Earth System Impacts on Humans Flashcards
Earth system impacts on human societies
- 8200 BP event
- The ‘browning’ of the Sahara
- Medieval warm period
- Little Ice Age
The 8200 BP event
The Lake Agassiz megaflood 8200 BP caused sea levels to rise 1.4 m -enough to displace
European coastal communities?
Kick-starting European agriculture?
The browning of the Sahara
A small change in Earth’s orbit
- leads to a small change in the distribution of solar radiation
- nudges the Earth System across a threshold
- As vegetation reduces the microclimate in the soil changes
- Leads to less vegetation and even drier conditions
- Amplification of initial climate signal caused by positive feedback
Medieval Warm Period
AD 950-1250
Evidence for impacts not so easy to find in Europe
Expansion of vineyards northwards in Europe
In Europe few records of famines etc - benign
times?
Little Ice Age in Europe
• Cooling 1150-1460 very cold 1560-1850
• Impacted all aspects of life
• Growing season perhaps 15-20% reduced
• Poor grain and wine harvests - 1816 the year ‘without
summer’
• Bad harvest in France 1788 led to bread riots, ‘let them
eat cake’, and the French Revolution?
• Malnutrition - influenza, malaria (ague), bubonic plague
• Abandonment of uplands
• Greater severity of storms
• Widespread Northern hemisphere phenomenon