De Blij Chapter 5A Notes

Página 1

Climate, Place, and Fate

there is no conclusive evidence that humans reached the Americas at the time of the Wisconsinan Glaciation, but in Eurasia (from Europe to China) it was a time of terrible environmental upheaval

Glaciers covered most of Europe during the Wisconsinan Glaciation

The glaciers that pushed into lower latitudes throughout the Northern Hemisphere during the Wisconsinan Glaciation grinded up rocks, blackened their base, and streaked their sides, while pushing a lot of rubble ahead of them

Lines of trees in today's Midwest landscape mark the morainal limits of the advance of those glacial "lobes"

In North America, the glacial ice went all the way to the Ohio River; in Europe, it crossed the Rhine; in the Rocky Mountains and European Alps, mountain glaciers coalesced to bury lower plains

The coniferous forests of the north shifted southward into Spain and Mexico

Equatorial rainforests in Africa, South America, and South Asia shrank and savannas started to form in their place

The Mediterranean and Caribbean became very cold from the Arctic coldness

18,000 years ago - warmth began to melt some of the glaciers on their margins

The people experiencing the increased warming trend thought it was just a temporary change, but the glaciers began to give way, dropping their pulverized load and exposing the ground below all over the landscape

the melted water from the glaciers formed rivers with lots of sediment - ex: the Mississippi Valley and Delta

Since the sea level was low due to glaciation, rivers, such as the Hudson, would carve deep canyons

Sea levels rose and the products of the Great Melt were drowned. This was evidence of physiographic turmoil around the world.

The Great Melt formed and widened the English Channel; filled the Baltic sea near the Scandinavian Peninsula; ice disappeared from Germany and Russia; glaciers of the Alps receded and the mountains' ice caps thinned

As the glaciers released their pulverized, powdered rock, powerful, storm-strength winds blew the stuff (called loess) into the air in choking clouds that made the Dust Bowl in the American Great Plains of the 1930s child's play by comparison

maps of loess deposits show association with the rivers fed by melting glacial ice: Huang, Danube, Mississippi-Ohio drainage

If humans really did not reach the Americas until 13,000 years ago, then they did not need to deal with this there, they did, however, have to deal with it in Europe and Asia.

The warming was so persistent that people began to migrate towards the poles

Warmer summers and milder winters opened opportunities for more secure livelihoods and larger communities

Página 2

One Final Surge

12,000 years ago, the ice had melted from southern regions in both North America and Europe; it was still in Canada, northern Europe, and northern Russia

because the ice sheets were lubricated, they started to slide downslope, coastward and into the ocean

One large ice sheet (about the size of a Canadian province) slid into the North Atlantic, causing disastrous waves along the coastlines from Europe to the Caribbean and chilling the ocean right back to glaciation-time-temperatures

This was called the Younger Dryas after a Tundra wildflower growing where the ice used to be

This disaster caused more than 1,000 years of cooling

The cooling was temporary and breif

10,000 years ago, temperatures were back on the global-warming track

the primary hypothesis - that a huge piece of northern ice sliding into the North Atlantic and caused the Younger Dryas - is being challenged today by scientists

The scientists postulate that some cosmic event, possibly a comet exploding close to the surface somewhere over the Northern Hemisphere, caused atmospheric conditions that resulted in this temporary cooling

a long term temperature trend can quickly be reversed an environmental incident

Página 3

Holocene Humanity

the post-Younger-Dryas warming period that has now lasted some 10,000 years is referred to by geologists as the Holocene Epoch

The only think the Holocene can be known as right now is another Pleistocene interglacial

The Holocene is a completely new cultural epoch

Hominins have been around for millions of years, modern humans, maybe 170,000, but nothing like the demographic or cultural explosion witnessed by the Holocene has ever happened before

Another name for the Holocene should be Anthropocene in recognition of the impact humans have had on the planet and its environment

Those who hypothesize that human pollution of the atmosphere is the sole cause of the recent average increase in planetary temperature point to humanity as the dominant environmental agent, further justification for the "Anthropocene"

One of the continuing points of scientific research (and debate) has to do with the Black Sea.

The Black Sea filled up very quickly about 8200 years ago.

The Black Sea is hypothesized to have filled up because of a mass of ice sliding off northernmost North America. This ice was smaller than the one that caused the Younger Dryas, but big enough to lower North Atlantic temperatures and raise sea levels. The raised sea levels caused water to pour through the Strait of Gibraltar into the Mediterranean Sea and then the Mediterranean overflowed into a lake that was then called the Black Sea.

Black Sea filled up at a rate of 15 cm each day.

The coastal villagers were forced to back away about 1.6 km (1 mile) daily.

When It was over, the surface of the Black Sea had Arisen 145 m and possibly caused the biblical legend of the great flood to be born.

There Is no doubt that something happened in the Black Sea Basin for which the locals were not prepared even though subsequent research casts doubt on this scenario.

Conditions stabilized enough following the postulated Black Sea crisis to allow climatologists to talk of a post-glacial Optimum, starting about 7,000 years ago and marking the time when global environmental conditions became rather like the ones we have now.

Post-glacial Optimum transmuted into another salubrious., the medieval Optimum

The medieval Optimum started around 2,000 years ago and it witnessed the expansion of settlements in Northern latitudes of Eurasia, the peopling of Iceland, and the colonization of Greenland.

About 3620 BP (before the present) island of Thira (Santorini), to the north of Crete in the Greek archipelago now known as the Cyclades, blew up in a Toba-like eruption that covered a wide area of the eastern Mediterranean with a thick layer of poisonous ash

Thira dealt Crete a fatal blow, opening the way to regional dominance of ancient Greece.

De-glaciation – the recession of ice and the opening of land to atmospheric conditions

De-glaciation continues long after the ice has disappeared

The Medieval Optimum certainly was a good time for two contemporaneous empires: the Romans (western Eurasia) and the Hans (eastern Eurasia)

the Roman Empire unified Europe and put a cultural stamp on it

The Empire of Han was China's formative Dynasty

The Han Capital was known as the Rome of China; Rome was known as the Ch’angan of the Mediterranean

The Silk Road transferred goods and tales of Splendor and power between East and West Eurasia

when it was warm the Romans planted grape vines in Britain and the left a thriving wine industry there

Europe's Medieval cities mushroomed as Architects endowed them with some of the civilizations Major Works: the Notre Dame Cathedral, the Cathedral at Chartres, the Cathedral at Canterbury, and others Gothic style architecture

superbly designed pagodas heralded the diffusion of Buddhism; Xian was the cultural capital and the largest city in the world

by the end of the Song Dynasty in 1279 oh, China had an estimated 100 million inhabitants

The Mongols invaded China to establish their Yuan Dynasty

in the west the mild and pleasant conditions prevailed for so long that they had become the new norm

The new norm in the west began to show signs of ending when winter's got colder and May frosts became a thing

Europe had the cold hit them before China did

Fall frosts led to local famines, persistent droughts hit some parts of Europe, destructive floods happened

Britain’s wine industry was erased

By the turn of the 14th century, alpine glaciers began to advance

nature seemed to be preparing for one of those climatic reversals so common during the Pleistocene

Página 4

The Little Ice Age

The little ice age was really just a minor glaciation

Happened In the 14th century

Caused increasing cold, decreasing rainfall, frigid winds, and shortened growing seasons - dwindling harvests, failing farms, and stormy seas that were bad for fishing

the little Ice Age cause famines to strike all over Europe

The Little Ice Age ended in the mid-nineteenth century and did not lead to a full-scale Pleistocene glaciation

the climatic record of this time was farmers' diaries, tree-ring research, ice cores, contemporary writings, illustrative paintings, and surviving sketches and drawings

Europe's climate fluctuated wildly often suddenly, so that recovery would be followed by renewed famine, as populations mushroomed and then collapsed again

In the fourteenth Century, the geography of eastern and western Eurasia became fatally interlocked

salubrious conditions enabled Mongols to thrive and expand

Mongol migrants and their horse Caravan picked up on the strain of bacteria that brings on the bubonic plague, and it's vector, the flea, rode into Europe on rats and people ahead of their relentless advance

The Black Death killed half of the population or more

Recovery from the Black Death, medical and environmental, did not start until the last quarter of the 15th century

in China at the same time, the full impact of the little Ice Age occurred after the end of the Mongol Dynasty (1368)

Ming rulers inherited populous states sustained by wheat in the north and rice in the center, link by the Grand Canal and other busy waterways in line late in the 14th century the Ming rulers authorized the construction of an ocean-going fleet that would stake China's claim and enhance its reputation in the Indian Ocean and beyond

The fleet numbered more than 6,000 ships, and carried sufficient fresh water and supplies to sale for 30 days

The first expedition was in 1405 and involved 315 ships and 27,000 men

The Chinese seemed poised to round the Cape of Good Hope and enter the Atlantic

When the first wave of the little Ice Age came to China, interior rains failed, rivers dried up, the wheat crop shrank, famines broke out, and social disorder and epidemics raged

the Ming rulers ordered and into the maritime expeditions and burned all of the ocean going vessels

Página 5

Crisis In Europe

Little Ice Age climate brought the second Agricultural Revolution

Farm implements were improved

Field methods got better, transportation and storage of produce involved less waste and lost, new crops were tried, marketing in the growing urban areas became more efficient

The century closed with one of the most extreme decades in Europe's environmental history

During the seventeenth Century, conditions worsened by a series of volcanic eruptions in Southeast Asia

These eruptions led to colder spells in an already frigid region

the. From about 1650 to 1850 is called the real little ice age

this was the coldest cycle of the millennium the coolest. Of the Millennium appears to coincide with the probable phase of minimum sunspot activity called the maunder minimum after the scientist who analyzed it

A better defined solar minimum, the Dalton minimum, marks the period between about 1795 and 1820 - the cold was not just in Europe

In his book, The Little Ice Age, archaeologist Brian Fagan describes how the Franz Josef Glacier on New Zealand's South Island “thrust down slope into the valley below, smashing into the great rainforest... felling giant trees like matchsticks”

The little ice age is why the Jamestown Colony collapsed so fast. There were other causes too, but the chief cause probably was environmental

While studying tree ring records, geographers found that the Jamestown area experienced a seven-year drought between 1606 and 1612

European colonies and Native Americans were in the same situation, and their relations worsened as they were forced to compete for dwindling food and falling water table

Volcanic eruption on Iceland in 1783 lasted for eight months

The Laki eruption lowered temperatures in North America by 7 degrees Fahrenheit and brought on a series of frigid winters in Europe, Russia, and even North America

In February 1784, ice blocked the entire lower Rhine River, producing the worst floods in recorded history and causing food shortages and general economic disasters

The French Revolution had other causes, but its timing undoubtedly was related to the food shortages recurring during that dreadful decade

The period from 1805 to 1820 was one of the coldest in the “real” Little Ice Age, and when Napoleon’s armies invaded Russia their biggest adversary was the bitter winter, with which Russian forces were more familiar

Página 6

Distant Threat

Just when it must have seemed that conditions could not have gotten any tougher, they did

Not because of an atmospheric event but as a result of a volcanic eruption on the other side of the planet

On April 5th, 1815, the Tambora volcano on the island of Sumbawa in what was then the Dutch East Indies rumbled to life

less than a week later, it was pulverized in a series of explosion, killing all but 26 of the Island's population of 12000

when it was over, the top four thousand feet of the volcano were gone and most of what is now Indonesia

tens of thousands died of famine in the months that followed because of the darkness enveloping the colony

Fields covered by poisonous ash and powder, waters clogged by trees and cinders, are rendered unbreathable by a fog of acid chemicals

Tambora's explosions rocketed in tens of millions of tons of ash into orbit, darkening skies around the world

By 1816, it was going to be a year without summer, a growing season without growth

In Europe, food shortages were acute and the grain prices rose rapidly, forcing governments to close their borders to prevent speculation

Food riots broke out in towns

In the US, the year without summer was especially difficult on the farms of New England where corn would not ripen, grain prices escalated, and the livestock market collapsed

1816 was a desperate year in the Little Ice Age

Página 7

The Human Factor

the little Ice Age ended mid-nineteenth century

the Industrial Revolution was gathering steam

the colonial era was transforming societies and economies from Central America to Southeast Asia

Europeans were populating and dominating distant land, fighting among themselves even as they exploited their imperial domains

Population growth was accelerating

around the time of the Tambora eruption, the population was about 1 billion, twice as much as it was at the beginning of the Little Ice Age

one major Interruption from approximately 1940 to 1970 since about 1850

How would the world cope today with a “year without summer,” not to mention a Toba catastrophe – or a sudden return to Pleistocene glaciation