Alas, the post-1622 Great Sea Toll records for Stockholm, recording the dates of first arrival and last departure for each shipping season, were requisitioned by the Swedish Army as-brace yourself-wadding for artillery. Nonetheless, useful records relative to the shipping industry have survived, and the climate observations from these records have been scaled and calibrated with overlapping instrumental data to reconstruct winter temperatures for Stockholm. These reveal that 1614-23 (-2.43oC) and 1624-33 (-2.20oC) were the second and fourth coldest decades since 1500. (The dangers of relying too much on the generic Little Ice Age label are shown by the fact that one of the five warmest decades, 1734-43, is within the conventional LIA.) The decade of 1634-43 was a bit warmer than 1624-33.
I have found reports of crop failures in Norway in 1632 and 1634 (GroveLIAAM, 67). These are probably attributable to the proximity of glaciers. The 1742 report of the court of inquiry on Elekrok stated "it was apparent to us that it was the nearness of the glacier which is the cause of crop failure on this farm . . . the ears on the side towards the glacier . . . were quite brown, and the other side green. . . ." (71).
The Netherlands. In East Friesland, on Sept. 1, 1637, there were great floods (Marusek 116). (The specific date won't be repeated in the new time line, but there may still be a propensity to flooding that autumn.)
For wheat prices, the first LIA climb came later than for England, possibly in the 1640s. Otherwise, the fluctuations were similar to those for England but smaller.
Germany. The walls of historic buildings at Tonning on the west coast of Schleswig-Holstein reveal that the flood of Oct. 11, 1634 reached a height of four feet above the ground surface. (LambCHMW 17). On Norstrand Island, 6,123 people drowned, and 50,000 livestock were lost (Rabeljee). This flood is mentioned in Grantville literature, but the up-timers didn't think to warn King Christian about it because they assumed it would be "butterflied away." Instead, it came ahead of schedule. See Boyes, "A Great Drowning of Men," Grantville Gazette 28.
The price of rye in Germany over four centuries has been analyzed. Peaks corresponded to a poor harvest-this could be because of climate, or because of warfare. Considering just 1590-1650, there were small peaks in 1590 and 1610, moderate ones in 1626, 1634 and 1649, and a large one in 1622. However, the worst one of all was that of 1816 (the "year without a summer") (Mandia, Fig. 17). Other than in 1634, the 1630s appear to have offered cheap rye-albeit not as cheap as in the "good years" of the 16th century. The high prices in 1634 were probably attributable to plague (Pfister2007, Fig. 8).
France. On October 6, 1632, southern France was so cold that sixteen of Louis XIII's bodyguards died from exposure (Marusek 115). The winter of 1638 was also severe; in Marseilles, the "water froze around the ships."(116).
Wine grapes will reach maturity more quickly if the growing season (April-September) is warm, than if it is cool. Based on the extensive wine harvest data, the summers of 1634-39 were warmer than the 1599-1791 mean (Ladurier; Chuine).
French wheat prices followed a pattern similar to that of British, but the fluctuations were more moderate (Flohn 44).
Switzerland. Based on historical documentary evidence, Pfister constructed crude thermal (warm months-cold months) and wetness (wet months-dry months) indexes for Switzerland. The 1630s appear to be a little on the warm side, and markedly on the dry side. The 1640s were colder, although nowhere near as cold as the 1670s, 1690s, or 1810s, and not as dry (LambCHMW 204).
In the Alps, we have the very visible evidence of the advance and retreat of the glaciers. Unfortunately, in the 17th century, we do not have good maps of their positions, and hence we have to rely on diaries and legal documents. In 1600-19, there are repeated descriptions of the destruction of houses, the failure of crops and the decline in tithes as a result of glacial advance (Ladurie 143ff).
It appears that the glaciers were more quiescent in the 1620s and 1630s, but they remained dangerous. A third of the cultivable land at Chaimonix was destroyed in 1628-30, and the Mattmarksee (influenced by the Allalin glacier) flooded in 1620, 1626, 1629, and 1633 (Aug. 21). In 1636, the people in the valley of Randa thought that the whole Zermatt glacier was coming down on top of them; forty people were killed by ejecta. In the 1640s, there were new glacial advances. In May, 1642, the Les Bois glacier was reportedly moving by "over a musket shot every day." Such ominous developments led to the famous June 1644 procession, led by the local bishop, to seek divine intervention to hold the glacier at bay (Ladurie, 165-173).
Wine harvest dates for fifteen locations in the Swiss Plateau and northwestern Switzerland have been used to reconstruct April-August temperatures. Harvest on year-day 285 indicated temperatures identical to those of the base period 1961-90; earlier harvests implying warmer temperatures. In 1632-33, temperatures were a little below base, whereas in 1634-39 they were higher, peaking at 1.78oC higher in 1638. The temperature anomalies in 1640-43 were negative (Meier).
Northern Italy. The second quarter of the seventeenth century was not marked, as was the first one, by any "great" winters (enough for large bodies of water to have ice thick enough to support people) or even "severe" winters (causing the death of animals and plants) (Alfani Graph 1.3). The flooding of tributaries (Tanaro and Bormida) of the Po was perhaps half as common as in the preceding quarter-century, but nonetheless more common than in the next one.
In 1629, a landslide, triggered by heavy rain, caused loss of life and property in the hamlet of Onera. In 1629-30, a plague epidemic killed about 27% of the population of Northern Italy, but the extent to which climatic factors contributed to its occurrence remains in dispute (Alfani). In 1632, there were complaints about both heat and drought (Marusek 115). In the lower Po valley, cereal yields were "seriously reduced in the period 1590-1630, especially." That was, of course, attributable to the flooding (Grove 129).
The Italian price of wheat in the LIA reached a peak just after 1600, then descended to a broad low in the 18th century, then climbed more moderately to twin peaks in the 19th (Flohn 44).
Spain. The period 1575-1650 was "generally wet," at least in the southeast. 1617 and 1626 were "deluge" years, and "catastrophic floods were unusually frequent between 1571 and 1630, especially in Catalonia." (Grove 129). There was major flood activity in 1630-1650, too (Llasat Fig. 5).
The Black Art of Reconstructing Past Climates
Crude thermometers appeared in the 17th century, and our oldest continuously monthly temperature records date back to 1659 (for central England). For that region, the coldest winter was in 1684, the coldest summer in 1725, and the coldest year overall was 1704 (Manley). Other early records are those for Berlin from 1697, for Hoofddorp and Zwanenberg/De Bilt in the Netherlands from 1706 and 1735, respectively, for Uppsala (Sweden) from 1739, and for St. Petersburg from 1726 (Flohn).
Clearly, this direct data doesn't tell us anything about what the temperatures were in 1631-39. However, it does help in calibrating "proxy" data.
A "proxy" is any observable variable of the fossil record (this term used in a broad sense) that can be reliably correlated with direct temperatures for part of the range of the record, so that the historical temperatures can be reconstructed for the rest of that range.
For our purposes, it isn't sufficient that the proxy be highly correlated with the actual temperature, it also must be "high resolution." For example, if we couldn't determine the age of a proxy value more accurately than the nearest decade, or if the proxy value reflected the temperatures over the preceding decade, then the resolution it offers is just decadal. We want resolution down to the annual level.
Here are some of the sources of high-resolution proxy data:
Ice Cores-the upper portion of an ice core exhibits a layered structure with annual variation; the light bands are formed by freshly fallen, clean summer snow and the dark bands are formed by old, dust-contaminated winter snow. The thickness of the light band is indicative of how much snowfall there was. Air bubbles in the ice preserve "fossil" air, in wh
ich the level of greenhouse gases can be measured. Also, oxygen isotope ratios are influenced by ocean temperatures. Obviously, ice cores are only available from a few parts of the world; notably Greenland, Antartica, and a few glaciers.
Tree Rings-the light colored layer grows in the spring and the dark colored one in late summer. Narrow rings are indicative of poor growth conditions, such as drought or severe winter. Tree ring data is available only where trees grow.
Corals-we can see annual variations in skeletal density and geochemical parameters. The light layers are from the summer and the dark layers from the winter. Oxygen isotope ratios are indicative of ocean temperatures. The most useful corals grow in shallow tropical waters.
Lake Sediments-these may exhibit seasonable variations (varving) in runoff sediment composition, which in turn are the result of summer temperature, rainfall, and winter snowfall.
Boreholes-the variation of temperature with depth has a detectable relationship to the history of temperature at the surface.
Speleotherms-these are stalactites, stalagmites and flowstones. Some provide annual resolution, as a result of visually detectable lamination, or a seasonal variation in trace elements. Layer thickness is related to surface rainfall and cave air temperature.
Historical accounts-these are most useful if they provide some kind of quantitative information.
There are technical problems with working with proxy data, but consideration of those problems is outside the scope of this article.
Climate Reconstructions: The North Atlantic Oscillation
In the mid-latitudes of the North Atlantic, the prevailing winds are from the west. These were convenient for mariners returning from the New World. However, those winds are also important because they bring moist air to Europe.
The direction and strength of the prevailing winds are controlled by the position and strength of a persistent low-pressure system over Iceland (the Icelandic Low), and a persistent high-pressure system over the Azores (the Azore High).
The atmosphere alternates between a state in which the pressure difference widens (positive phase, NAO+) and one in which it narrows (negative phase, NAO-). There are a number of ways the NAO may be quantified, but the simplest is as the normalized difference in pressure between a station in the Azores (or in Portugal) and one in Iceland. There is no significant periodicity in the switching between NAO+ and NAO-.
In NAO+, the westerlies are stronger, and more and stronger winter storms cross the north Atlantic, on a more northerly track. Temperatures are above average in the eastern United States and in northern Europe, and below average in northern Canada and Greenland and often in southern Europe, northern Africa and the Middle East. There is also above average precipitation in northern Europe, and below average in southern Europe. In NAO-, the effects are reversed.
The effects are strongest in winter. (NWS-CPC).
The North Atlantic Oscillation index has been reconstructed, on a seasonal basis, for 1500-1658 and monthly for 1659-2001 (LuterbacherNAO). Table 2-1shows its behavior for 1630-39. It can be seen that it was mostly in negative phase in that decade.
Climate Reconstructions: European Annual Average Temperatures
Looking first at reconstructed mean annual temperatures for Europe generally, Table 2-2A shows how the 1630s (with the years 1999-2000 for comparison) shape up.
LuterbacherTemp).
If we consider just the temperature column, it's clear why the up-timers feel a chill in the air. However, the coldness ranks (30-362) provide some perspective. And it's worth comparing those temperature to the averages (Table 2-2B) for each century, for the Maunder Minimum (1645-1715), the whole LIA (1500-1850), and the modern period (1851-2004).
We can see that only three years were below the average (8.2oC) for the LIA. The worst year of all (1635) was the 30th coldest year for the period studied (1500-2004). It was not the coldest year in living memory; that was probably 1573 (7.0oC, 2nd coldest), and down-timers will also remember 1587 (14th), 1595 (10th), 1600 (5th), 1601 (8th), 1608 (6th), and perhaps also 1565 (13th) and 1569 (9th).
So, yes, we are in the LIA-but not in the worst decade, by any means.
Climate Reconstructions: European Seasonal Average Temperatures
There are several references to the severity of winter in 1632 universe canon. Watching TV in 1633, Joyce and Gary find that "the news was about broken armies, new business, and, of course, the weather and what the little ice age meant to their future." (Huff and Goodlett, "Wish Book" Grantville Gazette 12). In January 1634, Eric Krentz tells Thorsten Engler, "I always hated January even before an up-timer told me we're in the middle of what they call 'the Little Ice Age.' " (Flint, 1634: The Baltic War, Chapter 14). Later, in late March 1634, Admiral Simpson is "a bit surprised that the river [Elbe] hadn't frozen, although intellectually he'd understood that the past winter hadn't really been as cold as it had sometimes felt, Little Ice Age or not." (Chapter 31). In Flint and DeMarce, 1635: The Dreeson Incident, we are told that "Winter in Thuringia during the Little Ice Age encouraged the layered look." (Chap. 41).
So, how did LIA winters (and other seasons), compare to those the up-timers would have been acclimated to, and just how bad were the 1630s as compared to other parts of the LIA?
We define the seasons as DJF (winter, December-January-February, and I assume that winter for 1630 starts with Dec. 1629), MAM (spring), JJA (summer) and SON (fall). Table 2-3provides the reconstructions for each of 1630-1639, the actual values for 1999 and 2000, and averages of values for the decade 1630-39, the 30-year period 1620-1649, 1645-1715 (the Maunder sunspot minimum), 1500-1850 (LIA) and 1851-2004 (Post-LIA). The coldest (bold blue) and warmest (italic red) winter, spring, summer, fall and entire year are marked.
I have calculated, but not shown, the seasonal coldness ranks. Looking first at winter (DJF), 1635 was the 32nd coldest in the study period. The next worst was 1637, ranking 129th. The mildest winter of the decade was that of 1633, ranking 408th. The LIA mean was -1.125C, so five years were better and five were worse, and the mean for our decade was a bit milder.
The springs (MAM) ranged in rank from 62nd to 459th coldest, the summers (JJA) from 92nd to 424th, and the falls (SON) from 60th to 372nd. For all three seasons, the mean for our decade was higher than the mean for the LIA.
Surprisingly, the mean for summer 1630-1639 was even higher than the mean for the post-LIA (1851-2004) period, although of course still cooler than the summers of 1999 and 2000.
We are lucky to have missed 1628, which was the thirteenth coldest summer (16.8oC) of 1500-2004.
Climate Reconstructions: Central European Monthly Average Temperatures
Monthly temperatures have been reconstructed for central Europe in 1630s, based on documentary evidence (mostly from sites in the present Germany, Czech Republic, and Switzerland). Unfortunately, these are available just as anomalies, that is, the difference between the actual temperature and the average(s) for the base period 1961-1990 (Dobrovolny). I emailed Dr. Dobrovolny, asking him for the base temperatures, but he didn't reply. So I used the KNMI Climate Explorer to download the CPC GHCN/CAMS t2m analysis (land) data, gridded at 0.5° intervals, and calculated the 1961-1990 base for central Europe myself. I assumed that Dobrovolny defined central Europe the same as his coworkers did in LuterbacherSLP.
In Table 2-4, I show first my derived monthly temperatures for each year of 1630-39, and the average and standard deviation for the decade. Next, I provide my 1961-99 base numbers. There're no guarantees that Dobrovolny had exactly the same base averages; his region and his modern data could have differed from mine. But since I stated the bases I used, you can reconstruct Dobrovolny's anomalies by subtracting them out. Finally, I present the mean and standard deviation for the period 1766-1850, from Luterbacher's monthly gridded reconstructions.
Please note that with the exception of 1630 and the first four months of 1631, this monthly data is subject to perturbation by the RoF. Since it's time-averaged data, the impact w
on't be as severe as for daily weather, but there will be some effect.
Climate Reconstructions: Mapping Post-RoF European Seasonal Average Temperatures
Of course, pan-European averages are all well and good, but different parts of Europe would no doubt fare differently. Fortunately, Luterbacher's climate reconstruction provides reconstructed seasonal temperature for each point on a 0.5 degree by 0.5 degree grid, over the range 25W-40E longitude; and 35N-70N latitude.
It's said that a picture is worth a thousand words, and I have created some revealing images from Luterbacher's gridded temperature data. Using Climate Explorer, I have compared the decade 1630-39 with 1990-99. The figures compare the decades for (Fig. 1A) the entire year, (1B) winter, (1C) spring, (1D) summer and (1E) autumn.
And using the National Climatic Data Center's visualization tool, I have created comparisons of the coldest and warmest winters (2A), springs (2B), summers (2C) and autumns (2D) of the 1630s. Note that each season has a different temperature scale:
Winter (DJF): coldest 1635, warmest 1632, scale -20 to +10C;
Spring (MAM): coldest 1635, warmest 1636, scale -5 to +25C;
Summer (JJA): coldest 1630, warmest 1637, scale +5 to +35C;
Fall (SON): coldest 1635, warmest 1630, scale -5 to +25C.
Which parts of Europe are unusually hot and which are unusually cold is very strongly influenced by the position, areal extent and persistence of the high and low pressure areas (see North Atlantic Oscillation) and the position and strength of the jet stream. Stagnant (blocking) patterns lead to persistent weather conditions that influence monthly and even seasonal averages. On the west side of a stationary NH high, warm air is pushed north, and on the east side, cold air is dragged south. So you may be warmed or cooled depending on where you stand. Moreover, a slight shift in the location of the blocking pattern from one year to the next might mean that you face extreme cold in the first year and extreme heat in the second (LambWCHA 110).
Grantville Gazette 37 gg-37 Page 23
