were collectively part of a relatively cool climate known as the “Little Ice Age,” average European temperatures during the period could change by nearly 2 degrees Celsius in just a few years. That pales in comparison to the likely scale of future anthropogenic warming, but for historians seeking insight into the climatic shifts we’ve already experienced the Little Ice Age is a great place to look.
The problem is, of course, that most societies within early modern Europe bore little resemblance to our own, and the historical writing we examine to contextualize the present was recorded by observers who frequently perceived weather very differently than we do now. In that alien world the Dutch Republic was unique, a society with capitalist socio-economic structures that seem instantly familiar, and were expressed in everything from remarkable rates of urbanization to incessant financial speculation. Admittedly not many of us are rabid Calvinists or troll the North Sea for herring, but searching the historical record for perfect analogues to ourselves is, of course, impossible. The surviving records kept by the politicians, merchants, farmers and mariners of the Republic provide some of history’s best insights into how we approach a changing climate.
After countless hours spent reading tattered correspondence, water-stained ship logbooks and half-burned diary entries - and thanking the Dutch archival system for its growing commitment to digitalization – a pattern emerges for the weary environmental historian of the Dutch Republic. In the seventeenth century Netherlands, those furthest removed from the environmental necessities of life were least likely to appreciate the importance of weather, even in a country prone to devastating storm floods. Logbooks kept aboard Dutch sailing ships abound with meteorological observation because recording the influence of wind was critical for contemporary navigation. Moreover, the seaworthiness of the vessel, the survival of its stores and the health of its crew were strongly tied to the weather that prevailed during a journey. No surprise, then, that during gales sailors scribbled fearful notes in the margins of their logs, before describing their relief when the weather cleared. Scattered among these reflections are hints that mariners whose work bound them to defined geographic locations perceived changes in patterns of prevailing weather related to shifts in the early modern climate. On the other hand, letters sent by the Republic’s political elite from its many urban centres have limited value for the environmental historian. Johan de Witt, the Republic’s leading political figure in the mid-seventeenth century, was apparently far more concerned about the financial ramifications of the state’s rising debt than even the most severe weather events of his time. To paraphrase Mark Twain, history may not exactly repeat itself, but it does have a tendency to rhyme.
For sailors, such apathy was not an option. The most telling examples of the tension occasionally kindled by these very different attitudes come from the naval wars in which the Republic was embroiled for much of its tenure as a European great power. The weather of the First Anglo-Dutch War was unusually stormy, although the causes were likely unrelated to a broader climatic shift. Fall and winter in the North Sea is almost always tempestuous, but in 1653 the Republic’s situation looked desperate, and in late October the Dutch Admiral – the wonderfully named Witte de With – was still on convoy duty. As he returned to the islands that surrounded the interior waters of the Republic his supplies were low and his crew was mutinous. The Republic’s governing body decided that Witte and his fleet should receive their supplies at sea, to prevent widespread desertion upon arrival at port. In a series of increasingly desperate letters De With begged his superiors to reconsider. Leaving the fleet at sea in the unpredictable and often violent autumn weather was courting suicide, De With insisted, but his masters were unmoved. On November 7th De With’s predictions came to pass when a severe gale sunk eleven warships and drowned some 1,400 seamen.
Historians frequently wrestle with the challenge of creating inclusive histories for societies in which literacy was the privilege of the elite. While those of us who piece together the history of climate frequently use sources that have been overlooked by other historians, we also require the kind of continuous, quantifiable records that were not usually kept by the poor. We may use the logbooks compiled by naval officers where other historians read the correspondence of wealthy merchants, but the reflections of ordinary sailors and dock workers are too often lost to us, as well. Of course, it was often precisely the poor – both urban and rural – whose work and play was most rooted in the unique environment of the Dutch Republic. Consequently, what we do know about, for example, small-scale farmers is intriguing. When the early modern climate cooled and persistent freezing halted travel through the Republic’s many canals, farmers abandoned their boats and used sleds to transport their goods. By switching easily between different modes of transportation, farmers, so attuned to the weather, adapted better than most within the Dutch Republic.
Today, most of us live in concrete jungles that may be oppressed by heat and cold but seem far removed from the environmental consequences of those fluctuations in temperature. A book I recently read about the shipwrecked child of a zookeeper included a passage that, for the environmental historian, provided a thought-provoking summary of the concept of “home.” To the protagonist of Life of Pi, home is a place where the environmental necessities of life, otherwise scattered across a vast geographic expanse, are collected for our convenience. The environmental historian will, of course, note that those environmental resources are not collected but rather connected for our benefit; no food is stored within our urban apartments that did not come from outside. The disastrous droughts of the past summer have reminded some of us that the environmental networks that sustain our urban lives are already strained in the face of an accelerating climatic shift, although many within the American states most affected were likely more impressed with Paul Ryan’s workout regime.
Ultimately, separation from the environments that support us has more to do with our psychology than our geography. As the climate cooled in the late seventeenth century Adriaen van der Goes, a lawyer in The Hague, described weather patterns and their repercussions in vivid letters to his brothers. Neither class nor geography excuses our apathy. Like the politicians who doomed De With’s fleet, we should know better, and, in knowing, we should care.