Fish have preferred water temperatures. During the LIA, cod and herring moved south, hurting the fisheries of Norway, Scotland and the Faeroe Islands, but benefiting the English (Mandia).
In 1630, the cheapest form of transportation was by water. However, except in far northern Europe, transport was dependent on
So that means that we need to ask when will geographically significant navigable rivers freeze and thaw, in which months will strategic harbors be closed by sea ice, and when will particular sea routes be endangered by icebergs.
Rainfall can also make a difference. In some parts of the world, rivers are navigable only for part of the year. Or in some years and not others.
Land transportation is also affected by climate. Snow can close a mountain pass, or simply make it slower to travel by road. Rainfall can turn dirt into mud, or make a ford impassable, or cause a flood that destroys a bridge.
On the other hand, the freezing of rivers (while not good for water travel) can make river crossings easier. In 1597-8, Matteo Ricci wrote that 'once winter sets in, all the rivers in northern China are frozen over so hard that navigation on them is impossible and a wagon may pass over them.' (Brooks 55).
Up-time transportation technology also has its vulnerabilities. Cold temperatures can reduce starter battery life, render fuel viscous, and cause engines to stutter. High temperatures make it easier for engines to overheat.
Climatic interference with transportation can make it more difficult to relieve a local famine by moving in food from elsewhere.
Prior to the RoF, messages traveled, at least over distances beyond line-of-sight, at pretty much the same speed as people and goods. On land, the fastest communications were those provided by a post horse system, and at sea, messages could be carried by a sailing ship built for speed and not burdened with a heavy cargo. The effect of climate on these channels of communication have already been discussed in the context of transportation.
The up-timers will be introducing radio and telegraph communications, and radio waves and electrical pulses travel at the speed of light. Of course, as a practical matter, it takes time for an operator to convert a message into transmissible form, and, at the receiving end, for another operator to convert it back again. If the message has to be relayed, then effective transmission times are increased. But it's still much faster than horse or ship.
Our climate is the result of the heating of the earth's land masses, oceans and atmosphere by solar radiation, coupled with the rotation of the earth about an axis tilted relative to its orbital plane.
The amount of solar variation emitted by the sun varies, and it turns out that there's a pretty good correlation between the number of sunspots and the solar output. All else being equal (and it rarely is), if solar output decreases, so will mean global temperature.
However, there is a more specific effect on radio communications. The solar radiation includes not only light photons, but also charged particles, and when those particles strike the earth's atmosphere, they ionize some of the air molecules. When solar output is high, the degree of atmospheric ionization is higher, and it is easier to bounce radio signals off the 'ionosphere' so that they can travel longer distances. The principle is explained in much more detail in Boatright, 'Radio in the 1632 Universe,'
Surface temperature doesn't have much of a direct effect on underground mining; the temperature underground is mostly a function of latitude. However, it can affect how easy it is to get miners and their goods to the mine, and to ship off the ore. A good case in point is that in the nineteenth century, cryolite could be mined in Greenland for only a small part of the year.
Rainfall is another matter. Drainage was a serious problem in both European and Japanese mines, and I imagine that in periods of heavy rainfall, the problem was exacerbated.
Industrial production presupposes the existence of healthy indoor temperatures. It is already a common practice to heat homes and shops during the winters in colder regions of the world. Factories in those climes will also need heating systems, and, if it gets colder, they will require more fuel (most likely wood or coal).
Summers in warmer regions are more of a problem, because the only form of cooling is ventilation. True air conditioning requires up-time technology. Fortunately, in those areas affected by the LIA, summer is not a major concern.
The effect of increased rainfall is a more subtle one; more rainfall will be associated with more humidity, which means more problems with decay (wood) and rust (iron). This may increase industrial demand, but it also means that the maintenance costs will be higher.
The conduct of war is also affected by climate, both indirectly and directly. If harvests are poor, it will be difficult to feed the troops and their work animals. If roads are muddy or snow-covered, troop movements will be slow. If the soldiers are not conditioned to the local climate, and properly dressed for it, there will be weather- associated deaths.
Climate begets weather, and one of the more piquant examples of the effect of weather on warfare was the January 23, 1795 capture of the Dutch fleet by the cavalry of the French Republic. It was trapped to the lee of Texel Island by ice.
The up-timers are coming from a West Virginia town. While Grantville is fictional, it is based on real-life Mannington, in north central West Virginia (Marion County). Climate data for Mannington goes back to 1948, but unfortunately it's spread over three different weather stations. For nearby Fairmont, there's continuous data from a single station.
Please note that interannual variability of even annual (let alone seasonal, monthly, or specific day of the year) temperatures is such that it is customary for weather services to calculate 'climatological normals' over a thirty-year period.
Table 1 shows the sort of climate that the up-timers of Grantville are accustomed to. From this we can estimate seasonal average temperatures as follows: winter (DJF), 31.7oF (-0.2oC); spring (MAM), 51.0 (10.6); summer (JJA), 70.5 (21.4); autumn (SON), 54.2 (12.3). The average of the daily minimums for January was 20.4oF.
(Climatography #81, #85)
Fairmont (ZIP code 26554) was in the 1990 USDA Plant Hardiness Zone 6A (average absolute annual minimum temperature in range -10 to -5oF, -20.6oC to -23.3oC), and in zone 6-7 of the 2006 Arbor Day Foundation update.
In this part of West Virginia, the first freezing temperatures (end of the growing season) is typically in the first half of October, and the last freezing temperature (preceding spring planting) in the first half of May. http://www.accuracyproject.org/w-FreezeFrost.html
In 2002, Mann presented a figure comparing temperatures for the period 1000-2000 for eight different parts of the world. Mann considers the LIA to be 1400-1900, and my comments are based on the reconstructed annual means. I will call an LIA 'low' if the temperature was less than the lowest value for that region during 1000- 1400.
Northern Hemisphere: the lows are in the late-16th, late-17th, and late- 19th centuries, with highs in the early 17th and mid 18th centuries.
West North America: the deep lows are in the late-16th and mid-19th centuries, and a shallower but broader low appears in the 17th. The highs are in the early-15th, mid-16th and late-18th centuries.
