Precipitation is generally a more important issue for plant growth than temperature. Drought at any time of the year can affect plant yields. Even winter, precipitation is important as the old English proverb “Year of snow, crops will grow” implies. Food supply varies as the precipitation varies. Ironically, this can occur at both ends. Too much rain and snow or too little both limit plant growth and therefore animal survival.
You can summarize human history in one word – hunger. Most people were malnourished, famished, or starving to death and unfortunately too many continue in that state today. It is improving significantly because of refrigeration, containers, sips, and better transport systems so we can move large quantities of foodstuffs quickly. Market systems are also improving and increasingly global. Some decry this trend, claiming it creates dependencies and opportunity for exploitation. Most recognize and accept the health benefits and security of supply it provides.
History books tell us a major human advance was the shift from hunter/gathering society to sedentary agriculture. It makes little sense from a dietary perspective. Dietitians tell us the approximately 24 foodstuffs consumed by hunter/gatherers is the ideal diet. Sedentary agriculture reduced the variety to about 5 basic foodstuffs. More importantly, it put us more at the mercy of the weather. I think the logical explanation is growing a crop gave us better control and provided security of supply. Introduction of the potato in Europe is a good example. It was a crop everyone could grow and was relatively easily stored through the winter. Today an increasing variety of foodstuffs from sedentary agriculture is bringing us back to a hunter/gatherer range so we have the benefits of both systems.
Historically famines occurred as rains failed. They affected hunter/gatherer and sedentary agriculture alike, although the latter could withstand the deprivation better because of storage. Drought is a fairly regular cycle over decades as it is in the middle latitudes. Tropical droughts are more frequent as they are caused by the El Niño/La Niña ocean cycles, which cycle more frequently.
A good example of an annual cycle in a hunter/gatherer society is shown for the Ojibway people of northwest Ontario. The traditional pattern is superimposed with, but wasn’t changed by, the fur-trading pattern. It improved conditions by providing better traps and guns. It didn’t provide improved storage.Source: Suffling and Fritz
The Ecology of a Famine:
Northwestern Ontario 1815–17.
In “The year Without a Summer” Ed., C.R Harington.
Canadian Museum of Nature, 1992
Each circle shows the time of year when that food was available. Waterfowl was available in spring and fall. Big Game (Moose and Caribou), the mainstay of the diet, was hunted year round. Hunting was easier in heavy snow because it slowed the animals more than the people.
Snowshoe Hares were available from fall through to spring and though not the food of choice was a mainstay. When the Snowshoe hare diminished in numbers, the people starved. Wild rice was a good high-calorie food source and hedge against starvation because it was stored for the winter. However, high water in late summer usually destroyed the crop. It also caused a reduced fishing potential.
Incidences of starvation at Osnaburgh House measured by number of journal references and number of people recorded as starving.
Source: Suffling and Fritz
The pattern of increased frequency of starvation from 1800 to 1830 is coincident with two climate events.
The major one was a period of low sunspot numbers called the Dalton Minimum. Basically, high sunspot numbers mean warmer temperatures, whereas low numbers mean colder temperatures.
The second one was the eruption of the volcano Tambora in Indonesia in 1815. It pushed already low global temperatures even lower and caused very heavy rains in Ojibway territory.
Source: Soon and Yaskell
The water being so remarkably high at this place the Indians is not made any rice worth while so that I have only got 64 gal in all. So that I am much afraid of starving in the winter as there is no fish to be got here when the water is so high in the fall.
“The Maunder Minimum and the Variable Sun/Earth Connection” (2003)
By January of 1816 the journal notes, “The men are already feeling the iron hand of want.” Throughout the Dalton Minimum period moose and caribou were also in short supply because of the very heavy snowfalls.
Hunter/gatherers could sometimes move to other food sources, but widespread poor conditions reduced the options. It didn’t take long before hunger prevented movement. Cold was also a bigger problem when hungry. William Cook noted in the York factory journal for 1811, “…it is perfectly consistent with the nature of the country that it is being not at all uncommon for one set of Indians to be absolutely starving while another party at he distance of 40 miles are living in the utmost profusion – so local are the haunts of animals in this part of the globe and so uncertain the daily supply.” No wonder Samuel Hearne found that in spite of the apparent abundance of food on the Barren grounds, half the people were frequently in danger of starving to death.