Little Ice Age – Big Chill, The History Channel Part I GEO165 – Study Sheet The Little Ice Age: Began 7 centuries ago Millions perished It was an abrupt cooling
Little Ice Age – Big Chill, The History Channel Part I GEO165 – Study Sheet The Little Ice Age: Began 7 centuries ago Millions perished It was an abrupt cooling Summer of 1653 priests use holy water to stop advancing glacier _____________________________________________ DE-BUNKING A POPULAR MYTH: HOW GLACIER GROWTH AND RETREAT WORKS
What happens to a glacier depends on two factors: 1. Temperature and 2. The amount of snowfall. A warmer atmosphere often results in greater frozen precipitation during winter and result in the GROWTH of glaciers. Even if the weather warms the snowline, where melt = accumulation can be found at lower and thus warmer altitudes if the balance between accumulation and snow melt is tilted towards accumulation.
Tropical glaciers in Africa have decreased in area by 60 to 70% on average since the early 1900s. The vast majority of all Himalayan glaciers have been retreating and thinning over the past thirty years, with accelerated losses over the last decade. Countries such as India rely on glacial melt water for much of their fresh water supplies. If glacial melt waters dry up, such countries will have to rely on just the monsoon rains - a very unreliable source of water. Arctic glaciers have all been receding (retreating), apart from in Scandinavia and Iceland where more precipitation has resulted in glacier growth. Large sections of the Greenland ice sheet (12% of the world's ice)appear to be sliding towards the sea.
If all the land ice melted, worldwide sea levels would rise by approximately 70 meters that's partly why scientists are so worried about global warming. _____________________________________________
During the last, great ice age – the Pleistocene 30% of earth was under ice Even a modest change in climate can cause big disruptions Little ice ageWas 2o-3o cooler (annual average, a big temp change) than today
New York harbor froze Inuit (Eskimos) sailed as far south Scotland 1816 - Year without a summer, or “1800 and Froze to Death” Grain prices in Europe rose – “let them eat cake” – contributed to The French Revolution Stradivarius violin – maybe a product of the Little Ice Age? What caused The Little Ice Age is a mystery? - a recurring cycle? - a blue print of our future? Weather instruments - data goes back only 200 yrs Scientists use proxy data - EXTRA INFO HERE -sediment cores (sea and lake cores called varves) -sea floor sediments - microscopic creatures that tell about climate - ratio of cold lovers to warm lovers is related to temperatute -lake sediments – annual layers use – pollen analysis, coleoptera beetles -ice cores – dust, atmospheric gasses from bubbles and oxygen isotope ratios extracted and thickness of ice layer measured. -tree rings – width is related to how ideal climate is for a tree species. At the mountain tree line or the northern and southern high latitudes mostly related to temperature -phenological data – dates of wine grape harvests, quantity of wine produced
-other sources – illustrations of glaciers, diaries, chronicles
Retreat of the Rhone Glacier Top: drawing 1750 Bottom: photo 1950 Human populations are alarmingly vulnerable to small drops in temp 1300 – Feudalism – the Little Ice Age begins before that it is a warm world called “The Medieval Climatic Optimum” of the “Little Climatic Optimum”. Medieval warm period was 4o-7o C warmer than now, with the Little Ice Age being 2o-3o cooler than today that means there was a 6o – 10o cooling 40Million to 60Million peasants inhabited Europe; their numbers grew dramatically during the warm period. The warm period -wine making in England 300 miles north of present limit -Building spree – Pisa gothic, cathedrals -average life span 35 years and even in the favorable climate Infant mortality was high - 50% dead before 1 year of age
Around 1300 cooling began abruptly The Little Ice Age exposed all society’s vulnerabilities
Vulnerability to disease 1347 bubonic plague – Black Death million died 1351 plague fades 51 million dead 1/3 of population Witch trials in Europe Pope Innocent VIII 1484 – decreed - cold climate caused by witches Vikings 4000 Viking colonists in Greenland Little Ice Age ended their daring explorations 1000AD – Vikings arrive in Greenland grass for livestock cod for fishing imported goods export walrus tusks polar bear skins during severe winters livestock stayed indoors and weakened many livestock perished switched food dependence from lamb to sea creatures known from isotopic studies waters became ice-choked, cut them off from the outside word -vikings starved sea ice cut them off Vikings themselves were part of the problem Inuit knew how to survive Inuit could fish all year long with ivory harpoons
Vikings did not adopt Inuit ways probably had little respect for those who they called “ugly little people” – kalia.
1408 Wedding - last recorded event with visitors from as far away as Iceland
are trying to solve the mystery of the Little Ice Age
Debate - What natural processes are involved? There is no clear consensus 1. Solar output may have been reduced by ½% Lesson - earth is sensitive to very small nudges 2. Volcanoes Ice cores go back 115k years – they contain sulfur deposits from 5 major volcanic eruptions each century of the Little Ice Age. Large volcanoes ejected gasses and particulates high into the atmosphere. Sulfur gasses + H2O make an H2SO4 cloud (sulfuric acid) that efficiently reflects sunlight 3. Ocean water Cold deep water circulation – called the thermohaline circulation – Cold dense water is formed in polar latitudes when the water is chilled and freezes leaving behind dense salty water that sinks. The Global Oceanic Conveyor Belt is the name of the circulation and it transports great amounts of heat pole ward and cold dense water equator ward. If global warming melts enough Arctic sea ice (and that is happening) there will be much less dense salty water, he circulation will slow and ironically global warming could cause a new ice age.
THE GLOBAL OCEANIC CONVEYOR SYSTEM
If the global circulation is disrupted by the flow of fresh water into northern oceans the mechanism for global warming could lead to cooling.
4. Maunder Minimum 1645 A.D. to 1715 A.D. almost a complete lack of sunspots. Sunspots are related to solar output being fewer in number when solar output is less. The coldest 7 decades of the Little Ice Age, 1645 – 1715, were 3oC cooler than the average for the Little Ice Age 1600’s cereal crops destroyed by cold, wet weather led to -> famine developed turnips and clover (for livestock) and other cold resistant crops along with cereal crops pastoral + cereal agriculture reduced reliance on cereal grains agriculture France did not adopt the new system – French Revolution
The potato became popular called the “devil’s plant” It was a sin to eat one potatoes protected from burning by invaders and cold by being buried in the ground, also they were more cold tolerant. France did not adopt potatoes French peasants rejected it
starvation was widespread
1789 - severe frosts and bitterly cold temps - cereal crops devastated 2 years in a row July 1789 - peasant riots eventually became the French Revolution Ireland - 1845 For 200 years potatoes stopped starvation But the Irish went from growing several varieties to one type, a watery and disease susceptible variety. The potato blight turned the tubers into inedible black goo 5 years of famine cholera and typhus killed many of the weakened populous 1851 crop recovered 1.5 million dead
Stradivarius Violin Was it a special varnish - no – nothing unique Did he use old wood from fallen buildings - no – tree ring dating shows the wood was growing during Stradivarius’ life Stradivarius and the Maunder Minimum Stradivarius born 1644 Maunder Minimum started 1645 Cold climate produced dense wood with great acoustics During the Maunder minimum – very slow growth, dense wood
Americans and beer/hard liquor From migration routes Northern Europeans lost grapes DURING The Little Ice Age – they then used grain for beer and distilled liquor instead of wine. They migrated with their customs to the U.S. – southern Europeans migrated later. War and the Little Ice Age Napoleon in Russia -30oF Spanish Armada sailed north around England to escape Two major storms killed thousands. Some froze to death in September Many washed over board
American Revolution Ice-choked Delaware River threatened
Year Without A Summer - 1816 Mount Tambora – injected much sulfur into atmosphere H2SO4 cloud (sulfuric acid) reflected much sunlight high in the atmosphere
Literature Mary Shelly writes Frankenstein on vacation Food Switzerland, France, England – food riots United States 1816 - Snow all summer in New England – “Eighteen Hundred and Froze to Death” Pushed nation west After the War of 1812 and the economic recession Then the Year Without A Summer What caused it? Volcanoes Oceanic Conveyor – Warming can lead to cooling Maunder Minimum/Solar output Will Climate Change destabilize the world in the future? With many more people, food supplies stressed
WILL FUTURE CLIMATE SHIFTS CAUSE GEOPOLITICAL INSTABILITY?