Human and Nature Dynamics (HANDY):
Modeling Inequality and Sustainability
Extrait (pages 24-28):
Review of Some Historical Collapses
• Collapse of the Roman Empire – Well known, but not the first rise and collapse in Europe.
• Minoan Civilization
• Mycenaean Civilization – Complete and Total Collapse (in Greece, 2K BC) – Population dropped by an order of magnitude, – Urban areas abandoned, – Literacy completely lost – Recovery took 4 to 5 centuries History is also full of Cycles of Rise and Decline
• Mesopotamian History: – the Sumerians, the Akkadians, Assyrians, Babylonians, Achaemenids, Seleucids, Parthians, Sassanids, Umayyads, and Abbasids.
• Egyptian History , – Three distinct cycles of Rise And Collapse in Ancient Egypt : – More Cycles after Egypt was conquered by the Persians, Greeks, Romans, Arabs, Turks, and British
• Chinese History – Zhou, Han, Song, Ming, & Ching Empires – all were followed by a decline or a collapse. Indian History : – Indus Valley Civilization, Mauryan Empire, Gupta Empire, A Dark Ages, Empire under Harsha. Finally by many Foreign Conquests by Arabs, Moguls, British Collapses Not Restricted to the “ Old World ”
• Collapse of Maya Civilization in the Yucatan – One of the best-known cases – Partly because of the Depth of the Collapse
• As Diamond [2005] puts it, “ the disappearance of between 90 and 99% of the Maya population after A.D.800. ”
• Other Rise and Collapse Cycles in Mesoamerica:
• Central Mexico : – The Olmecs , The Toltecs , Teotihuacan (the sixth largest city in the world in the 7th C), Monte Alban Many others examples from around the World:
• Mississippi Valley Cultures such as: – Cahokia, – The Hopewell Complex
• South West US Cultures such as – The Pueblo and – The Hohokam,
• Andean Civilizations such as – Huari, Tiwanaku,
• Sub-Saharan African Civilizations such as Great Zimbabwe, and
• Collapses in the Pacific Islands , – Easter Island is the most well known.
Conclusion (page 52):
Summary
• We are using up in 200+ years the fossil fuels that nature accumulated over millions of years .
Same with fossil water.
• The use of fossil fuels for agriculture increased food production and population after 1950.
• HANDY I “thought experiments” show that reducing :
1. Social inequality
2. Population growth
3. Depletion per capita allow society to become sustainable .
• HANDY II: Adding non-renewables
1. Increases maximum population by ~20 times.
2. Postpones collapse by about 200-300 years
3. If the transition from fossil to renewables (solar and winds) is done early enough, it is possible to avoid the collapse.
We are NOT modeling the coupled Earth-Human System!
• We need to couple them to provide feedbacks!
• Data assimilation can help tune the coupled models
Source (fichier pdf de 53 pages, en anglais) : http://www.pitt.edu/~trenchea/NAPFF/Presentations/Eugenia_Kalnay_HANDY-population-ClimChange.pdf
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