Sam White the Real Little Ice Age Between C.1300 and C.1850 A.D

Home , Global cooling, Little Ice Age, Proxy (climate)

Journal of Interdisciplinary History, xliv:3 (Winter, 2014), 327–352.

THE REAL LITTLE ICE AGE Sam White The Real Little Ice Age Between c.1300 and c.1850 a.d. the world became, on average, slightly but signiªcantly colder. The change varied over time and space, and its causes remain un- certain. Nevertheless, this cooling constitutes a meaningful climate event, with signiªcant historical consequences. Both the cooling trend and its effects on humans appear to have been particularly Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 acute from the late sixteenth to the late seventeenth century in much of the Northern Hemisphere. This article explains why climatologists and historians are conªdent that these changes occurred. On close examination, the objections raised in this issue of the journal by Kelly and Ó Gráda turn out to be entirely unfounded. The proxy data for early modern global cooling (such as tree rings and ice cores) are robust, and written weather descriptions and observations of physical phenomena (such as glacial movements and river freezings) by and large offer independent conªrmation. Kelly and Ó Gráda’s proposed alternative measures of climate and climate change suffer from serious ºaws. As we review the evidence and refute their criticisms, it will become clear just how solid the case for the Little Ice Age (lia) has become. the case for the little ice age The evidence for early modern global cooling comes, ªrst and foremost, from extensive research into physical proxies, including ice cores, tree rings, corals, and speleothems (stalagmites and stalactites). The precise techniques of extracting climate data from these samples are not important in this context. What matters is that each type of sample provides a physical record that correlates reasonably well to a climate variable, and that researchers can take reliable high-resolution measurements of that record and calibrate them against modern instrumental measurements. For instance, if instrumental measurements

Sam White is Assistant Professor of History, Ohio State University, and co-founder of the Climate History Network (climatehistorynetwork.com). He is the author of The Climate of Rebellion in the Early Modern Ottoman Empire (New York, 2011). The author thanks Franz Mauelshagen, Dagomar Degroot, A. T. White, and the journal editors for their comments on this article. © 2013 by the Massachusetts Institute of Technology and The Journal of Interdisciplinary History, Inc., doi:10.1162/JINH_a_00574 328 | SAM WHITE demonstrate that summer temperature explains much of the variation in the annual growth rings of a large sample of Scandinavian trees, researchers can use older growth rings from those trees to estimate pre-instrumental summer temperatures for the calibrated region.1 No proxy record gives a perfect reconstruction. Yet when used carefully, proxies can produce valuable results. The results of most longer-term proxies and large-scale multiproxy studies (that Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 is, studies modeling temperatures from many different proxy sources) point overwhelmingly to signiªcant cooling from c.1300 to c.1850, including a distinct cooling in much of the Northern Hemisphere from the late sixteenth to the seventeenth century. The evidence for this trend is by no means limited to a couple of contested studies, as Kelly and Ó Gráda imply, nor only to tree rings in Europe. A wide variety of regional proxies, ranging from Greenland ice cores to South African speleothems, point in the same direction. Even in the Antarctic, borehole temperature data point to the lia as the “largest climate anomaly of the last 1000 years,” with temperatures on average 0.52 Ϯ 0.28°C colder than those of the last century. A German speleothem study now con- ªrms a cooling phase from c.1300 to c.1800 for Europe in particular. The most recent long-term global temperature reconstruction, employing seventy-three world-wide proxy records of different kinds, found unambiguous signs of the lia, particularly from c.1500 to c.1800. Even within error bars, this cooling stands out as undoubtedly the most pronounced global climate anomaly of the past 8,000 years (until contemporary global warming).2

1 For a sense of the range of proxy data, methods, and issues, see, for example, Philip D. Jones et al., “High-Resolution Palaeoclimatology of the Last Millennium: A Review of Cur- rent Status and Future Prospects,” The Holocene, XIX (2009), 3–49. In the four years since that article, the coverage and resolution of proxies has continued to improve apace. 2 Readers concerned that “modeling” is somehow less solid than “measurement” should understand that even contemporary meteorological data routinely combine the two. See Paul N. Edwards, A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming (Cambridge, Mass., 2010). For examples of the wide range of regional proxies that indicate cooling, see Paul A. Mayewski et al., “Holocene Climate Variability,” Quaternary Research, LXII (2004), 243–255. Anais J. Orsi, Bruce D. Cornuelle, and Jeffrey P. Severinghaus, “Little Ice Age Cold Interval in West Antarctica: Evidence from Borehole Temperature at the West Antarctic Ice Sheet (WAIS) Divide,” Geophysical Research Letters, XXXIX (2012), L09710 (quotation taken from the abstract); Nerilie J. Abram et al., “Acceleration of Snow Melt in an Antarctic Peninsula Ice Core during the Twentieth Century,” Nature Geoscience, VI (2013), 404–411, suggest that the greatest cooling was in the ªfteenth century. Strong conªrmation of Southern Hemisphere cooling also appears in Lonnie G. Thompson et al., “Annually Re- THE REAL LITTLE ICE AGE | 329 Kelly and Ó Gráda respond to such evidence in a mere two footnotes. The ªrst footnote makes the unsupported claim, “While tree rings might seem like a more systematic source [of past climate], annual growth rings only reºect weather for trees at the edge of their geographical ranges that are under stress from cold or arid conditions, which is not the case for most of Europe.” This claim is highly misleading, if not simply false. Climatologists make use of tree rings as temperature proxies across a wide geographical Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 range for several obvious reasons. First, since different types of trees have different ranges and different sensitivities, much of the temperate world is at the edge of at least one species’ range, and researchers can create reconstructions using multiple species. Second, trees on mountains and hills (where the oldest trees are often found) are more sensitive to temperature variations, but they can nonetheless offer a reasonable record of regional temperatures. Third, even away from the edge of their range, trees do not grow at the same rate every year. Seasonal temperature and/or precipitation in temperate climates determine some part of the variance in annual growth, though probably not as much as in more extreme climates. In any case, climatologists produce reliable tree ring- based temperature records not only for extreme areas, such as Scan- dinavia, but also for more temperate regions, such as Ireland.3 The second problematical footnote tries to dismiss proxy data in general by appealing to a statistical study by McShane and Wyner. Yet the claim that this work refutes evidence of the lia is equally misleading. McShane and Wyner are not primarily concerned with whether proxies reconstruct such longer-term trends as the lia but with the supposed inability of proxy-based reconstructions to beat sophisticated null models in reproducing inter- solved Ice Core Records of Tropical Climate Variability over the Past ϳ1800 Years,” Science CCCXL (2013), 945–950. The German study is Jurgen Fohlmeister et al., “Bunker Cave Sta- lagmites: An Archive for Central European Holocene Climate Variability,” Climate of the Past, VIII (2012), 1751–1764. Shaun A. Marcott et al., “A Reconstruction of Regional and Global Temperature for the Past 11,300 Years,” Science, CCCIX (2013), 1198–1201. 3 For a discussion of tree-ring limitations and techniques to overcome them, see A. M. García-Suárez, C. J. Butler, and M. G. L. Baillie, “Climate Signal in Tree-Ring Chronologies in a Temperate Climate: A Multi-species Approach,” Dendrochronologia, XXVII (2009), 183– 198. For a recent example, see Ulf Büntgen et al., “Filling the Eastern European Gap in Mil- lennium-Long Temperature Reconstructions,” Proceedings of the National Academy of Sciences, CX (2013), 1773–1778. Climatologists can now also measure isotopic ratios and maximum latewood density to draw further data from tree rings. 330 | SAM WHITE annual variability over shorter periods in the instrumental record. They even offer four different possibilities for this inability, three of them dealing with how data are handled or whether their own test is too demanding.4 As a worst-case scenario, McShane and Wyner contend, “It is possible that the proxies are in fact too weakly connected to global annual temperature to offer a substantially predictive (as well as re- constructive) model over the majority of the instrumental period.” They Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 even concede, “This is not to suggest that proxies are unable to detect large variations in global temperature (such as those that distin- guish our current climate from an ice age). Rather, we suggest it is possible that natural proxies cannot reliably detect the small and largely unpredictable changes in annual temperature that have been ob- served over the majority of the instrumental period.” In fact, they note, “It is well known and generally agreed that the several hundred years before the industrial revolution were a comparatively cool ‘lia.’” Their own Bayesian reconstruction technique for the past millennium of climate produces a result similar to the studies that Kelly and Ó Gráda try to dismiss, albeit with larger uncertainty bands. Even within these high uncertainty bands—mostly a result of proxy-data collections that were limited at the time of their writing—global cooling from c.1300 to c.1850 still appears highly likely.5 In 2013, Tingley and Huybers employed a Bayesian reconstruction technique but with more proxy-data inputs; they reached stronger conclusions. Although their study focuses on only the past 600 years, thus not addressing cooling since the fourteenth century, it ªnds that since c. 1450, “the 100-year cooling trend with the largest magnitude occurred between 1547 and 1646 at a rate of 0.71°C per century (90% uncertainty is Ϫ0.88°C to Ϫ0.54°).” They add that “this early cooling trend, whose magnitude rivals that of the recent warming, also indicates that the proxy record is capable of capturing large, persistent temperature variations.” They conªrm that the results are robust across different proxies and instrumental measurements—in other words, that ice cores, lake varves, and tree rings all give similar results either individually or in

4 Blakeley B. McShane and Abraham J. Wyner, “A Statistical Analysis of Multiple Temper- ature Proxies: Are Reconstructions of Surface Temperatures over the Last 1000 Years Reli- able?” Annals of Applied Statistics, V (2011), 5–44. 5 Ibid., 23–24 (emphasis added), 26. THE REAL LITTLE ICE AGE | 331 combination—a conclusion previously reached by Moberg et al. in 2005.6 In fact, nothing in the criticisms of Kelly and Ó Gráda or McShane and Wyner explains away the agreement among proxy types and samples for global and Northern Hemisphere cooling between c.1300 and c.1850. It is this consistency as much as any other factor that makes the proxy evidence so convincing. Moreover, as more data are collected, proxy results become aligned ever more Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 closely with the modern instrumental record. In short, there is every reason to be conªdent that the proxy record will continue to conªrm the presence of widespread cooling in the early modern period. Historians and historical climatologists studying the lia can rely on ªrm backing from robust scientiªc data.7 Kelly and Ó Gráda’s proposed alternative measure of climate change turns out to be deeply ºawed. Starting from the assumption (incorrect, as we have seen) that proxy data are unreliable, the authors argue that we must make use of documentary evidence. The authors then narrow down that documentary evidence to just two records—a reconstruction of temperature in the Low Countries based on such information as river tolls and mill opera- tions, and a record of English grain prices. They argue that since the Low Countries series accurately predicts English grain prices from 1270 to 1450, it must be an especially reliable proxy. Hence, relying heavily on this single measurement, with a starting point of c. 1300, they ªnd no evidence of long-term trends or cycles in temperature that would serve to corroborate the existence of an lia. Both their measurements and their conclusions contain nu- merous insurmountable problems. The ªrst set of problems arises from the use of documentary evidence to make long-term climate reconstructions. In most cases, such evidence, if used properly, undeniably contributes to our understanding of past climates,

6 Martin P. Tingley and Peter Huybers, “Recent Temperature Extremes at High Northern Latitudes Unprecedented in the Past 600 Years,” Nature, CDXCVI (2013), 201; Anders Moberg et al., “Highly Variable Northern Hemisphere Temperatures Reconstructed from Low- and High-Resolution Proxy Data,” ibid., CDXXXIII (2005), 613–617. 7 D. M. Anderson et al., “Global Warming in an Independent Record of the Past 130 Years,” Geophysical Research Letters, XL (2013),189–193, employ 173 temperature-sensitive proxies and achieve a correlation of 0.76. Using a more limited record, they ªnd the coldest temperatures of the early modern era to have occurred from c.1600 to c.1700, with upward trends starting as early 1730 (192). 332 | SAM WHITE sometimes adding considerable precision, detail, and resolution to proxy-based climate reconstructions, particularly for lia Europe. Nevertheless, it would be arbitrary and misleading to dismiss the proxy data in favor of a documentary-only approach to past climate, especially in Kelly and Ó Gráda’s case, since they rely on the weakest element of the documentary record—its ability to reconstruct centuries-long trends. Few human observers lived long enough, or remembered well enough, to record long-term shifts in Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 averages, especially in pre-industrial times. Moreover, long-term trends or cycles in climate become exceedingly difªcult to trace from such records as tolls or prices when human practices, infrastructure, and institutions change faster than environmental conditions. Historical climatologists try to compensate for these problems by carefully analyzing observations and compensating for shifts in conditions. Yet in the matter of centuries-long trends, they face much more daunting hurdles than do climatologists who work with the more consistent, homogenous, and quantiªable data in physical proxies.8 Kelly and Ó Gráda’s particular selection of documentary sources only makes things worse. At ªrst glance, the two most complete, continuous set of written records might appear to be the best ones to reconstruct climate in the past. Yet these two sources introduce a subtle but powerful bias into the observations: Coun- tries with the most continuous, homogenous records tended to have the strongest institutions and fewest major internal distur- bances. They likely avoided the worst climate extremes, or they adapted well to changing weather. This is certainly the case for the early modern Netherlands. The Dutch enjoyed arguably the most resilient economy in the world during the worst of the Northern Hemisphere lia (late sixteenth century through the seventeenth century), with little damage from climatic variation. The apparent absence of long-term change in the documentary climate reconstruction likely reºects effective long-term Dutch adaptation by improving infrastructure and adjusting agricultural and transportation activities.9

8 Rudolf Brázdil et al., “Historical Climatology in Europe—The State of the Art,” Climatic Change, LXX (2005), 363–430. 9 For the resilience of the Dutch economy, see Jan de Vries and Adriaan van der Woude, The First Modern Economy: Success, Failure, and Perseverance of the Dutch Economy, 1500–1815 (New York, 1997); de Vries, “Measuring the Impact of Climate on History: The Search for THE REAL LITTLE ICE AGE | 333 The English grain-price series presents even more serious issues. Prices in general have been a contentious source of climate data, and English wheat prices may be particularly problematical. Although England did not endure the lia as easily as the Nether- lands did, it fared better economically and demographically than most of the rest of the world. Compared to France or Central Eu- rope, England’s milder Atlantic climate, diversiªed rural economy, and access to maritime imports undoubtedly helped its grain prices Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 to adjust to long-term climate trends. Controlling for inºation and disregarding the extremes of the 1590s and 1690s (an arbitrary con- cession), Kelly and Ó Gráda suggest that English grain prices hov- ered around a constant mean (otherwise the correlation with the Low Countries data would break down). If this result truly reºects a stable climate, rather than English adaptation, we might expect to ªnd it elsewhere in Europe. However, Pªster has shown, for instance, that even controlling for inºation, rye prices in Nuremberg reveal a distinctly higher mean between c.1570 and 1630, just when proxy climate records indicate the most rapid cooling in the Northern Hemisphere and detailed Swiss records show the greatest frequency of lia-type weather events. The lack of such a trend in Dutch and English records can easily be explained through Dutch and English adaptation. The presence of such a trend in Central Europe is harder to explain except as a reºection of climate change.10 Yet another set of serious problems arises from the way in which Kelly and Ó Gráda compare the Dutch weather records with the English grain prices, arguing that their correlation to each other proves the strength of each reconstruction. The phenomena

Appropriate Methodologies,” Journal of Interdisciplinary History, X (1980), 599–630 (note that the studies by Christian Pªster, cited in the following paragraphs, answer de Vries’ concerns about quantitative indications of climate change). For the adaptations in Dutch commercial and transportation networks in particular, see de Vries, Barges and Capitalism: Passenger Trans- portation in the Dutch Economy, 1632–1839 (Utrecht, 1981), 289–315; Dagomar Degroot, “Conºuences of Climate and Crisis: Water, Weather and Transportation in the Dutch Re- public, 1650–1750,” paper presented at the annual meeting of the American Society for Envi- ronmental History, Toronto, April 6, 2013. 10 Franz Mauelshagen, Klimageschichte der Neuzeit, 1500–1900 (Darmstadt, 2010), 89–93; An- drew Appleby, “Grain Prices and Subsistence Crises in England and France, 1590–1740,” Jour- nal of Economic History, XXXIX (1979), 865–887. Christian Pªster, “Climatic Extremes, Recurrent Crises and Witch Hunts: Strategies of European Societies in Coping with Exoge- nous Shocks in the Late Sixteenth and Early Seventeenth Centuries,” Medieval History Journal, X (2007), 50–51. 334 | SAM WHITE under comparison are not exactly the climates of the Low Coun- tries and of England. Kelly and Ó Gráda have calibrated only a proxy of the Low Countries’ climate (the documentary-based index) to a distant reference period (1270 to 1450) of a proxy (price) of a proxy (grain yield) of a single English season (summer). The result is not a record of English climate from the Low Countries data but a reºection of a reºection of a reºection of a part of the English climate. Even if the correlation is high at each stage, the connec- Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 tion that one can draw in this context between the Low Countries climate index and the English climate—much less the climate of Europe or Eurasia—is tenuous. More importantly, aside from the serious problems outlined in the previous paragraphs, the agreement between the Low Coun- tries’ and English results would not demonstrate independent con- ªrmation of European temperature trends at all; the results probably correlate because they both reºect another climate variable altogether. As Robinson clearly demonstrated, Van Engelen’s winter severity index, upon which Kelly and Ó Gráda rely for their Low Countries’ reconstruction, basically tracks a twenty-ªve-year moving average of the North Atlantic Oscillation (nao) index. Since a low nao can also bring bad weather for English crops, it is more likely than not that the nao created much of the correlation between the two series. In other words, Kelly and Ó Gráda have not found a superior long-term reconstruction for European or even regional climate so much as a mediocre reconstruction for ºuctuations in the nao.11 Still more troublesome is Kelly and Ó Gráda’s ªxation on these studies to make claims about the entire lia. The crux of their argument turns on the failure to ªnd clear climate signals (cycles and trends) amid the noise of annual temperature variations—an issue with which climatologists are all too familiar. In appealing to the Slutsky effect, Kelly and Ó Gráda have not detected a novel snag that somehow evaded hundreds of climate scientists. Clima- tology deals extensively in sophisticated statistical techniques to spot patterns in the data and test them for strength and signiªcance. To that end, climatologists work to obtain large datasets and employ methods to identify clear climate signals and minimize noise.

11 Peter J. Robinson, “Ice and Snow in Paintings of Little Ice Age Winters,” Weather, LX (2005), 37. THE REAL LITTLE ICE AGE | 335 For instance, in examining whether sunspot cycles created lia cooling, climatologists do not select small sets of raw data to look for obvious patterns; they take temperature reconstructions from around the world and smooth out other obviously competing short-term forcings, such as El Niños and volcanic eruptions. By conªning themselves to local document-based reconstructions, Kelly and Ó Gráda amplify the noise and obscure the signals. Even if their data were not already questionable on the grounds outlined Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 above, they would tell us little about global temperature trends, much as our own personal observations and local weather phenomena, no matter how carefully compiled, would neither prove nor disprove contemporary global warming.12 Moreover, if we view the lia as an average cooling trend beginning c.1300, none of the studies that Kelly and Ó Gráda cite are long enough to capture the whole phenomenon. Their Low Countries’ temperature series does not begin until 1300; Shabalova and van Engelen, the authors of that series, explained elsewhere that the volume of data does not rise substantially until the ªfteenth century. Kelly and Ó Gráda cite only one series, that compiled by Glaser and Rieman, that extends back far enough to capture the entire lia in relation to the medieval period (again, only allowing for generous inferences from limited records until c.1400). This reconstruction is conspicuously absent from Kelly and Ó Gráda’s charts of historical series (see Figure 3 of their article in this issue)—no doubt because it clearly suggests that the period between roughly 1400 and 1900, apart from a mild phase in the mid- 1700s, was distinctly cooler on average than the centuries before or after.13 At most, Kelly and Ó Gráda might argue from their data that the nao, more than long-term cooling, deªned Dutch and English experiences of one phase of early modern climate (a possibility granted only under the highly questionable assumption that their

12 Petra Breitenmoser et al., “Solar and Volcanic Fingerprints in Tree-Ring Chronologies over the Past 2000 Years,” Palaeogeography, Palaeoclimatology, Palaeoecology, CCCXIII/XIV (2012), 127–139. The results in this case are still inconclusive, but they suggest that sunspot cycles may well have played a role. 13 M. V. Shabalova and Aryan F. V. van Engelen, “Evaluation of a Reconstruction of Win- ter and Summer Temperatures in the Low Countries, AD 764–1998,” Climatic Change, LVIII (2003), 219–242; Rüdiger Glaser and Dirk Riemann, “A Thousand-Year Record of Temper- ature Variations for Germany and Central Europe Based on Documentary Data,” Journal of Quaternary Science, XXIV (2009), 437–449. 336 | SAM WHITE documentary series proves as reliable as the proxy evidence for centuries-long trends). Yet even if so, it would still be more accu- rate and more helpful to invoke the lia than to reject it. Studies have now linked early modern global cooling to a reorganization in the nao itself.14 Finally, lest we forget, long-term climate reconstructions, both proxy and documentary, have spread far beyond Europe. Sufªce it to say that climatologists and historians have gathered data Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 from a range of physical and written sources across Asia and now increasingly in the Americas, Africa, Australia, and Oceania. Chi- nese and Japanese sources have supported particularly strong reconstructions of lia climate changes, as well as solid historical studies of their impacts. In short, historians and historical climatologists concerned with the lia are not in any way the old-fashioned, marginalized group of climate determinists that Kelly and Ó Gráda have made them out to be. These scholars are, for the most part, building on robust, state-of-the-art research. Kelly and Ó Gráda’s position lies well outside the mainstream and rests on questionable foundations.15 anecdotes and images Kelly and Ó Gráda devote the latter half of their article to attacking popular historical anecdotes and images of lia cooling, such as the collapse of Viking Greenland and the advance of Alpine glaciers. This entire discussion is a red herring. As we have seen, the principal evidence for the lia comes from proxy data, whereas documentary reconstructions can help us to understand particular periods and details of climate, as well as the human dimensions of climate and weather. Historians offer images and anecdotes as illustrations of the lia, not as proofs. Kelly and Ó Gráda have clearly picked through popular history as a way to knock down straw men, not to offer a substantial refutation of serious arguments about early modern global cooling. Nonetheless, their examples are worth examining for two reasons. First, certain kinds of phenological evidence (observations of such physical phe- 14 See, for example, A. G. Dawson et al., “Greenland (GISP2) Ice Core and Historical In- dicators of Complex North Atlantic Climate Changes during the Fourteenth Century,” The Holocene, XVII (2007), 427–434. 15 A full list of the physical and written sources would run to several pages. For a searchable bibliographical database, see http://climatehistorynetwork.com/bibliography/. For China, see especially Timothy Brook, The Troubled Empire: China in the Yuan and Ming Dynasties (Cambridge, Mass., 2010). THE REAL LITTLE ICE AGE | 337 nomena as river freezings) can indeed offer signiªcant conªrm- ation of early modern cooling and extremes. Since Kelly and Ó Gráda have opted for soft targets, we ought to investigate some of the harder evidence at hand. Second, even some of their chosen straw men turn out to be made of stronger stuff. In several places, they have either overlooked or misused available studies to arrive at questionable conclusions. Wine in Medieval England Kelly and Ó Gráda correctly point Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 out that evidence for wine production in medieval England remains ambiguous, hardly consituting ªrm evidence of climate change. Yet the entire issue is irrelevant, and their discussion is highly misleading. England was never known for its wine industry (although global warming could change that). The lia is hardly necessary to explain its demise. Hints of widespread vineyards in the historical record were once used as evidence for the still-con- troversial “Medieval Warm Period,” but this debate has no bearing on the issue of early modern cooling. Moreover, by dwelling on this tangential matter of wine in England, Kelly and Ó Gráda side- step an entire well-established ªeld of phenology from grape harvests. As an indicator of long-term climate trends, grape harvests and harvest dates can suffer from some of the same shortcomings as documentary data—namely, the potential for short lifetimes and cumulative adaptations to obscure gradual changes. However, these studies point, on the whole, to cooler summers in early modern Europe, offering another useful source for short-term variations and extremes. The utter loss of grape harvests and vineyards is also a recurring element in descriptions of freezing lia winters and often a good indicator of their severity.16 Grape harvests, however, represent only one useful sort of bi- ological proxy for climate. In today’s warming world, all sorts of plants and animals are changing their seasonal ranges and behaviors; 16 For global warming and British wine, see http://www.guardian.co.uk/lifeandstyle/ wordofmouth/2013/may/07/climate-change-transforming-british-wine (accessed May 14, 2013); for vineyards and climate, Isabelle Chuine et al., “Historical Phenology: Grape Ripening as a Past Climate Indicator,” Nature, CDXXXII (2004), 289–290; V. Daux et al., “An Open-access Database of Grape Harvest Dates for Climate Research: Data Description and Quality Assessment,” Climate of the Past, VIII (2012),1403–1418; N. Etien et al., “A Bi- Proxy Reconstruction of Fontainebleau (France) Growing Season Temperature from a.d. 1596 to 2000,” ibid., IV (2008), 91–106; E. Garnier et al., “Grapevine Harvest Dates in Besançon (France) Between 1525 and 1847: Social Outcomes or Climatic Evidence?” Climatic Change, CIV (2011), 703–727; J. Guiot, “Last-Millennium Summer-Temperature Variations in Western Europe Based on Proxy Data,” The Holocene, XV (2005), 489–500. 338 | SAM WHITE a few cases demonstrate similar types of changes during the lia. The most famous and well-documented one is the blooming dates of Japanese cherry blossoms, the records of which were kept metic- ulously for more than seven centuries. Calibrated to modern instrumental data, they give clear evidence of early modern cooling.17 lia Landscapes As noted above, historians employ anecdotes of the lia as illustrations rather than proofs: early modern paintings, such as Pieter Brueghel’s Hunters in the Snow, are literally a case in Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 point. Historians have turned to these paintings simply as evocative images of meteorological conditions evidenced by more conven- tional data. Yet as studies of early modern art demonstrate, the de- velopment of the European winter landscape genre closely parallels the strongest phase of the lia in northern latitudes (c.1550 to 1650—see proxy studies above). Neuberger found that paintings with dark, cloudy skies peaked in the period from 1550 to 1849. Burroughs, whom Kelly and Ó Gráda describe as “more circum- spect,” actually states that the onset of extreme cold, particularly the great winter of 1565, inspired Brueghel’s winter images, which were the ªrst of their kind in Europe. Moreover, both Burroughs and de Kraker have pointed to the inºuence of the great winter of 1608 on Hendrick Avercamp. Robinson raised another possible climatic inºuence. He noted that snowier and sunnier depictions of winters in the Netherlands also seemed to follow appropriate phases of the nao that brought wetter and milder or clearer and colder weather, respectively.18 Kelly and Ó Gráda’s claim that the decline of winter landscapes after 1660 constitutes “awkward timing from the standpoint of lia historiography” is simply incorrect. As previously noted, 1660 roughly marked the end of the strongest cooling phase in the Northern Hemisphere. The decline of winter landscapes could even be conªrmation of climate’s inºuence on art, were it not that fashions would likely change after a century, anyway. These connections between climate and painting remain imperfect, provid-

17 Yasuyuki Aono and Keiko Kazui, “Phenological Data Series of Cherry Tree Flowering in Kyoto Japan and Its Application to Reconstruction of Springtime Temperatures since the 9th Century,” International Journal of Climatology, XXVIII (2008), 905–914. 18 Hans Neuberger, “Climate in Art,” Weather, XXV (1970), 46–56; William J. Burroughs, “Winter Landscapes and Climatic Change,” Weather, XXXVI (1981), 353, 354; Adriaan M. J. de Kraker, “The Little Ice Age: Harsh Winters Between 1550 and 1650,” in Pieter Roelofs (ed.), Hendrick Avercamp: Master of the Ice Scene (Amsterdam, 2009), 23–29; Robinson, “Ice and Snow.” THE REAL LITTLE ICE AGE | 339 ing only circumstantial evidence for one phase of the lia. Yet given the wide range of possible inºuences on art, it is remarkable that we can ªnd such connections at all. The discussion of lia art also raises the broader issue of climate’s inºuence on cultural phenomena, which Kelly and Ó Gráda explicitly avoid. According to Behringer and others, the strongest phase of Northern Hemisphere cooling, c.1550 to c.1650, coin- cided with a number of cultural movements and social activities Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 that may reºect the direct or indirect inºuence of extreme weather and climate. Regardless of whether Behringer’s conclusions are valid, or whether such cultural connections would constitute proof of global cooling, the coincidence of so many distinct cultural trends—ranging from warmer architecture and clothing to such ar- tistic motifs as vanitas and ars moriendi and gloomy winter poetry— remains suggestive. The statistical correlation between periods of colder climate and the increase in witch-hunts during the late 1500s, as well as the rising incidence of European conºict during the 1600s, are especially noteworthy in this respect. Nor are such cultural and social developments restricted to Europe. Brook, for one, found similar reºections of climate-induced crisis in China.19 Greenland Viking and the Nordic Countries The demise of the two Viking settlements on Greenland is sometimes offered as an in- teresting anecdote of the lia. Whatever the reason for their disappearance, it has little bearing on the case for early modern global cooling. Nevetheless, there is good reason to believe that climate

19 For climate and culture in general, see Wolfgang Behringer, Hartmut Lehmann, and Pªster (eds.), Kulturelle Konsequenzen der “Kleinen Eiszeit” (Göttingen, 2005); Behringer, A Cultural History of Climate (Malden, Mass., 2010); Pªster and Brázdil, “Climatic Variability in Sixteenth-Century Europe and Its Social Dimension: A Synthesis,” Climatic Change, XLIII (1999), 5–53. For witch-hunts, see Behringer, “Weather, Hunger and Fear: Origins of the European Witch-Hunts in Climate, Society and Mentality,” German History, XIII (1995), 1– 27; idem, “Climatic Change and Witch Hunting: The Impact of the Little Ice Age on Mental- ities,” Climatic Change, XLIII (1999), 335–351; Emily Oster, “Witchcraft, Weather and Eco- nomic Growth in Renaissance Europe,” Journal of Economic Perspectives, XVIII (2004), 215– 228; Pªster, “Climatic Extremes.” For climate and conºict, see Büntgen et al., “2500 Years of European Climate Variability and Human Susceptibility,” Science, CCCXXXI (2011), 578– 582; Richard S. J. Tol and Sebastian Wagner, “Climate Change and Violent Conºict in Eu- rope over the Last Millennium,” Climatic Change, XCIX (2010), 65–79; David D. Zhang et al., “The Causality Analysis of Climate Change and Large-Scale Human Crisis,” Proceedings of the National Academy of Sciences, CVIII (2011), 17296–17301; Geoffrey Parker, Global Crisis: War, Climate Change and Catastrophe in the Seventeenth Century (New Haven, 2013), 26–54. For China, see Brook, The Confusions of Pleasure: Commerce and Culture in Ming China (Berkeley, 1998); idem, Troubled Dynasty. 340 | SAM WHITE played an important role. Kelly and Ó Gráda claim, “In accounting for the collapse of Greenland’s small Norse colony in the ªfteenth century, recent scholarship has tended to de-emphasize the role of climate, proposing several potential competing explanations in- stead.” But they have evidently misread, or not read, much of the recent scholarship.20 In brief, the complex case for climate’s involvement in the settlements’ collapse builds on four ªndings: (1) Greenland ice-core Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 temperature reconstructions demonstrate that the Vikings arrived during an unusually warm period and that their settlements disappeared during particularly cold decades (usually identiªed with the onset of the lia). (2) The settlers’ pastoral economy, particularly hay production for cattle, remained exceptionally vulnerable to re- peated cold years. (3) Despite some diversiªcation of food sources, livestock remained a critical food supply in late winters and early springs. (4) The circumstances of each settlement’s disappearance suggest sudden crisis and perhaps starvation. Such long-term factors as changing trade patterns, Inuit conºict, and demographic weak- nesses probably contributed in important ways to the Viking settlements’ lack of resilience. However, none of them explains when and how the settlements actually disappeared. Vulnerability to prolonged cold spells during the onset of the lia does. McGovern, whom Kelly and Ó Gráda quote out of context, has actually been a leading proponent of a role for climate change in the settlements’ disappearance, even while rejecting simplistic climate de- terminism.21 Recent years have seen a renewed debate about the fate of the Greenland settlements and their signiªcance for contemporary climate change. However, this debate has focused on whether the Vi- kings properly adapted to their environment or whether they were blinded by cultural conservatism, as Diamond argued. This ques-

20 See Lisa K. Barlow et al., “Interdisciplinary Investigations of the End of the Norse West- ern Settlement in Greenland,” The Holocene, VII (1997), 489–499; William J. D’Andrea et al., “Abrupt Holocene Climate Change as an Important Factor for Human Migration in West Greenland,” Proceedings of the National Academy of Sciences, CVIII (2011), 9765–9769; William Patterson, “Two Millennia of North Atlantic Seasonality and Implications for Norse Col- onies,” ibid., CVII (2010), 5306–5310. 21 Thomas McGovern, “Climate, Correlation, and Causation in Norse Greenland,” Arctic Anthropology, XXVIII (1991), 77–100; idem, “The Demise of Norse Greenland,” in William Fitzhugh and Elisabeth Ward (eds.), Vikings: The North Atlantic Saga (Washington, D.C., 2000), 327–339. THE REAL LITTLE ICE AGE | 341 tion has produced new research that emphasizes the role of the lia in the end of Viking Greenland. As Dugmore et al. demonstrate, the Vikings had adapted to their new conditions and endured lesser periods of cold. Yet lia cooling pushed their society past its ecological limits.22 Besides marginal cases with limited evidence, such as that of Viking Greenland, tax and land records demonstrate the impact of the lia on settlement in Northern Europe. In general, European Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 settlement patterns from the mid-fourteenth to the late sixteenth centuries were dominated by population loss and recovery from the Black Death. However, in at least two instances, comprehen- sive geographical surveys also clearly reveal the inºuence of climate. Several lines of evidence point to the lia as responsible for both the timing and the distribution of Norway’s loss of more than half of its settlements and population during the fourteenth century. Losses began after the onset of cooling during the 1310s but before the Black Death, sometimes coinciding with famine events. The fact that settlement losses were lower in Norway’s ªshing villages and higher in its upland, inland, and northern regions and that they were worse in Norway as a whole than in Sweden testiªes to the vulnerability of grain agriculture in a colder climate. Similarly, Parry has shown in detail how lia cooling restricted the range of cultivable land in Scotland, driving out settlements from higher latitudes and altitudes.23 Even if, as Kelly and Ó Gráda argue, the general population in northern countries increased faster than did that of Europe as a whole from the sixteenth to the eighteenth century, the evidence for early modern global cooling would suffer no setback. First, given the extent of settlement loss described above, countries such as Norway may have needed more time to recover from their higher mortality in the fourteenth century. Second, Scandinavia 22 Jared Diamond, Collapse: How Societies Choose to Fail or Succeed (New York, 2005); Joel Berglund, “Did the Medieval Norse Society in Greenland Really Fail?” in Patricia A. McAnany and Norman Yoffee (eds.), Questioning Collapse: Human Resilience, Ecological Vulner- ability, and the Aftermath of Empire (New York, 2010), 45–70; Andrew J. Dugmore et al., “Cul- tural Adaptation, Compounding Vulnerabilities and Conjunctures in Norse Greenland,” Proceedings of the National Academy of Sciences, CIX (2012), 3658–3663. 23 Svend Gissel et al., Desertion and Land Colonization in the Nordic Countries c.1300–1600: Comparative Report from the Scandinavian Research Project on Deserted Farms and Villages (Stock- holm, 1981), 69, 94, 103, 122, 142, 177–178, 240; Audun Dybdahl, “Climate and Demo- graphic Crises in Norway in Medieval and Early Modern Times,” The Holocene, XXII (2012), 1159–1167; Martin L. Parry, Climate Change, Agriculture and Settlement (Folkstone, 1978). 342 | SAM WHITE was not as directly affected by the conºicts of the seventeenth- century as was Germany or the Ottoman Empire—lands that car- ried more demographic weight in early modern Europe. More- over, Scandinavia was less exposed to early modern outbreaks of bubonic plague, which were still a threat in Southern Europe. Nor is it necessarily true that northern populations “would presumably have been more vulnerable to global cooling than those of Europe as a whole.” Climate vulnerability is a consequence of many fac- Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 tors, including population density, which was lower in Scandinavia and Switzerland than elsewhere in Europe. Moreover, all of Eu- rope, including the Mediterranean, was subject to unusually severe winters and droughts, as well as the population loss resulting from famine, disease, and conºict.24 Cereal Yields in England Kelly and Ó Gráda’s discussion of English cereal yields as an indicator of long-term climate change, supposedly to refute Lamb’s and Fagan’s claims that the lia short- ened growing seasons, presents further difªculties. First, as already discussed, grain varieties and agricultural practices would likely have adapted to a changing climate over the long term. Second, the growth in total English acreage from the late ªfteenth to the seventeenth century does not so much indicate better growing conditions as it does a growing population, which was for the most part a recovery from losses in the fourteenth-century Great Famine and Black Death. Third, the rising number of working days almost certainly reºects population growth and declining wages, the need to use more labor to raise yields as land per person diminished, and a growing need for cash wages as market goods began to displace subsistence goods—not to mention the elimination of saints’ days after the Reformation. Whether or not Lamb and Fagan make a good case for shorter growing seasons, Kelly and Ó Gráda have done nothing to refute it. Glaciers As Kelly and Ó Gráda explain, the Little Ice Age was once strongly identiªed with the advance of glaciers, whose dra- matic retreat is now used to demonstrate global warming. They argue that since a number of glaciers do not reveal clear trends between the late sixteenth and nineteenth centuries, glacial move- ment does not indicate an lia. The claim is both irrelevant and mis-

24 For seventeenth-century Scandanavia in context, see Parker, Global Crisis, 211–254; for a more detailed examination of climatic effects in the Ottoman Empire, see White, The Climate of Rebellion in the Early Modern Ottoman Empire (New York, 2011). THE REAL LITTLE ICE AGE | 343 leading. Contemporary scholars rarely rely on glaciers alone for evidence of the lia. Moreover, as with their documentary reconstructions, Kelly and Ó Gráda’s charts do not extend into the past far enough to put the lia into proper context. The studies that they cite can give no indication of whether the early modern world cooled or not, though they appear to support the cooling trend of the late sixteenth to mid-seventeenth century found in the proxy records. Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 The authors have selectively used examples to obscure wider trends. As Grove concluded, in what is still the most comprehen- sive study of global glacier movements,

In any single region, the number of moraines deposited and surviv- ing varies from one glacier to another according to local topogra- phy and conditions, such as the amount of debris released onto glacier tongues. Nonetheless there is a striking consistency in the timing of the main advances. In Europe they have been dated to around 1320, 1380, 1580 to 1610, 1690 to 1700, in the 1770s, around 1820 and 1850, in the 1880s, 1920s and 1960s. Where information is available it appears that this timetable was also followed in many parts of the world outside Europe, with familiar dates ap- pearing in the moraine records over the last four centuries from Canada and Alaska and from the mid nineteenth century onwards in the Pyrenees, Caucasus, Himalaya and China, where records are shorter.25

The diagram accompanying this text in Grove’s Little Ice Age shows that most advances in the Northern Hemisphere peaked in the eighteenth century. The author adds, “The common behavior of nearly all the world’s glaciers is their recession over the last hundred or one hundred and ªfty years.” In short, glaciers cannot prove the existence of an lia, but, by and large, they can conªrm it. Any refutation of early modern global cooling would have to meet the considerable challenge of explaining away the global trend of glacial advance and retreat.26 London’s Frost Fairs The occasional freezing of the Thames in early modern London does not prove the lia either; no serious scholar claims that it does. It provides a striking illustration of lia cold, as well as a colorful anecdote of human experience. Kelly and 25 Jean Grove, Little Ice Ages: Ancient and Modern (London, 2004; orig. pub. 1988), II, 562. 26 Ibid. 344 | SAM WHITE Ó Gráda are correct that the Thames could freeze only so long as the old London Bridge blocked ice ºows. Yet in supposedly refuting the value of this anecdote, they unintentionally bring in evidence of lia cooling. First, the frequency of freezings roughly matches what the Northern Hemisphere proxy trends appear to predict, peaking in the seventeenth century. Second, focusing solely on years theoretically cold enough to freeze the river, Kelly and Ó Gráda ªnd that such cold extremes occurred about twice as Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 frequently from the seventeenth to the nineteenth century as they did from 1900 to 1980. Moreover, as in their discussion of medieval English vineyards, Kelly and Ó Gráda appear to have picked an easy target to avoid confronting more serious evidence. Although the frost fairs offer some of the most famous images of the lia, they are hardly the most salient or the most signiªcant phenological indications of freezing weather. Many other events point to the greater frequency of severe winters during the centuries of the lia. For instance, Behringer points to twelve centuries of observations of so-called Seegfrörnen—the icing of deep Alpine lakes that occurs only during prolonged periods at Ϫ20°C or below. From the tenth to the thirteenth centuries, such freezing occurred on average less than twice a century. However, the fourteenth century witnessed ªve Seeg- frörnen, and the ªfteenth and sixteenth centuries seven each, including every ªfth year from 1560 to 1575, during the onset of the strongest phase of the lia. Likewise, a 1,000-year record of the freezing of the Rhone reveals far more episodes during the fourteenth century and from the late sixteenth to the nineteenth century than before or since, just as the proxy-temperature data predict.27 Other records offer evidence of exceptional extremes, hardly conceivable in the present century. To take one example, the Istan- bul Bosphorus froze in 1621, apparently allowing people to walk from Asia to Europe on the ice. Another example occurred in 1658, when “the Swedish army with all its artillery marched 20 miles over the Danish Sound from Jutland to Copenhagen.” In the great winter of 1709, French wine burst its bottles, and seawater froze in the Bay of Marseilles. Again, the signs of cooling extended

27 Behringer, Cultural History of Climate, 90–91; Maurice Jorda and Jean-Christophe Roditis, “Les épisodes de gel du Rhône depuis l’an mil: Périodisation, interprétation paléoclimatique,” Méditerranée, LXXVIII (1993),19–30. THE REAL LITTLE ICE AGE | 345 far beyond Europe. Records of freezing events also provide clear signals of the lia in China and Japan.28 Far from calling the lia into question, a close examination of historical anecdotes and phenology offers solid independent con- ªrmation of the early modern cooling found in the proxy record. Moreover, these images bring to light the connections among global average climate change, extreme events, and human experiences. Understanding these connections proves critical in deªning Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 and conceptualizing the lia as both a climatic and historical event, as the next part of this article examines. defining the little ice age In the end, Kelly and Ó Gráda have raised only one salient concern—that deªnitions of the lia remain inconsistent. This section will explain this inconsistency and how historians might make better use of the term “Little Ice Age.” Early modern cooling was driven by multiple climate forcings (orbital, solar, and volcanic), and no forcing produces uniform results across time and space. The same cooling could generate a range of effects on different geographical and temporal scales. More- over, shifts in demography and technology also meant that the most pronounced climate ºuctuations did not always coincide with the greatest impact on humans. These complexities do not alter the reality of early modern global cooling, but they do warn against facile deªnitions. The major underlying factor in early modern cooling appears to be orbital forcing. Slight changes in the earth’s rotation on its axis and revolution around the sun have slowly reduced the inten- sity of solar radiation reaching the Northern Hemisphere since its peak at least eight millennia ago, leading to a gradual cooling that accelerated c.1300 a.d. Alhough the case for the lia in no way de- pends on it, a reasonable argument can be made that if not for man-

28 White, Climate of Rebellion, 123–125. The trek across the Bosphorus is so unimaginable in today’s climate that I did not believe it myself until I found four independent eyewitness accounts. For the Swedish army’s march, see Parker, Global Crisis, 6; for the great winter of 1709, W. Gregory Monahan, Year of Sorrows: The Great Famine of 1709 in Lyon (Columbus, Ohio, 1993), 72–73; for China, Quansheng Ge et al., “Winter Half-Year Temperature Re- construction for the Middle and Lower Reaches of the Yellow River and Yangtze River, China, during the Past 2000 Years,” The Holocene, XIII (2003), 933–940; for Japan, Bruce L. Batten, “Climate Change in Japanese History and Prehistory: A Comparative Overview,” Occasional Papers in Japanese Studies Number 2009–01, Edwin O. Reischauer Institute of Japanese Studies (Harvard University, 2009). 346 | SAM WHITE made greenhouse gas emissions (from millennia of farming and de- forestation, as well as more recent coal and oil burning), the past millennia would have seen a return to another ice age. Neverthe- less, orbital forcing does not exclude other causes; nor does it explain short- to medium-term variations in regional or global climate. Climatologists have presented good evidence for the role of volcanic forcing (cooling from upper-atmosphere sulphates and dust veils from large eruptions) and solar forcing (variations in Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 solar output, sometimes tied to sunspot cycles) during phases of the lia.29 The latest continental-scale multiproxy reconstructions offer the best guide to understanding long-term changes, short-term forcings, and regional variations during the last millennium of climate. As Ahmed et al.’s major new study explains, “The most co- herent feature in nearly all of the regional temperature reconstructions is a long-term cooling trend, which ended in the nineteenth century.” On every continent, the ªrst four centuries of the last millennium (1000 to 1400) were warmer than the following four centuries (1400 to 1800). Yet this cooling began about a century sooner in the Arctic, Europe, and Asia than in South America and Australia, which continued to experience warmer conditions until c.1370. All of the inhabited continents were cooling consistently by c.1580. Within this era of cooling, broadly deªned (1251 to 1820), the world also experienced nine periods of about thirty years each with clustered volcanic and solar forcing and cooler average global temperatures—particularly in the late thirteenth to early fourteenth century, the late ªfteenth century, the late sixteenth to early seventeenth century, the late seventeenth century, and the early nineteenth century.30 These data clearly demonstrate pronounced early modern global cooling, which merits the appellation “Little Ice Age.” They do not dictate a single way to deªne that era. One could still deªne

29 Darrell S. Kaufman et al., “Recent Warming Reverses Long-Term Arctic Cooling,” Sci- ence, CCCXXV (2009), 1236–1239; Jan Esper et al., “Orbital Forcing of Tree-Ring Data,” Nature Climate Change, II (2012), 862–866. For the effects of man-made gas emissions, see William F. Ruddiman, Plows, Plagues, and Petroleum: How Humans Took Control of Climate (Princeton, 2005); for an overview of how volcanic and solar factors interacted with long- term orbital forcing, Heinz Wanner et al., “Mid- to Late Holocene Climate Change: An Overview,” Quaternary Science Reviews, XXVII (2008), 1791–1828. 30 Moinuddin Ahmed et al., “Continental-Scale Temperature Variability during the Past Two Millennia,” Nature Geoscience, VI (2013), 339–346 (quotation from the abstract). THE REAL LITTLE ICE AGE | 347 away the period by posing arbitrary standards of uniformity and synchronicity—but that would be a semantic quibble, not a serious argument. With such an approach, no doubt, one could deªne away global warming as well and any number of other inconve- nient truths. Even contemporary climate change has been spatially uneven, and entire decades have elapsed in the past century with stable or even cooling average temperatures. But variation and noise do not invalidate the underlying climatic shift.31 Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 The overall strength of the long-term cooling trend is why climatologists now conªdently speak of a “Little Ice Age” despite its spatial and temporal complexities. Kelly and Ó Gráda do cite an Intergovernmental Panel on Climate Change (ipcc) statement that supposedly calls the term Little Ice Age into question. However, the citation highlights only their dated source base and unfamiliarity with the ªeld of climatology. The statement in question comes from the ipcc Third Assessment Report, based on data more than a decade old. It is concerned with refuting exaggerated claims that the lia, and particularly the “Medieval Warm,” were comparable to contemporary climate change, and therefore that global warming is natural. As even a cursory inspection reveals, the newer Fourth Assessment Report takes a drastically different approach, referring to the lia repeatedly and unproblematically as a period of global cooling: for example, “There is no exact agreement as to which dates mark the beginning and end of the Little Ice Age, but from about 1350 to about 1850 is one reasonable estimate.” “In the past, the cryosphere has undergone large variations on many time scales associated with ice ages and with shorter-term variations like the Younger Dryas or the Little Ice Age.” “Formation of large and hazardous lakes is occurring as glacier termini retreat from prominent Little Ice Age moraines, especially in the steep Him- alaya and Andes.” Or one may simply consult the glossary under “Little Ice Age”: “An interval between approximately AD 1400 and 1900 when temperatures in the Northern Hemisphere were generally colder than today’s, especially in Europe.”32 31 For a nontechnical analysis of temperature trends during global warming, see Nate Sil- ver, The Signal and the Noise: Why Most Predictions Fail—but Some Don’t (New York, 2012), 370–411. 32 For the search of the Fourth Assessment Report, see http://www.ipcc.ch/search/ searchassessmentreports.shtml#.UZE0r5WEybw (accessed May 13, 2013). Please note that as an expert reviewer, I am not free to discuss current drafts of the latest Fifth Assessment Re- port. 348 | SAM WHITE The challenge for historians is to conceptualize the lia in ways that capture the most important elements of change. Deªning the Little Ice Age is not just a matter of data but a matter of judg- ment. Like any issue of historical periodization, it raises profound questions of what we value and why. Do we care about the whole globe, the inhabited parts, or only agricultural civilizations? Do we care more about long-term averages, decadal-scale ºuctuations, or the frequency of extremes? Do we care more about year-to-year Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 impacts or more about unique historical crises? The answers will yield different conceptualizations, which emphasize different aspects of a large and complex picture. But at this point, we can identify three plausible deªnitions and explore their implications. Deªnition 1: A Cooling World c.1400 to c.1850 Parts of Europe and Asia may have begun cooling earlier, but to avoid anthropo- centric bias, the lia is identiªed in this context with global cooling in both hemispheres. According to the most recent data, this cooling began c.1400 and ended when the man-made greenhouse-gas effect cancelled the long-term effects of orbital forcing c.1850. This era also underwent several periods of solar/volcanic forcing, but these short-term events did not fundamentally alter the underlying cooling trend; nor were they unique to these centuries. This deªnition focuses on the long term. It also presents the best comparison or contrast with global warming, since it deals only with falling average temperatures on every continent. It best captures large-scale environmental changes and major shifts in at- mospheric circulation, and their effects on people, even those without agriculture or written records. It emphasizes changing margins of human settlement—not only the disputed case of Vi- king Greenland but also undocumented settlements, like those in the Paciªc islands. It evaluates societal responses by their long-term adaptability and transformability rather than short-term resistance or resilience. This deªnition may best serve the natural sciences.33 Deªnition 2: An Age of Extremes c.1310s to c.1810s The lia was an era of recurring ºuctuations that began with the devastating

33 For climate changes in the Paciªc, see Patrick Nunn, “Environmental Catastrophe in the Paciªc Islands Around a.d. 1300,” Geoarchaeology, XVI (2000), 715–740; idem and James M. R. Britton, “Human-Environment Relationships in the Paciªc Islands around a.d. 1300,” Environment and History, VII (2001), 3–22. For the terminology of vulnerability, resilience, adaptability, and transformability, see Brian Walker et al., “Resilience, Adaptability, and Transformability in Social-Ecological Systems,” Ecology and Society, IX (2004), 5. THE REAL LITTLE ICE AGE | 349 “Great Famine” of Europe in the 1310s and ended with the “last great subsistance crisis of the Western world” in the 1810s. Such ºuctuations, driven by variations in solar output and especially volcanic eruptions, were not conªned to these centuries, but they were evidently more frequent and severe during this era. These events took place against a backdrop of global cooling, which likely aggravated the severity of the ºuctuations but was often too gradual to be directly noticed in temperate regions. Although the cooling Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 trend did not become global until c.1400, it was already evident in the most populated parts of the world by the 1300s—hence the wider periodization.34 lia climate ºuctuations brought clusters of extreme events, also visible as large dips in moving averages of temperature and, in some cases, precipitation. These clustered extremes could seriously destabilize economies and empires and spell misery and high mortality for entire generations, as in Anatolia from the 1590s to 1610; in France, Scotland, and Finland from the 1690s to 1710; or around the world from the 1780s to the 1790s. Even briefer episodes, such as the extreme European winters from 1740 through 1742, could produce serious lasting effects, including epidemics and the death of livestock. Collectively, these episodes inºuenced the char- acter of the late medieval and early modern world, strongly inºu- encing demographic trends and economic cycles, and probably the long-term success of some states and the fall of others, not only in Europe but across the world.35 This second deªnition emphasizes the human dimension of the lia. It has a slight Eurocentric bias, since it focuses on well- documented climatic and historical episodes, and it begins and ends with predominately Western events. However, it also captures re-

34 William C. Jordan, The Great Famine: Northern Europe in the Early Fourteenth Century (Princeton, 1996); John D. Post, The Last Great Subsistence Crisis in the Western World (Balti- more, 1977). 35 For Anatolia, see White, Climate of Rebellion; for France, Marcel Lachiver, Les années de misère: La famine au temps du Grand Roi, 1680–1720 (Paris, 1991); for the 1780s–1790s, Richard Grove, “The Great El Niño of 1789–93 and Its Global Consequences,” Medieval History Jour- nal, X (2007), 75–98; for the 1740s, Post, Food Shortage, Climatic Variability, and Epidemic Dis- ease in Preindustrial Europe (Ithaca, 1985); for changes in demographic trends and economic cycles even in such relatively temperate and resilient countries as England, Bruce Campbell, “Nature as Historical Protagonist: Environment and Society in Pre-Industrial England,” Eco- nomic History Review, LXIII (2009), 1–34; for the rise and fall of states, Victor Lieberman, “Charter State Collapse in Southeast Asia, ca. 1250–1400, as a Problem in Regional and World History,” American Historical Review, CXVI (2011), 937–963. 350 | SAM WHITE curring extremes in such other regions as Ming and Qing China, as well as certain global events. By emphasizing ºuctuations over trends, it does not capture large-scale environmental developments and weakens comparisons with contemporary climate change (although it raises the important point that even in the coming century, variability and extremes are probably more threatening than average warming). In terms of human experience, it emphasizes short-term vulnerabilities and resilience more than long-term Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 adaptability and changing conditions. Deªnition 3: A General Crisis c.1580 to c.1710 This deªnition narrows the lia to its most vital effects during its strongest phase. Although cooling may have begun centuries earlier, it evidently accelerated during the late 1500s, especially in the more populous Northern Hemisphere. The cold of the early fourteenth century may have brought disasters to late medieval Northern Europe and Ming China but only as isolated incidences. From the mid- fourteenth to mid-sixteenth centuries, the demography of Eurasia was mainly determined by loss and recovery from the Black Death, and that of Amerindians by diseases of the Columbian Exchange. Because populations were far from their ecological limits, climate ºuctuations had more limited impacts. The late sixteenth century brought a perfect storm of population pressures and rapid cooling. Recently recovered populations across Eurasia faced harvest failures, rising prices, and the threat or reality of famine, while early settlers in North America froze and starved in harsh winters. These pressures led to economic and po- litical crises and then to chronic war and rebellion, ªrst in such en- vironmentally vulnerable regions as the Mediterranean but later across Eurasia. The mid-seventeenth century witnessed the culmi- nation of these disasters, most of all in Europe and China but even in West Africa and Southeast Asia, justifying the designation “general crisis.” Extreme cold and famine continued through the 1690s and in the great winter of 1709. Most of the eighteenth century, however, brought a milder climate. Moreover, growing maritime trade, as well as new overseas colonies, agricultural technologies, and crops from the Columbian Exchange, began to make people less vulnerable to the effects of a colder climate. The “year without a summer” in 1816 marked a last isolated global disaster. The world would not begin warming until c.1850, but for most people, THE REAL LITTLE ICE AGE | 351 the age of climate-driven crisis from global cooling had already passed.36 This deªnition again focuses on the human experience of the lia, but it also encompasses the reality of accelerated cooling from c.1550 to c.1650 as reºected in the proxy data. It remains biased to- ward European history but less than once thought, as ongoing research reveals the global dimensions of the seventeenth-century general crisis. Moreover, it deals largely with one major global Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 anomaly rather than a gradual centuries-long trend or several smaller ºuctuations. In terms of the human experience, it highlights long-term issues of adaptability and transformability, as well as issues of short-term resistance and resilience. These deªnitions are not mutually exclusive. Each of them has its strengths and limitations, and each of them incorporates one or more aspects of early modern climate change. In one version or another, all of them will probably continue to circulate in the clima- tological and historical literature for some time to come. Which- ever of the three is the real lia, the evidence remains clear: The lia was real.

Whenever reputable scholars disagree about one issue or another, other historians tend to declare the matter a “debate” and leave it at that. However, there is not at present any substantial debate about whether global climate cooled between c.1300 and c.1850, or whether that cooling had signiªcant human impacts. Kelly and Ó Gráda’s article is a peculiar—and entirely unfounded—criticism of robust and widely accepted climate science, generally con- ªrmed by historical records. Notwithstanding occasional exaggerated claims by overzealous proponents, and inconsistent use of the term “Little Ice Age” by others, Kelly and Ó Gráda’s criticisms of lia climatology and history amount to throwing out a healthy baby with at most a little bathwater. The lia is not a dogma. It is an increasingly ªrm consensus backed by considerable evidence across a variety of sources. To dis-

36 For West Africa, see George Brooks, Landlords and Strangers: Ecology, Society, and Trade in Western Africa, 1000–1630 (Boulder, 1993); James Webb, Desert Frontier: Ecological and Economic Change Along the Western Sahel, 1600–1850 (Madison, 1995); for Indonesia, Peter Boomgaard, “Crisis Mortality in Seventeenth Century Indonesia,” in Ts’ui-jung Liu et al. (eds.), Asian Population History (New York, 2001), 191–220. 352 | SAM WHITE prove it, or even to call it into question, would mean ªnding systematic errors in several types of proxy data. It would require (1) a convincing alternative explanation for the consistent agreement of these records, both with each other and with phenological observations and short-term trends in documentary data; (2) reliable alternative sources pointing to stable or rising temperatures; (3) the examination of sources outside Europe; and (4) proof that historians have been inaccurate, not merely inconsistent, in their use of Downloaded from http://direct.mit.edu/jinh/article-pdf/44/3/327/1706251/jinh_a_00574.pdf by guest on 28 September 2021 the term. Kelly and Ó Gráda have not cleared any of these hurdles, or even come close. The refutation of their arguments demon- strates just how strong the evidence for the lia has become and just how important it is for historians to take it seriously.