Little Ice Age By B Lukas History 141 # 71154 Instructor: Dr. M Arguello
What is Little Ice Age? Little Ice Age or LIA is a period of cooling that occurred after a time of warm climate in North Atlantic Region called the Medieval Warm Period or Medieval Climate Optimum. The term was introduced into scientific literature by François E. Matthes in 1939.
Timeline There is no agreed beginning year to the Little Ice Age, although there is a frequently referenced series of events preceding the known climatic minima. Starting in the 13th century, Park Ice began advancing southwards in the North Atlantic , as did glaciers in Greenland. The three years of torrential rains beginning in 1315 ushered in an era of unpredictable weather in Northern Europe which did not lift until the 19th century. here is anecdotal evidence of expanding glaciers almost worldwide. In contrast, a climate reconstruction based on glacial length shows no great variation from 1600 to 1850, though it shows strong retreat thereafter. NASA defines the term as a cold period between 1550 AD and 1850 AD and notes three particularly cold intervals: one beginning about 1650, another about 1770, and the last in 1850, each separated by intervals of slight warming.
Scientists have tentatively identified these possible causes of the Little Ice Age:
Orbital Forcing is the effect on climate of slow changes in the tilt of the Earth’s axis and shape of the orbit . These orbital changes change the total amount of sunlight reaching the Earth by up to 25% at mid-latitudes (from 400 to 500 Wm−2 at latitudes of 60 degrees). In this context, the term "forcing" signifies a physical process that affects the Earth's climate.
Solar Variation or Solar Activity is the change in the amount of radiation emitted by the Sun radiation and in its spectral distribution over years to millennia. These variations have periodic components, the main one being the approximately 11-year solar cycle (or sunspot cycle).
Volcanic activity ; When a volcano erupts, its ash reaches high into the atmosphere and can spread to cover the whole Earth. This ash cloud blocks out some of the incoming solar radiation, leading to worldwide cooling that can last up to two years after an eruption. Also emitted by eruptions is sulfur sulfur in the form of SO2 gas . When this gas reaches the stratosphere, it turns into sulfuric acid particles, which reflect the sun's rays, further reducing the amount of radiation reaching Earth's surface.
Ocean Conveyor slowdown is process of slowing of temperature and haline referring to salt content, factors which together determine the density of sea water or the term is thermohaline circulation (THC). The circulation could have been interrupted by the introduction of a large amount of fresh water to the North Atlantic, possibly caused by a period of warming before the Little Ice Age known as the Medieval Warm Period . There is some concern that shutdown of thermohaline circulation could happen again as a result of the present warming period.
Decreased human populations have influences on climate began earlier than is normally supposed and that major population declines in Eurasia and the Americas reduced this impact, leading to a cooling trend. William Ruddiman has proposed that somewhat reduced populations of Europe, East Asia, and the Middle East during and after the Black Death caused a decrease in agricultural activity. He suggests reforestation took place, allowing more carbon dioxide uptake from the atmosphere, which may have been a factor in the cooling noted during the Little Ice Age.
The Impact of Little Ice Age The colder weather impacted economics, agriculture, health, social unrest and even art and literature .
Impact on Economics
Increasing grain prices and lower wine production were some of examples of economic impact by the dramatic cooling of the climate. Due to famine, storms, and growth of glaciers ,many farmsteads were destroyed, which resulted in less tax revenues collected due to decreased value of the properties (Lamb, 1995.) Not all of the economic impact was bad. The fertile fishing grounds of the present day Newfoundland Banks were thought to have been found by fisherman in the late 1400's who were looking for the fish stocks that had deserted their former grounds as the result of the movement of colder waters from the north (Lamb, 1995.)
Lamb (1966) points out that the growing season changed by 15 to 20 percent between the warmest and coldest times of the millennium. That is enough to affect almost any type of food production, especially crops highly adapted to use the full-season warm climatic periods. During the coldest times of the LIA, England's growing season was shortened by one to two months compared to present day values. The availability of varieties of seed today that can withstand extreme cold or warmth, wetness or dryness, was not available in the past. Therefore, climate changes had a much greater impact on agricultural output in the past.
Prices of Wheat in Various Country VS Time (Source Lamb 1995)
Death & Famine killed millions people and poor nutrition decreased the stature of the Vikings in Greenland and Iceland. Malnutrition led to a weakened immunity to a variety of illnesses. In England, malnutrition aggravated an influenza epidemic of 1557-8 in which whole families died. In fact, during most of the 1550's deaths outnumbered births (Lamb, 1995.) The Black Death (Bubonic Plague) was hastened by malnutrition all over Europe. One might not expect a typically tropical disease such as malaria to be found during the LIA, but Reiter (2000) has shown that it was an important cause of illness and death in several parts of England. The English word for malaria was ague, a term that remained in common usage until the nineteenth century.
Dennis Avery Remind Us How Painful Cold The Little Ice Was Painting of The Sun went to sleep between 1645 and 1715 by Alamy
The winter of 1709-40 killed many people in France. After that there was no spring and only a damp, cool summer which spoiled the wheat harvest. The poor rebelled and the governor of Liège told the rich to "fire into the middle of them. That's the only way to disperse this riffraff, who want nothing but bread and loot." (Ladurie, 1971)
In England, the effect of starvation and the poor condition of the country encouraged men to enlist during the War of the Roses (1455-1485.) As tillable land was converted to other uses such as sheep rearing, the landlords who organized the conversions became the focus of many hostilities.
One group in particular suffered from the poor conditions - people thought to be witches (Behringer, 1999.) Weather-making was thought to be among the traditional abilities of witches and during the late fourteenth and fifteenth centuries many saw a great witch conspiracy. Extensive witch hunts took place during the most severe years of the LIA, as people looked for scapegoats to blame for their suffering.
In northern France in 1788, after an unusually bad winter, May, June, and July were excessively hot, which caused the grain to shrivel. On July 13, just at harvest time, a severe hailstorm (which typically occurs when there is very cold air aloft) destroyed what little crops were left. From that bad harvest of 1788 came the bread riots of 1789 which led to Marie Antoinette's alleged remark " Let them eat cake," and the storming of the Bastille.
Neuberger (1970) studied more than 12,000 paintings in 41 art museums in the United States and eight European countries to test his hypothesis that paintings would accurately reveal the climate record. These paintings covered the period from 1400 to 1967. He categorized the blueness of the sky into a three-step scale consisting of pale blue, medium blue, and deep blue. Cloudiness was estimated according to the U.S. airways code: clear (less than 10 percent coverage), scattered (10 to 50 percent), broken (60 to 90 percent), and overcast (more than 90 percent cloud coverage.) In addition, the types of clouds were observed according to four families: high, middle, low, and convective (vertically-developed) clouds. Neuberger separated his data into three epochs.
In 1816, "the year without a summer," many Europeans spent their summers around the fire. Mary Shelley was inspired to write Frankenstein, and Polidori, The Vampire. Both authors, together with Byron and Percy Shelley, were in Switzerland, near Lake Geneva where Byron said "We will each write a ghost story." Percy Shelley also referred to a glacier in his poem " Mont Blanc " when he wrote " …and wall impregnable of beaming ice. The race of man flies far in dread; his work and dwelling vanish…"