Recent Historical Climate Change

Describe the early Holocene instability:

• 8.2kya a 150k cubic km flood from Lake Agassiz switched off the Gulf Stream

• 1-2 degree temp drop and 1.4m sea level rise

• May have kick-started European agriculture

Describe the browning of the Sahara:

• ~6kya reduced solar insolation weakened the African monsoon

• Falling vegetation cover contributed to a +ve feedback loop

Describe the Medieval Climate Anomaly (MCA):

• 950-1250 AD

• Mayan collapse ~1000AD linked to 4 droughts over 150 years

• Fewer records of famines in Europe

Describe the Pacific migration:

• 950-1150 AD, the movement of the ITCZ northwards led to regional drought + winds that promote eastward travel 

• 1150-1300 AD, the ITCZ moved south, creating wetter conditions in eastern Polynesia (promotes establishment) 

Describe the Little Ice Age:

• Cool period between 1150 – 1850 

• Growing season was 15-20% reduced 

• Poor harvests, disease, and greater severity of storms 

• Experienced across the northern hemisphere