Meteorology and Civilization

November 12, 2007

Civilization

• Small groups of people to large urban areas change local meteorology through– Deforestation– Fire

– Changes in vegetation cover (CO2 absorption)

– Grazing animals– Mining– Changes in water

Civilization

• Changes in weather and climate are more pronounced on peoples or politics that are in marginal situations– Areas on the fringes of settlement, near

uplands, lowlands, polar, or desert limits

Civilizations

• Ancient Egypt after 5000 years before present (ybp) – summer monsoon weakened across tropics

• Akkadian Empire (Syria) after 4200 ybp – abandoned during period of increased aridity and dust storms

• Maya (Yucatan) after AD 860 – drought

• Anasazi (Colorado) AD 1300 - drought

El Nino and Civilization

• Large human populations susceptible to small changes in climate

• El Nino – small climatic disruption – big killer in areas where population too high

• Over the past 150 years, its killed 3 times more humans than the Black Death

• High death rates in animal world because the biosphere has not yet adapted to the phenomenon

1876-78 El Nino

El Nino and Civilization

• Established 5000 years ago– Reconstructed using fish bones

• Possible causes:– Sea level rise and warming– Land bridge between Americas– Sunspots– Volcanic activity

El Nino and Civilization

• Did El Nino create the Third World?

• El Nino Drought Belt: China, India, Indonesia, Philippines, Brazil, East and South Africa

• Ecological Poverty: depletion or loss of entitlement to the natural resource base of traditional agriculture constituted a causal triangle with increased household poverty and state decapitation

El Nino and Civilization

• El Ninos of late 19th century allowed Europeans to seize land and impoverish populations in the tropics – traditional economy and social structure that created self-sufficiency destroyed

1997-98 El Nino

El Nino and Civilization

• Indonesia 1997-98

• Raised air temperatures 1.4°F (equivalent to 100 years of global warming)

• Droughts brought fires

• Decades of deforestation had decreased local rainfall, raised temperatures, and exposed flammable peat soils

• Complete societal breakdown

El Nino and Civilization

• El Nino 1888 produced the Great Ethiopian Famine killing 1/3 of population and 90% of livestock

• In this region, El Nino produces drought during growing season and monsoons during harvest season

• 1972-73 El Nino killed 200,000

• 1982-83 El Nino killed 300,000

• 1997-98 El Nino in Ethiopia

• May 1997 warning issued that summer rains would be less

• Suggestions of planting drought resistance crops and harvesting before unseasonable rains began

• Chaos averted

El Nino and Civilization

Civilizations

• CO2 began to increase steadily in the atmosphere 8000 years ago through deforestation

• By 2000 years ago, large tracts of Europe and Asia deforested

• 1086 England – 85% of arable land was is pasture or crops, 15% forest

• Methane began increasing 5000 years ago– Rice production, livestock, burning, human

waste

2 x CO2 World

2 x CO2 World

• In the mid- and high-latitudes, a one-month shift in seasons

• 2 months more of summer and milder winters

• In tropics and subtropics, less change in temperature but increasing aridity

• IPCC mid-range projection means 1000ft increase in sea level this century

• Acidification of oceans

4 X CO2 World

4 X CO2 World

• Between 2200 and 2300• No sea ice• Trees on Antarctica• Elimination of remaining mountain glaciers• Elimination of shallow permafrost and

tundra• Larger magnitude droughts in lower and

midlatitudes• Feedback mechanisms?

Thermohaline Circulation

Glacial Expansion