RECOVERY FROM THE LIA AS SEEN IN THE CENTRAL ENGLAND TEMPERATURES 

RELATED POST: [SUPERSTITION, CONFIRMATION BIAS. & CLIMATE CHANGE]

The climate history of Europe records the so called Medieval Warm Period (MWP) that peaked in the period 900-1200 AD at about 0.8C warmer than the average for the millennium that preceded it. Soon thereafter, Europe plunged into a period of global cooling 1303-1860 AD at about 1C cooler than the Medieval Warm Period. It is thought that the cooling was initiated by aerosols from a large scale global volcanism event (see bibliography below and related post on aerosols [LINK] ).

This cold period, known as the Little Ice Age (LIA), was a period of great hardship for Europeans. Canals and rivers were frozen, growth of sea ice around Iceland closed down harbors and shipping, hailstorms and snowstorms were heavy and frequent, and road and water transport was made difficult or impossible. Agricultural failure and consequent starvation and death devastated Europe. The Scandinavian colonies in Greenland starved to death and disappeared (Matthews/Briffa, 2005) (Soon/Baliunas, 2003).

To the Europeans of the time used to relative warmth and agricultural wealth, these extreme weather events seemed abnormal, unusual and bizarre and therefore likely to have evil other-worldly causes and explanations. The human tendency to look for cause and effect relationships in extreme weather predicament and their usual solutions (Maller, 1933), drove the LIA Europeans to climate action not unlike the sorcery killings of Melanesia described in a related post [LINK] .

LIA BIBLIOGRAPHY

1. 1985: Whittington, Graeme. “The little ice age and Scotland’s weather.” Scottish Geographical Magazine 101.3 (1985): 174-178. Some 10,000 years ago with the disappearance of the last Devensian ice, the climate of the British Isles began a slow but general warming. This continued until the middle of the fifteenth century when the Little Ice Age developed, ushering in several centuries of colder weather and violent fluctuations in weather associated with the expansion of the circumpolar vortex. Detailed information of the effect on Scotland’s weather of this major climatic disturbance is rare but The Chronicle of Fifewritten in the seventeenth century by John Lamont does provide some remarkable insights.
2. 1986: Thompson, Lonnie G., et al. “The Little Ice Age as recorded in the stratigraphy of the tropical Quelccaya ice cap.” Science234.4774 (1986): 361-364. The analyses of two ice cores from a southern tropical ice cap provide a record of climatic conditions over 1000 years for a region where other proxy records are nearly absent. Annual variations in visible dust layers, oxygen isotopes, microparticle concentrations, conductivity, and identification of the historical (A.D. 1600) Huaynaputina ash permit accurate dating and time-scale verification. The fact that the Little Ice Age (about A.D. 1500 to 1900) stands out as a significant climatic event in the oxygen isotope and electrical conductivity records confirms the worldwide character of this event.
3. 1990: Clark, James S. “Fire and climate change during the last 750 yr in northwestern Minnesota.” Ecological Monographs 60.2 (1990): 135-159. Charcoal stratigraphic analysis and fire scars on red pine (Pinus resinosa) trees were used to determine spatial and temporal occurrence of fire in 1 km² of old—growth mixed conifer/hardwood forests in northwestern Minnesota. Charcoal was analyzed year by year on petrographic thin sections from annually laminated sediments of three small (≤5 ha) lakes having adjacent catchments. Dated fire scars (n = 150) from recent treefalls provided an independent record of the spatial patterns of past burns. Sedimentology of the varved sediments, water—balance models that use 150 yr of instrumental temperature and precipitation data, and published data were used to identify climate changes in separate studies, and they were used in this study to examine the possible connection between changing fire regimes and climate change. Fire—history data were used to show the changing probability of fire with time since the last fire and the effects of spatial variance (slope and aspect) on the distribution of fires through time. Over the last 750 yr, fire was most frequent (8.6 ± 2.9—yr intervals) during the warm/dry 15th and 16th centuries. Intervals were longer (13.2 ± 8.0 yr) during cooler/moister times from AD 1240 to 1440 and since 1600 (the Little Ice Age). The fire regime during the Little Ice Age consisted of periods during the mid—18th and mid—19th centuries characterized by longer fire intervals of 24.5 ± 10.4 and 43.6 ± 15.9 yr, respectively, and short—term warm/dry periods from 1770 to 1820 and 1870 to 1920 when intervals were 17.9 ± 10.6 and 12.7 ± 10.1, respectively. The probability of fire increased through time, probably in step with fuel accumulation. South— and west—facing slopes burned more frequently than did north and east aspects. Fire suppression began in 1910. During warm periods, probability of fire was sufficiently high that a continuous litter layer was all that was necessary for fire to spread and scar trees. During cool and moist times fire was most likely to occur in years with higher moisture deficits. The combined methods for fire—history analysis provided a more detailed spatial and temporal documentation of fire regimes than has previously been possible from analysis of fire scars or of charcoal counts derived from fossil pollen preparations. Results support predictions of particle—motion physics that thin sections record a local fire history. Because climate varies continuously, the responsiveness of disturbance regime to short— and long—term climatic change suggests caution in the interpretation of fire frequencies that derive from space/time analogies or extrapolation from short—term data.
4. 1993: Bradley, Raymond S., and Philip D. Jonest. “‘Little Ice Age’summer temperature variations: their nature and relevance to recent global warming trends.” The Holocene 3.4 (1993): 367-376. Climatic changes resulting from greenhouse gases will be superimposed on natural climatic variations. High-resolution proxy records of past climate can be used to extend our perspective on regional and hemispheric changes of climate back in time by several hundred years. Using historical, tree-ring and ice core data, we examine climatic variations during the period commonly called the ‘Little Ice Age’. The coldest conditions of the last 560 years were between AD 1570 and 1730, and in the nineteenth century. Unusually warm conditions have prevailed since the 1920s, probably related to a relative absence of major explosive volcanic eruptions and higher levels of greenhouse gases.
5. 1995: Behringer, Wolfgang. “Weather, hunger and fear: Origins of the European Witch Hunts in Climate, Society and Mentality.” German History 13.1 (1995)LINK: LINK TO PDF OF BEHRINGER 1995
6. 1996: Rumsby, Barbara T., and Mark G. Macklin. “River response to the last neoglacial (the ‘Little Ice Age’) in northern, western and central Europe.” Geological Society, London, Special Publications 115.1 (1996): 217-233. Climate changes since AD 1200 have been of high magnitude. Significant lowering of temperatures occurred during the neoglacial (‘Little Ice Age’), between AD 1200–1400 and AD 1600–1800 with maximum cooling in the mid-late eighteenth century. At this time many European valley/cirque glaciers reached their maximum extent since the late Pleistocene. Neoglaciation was followed by an overall warming trend, although with significant reversals superimposed. Alongside these temperature changes were variations in the nature and amount of precipitation, and in consequence, river basins in north, west and central Europe experienced enhanced fluvial activity between 1250 and 1550 and particularly between 1750 and 1900. These phases coincide with periods of climatic transition; cooling after the Medieval optimum and warming during the latter stages of the Little Ice Age respectively. In contrast, the intervening period (1550–1750), which corresponds with the most severe phases of the last neoglacial, was associated with lower rates of fluvial activity.
7. 1996: Keigwin, Lloyd D. “The little ice age and medieval warm period in the Sargasso Sea.” Science (1996): 1504-1508. Sea surface temperature (SST), salinity, and flux of terrigenous material oscillated on millennial time scales in the Pleistocene North Atlantic, but there are few records of Holocene variability. Because of high rates of sediment accumulation, Holocene oscillations are well documented in the northern Sargasso Sea. Results from a radiocarbondated box core show that SST was ∼1°C cooler than today ∼400 years ago (the Little Ice Age) and 1700 years ago, and ∼1°C warmer than today 1000 years ago (the Medieval Warm Period). Thus, at least some of the warming since the Little Ice Age appears to be part of a natural oscillation.
8. 1997: Overpeck, Jonathan, et al. “Arctic environmental change of the last four centuries.” science 278.5341 (1997): 1251-1256. A compilation of paleoclimate records from lake sediments, trees, glaciers, and marine sediments provides a view of circum-Arctic environmental variability over the last 400 years. From 1840 to the mid-20th century, the Arctic warmed to the highest temperatures in four centuries. This warming ended the Little Ice Age in the Arctic and has caused retreats of glaciers, melting of permafrost and sea ice, and alteration of terrestrial and lake ecosystems. Although warming, particularly after 1920, was likely caused by increases in atmospheric trace gases, the initiation of the warming in the mid-19th century suggests that increased solar irradiance, decreased volcanic activity, and feedbacks internal to the climate system played roles.
9. 1998: Fischer, Hubertus, et al. “Little ice age clearly recorded in northern Greenland ice cores.” Geophysical Research Letters25.10 (1998): 1749-1752. Four ice cores drilled in the little investigated area of northern and northeastern Greenland were evaluated for their isotopic (δ¹⁸O) and chemical content. From these rather uniform records a stable isotope temperature time series covering the last 500 years has been deduced, which reveals distinct climate cooling during the 17th and the first half of the 19th century. Timing of the preindustrial temperature deviations agrees well with other northern hemisphere temperature reconstructions, however, their extent (∼1°C) significantly exceeds both continental records as well as previous southern and central Greenland ice core time series. A 20–30% increase in the sea salt aerosol load during these periods supports accompanying circulation changes over the North Atlantic. Comparison with records of potential natural climate driving forces points to an important role of the long‐term solar influence but to only episodically relevant cooling during years directly following major volcano eruptions.
10. 1999: Lean, Judith, and David Rind. “Evaluating sun–climate relationships since the Little Ice Age.” Journal of Atmospheric and Solar-Terrestrial Physics 61.1-2 (1999): 25-36. From the coldest period of the Little Ice Age to the present time, the surface temperature of the Earth increased by perhaps 0.8°C. Solar variability may account for part of this warming which, during the past 350 years, generally tracks fluctuating solar activity levels. While increases in greenhouse gas concentrations are widely assumed to be the primary cause of recent climate change, surface temperatures nevertheless varied significantly during pre-industrial periods, under minimal levels of greenhouse gas variations. A climate forcing of 0.3 W m⁻² arising from a speculated 0.13% solar irradiance increase can account for the 0.3°C surface warming evident in the paleoclimate record from 1650 to 1790, assuming that climate sensitivity is 1°C W⁻¹ m⁻² (which is within the IPCC range). The empirical Sun–climate relationship defined by these pre-industrial data suggests that solar variability may have contributed 0.25°C of the 0.6°C subsequent warming from 1900 to 1990, a scenario which time dependent GCM simulations replicate when forced with reconstructed solar irradiance. Thus, while solar variability likely played a dominant role in modulating climate during the Little Ice Age prior to 1850, its influence since 1900 has become an increasingly less significant component of climate change in the industrial epoch. It is unlikely that Sun–climate relationships can account for much of the warming since 1970, not withstanding recent attempts to deduce long term solar irradiance fluctuations from the observational data base, which has notable occurrences of instrumental drifts. Empirical evidence suggests that Sun–climate relationships exist on decadal as well as centennial time scales, but present sensitivities of the climate system are insufficient to explain these short-term relationships. Still to be simulated over the time scale of the Little Ice Age to the present is the combined effect of direct radiative forcing, indirect forcing via solar-induced ozone changes in the atmosphere, and speculated charged particle mechanisms whose pathways and sensitivities are not yet specified.
11. 1999: Behringer, Wolfgang. “Climatic change and witch-hunting: the impact of the Little Ice Age on mentalities.” Climatic Change43.1 (1999): 335-351. In addition to objective climatic data, subjective or social reactions can also serve as indicators in the assessment of climatic changes. Concerning the Little Ice Age the conception of witchcraft is of enormous importance. Weather-making counts among the traditional abilities of witches. During the late 14^th and 15^th centuries the traditional conception of witchcraft was transformed into the idea of a great conspiracy of witches, to explain “unnatural” climatic phenomena. Because of their dangerous nature, particularly their ability to generate hailstorms, the very idea of witches was the subject of controversial discussion around 1500. The beginnings of meteorology and its emphasis of “natural” reasons in relationship to the development of weather must be seen against the background of this demoniacal discussion. The resurgence of the Little Ice Age revealed the susceptibility of society. Scapegoat reactions may be observed by the early 1560s even though climatologists, thus far, have been of the opinion that the cooling period did not begin until 1565. Despite attempts of containment, such as the calvinistic doctrine of predestination, extended witch-hunts took place at the various peaks of the Little Ice Age because a part of society held the witches directly responsible for the high frequency of climatic anomalies and the impacts thereof. The enormous tensions created in society as a result of the persecution of witches demonstrate how dangerous it is to discuss climatic change under the aspects of morality.
12. 1999: Free, Melissa, and Alan Robock. “Global warming in the context of the Little Ice Age.” Journal of Geophysical Research: Atmospheres 104.D16 (1999): 19057-19070. Understanding the role of volcanic and solar variations in climate change is important not only for understanding the Little Ice Age but also for understanding and predicting the effects of anthropogenic changes in atmospheric composition in the twentieth century and beyond. To evaluate the significance of solar and volcanic effects, we use four solar reconstructions and three volcanic indices as forcings to an energy‐balance model and compare the results with temperature reconstructions. Our use of a model representing the climate system response to solar and volcanic forcings distinguishes this from previous direct comparisons of forcings with temperature series for the Little Ice Age. Use of the model allows us to assess the effects of the ocean heat capacity on the evolution of the temperature response. Using a middle‐of‐the‐road model sensitivity of 3°C for doubled CO₂, solar forcings of less than 0.5% are too small to account for the cooling of the Little Ice Age. Volcanic forcings, in contrast, give climate responses comparable in amplitude to the changes of the Little Ice Age. A combination of solar and volcanic forcings explains much of the Little Ice Age climate change, but these factors alone cannot explain the warming of the twentieth century. The best simulations of the period since 1850 include anthropogenic, solar, and volcanic forcings.
13. 1999: Bond, Gerard C., et al. “The North Atlantic’s 1‐2 kyr climate rhythm: relation to Heinrich events, Dansgaard/Oeschger cycles and the Little Ice Age.” Mechanisms of global climate change at millennial time scales 112 (1999): 35-58. New evidence from deep-sea sediment cores in the subpolar North Atlantic demonstrates that a significant component of sub-Milankovitch climate variability occurs in distinct 1-2 kyr cycles. We have traced that cyclicity from the present to within marine isotope stage 5, an interval spanning more than 80 kyrs. The most robust indicators of the cycle are repeated increases in the percentages of two petrologic tracers, Icelandic glass and hematite-stained grains. Both are sensitive measures of ice rafting episodes associated with ocean surface coolings. The petrologic tracers exhibit a consistent relation to Heinrich events, implying that mechanisms forcing Heinrich events were closely linked to those forcing the cyclicity. Our records further suggest that Dansgaard/Oeschger events may be amplifications of the cycle brought about by the impact of iceberg (fresh water) discharges on North Atlantic thermohaline circulation. The tendency of thermohaline circulation to undergo threshold behavior only when fresh water input is relatively large may explain the absence of Dansgaard/Oeschger events in the Holocene and their long pacings (thousands of years) in the early part of the glaciation. Finally, evidence from cores near Newfoundland confirms previous suggestions that the Little Ice Age was the most recent cold phase of the 1-2 kyr cycle and that the North Atlantic tended to oscillate in a muted Dansgaard/Oeschger-like mode during the Holocene.
14. 1999: Pfister, Christian, and Rudolf Brázdil. “Climatic variability in sixteenth-century Europe and its social dimension: a synthesis.” Climatic Variability in Sixteenth-Century Europe and Its Social Dimension. Springer, Dordrecht, 1999. 5-53.

    The introductory paper to this special issue of Climatic Change summarizes the results of an array of studies dealing with the reconstruction of climatic trends and anomalies in sixteenth-century Europe and their impact on the natural and the social world. Areas discussed include glacier expansion in the Alps, the frequency of natural hazards (floods in central and southern Europe and storms on the Dutch North Sea coast), the impact of climate deterioration on grain prices and wine production, and finally, witch-hunts. The documentary data used for the reconstruction of seasonal and annual precipitation and temperatures in central Europe (Germany, Switzerland and the Czech Republic) include narrative sources, several types of proxy data and 32 weather diaries. Results were compared with long-term composite tree ring series and tested statistically by cross-correlating series of indices based on documentary data from the sixteenth century with those of simulated indices based on instrumental series (1901–1960). It was shown that series of indices can be taken as good substitutes for instrumental measurements. A corresponding set of weighted seasonal and annual series of temperature and precipitation indices for central Europe was computed from series of temperature and precipitation indices for Germany, Switzerland and the Czech Republic, the weights being in proportion to the area of each country. The series of central European indices were then used to assess temperature and precipitation anomalies for the 1901–1960 period using transfer functions obtained from instrumental records. The statistical analysis of these series of estimated temperature and precipitation anomalies yielded features which are similar to those obtained from instrumental series. Results show that winter temperatures remained below the 1901–1960 average except in the 1520s and 1550s. Springs fluctuated from 0.3°C to 0.8°C below this average. Summer climate was divided into three periods of almost equal length. The first was characterized by an alternation of cool and warmer seasons. The second interval was 0.3°C warmer and between 5 and 6% drier than in the 1901–1960 period. It is emphasized that this warm period included several cold extremes in contrast to the recent period of warming. Summers from 1560 were 0.4°C colder and 4% more humid. Autumns were 0.7°C colder in the 1510s and 20% wetter in the 1570s. The deterioration of summer climate in the late sixteenth century initiated a second period of enlarged glaciers in this millennium (the first having been in the fourteenth century) which did not end until the late nineteenth century. An analysis of forcing factors (solar, volcanic, ENSO, greenhouse) points only to some volcanic forcing. In order to understand circulation patterns in the sixteenth century in terms of synoptic climatology, proxy information was mapped for a number of anomalous months. Attempts to compare circulation patterns in the sixteenth century with twentieth-century analogues revealed that despite broad agreements in pressure patterns, winters with distinct northeasterly patterns were more frequent in the sixteenth century, whereas the declining summer temperatures from the mid-1560s seem to be associated with a decreasing frequency of anticyclonic ridging from the Azores’ center of action towards continental Europe. The number of severe stonns on the Dutch North Sea coast was four times greater in the second half of the century than in the first. A more or less continuous increase in the number of floods over the entire century occurred in Germany and the Czech lands. The Iberian peninsula and the Garonne basin (France) had the greatest number of severe floods in the 1590s. The analysis of the effects of climate on rye prices in four German towns involved a model that included monthly temperatures and precipitation values known to affect grain production. The correlation with rye prices was found significant for the entire century and reached its highest values between 1565 and 1600. From the 1580s to the turn of the century wine production slumped almost simultaneously in four regions over a distance of 800 kilometers (Lake Zurich to western Hungary). This had far-reaching consequences for the Habsburg treasury and promoted a temporary shift in drinking habits from wine to beer. Peasant communities which were suffering large collective damage from the effects of climatic change pressed authorities for the organization of witch-hunts. Seemingly most witches were burnt as scapegoats of climatic change.

15. 2000: Luckman, Brian H. “The little ice age in the Canadian Rockies.” Geomorphology 32.3-4 (2000): 357-384. This paper reviews the evidence and history of glacier fluctuations during the Little Ice Age (LIA) in the Canadian Rockies. Episodes of synchronous glacier advance occurred in the 12th–13th, early 18th and throughout the 19th centuries. Regional ice cover was probably greatest in the mid-19th century, although in places the early 18th century advance was more extensive. Glaciers have lost over 25% of their area in the 20th century. Selective preservation of the glacier record furnishes an incomplete chronology of events through the 14th–17th centuries. In contrast, varve sequences provide continuous, annually resolved records of sediments for at least the last millennium in some highly glacierized catchments. Such records have been used to infer glacier fluctuations. Evaluation of recent proxy climate reconstructions derived from tree-rings provides independent evidence of climate fluctuations over the last millennium. Most regional glacier advances follow periods of reduced summer temperatures, reconstructed from tree rings particularly ca. 1190–1250, 1280–1340, 1690s and the 1800s. Reconstructed periods of higher precipitation at Banff, Alberta since 1500 are 1515–1550, 1585–1610, 1660–1680 and the 1880s. Glacier advances in the early 1700s, the late 1800s and, in places, the 1950–1970s reflect both increased precipitation and reduced summer temperatures. Negative glacier mass balances from 1976 to 1995 were caused by decreased winter balances. The glacier fluctuation record does not contain a simple climate signal: it is a complex response to several interacting factors that operate at different timescales. Evaluation of climate proxies over the last millennium indicates continuous variability at several superimposed timescales, dominated by decade–century patterns. Only the 19th century shows a long interval of sustained cold summers. This suggests that simplistic concepts of climate over this period should be abandoned and replaced with more realistic records based on continuous proxy data series. The use of the term LIA should be restricted to describing a period of extended glacier cover rather than being used to define a period with specific climate conditions.
16. 2000: Reiter, Paul. “From Shakespeare to Defoe: malaria in England in the Little Ice Age.” Emerging infectious diseases 6.1 (2000): Present global temperatures are in a warming phase that began 200 to 300 years ago. Some climate models suggest that human activities may have exacerbated this phase by raising the atmospheric concentration of carbon dioxide and other greenhouse gases. Discussions of the potential effects of the weather include predictions that malaria will emerge from the tropics and become established in Europe and North America. The complex ecology and transmission dynamics of the disease, as well as accounts of its early history, refute such predictions. Until the second half of the 20th century, malaria was endemic and widespread in many temperate regions, with major epidemics as far north as the Arctic Circle. From 1564 to the 1730s the coldest period of the Little Ice Age malaria was an important cause of illness and death in several parts of England. Transmission began to decline only in the 19th century, when the present warming trend was well under way. The history of the disease in England underscores the role of factors other than temperature in malaria transmission.
17. 2001: Ogilvie, Astrid EJ, and Trausti Jónsson. “” Little ice age” research: A perspective from Iceland.” Climatic Change 48.1 (2001): 9-52. The development during the nineteenth and twentieth centuries of the sciences of meteorology and climatology and their subdisciplines has made possible an ever-increasing understanding of the climate of the past. In particular, the refinement of palaeoclimatic proxy data has meant that the climate of the past thousand years has begun to be extensively studied. In the context of this research, it has often been suggested that a warm epoch occurred in much of northern Europe, the north Atlantic, and other parts of the world, from around the ninth through the fourteenth centuries, and that this was followed by a decline in temperatures culminating in a “Little Ice Age” from about 1550 to 1850 (see e.g. Lamb, 1965, 1977; Flohn, 1978). The appelations “Medieval Warm Period” and “Little Ice Age” have entered the literature and are frequently used without clear definition. More recently, however, these terms have come under closer scrutiny (see, e.g. Ogilvie, 1991, 1992; Bradley and Jones, 1992; Mikami, 1992; Briffa and Jones, 1993; Bradley and Jones, 1993; Hughes and Diaz, 1994; Jones et al., 1998; Mann et al., 1999; Crowley and Lowery, 2000). As research continues into climatic fluctuations over the last 1000 to 2000 years, a pattern is emerging which suggests a far more complex picture than early research into the history of climate suggested. In this paper, the origins of the term “Little Ice Age” are considered. Because of the emphasis on the North Atlantic in this volume, the prime focus is on research that has been undertaken in this region, with a perspective on the historiography of historical climatology in Iceland as well as on the twentieth-century climate of Iceland. The phrase “Little Ice Age” has become part of the scientific and popular thinking on the climate of the past thousand years. However, as knowledge of the climate of the Holocene continues to grow, the term now seems to cloud rather than clarify thinking on the climate of the past thousand years. It is hoped that the discussion here will encourage future researchers to focus their thinking on exactly and precisely what is meant when the term “Little Ice Age” is used.
18. 2001: Grove, Jean M. “The initiation of the” Little Ice Age” in regions round the North Atlantic.” Climatic change 48.1 (2001): 53-82. The “Little Ice Age” was the most recent period during which glaciers extended globally, their fronts oscillating about advanced positions. It is frequently taken as having started in the sixteenth or seventeenth century and ending somewhere between 1850 and 1890, but Porter (1981) pointed out that the “Little Ice Age” may ‘have begun at least three centuries earlier in the North Atlantic region than is generally inferred’. The glacial fluctuations of the last millennium have been traced in the greatest detail in the Swiss Alps, where the “Little Ice Age” is now seen as starting with advances in the thirteenth century, and reaching an initial culmination in the fourteenth century. In the discussion here, evidence from Canada, Greenland, Iceland, Spitsbergen and Scandinavia is compared with that from Switzerland. Such comparisons have been facilitated by improved methods of calibrating radiocarbon dates to calendar dates and by increasing availability of evidence revealed during the current retreat phase. It is concluded that the “Little Ice Age” was initiated before the early fourteenth century in regions surrounding the North Atlantic.
19. 2002: Hendy, Erica J., et al. “Abrupt decrease in tropical Pacific sea surface salinity at end of Little Ice Age.” Science 295.5559 (2002): 1511-1514. A 420-year history of strontium/calcium, uranium/calcium, and oxygen isotope ratios in eight coral cores from the Great Barrier Reef, Australia, indicates that sea surface temperature and salinity were higher in the 18th century than in the 20th century. An abrupt freshening after 1870 occurred simultaneously throughout the southwestern Pacific, coinciding with cooling tropical temperatures. Higher salinities between 1565 and 1870 are best explained by a combination of advection and wind-induced evaporation resulting from a strong latitudinal temperature gradient and intensified circulation. The global Little Ice Age glacial expansion may have been driven, in part, by greater poleward transport of water vapor from the tropical Pacific
20. 2002: Mann, Michael E. “Little ice age.” Encyclopedia of global environmental change 1 (2002): 504-509. The term Little Ice Age is reserved for the most extensive recent period of mountain glacier expansion and is conventionally defined as the 16th–mid 19th century period during which European climate was most strongly impacted. This period begins with a trend towards enhanced glacial
    conditions in Europe following the warmer conditions of the so-called medieval warm period or medieval climatic optimum of Europe (see Medieval Climatic Optimum, Volume 1), and terminates with the dramatic retreat of these glaciers during the 20th century. While there is evidence that many other regions outside Europe exhibited periods of cooler conditions, expanded glaciation, and significantly altered climate conditions, the timing and nature of these variations are highly variable from region to region, and the notion of the Little Ice Age as a globally synchronous cold period has all but been dismissed (Bradley and Jones, 1993; Mann et al., 1999). If defined as a large-scale event, the Little Ice Age must instead be considered a time of modest cooling of the Northern Hemisphere, with temperatures dropping by about 0.6 °C during the 15th–19th
21. 2003: Nesje, Atle, and Svein Olaf Dahl. “The ‘Little Ice Age’–only temperature?.” The Holocene 13.1 (2003): 139-145. Understanding the climate of the last few centuries, including the ‘Little Ice Age’, may help us better understand modern-day natural climate variability and make climate predictions. The conventional view of the climate development during the last millennium has been that it followed the simple sequence of a ‘Mediaeval Warm Period’, a cool ‘Little Ice Age’ followed by warming in the later part of the nineteenth century and during the twentieth century. This view was mainly based on evidence from western Europe and the North Atlantic region. Recent research has, however, challenged this rather simple sequence of climate development in the recent past. Data presented here indicate that the rapid glacier advance in the early eighteenth century in southern Norway was mainly due to increased winter precipitation: mild, wet winters due to prevailing ‘positive North Atlantic Oscillation (NAO) weather mode’ in the first half of the eighteenth century; and not only lower summer temperatures. A comparison of recent mass-balance records and ‘Little Ice Age’ glacier fluctuations in southern Norway and the European Alps suggests that the asynchronous ‘Little Ice Age’ maxima in the two regions may be attributed to multidecadal trends in the north–south dipole NAO pattern.
22. 2004: Oster, Emily. “Witchcraft, weather and economic growth in Renaissance Europe.” Journal of Economic Perspectives 18.1 (2004): 215-228. between the thirteenth and nineteenth centuries, as many as one million individuals in Europe were executed for the crime of witchcraft. The majority of the trials and executions took place during the sixteenth and seventeenth centuries. During this period, the speed and volume of executions were astonishing: in one German town, as many as 400 people were killed in a single day (Midelfort, 1972). The trials were ubiquitous: conducted by both ecclesiastical and secular courts; by both Catholics and Protestants. The victims were primarily women, primarily poor and disproportionately widows. The persecutions took place throughout Europe, starting and ending earlier in southwest Europe than in the northern and eastern areas, and spread even across the Atlantic Ocean to Salem, Massachusetts. Although witchcraft trials in Europe and America largely ended by the late eighteenth century, witchcraft accusations and killings still take place in many countries today, particularly in the developing world. For example, witchcraft is often blamed for AIDS deaths in sub-Saharan Africa (Ashforth, 2001), and Miguel (2003) shows that negative economic shocks are associated with increases in witch killing in modern Tanzania. Belief in the witch, and fear of her, is enduring. While much work has been done on the motivations behind the European trials, the large-scale causes remain unknown. The existing work has primarily been concerned with the factors that played into trials on a small scale—why a certain individual was targeted or why a certain type of individual was targeted in a given area. This work has indicated that there was a diverse set of issues that played into trials on an individual level. More broadly, however, there are few causal explanations
    for why witchcraft trials happened at all and on such a large scale in so many
    y Emily Oster is a Ph.D. student in economics, Harvard University, Cambridge, Massachusetts. Her e-mail address is eoster@post.harvard.edu. Journal of Economic Perspectives—Volume 18, Number 1—Winter 2004—Pages 215–228 areas at the times that they did. The earliest trials, going back to the thirteenth century, were the work of church institutions, particularly the Catholic Inquisition, but the mass of trials later in the period saw very little formal church involvement of this type. Various hypotheses have been offered: for example, a need by the male medical profession to rid the world of midwives and female folk healers (Ehrenreich and English, 1973); a perceived need for moral boundaries by the Catholic church (Ben-Yehuda, 1980); or an increase in syphilis and subsequent increase in the mentally ill, who were then targeted as witches (Ross, 1995). This paper explores the possibility that the witchcraft trials are a large-scale example of violence and scapegoating prompted by a deterioration in economic conditions. In this case, the downturn was brought on by a decrease in temperature and resulting food shortages. The most active period of the witchcraft trials coincides with a period of lower than average temperature known to climatologists as the “little ice age.” The colder temperatures increased the frequency of crop failure, and colder seas prevented cod and other fish from migrating as far north, eliminating this vital food source for some northern areas of Europe (Fagan, 2000). Several kinds of data show more than a coincidental relationship between witch trials, weather and economic growth. In a time period when the reasons for changes in weather were largely a mystery, people would have searched for a scapegoat in the face of deadly changes in weather patterns. “Witches” became target for blame because there was an existing cultural framework that both allowed their persecution and suggested that they could control the weather. Background on Witchcraft and the Little Ice Age
23. 2005: Matthews, John A., and Keith R. Briffa. “The ‘Little Ice Age’: re‐evaluation of an evolving concept.” Geografiska Annaler: Series A, Physical Geography 87.1 (2005): 17-36. This review focuses on the development of the ‘Little Ice Age’ as a glaciological and climatic concept, and evaluates its current usefulness in the light of new data on the glacier and climatic variations of the last millennium and of the Holocene. ‘Little Ice Age’ glacierization occurred over about 650 years and can be defined most precisely in the European Alps (c. AD 1300–1950) when extended glaciers were larger than before or since. ‘Little Ice Age’ climate is defined as a shorter time interval of about 330 years (c. AD 1570–1900) when Northern Hemisphere summer temperatures (land areas north of 20°N) fell significantly below the AD 1961–1990 mean. This climatic definition overlaps the times when the Alpine glaciers attained their latest two highstands (AD 1650 and 1850). It is emphasized, however, that ‘Little Ice Age’ glacierization was highly dependent on winter precipitation and that ‘Little Ice Age’ climate was not simply a matter of summer temperatures. Both the glacier‐centred and the climate‐centred concepts necessarily encompass considerable spatial and temporal variability, which are investigated using maps of mean summer temperature variations over the Northern Hemisphere at 30‐year intervals from AD 1571 to 1900. ‘Little Ice Age’‐type events occurred earlier in the Holocene as exemplified by at least seven glacier expansion episodes that have been identified in southern Norway. Such events provide a broader context and renewed relevance for the ‘Little Ice Age’, which may be viewed as a ‘modern analogue’ for the earlier events; and the likelihood that similar events will occur in the future has implications for climatic change in the twenty‐first century. It is concluded that the concept of a ‘Little Ice Age’ will remain useful only by (1) continuing to incorporate the temporal and spatial complexities of glacier and climatic variations as they become better known, and (2) by reflecting improved understanding of the Earth‐atmosphere‐ocean system and its forcing factors through the interaction of palaeoclimatic reconstruction with climate modelling.
24. 2005: Brázdil, Rudolf, et al. “Historical climatology in Europe–the state of the art.” Climatic change 70.3 (2005): 363-430. This paper discusses the state of European research in historical climatology. This field of science and an overview of its development are described in detail. Special attention is given to the documentary evidence used for data sources, including its drawbacks and advantages. Further, methods and significant results of historical-climatological research, mainly achieved since 1990, are presented. The main focus concentrates on data, methods, definitions of the “Medieval Warm Period” and the “Little Ice Age”, synoptic interpretation of past climates, climatic anomalies and natural disasters, and the vulnerability of economies and societies to climate as well as images and social representations of past weather and climate. The potential of historical climatology for climate modelling research is discussed briefly. Research perspectives in historical climatology are formulated with reference to data, methods, interdisciplinarity and impacts.
25. 2006: Bräuning, Achim. “Tree-ring evidence of ‘Little Ice Age’glacier advances in southern Tibet.” The Holocene 16.3 (2006): 369-380. The history of late Holocene glacier fluctuations in eastern Tibet was studied by determining the ages of trees growing on glacier deposits. Maximum tree ages yield minimum ages of AD 1760 and 1780 for moraine formation at the maximum extent of the ‘Little Ice Age’ glacier advances in two glacier forefields. Subsequent moraines could be dated to the beginning of the nineteenth and the beginning of the twentieth century. Larch trees from a third glacier forefield in southeastern Tibet show evidence of glacier activity from 1580 to 1590, from the end of the eighteenth to the beginning of the nineteenth century and from 1860 to 1880. One glacier at Mt Gyalaperi recently advanced in both 1951 and 1987. Periods of glacier advances can partly be correlated with periods of growth reductions in chronologies of total ring width and maximum latewood density derived from trees growing on slopes above the glacier valleys. Correlation functions with meteorological data suggest that maximum latewood density of subalpine Picea balfouriana, Larix griffithii and Abies delavayi var.motouensis is positively correlated with summer temperature, while ring width of these species and of subalpine Juniperus tibetica is also sensitive to winter conditions prior to the growing season.
26. 2006: Pfister, Christian. “Climatic extremes, recurrent crises and witch hunts: strategies of European societies in coping with exogenous shocks in the late sixteenth and early seventeenth centuries.” The Medieval History Journal 10.1-2 (2006): 33-73. In the late sixteenth and early seventeenth centuries, continental Europe north of the Alps was afflicted by a 13-year cycle of frequent cold and rainy summers which was the result of a series of volcanic explosions in the tropics. The inclement weather led to recurrent subsistence crises and to multiple floods in the Alps following from extensive glacier advances. This article discusses the relationship between ‘climate’ and ‘history’ from the example of this unique period. The vulnerability of food production in Europe to climatic hazard is assessed from an impact model. The result shows that the period 1560 to 1630 is most prominently marked by a high level of climatic stress. Likewise, this study demonstrates how authorities in Val Aosta (Italy) responded to annually recurrent floods in the 1590s triggered by the advancing Ruitor glacier. Finally, by confirming the thesis advanced by Wolfgang Behringer relating extensive witch hunts during that period to climatic change and recurrent subsistence crises, this article makes a plea for bridging the gap separating studies of climate from those of culture.
27. 2006: Pfister, Christian, and Rudolf Brázdil. “Social vulnerability to climate in the” Little Ice Age“: an example from Central Europe in the early 1770s.” Climate of the Past 2.2 (2006): 115-129. The paper is oriented on social vulnerability to climate in Switzerland and in the Czech Lands during the early 1770s. Documentary sources of climate related to man-made archives are discussed. Methods of temperature and precipitation reconstruction based on this evidence as well as climate impact analyses are presented. Modelling of Little Ice Age-type Impacts (LIATIMP) is applied to highlight climate impacts during the period 1750?1800 in the Swiss Plateau and in the Czech Lands. LIATIMP are defined as adverse climate situations affecting agricultural production, mainly in terms of rainy autumns, cold springs and rainy harvest-periods. The most adverse weather patterns according to this model occurred from 1769 to 1771 causing two, in the case of the Czech Lands even three successive harvest failures. The paper addresses the social and economic consequences of this accumulation of climatic stress and explores how the authorities and the victims dealt with this situation.
28. 2008: Crowley, Thomas J., et al. “Volcanism and the little ice age.” PAGES news 16.2 (2008): 22-23.  Although solar variability has often been considered the primary agent for LIA cooling, the most comprehensive test of this explanation (Hegerl et al., 2003) points instead to volcanism being substantially more important, explaining as much as 40% of the decadal-scale variance during the LIA. Yet, one problem that has continually plagued climate researchers is that the paleovolcanic record, reconstructed from Antarctic and Greenland ice cores, cannot be well calibrated against the instrumental record. This is because the primary in-strumental volcano reconstruction used by the climate community is that of Sato et al. (1993), which is relatively poorly con-strained by observations prior to 1960 (es-pecially in the southern hemisphere). Here, we report on a new study that has successfully calibrated the Antarctic sulfate record of volcanism from the 1991 eruptions of Pinatubo (Philippines) and Hudson (Chile) against satellite aerosol op-tical depth (AOD) data (AOD is a measure of stratospheric transparency to incoming solar radiation). A total of 22 cores yield an area-weighted sulfate accumulation rate of 10.5 kg/km2, which translates into a conversion rate for AOD of 0.011 AOD/kg/km2 sulfate. We validated our time series by comparing a canonical growth and decay curve for eruptions for Krakatau (1883), the 1902 Caribbean eruptions (pri marily Santa Maria), and the 1912 eruption of Novarupta/Katmai (Alaska) against a reanalysis (Stothers, 1996) of the original AOD data and lunar eclipse estimates of AOD for Krakatau (Keen, 1983). The agreement (Fig. 1) is very good—essentially within the uncertainty of the independent data. Our new ice core reconstruction shows several significant disagreements with the Sato et al. (1993).
29. 2009: Masiokas, M. H., et al. “Little Ice Age fluctuations of small glaciers in the Monte Fitz Roy and Lago del Desierto areas, south Patagonian Andes, Argentina.” Palaeogeography, Palaeoclimatology, Palaeoecology 281.3-4 (2009): 351-362. Current knowledge about late Holocene glacier fluctuations in the south Patagonian Andes is mainly based on evidence from large outlet glaciers of the North and South Patagonian Icefields, and few data exist for the smaller glaciers elsewhere in the region. Here we provide dendrogeomorphological evidence for Little Ice Age (LIA) and post-LIA activity for five small glaciers near the northeast margin of the South Patagonian Icefield. The study sites include Glaciar Torre and Piedras Blancas in the Monte Fitz Roy area, and three adjacent glaciers near Lago del Desierto. At these sites the LIA maximum position was identified by massive moraines with mature trees dating to the late 1500s–early 1600s. Several older moraines were observed beyond these limits but could not be precisely dated. Relatively synchronous advances occurred at most glaciers in the early 1700s and were dated using living trees and in situ, subfossil material. All glaciers show three to five subsequent advances mostly concentrated between the mid-19th and early 20th centuries. Estimates based on Landsat TM imagery indicate these glaciers lost between 15 and 46% of their LIA areas by 1984 and a further 5–18% by 2005, with the smallest glaciers showing the greatest proportional loss. Paired comparisons of contemporary and the earliest known photography for the glaciers in the Fitz Roy area confirm this mass loss. These results provide important new information on the glacier history of this area but additional, more precisely-dated records are needed from many more sites before we can fully elucidate the complex late Holocene glacial history of this region.
30. 2009: Mann & Zhang. “Global signatures and dynamical origins of the Little Ice Age and Medieval Climate Anomaly.” Science 326.5957 (2009): 1256-1260. Global temperatures are known to have varied over the past 1500 years, but the spatial patterns have remained poorly defined. We used a global climate proxy network to reconstruct surface temperature patterns over this interval. The Medieval period is found to display warmth that matches or exceeds that of the past decade in some regions, but which falls well below recent levels globally. This period is marked by a tendency for La Niña–like conditions in the tropical Pacific. The coldest temperatures of the Little Ice Age are observed over the interval 1400 to 1700 C.E., with greatest cooling over the extratropical Northern Hemisphere continents. The patterns of temperature change imply dynamical responses of climate to natural radiative forcing changes involving El Niño and the North Atlantic Oscillation–Arctic Oscillation.
31. 2010: Dull, Robert A., et al. “The Columbian encounter and the Little Ice Age: Abrupt land use change, fire, and greenhouse forcing.” Annals of the Association of American Geographers100.4 (2010): 755-771. Pre-Columbian farmers of the Neotropical lowlands numbered an estimated 25 million by 1492, with at least 80 percent living within forest biomes. It is now well established that significant areas of Neotropical forests were cleared and burned to facilitate agricultural activities before the arrival of Europeans. Paleoecological and archaeological evidence shows that demographic pressure on forest resources—facilitated by anthropogenic burning—increased steadily throughout the Late Holocene, peaking when Europeans arrived in the late fifteenth century. The introduction of Old World diseases led to recurrent epidemics and resulted in an unprecedented population crash throughout the Neotropics. The rapid demographic collapse was mostly complete by 1650, by which time it is estimated that about 95 percent of all indigenous inhabitants of the region had perished. We review fire history records from throughout the Neotropical lowlands and report new high-resolution charcoal records and demographic estimates that together support the idea that the Neotropical lowlands went from being a net source of CO₂ to the atmosphere before Columbus to a net carbon sink for several centuries following the Columbian encounter. We argue that the regrowth of Neotropical forests following the Columbian encounter led to terrestrial biospheric carbon sequestration on the order of 2 to 5 Pg C, thereby contributing to the well-documented decrease in atmospheric CO₂ recorded in Antarctic ice cores from about 1500 through 1750, a trend previously attributed exclusively to decreases in solar irradiance and an increase in global volcanic activity. We conclude that the post-Columbian carbon sequestration event was a significant forcing mechanism of Little Ice Age cooling.
32. 2011: Bertler, N. A. N., P. A. Mayewski, and L. Carter. “Cold conditions in Antarctica during the Little Ice Age—Implications for abrupt climate change mechanisms.” Earth and Planetary Science Letters 308.1 (2011): 41-51. The Little Ice Age (LIA) is one of the most prominent climate shifts in the past 5000 yrs. It has been suggested that the LIA might be the most recent of the Dansgaard–Oeschger events, which are better known as abrupt, large scale climate oscillations during the last glacial period. If the case, then according to Broecker (2000a, 2000b) Antarctica should have warmed during the LIA, when the Northern Hemisphere was cold. Here we present new data from the Ross Sea, Antarctica, that indicates surface temperatures were ~ 2 °C colder during the LIA, with colder sea surface temperatures in the Southern Ocean and/or increased sea-ice extent, stronger katabatic winds, and decreased snow accumulation. Whilst we find there was large spatial and temporal variability, overall Antarctica was cooler and stormier during the LIA. Although temperatures have warmed since the termination of the LIA, atmospheric circulation strength has remained at the same, elevated level. We conclude, that the LIA was either caused by alternative forcings, or that the sea-saw mechanism operates differently during warm periods.
33. 2011: Morellón, Mario, et al. “Climate changes and human activities recorded in the sediments of Lake Estanya (NE Spain) during the Medieval Warm Period and Little Ice Age.” Journal of Paleolimnology 46.3 (2011): 423-452. A multi-proxy study of short sediment cores recovered in small, karstic Lake Estanya (42°02′ N, 0°32′ E, 670 m.a.s.l.) in the Pre-Pyrenean Ranges (NE Spain) provides a detailed record of the complex environmental, hydrological and anthropogenic interactions occurring in the area since medieval times. The integration of sedimentary facies, elemental and isotopic geochemistry, and biological proxies (diatoms, chironomids and pollen), together with a robust chronological control, provided by AMS radiocarbon dating and ²¹⁰Pb and ¹³⁷Cs radiometric techniques, enabled precise reconstruction of the main phases of environmental change, associated with the Medieval Warm Period (MWP), the Little Ice Age (LIA) and the industrial era. Shallow lake levels and saline conditions with poor development of littoral environments prevailed during medieval times (1150–1300 AD). Generally higher water levels and more dilute waters occurred during the LIA (1300–1850 AD), although this period shows a complex internal paleohydrological structure and is contemporaneous with a gradual increase of farming activity. Maximum lake levels and flooding of the current littoral shelf occurred during the nineteenth century, coinciding with the maximum expansion of agriculture in the area and prior to the last cold phase of the LIA. Finally, declining lake levels during the twentieth century, coinciding with a decrease in human pressure, are associated with warmer climate conditions. A strong link with solar irradiance is suggested by the coherence between periods of more positive water balance and phases of reduced solar activity. Changes in winter precipitation and dominance of NAO negative phases would be responsible for wet LIA conditions in western Mediterranean regions. The main environmental stages recorded in Lake Estanya are consistent with Western Mediterranean continental records, and show similarities with both Central and NE Iberian reconstructions, reflecting a strong climatic control of the hydrological and anthropogenic changes during the last 800 years.
34. 2012: Orsi, Anais J., 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 39.9 (2012).  The largest climate anomaly of the last 1000 years in the Northern Hemisphere was the Little Ice Age (LIA) from 1400–1850 C.E., but little is known about the signature of this event in the Southern Hemisphere, especially in Antarctica. We present temperature data from a 300 m borehole at the West Antarctic Ice Sheet (WAIS) Divide. Results show that WAIS Divide was colder than the last 1000‐year average from 1300 to 1800 C.E. The temperature in the time period 1400–1800 C.E. was on average 0.52 ± 0.28°C colder than the last 100‐year average. This amplitude is about half of that seen at Greenland Summit (GRIP). This result is consistent with the idea that the LIA was a global event, probably caused by a change in solar and volcanic forcing, and was not simply a seesaw‐type redistribution of heat between the hemispheres as would be predicted by some ocean‐circulation hypotheses. The difference in the magnitude of the LIA between Greenland and West Antarctica suggests that the feedbacks amplifying the radiative forcing may not operate in the same way in both regions
35. 2012: Nussbaumer, Samuel U., and Heinz J. Zumbühl. “The Little Ice Age history of the Glacier des Bossons (Mont Blanc massif, France): a new high-resolution glacier length curve based on historical documents.” Climatic Change 111.2 (2012): 301-334. Historical and proxy records document that there is a substantial asynchronous development in temperature, precipitation and glacier variations between European regions during the last few centuries. The causes of these temporal anomalies are yet poorly understood. Hence, highly resolved glacier reconstructions based on historical evidence can give valuable insights into past climate, but they exist only for few glaciers worldwide. Here, we present a new reconstruction of length changes for the Glacier des Bossons (Mont Blanc massif, France), based on unevaluated historical material. More than 250 pictorial documents (drawings, paintings, prints, photographs, maps) as well as written accounts have been critically analysed, leading to a revised picture of the glacier’s history, especially from the mid-eighteenth century up to the 1860s. Very important are the drawings by Jean-Antoine Linck, Samuel Birmann and Eugène Viollet-le Duc, which depict meticulously the glacier’s extent during the vast advance and subsequent retreat during the nineteenth century. The new glacier reconstruction extends back to AD 1580 and proves maxima of the Glacier des Bossons around 1610/1643, 1685, 1712, 1777, 1818, 1854, 1892, 1921, 1941, and 1983. The Little Ice Age maximum extent was reached in 1818. Until the present, the glacier has lost about 1.5 km in length, and it is now shorter than at any time during the reconstruction period. The Glacier des Bossons reacts faster than the nearby Mer de Glace (glacier reconstruction back to AD 1570 available). The Mont Blanc area is, together with the valley of Grindelwald in the Swiss Alps (two historical glacier reconstructions available back to AD 1535, and 1590, respectively), among the two regions that are probably best-documented in the world regarding historical glacier data
36. 2012: Miller, Gifford H., et al. “Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea‐ice/ocean feedbacks.” Geophysical Research Letters 39.2 (2012). Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century‐scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. Here we present precisely dated records of ice‐cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea‐ice/ocean feedbacks long after volcanic aerosols are removed. Our results suggest that the onset of the LIA can be linked to an unusual 50‐year‐long episode with four large sulfur‐rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea‐ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required.
37. 2013: Kelly, Morgan, and Cormac Ó Gráda. “The waning of the little ice age: climate change in early modern Europe.” Journal of Interdisciplinary History 44.3 (2013): 301-325. The supposed ramifications of the Little Ice Age, a period of cooling temperatures straddling several centuries in northwestern Europe, reach far beyond meteorology into economic, political, and cultural history. The available annual temperature series from the late Middle Ages to the end of the nineteenth century, however, contain no major breaks, cycles, or trends that could be associated with the existence of a Little Ice Age. Furthermore, the series of resonant images, ranging from frost fairs to contracting glaciers and from dwindling vineyards to disappearing Viking colonies, often adduced as effects of a Little Ice Age, can also be explained without resort to climate change.
38. 2013: White, Sam. “The real little ice age.” Journal of Interdisciplinary History 44.3 (2013): 327-352. The Little Ice Age is not a dogma. It is an increasingly firm consensus backed by considerable evidence across a variety of sources. To disprove it, or even to call it into question, would mean finding systematic errors in several types of proxy data. Kelly and Ó Gráda have not cleared any of these hurdles, or even come close. The refutation of their arguments demonstrates just how strong the evidence for the Little Ice Age has become and just how important it is for historians to take it seriously.
39. 2013: Lehner, Flavio, et al. “Amplified inception of European Little Ice Age by sea ice–ocean–atmosphere feedbacks.” Journal of Climate 26.19 (2013): 7586-7602. The inception of the Little Ice Age (~1400–1700 AD) is believed to have been driven by an interplay of external forcing and climate system internal variability. While the hemispheric signal seems to have been dominated by solar irradiance and volcanic eruptions, the understanding of mechanisms shaping the climate on a continental scale is less robust. In an ensemble of transient model simulations and a new type of sensitivity experiments with artificial sea ice growth, the authors identify a sea ice–ocean–atmosphere feedback mechanism that amplifies the Little Ice Age cooling in the North Atlantic–European region and produces the temperature pattern suggested by paleoclimatic reconstructions. Initiated by increasing negative forcing, the Arctic sea ice substantially expands at the beginning of the Little Ice Age. The excess of sea ice is exported to the subpolar North Atlantic, where it melts, thereby weakening convection of the ocean. Consequently, northward ocean heat transport is reduced, reinforcing the expansion of the sea ice and the cooling of the Northern Hemisphere. In the Nordic Seas, sea surface height anomalies cause the oceanic recirculation to strengthen at the expense of the warm Barents Sea inflow, thereby further reinforcing sea ice growth. The absent ocean–atmosphere heat flux in the Barents Sea results in an amplified cooling over Northern Europe. The positive nature of this feedback mechanism enables sea ice to remain in an expanded state for decades up to a century, favoring sustained cold periods over Europe such as the Little Ice Age. Support for the feedback mechanism comes from recent proxy reconstructions around the Nordic Seas.
40. 2013: Schleussner, Carl-Friedrich, and G. Feulner. “A volcanically triggered regime shift in the subpolar North Atlantic Ocean as a possible origin of the Little Ice Age.” Climate of the Past 9.3 (2013). Among the climatological events of the last millennium, the Northern Hemisphere Medieval Climate
    Anomaly succeeded by the Little Ice Age are of exceptional importance. The origin of these regional climate anomalies remains a subject of debate and besides external influences like solar and volcanic activity, internal dynamics of the climate system might have also played a dominant role. Here, we present transient last millennium simulations of the fully coupled model of intermediate complexity Climber 3α forced with stochastically reconstructed wind-stress fields. Our results indicate that short-lived volcanic eruptions might have triggered a cascade of sea ice–ocean feedbacks in the North Atlantic, ultimately leading to a persistent regime shift in the ocean circulation. We find that an increase in the Nordic Sea sea-ice extent on decadal timescales as a consequence of major volcanic eruptions in our model leads to a spin-up of the subpolar gyre and a weakened Atlantic meridional overturning circulation, eventually causing a persistent, basin-wide cooling. These results highlight the importance of regional climate feedbacks such as a regime shift in the subpolar gyre circulation for understanding the dynamics of past and future climate.
41. 2014: Knudsen, Mads Faurschou, et al. “Evidence for external forcing of the Atlantic Multidecadal Oscillation since termination of the Little Ice Age.” Nature Communications 5 (2014): 3323. The Atlantic Multidecadal Oscillation (AMO) represents a significant driver of Northern Hemisphere climate, but the forcing mechanisms pacing the AMO remain poorly understood. Here we use the available proxy records to investigate the influence of solar and volcanic forcing on the AMO over the last ~450 years. The evidence suggests that external forcing played a dominant role in pacing the AMO after termination of the Little Ice Age (LIA; ca. 1400–1800), with an instantaneous impact on mid-latitude sea-surface temperatures that spread across the North Atlantic over the ensuing ~5 years. In contrast, the role of external forcing was more ambiguous during the LIA. Our study further suggests that the Atlantic Meridional Overturning Circulation is important for linking external forcing with North Atlantic sea-surface temperatures, a conjecture that reconciles two opposing theories concerning the origin of the AMO.
42. 2014: Lorrey, Andrew, et al. “The Little Ice Age climate of New Zealand reconstructed from Southern Alps cirque glaciers: a synoptic type approach.” Climate dynamics 42.11-12 (2014): 3039-3060. Little Ice Age (LIA) austral summer temperature anomalies were derived from palaeoequilibrium line altitudes at 22 cirque glacier sites across the Southern Alps of New Zealand. Modern analog seasons with temperature anomalies akin to the LIA reconstructions were selected, and then applied in a sampling of high-resolution gridded New Zealand climate data and global reanalysis data to generate LIA climate composites at local, regional and hemispheric scales. The composite anomaly patterns assist in improving our understanding of atmospheric circulation contributions to the LIA climate state, allow an interrogation of synoptic type frequency changes for the LIA relative to present, and provide a hemispheric context of the past conditions in New Zealand. An LIA summer temperature anomaly of −0.56 °C (±0.29 °C) for the Southern Alps based on palaeo-equilibrium lines compares well with local tree-ring reconstructions of austral summer temperature. Reconstructed geopotential height at 1,000 hPa (z1000) suggests enhanced southwesterly flow across New Zealand occurred during the LIA to generate the terrestrial temperature anomalies. The mean atmospheric circulation pattern for summer resulted from a crucial reduction of the ‘HSE’-blocking synoptic type (highs over and to the west of NZ; largely settled conditions) and increases in both the ‘T’- and ‘SW’-trough synoptic types (lows passing over NZ; enhanced southerly and southwesterly flow) relative to normal. Associated land-based temperature and precipitation anomalies suggest both colder- and wetter-than-normal conditions were a pervasive component of the base climate state across New Zealand during the LIA, as were colder-than-normal Tasman Sea surface temperatures. Proxy temperature and circulation evidence were used to corroborate the spatially heterogeneous Southern Hemisphere composite z1000 and sea surface temperature patterns generated in this study. A comparison of the composites to climate mode archetypes suggests LIA summer climate and atmospheric circulation over New Zealand was driven by increased frequency of weak El Niño-Modoki in the tropical Pacific and negative Southern Annular Mode activity.
43. 2015: Chen, Jianhui, et al. “Hydroclimatic changes in China and surroundings during the Medieval Climate Anomaly and Little Ice Age: spatial patterns and possible mechanisms.” Quaternary Science Reviews 107 (2015): 98-111.

    Investigating hydroclimatic changes during key periods such as the Medieval Climate Anomaly (MCA, 1000–1300 AD) and the Little Ice Age (LIA, 1400–1900 AD) is of fundamental importance for quantifying the responses of precipitation to greenhouse gas-induced warming on regional and global scales. This study synthesizes the most up-to-date and comprehensive proxy moisture/precipitation records during the past 1000 years in China and surroundings. The proxy data collected include 34 records from arid central Asia (ACA) and 37 records from monsoonal Asia. Our results demonstrate a pattern of generally coherent regional moisture variations during the MCA and LIA. In mid-latitude Asia north of 30°N, monsoonal northern China (North China and Northeast China) was generally wetter, while ACA (Northwest China and Central Asia) was generally drier during the MCA than in the LIA (a West–East mode). The boundary between wetter northern China and drier ACA was roughly consistent with the modern summer monsoon boundary. In monsoonal China to the east of 105°E, the northern part was generally wetter, while the southern part was generally drier during the MCA than in the LIA (a North–South mode), with a boundary roughly along the Huai River at about 34°N. These spatial patterns of moisture/precipitation variations are also identified by instrumental data during the past 50 years. In order to understand the possible mechanisms related to the moisture variations during the MCA and LIA, we investigate the major SST and atmospheric modes (e.g. the El Niño/Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO) and the North Atlantic Oscillation (NAO)) which affect the moisture/precipitation variations in the study region using both the instrumental data and the reconstructed time series. It is found that the ENSO may play an important role in determining hydroclimatic variability over China and surroundings on a multi-centennial time-scale; and that the foregoing spatial patterns could be attributed to the La Niña-like (El Niño-like) condition during the MCA (LIA). In addition, AMO and NAO may also have their own contributions.

44. 2015: Yan, Hong, et al. “Dynamics of the intertropical convergence zone over the western Pacific during the Little Ice Age.” Nature Geoscience 8.4 (2015): 315. Precipitation in low latitudes is primarily controlled by the position of the intertropical convergence zone, which migrates from south to north seasonally. The Little Ice Age (defined as AD 1400–1850) was associated with low solar irradiance and high atmospheric aerosol concentrations as a result of several large volcanic eruptions. The mean position of the intertropical convergence zone over the western Pacific has been proposed to have shifted southwards during this interval, which would lead to relatively dry Little Ice Age conditions in the northern extent of the intertropical convergence zone and wet conditions around its southern limit. However, here we present a synthesis of palaeo-hydrology records from the Asian–Australian monsoon area that documents a rainfall distribution that distinctly violates the expected pattern. Our synthesis instead documents a synchronous retreat of the East Asian Summer Monsoon and the Australian Summer Monsoon into the tropics during the Little Ice Age, a pattern supported by the results of our climate model simulation of tropical precipitation over the past millennium. We suggest that this pattern over the western Pacific is best explained by a contraction in the latitudinal range over which the intertropical convergence zone seasonally migrates during the Little Ice Age. We therefore propose that rather than a strict north–south migration, the intertropical convergence zone in this region may instead expand and contract over decadal to centennial timescales in response to external forcing.
45. 2015: Fischer, A., et al. “Tracing glacier changes in Austria from the Little Ice Age to the present using a lidar-based high-resolution glacier inventory in Austria.” The Cryosphere 9.2 (2015): 753-766. Glacier inventories provide the basis for further studies on mass balance and volume change, relevant for local hydrological issues as well as for global calculation of sea level rise. In this study, a new Austrian glacier inventory has been compiled, updating data from 1969 (GI 1) and 1998 (GI 2) based on high-resolution lidar digital elevation models (DEMs) and orthophotos dating from 2004 to 2012 (GI 3). To expand the time series of digital glacier inventories in the past, the glacier outlines of the Little Ice Age maximum state (LIA) have been digitalized based on the lidar DEM and orthophotos. The resulting glacier area for GI 3 of 415.11 ± 11.18 km² is 44% of the LIA area. The annual relative area losses are 0.3% yr⁻¹ for the ~119-year period GI LIA to GI 1 with one period with major glacier advances in the 1920s. From GI 1 to GI 2 (29 years, one advance period of variable length in the 1980s) glacier area decreased by 0.6% yr⁻¹ and from GI 2 to GI 3 (10 years, no advance period) by 1.2% yr⁻¹. Regional variability of the annual relative area loss is highest in the latest period, ranging from 0.3 to 6.19% yr⁻¹. The mean glacier size decreased from 0.69 km² (GI 1) to 0.46 km² (GI 3), with 47% of the glaciers being smaller than 0.1 km² in GI 3 (22%).
46. 2015: Atwood, A., et al. “Possible Mechanisms of a Southward Shift in Tropical Precipitation During the Little Ice Age.” AGU Fall Meeting Abstracts. 2015. A number of tropical hydroclimate reconstructions provide evidence for substantial changes in tropical rainfall patterns over the last millennium. One of the hypothesized features of the climate during the Little Ice Age (LIA; ca. 1300-1800 CE) is a more southerly position of the Intertropical Convergence Zone (ITCZ). We evaluate the evidence for, and mechanisms of, a southward shift of tropical precipitation during the LIA, utilizing the last millennium simulations in the Coupled Model Intercomparison Project Phase 5/Paleoclimate Intercomparison Project Phase 3 archive. Six out of the seven model simulations analyzed demonstrate a southward shift in tropical precipitation during the LIA in (as determined by a decrease in tropical precipitation asymmetry between the Northern Hemisphere and Southern Hemisphere). While a southward shift of tropical precipitation during the LIA appears to be a robust feature across model simulations, the change is small and is manifested in the different model simulations in largely disparate ways. However, some common features emerge. We compare the simulated precipitation changes to proxy records and discuss to what extent the precipitation changes appear to be driven by thermodynamic scaling principles (i.e. a wet-get-drier, dry-get-wetter scenario associated with global cooling) and to what extent they appear to be tied to circulation changes in the atmosphere (e.g. a southward shift of the Intertropical Convergence Zone).
47. 2016: Felis, T., et al. “Extreme aridity and mild temperatures in the Middle East during the late Little Ice Age indicated by paired coral Sr/Ca and delta18O from the northern Red Sea.” AGU Fall Meeting Abstracts. 2016. Throughout the global deserts, annually resolved reconstructions of temperature that extend the short instrumental record are virtually absent, and proxy records of aridity are difficult to obtain. The Little Ice Age ( 1450-1850) is thought to have been characterized by generally cold conditions in many regions of the globe with little commonality regarding the hydroclimate. However, due to a lack of annually resolved natural archives in the Sahara and Arabian Desert, the precise characteristics of Middle Eastern climate during the Little Ice Age are unknown. Here we show, based on subseasonally resolved proxy records using corals from the northern Red Sea that the Middle East did not experience pronounced cooling during the late Little Ice Age (1751-1850). Instead, it was characterised by an even more arid climate than today. From our coral records and early instrumental data we conclude that Middle Eastern aridity resulted from a blocking-like atmospheric circulation over central Europe that weakened the moist Mediterranean westerlies and favoured the advection of dry continental air from Eurasia. We find that this extreme aridity terminated abruptly between 1850 and 1855 due to an atmospheric circulation change over the European-Middle East area at the end of the Little Ice Age with profound impacts on regional hydroclimate. Our results provide a hydroclimatic perspective on the resettlement of abandoned areas of the historical Fertile Crescent following the Little Ice Age. Furthermore, we speculate such an atmospheric blocking could have prevailed during other North Atlantic-European cold events of the Holocene epoch, and may explain the northern Mesopotamian aridification at 4,200 years ago that is thought to have led to the collapse of ancient civilizations.
48. 2016: Büntgen, Ulf, et al. “Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 AD.” Nature Geoscience 9.3 (2016): 231-236. Climatic changes during the first half of the Common Era have been suggested to play a role in societal reorganizations in Europe^1,2 and Asia^3,4. In particular, the sixth century coincides with rising and falling civilizations^1,2,3,4,5,6, pandemics^7,8, human migration and political turmoil^{8,9,10,11,12,13}. Our understanding of the magnitude and spatial extent as well as the possible causes and concurrences of climate change during this period is, however, still limited. Here we use tree-ring chronologies from the Russian Altai and European Alps to reconstruct summer temperatures over the past two millennia. We find an unprecedented, long-lasting and spatially synchronized cooling following a cluster of large volcanic eruptions in 536, 540 and 547 AD(ref. 14), which was probably sustained by ocean and sea-ice feedbacks^15,16, as well as a solar minimum¹⁷. We thus identify the interval from 536 to about 660 AD as the Late Antique Little Ice Age. Spanning most of the Northern Hemisphere, we suggest that this cold phase be considered as an additional environmental factor contributing to the establishment of the Justinian plague^7,8, transformation of the eastern Roman Empire and collapse of the Sasanian Empire^1,2,5, movements out of the Asian steppe and Arabian Peninsula^8,11,12, spread of Slavic-speaking peoples^9,10 and political upheavals in China¹³.
49. 2018: Graeter, K. A., et al. “Ice Core Records of West Greenland Melt and Climate Forcing.” Geophysical Research Letters 45.7 (2018): 3164-3172. Remote sensing observations and climate models indicate that the Greenland Ice Sheet (GrIS) has been losing mass since the late 1990s, mostly due to enhanced surface melting from rising summer temperatures. However, in situ observational records of GrIS melt rates over recent decades are rare. Here we develop a record of frozen meltwater in the west GrIS percolation zone preserved in seven firn cores. Quantifying ice layer distribution as a melt feature percentage (MFP), we find significant increases in MFP in the southernmost five cores over the past 50 years to unprecedented modern levels (since 1550 CE). Annual to decadal changes in summer temperatures and MFP are closely tied to changes in Greenland summer blocking activity and North Atlantic sea surface temperatures since 1870. However, summer warming of ~1.2°C since 1870–1900, in addition to warming attributable to recent sea surface temperature and blocking variability, is a critical driver of high modern MFP levels.
50. 2018: Slawinska, Joanna, and Alan Robock. “Impact of volcanic eruptions on decadal to centennial fluctuations of Arctic sea ice extent during the last millennium and on initiation of the Little Ice Age.” Journal of Climate 31.6 (2018): 2145-2167. This study evaluates different hypotheses of the origin of the Little Ice Age, focusing on the long-term response of Arctic sea ice and oceanic circulation to solar and volcanic perturbations. The authors analyze the Last Millennium Ensemble of climate model simulations carried out with the Community Earth System Model at the National Center for Atmospheric Research. The authors examine the duration and strength of volcanic perturbations, and the effects of initial and boundary conditions, such as the phase of the Atlantic multidecadal oscillation. They evaluate the impacts of these factors on decadal-to-multicentennial perturbations of the cryospheric, oceanic, and atmospheric components of the climate system. The authors show that, at least in the Last Millennium Ensemble, volcanic eruptions are followed by a decadal-scale positive response of the Atlantic multidecadal overturning circulation, followed by a centennial-scale enhancement of the Northern Hemispheric sea ice extent. It is hypothesized that a few mechanisms, not just one, may have to play a role in consistently explaining such a simulated climate response at both decadal and centennial time scales. The authors argue that large volcanic forcing is necessary to explain the origin and duration of Little Ice Age–like perturbations in the Last Millennium Ensemble. Other forcings might play a role as well. In particular, prolonged fluctuations in solar irradiance associated with solar minima potentially amplify the enhancement of the magnitude of volcanically triggered anomalies of Arctic sea ice extent.
51. 2018: Magnan, Gabriel, et al. “Impact of the Little Ice Age cooling and 20th century climate change on peatland vegetation dynamics in central and northern Alberta using a multi-proxy approach and high-resolution peat chronologies.” Quaternary Science Reviews 185 (2018): 230-243. Northern boreal peatlands are major terrestrial sinks of organic carbon and these ecosystems, which are highly sensitive to human activities and climate change, act as sensitive archives of past environmental change at various timescales. This study aims at understanding how the climate changes of the last 1000 years have affected peatland vegetation dynamics in the boreal region of Alberta in western Canada. Peat cores were collected from five bogs in the Fort McMurray region (56–57° N), at the southern limit of sporadic permafrost, and two in central Alberta (53° N and 55° N) outside the present-day limit of permafrost peatlands. The past changes in vegetation communities were reconstructed using detailed plant macrofossil analyses combined with high-resolution peat chronologies (¹⁴C, atmospheric bomb-pulse ¹⁴C, ²¹⁰Pb and cryptotephras). Peat humification proxies (C/N, H/C, bulk density) and records of pH and ash content were also used to improve the interpretation of climate-related vegetation changes. Our study shows important changes in peatland vegetation and physical and chemical peat properties during the Little Ice Age(LIA) cooling period mainly from around 1700 CE and the subsequent climate warming of the 20th century. In some bogs, the plant macrofossils have recorded periods of permafrost aggradation during the LIA with drier surface conditions, increased peat humification and high abundance of ericaceous shrubs and black spruce (Picea mariana). The subsequent permafrost thaw was characterized by a short-term shift towards wetter conditions (Sphagnum sect. Cuspidata) and a decline in Picea mariana. Finally, a shift to a dominance of Sphagnum sect. Acutifolia (mainly Sphagnum fuscum) occurred in all the bogs during the second half of the 20th century, indicating the establishment of dry ombrotrophic conditions under the recent warmer and drier climate conditions.