<200,000 years ago
1. Water cycle
2. Oceans (marine life)
4. Ozone layer
5. Land life evolves
6. Modern humans
Paleo-climate record show..
-average global surface temperature varied by +/- 20° C.
- age of the dinosaurs had no ice.
The key to life on Earth is water condensing to liquid.
-during the last glacial max 20,000 yrs ago, land bridges were formed as sea levels
dropped by hundreds of meters.
-people migrated and became isolated when glacial melted!
-isolation changes with season & latitude due to Earth’s curvature, tilt and orbit.
- this varies due to the angle between earth and sun
-perpendicular angle 90°= more concentrated energy from sun.
Most intense area of isolation pattern
1. Vernal (spring) Equinox 0°
2. Summer Solstice 23.5° North
3. Autumn Equinox 0°
4. Winter Solstice 23.5 South
Radiation is greatest between tropics
-energy returns back to space as infrared radiation, some trapped by GHGs in
-energy imbalance (produces) drives
1. steady troposphere airflow from tropics to pole, creating wind circulation.
2. surface ocean, top 200 m circulates.
-air rising from Earth’s surface is
-warm, moist, low pressure, light and rises
this causes clouds and rain.
-dry air is dense and descends, this is called subtropical high and is located 30°
North/South of ITCZ.
-water okays a role in moderating land temperatures because it warms and cools
slowly. SOUTH AMERICA
1. coastal lowlands (~100-200 km wide)
2. shield/plateau (agriculture, mineral wealth, later discovered)
Amazon tropics, why diversity?!
1. ice free terrain, climate stability
2. cycle of fragmentation and reconnection with glacial advances and
3. Most year-round solar energy for photosynthesis and plant biomass
=incredible degree of specialization
the burning season
-during summer months when ITCZ is not over Amazonian and therefore less
-clearing the forest
release of stored carbon + diminished segregation capacity, harder to
-low elevation of less than 200m
-low stream gradient 2-3cm/km
-Andes is a source of sediment (13.5 tons/s)
-mouth releases 1 B tons/yr
-have channel shift over time due to rainfall or drought.
1. enslaved (largely unsuccessful)
2. fought back
sugar, gold and diamonds used slavery as labor,
coffee market was driven by migration of Europeans. AFRICA
-agriculture revolution happened in major “hearth” regions around the ITCZ/
-improved crops/animals farming with techniques.
-the rise of agriculture brought rise to:
3. tributary states
+trading networks between civilizations.
Solar, biomass and wind powered societies=living carbon energy revolution age.
Empires of Ghana, Mali, Songhai were quire developed before European influence.
-capital of Mali and Songhai empires had 100,000 people.
-major “port” and the centre of education, culture and religion
-threatened by desertification
Fall of Songhai
Proximate cause -> military defeat
Long term cause -> European trade on coast marginalizes trans Saharan
route in the south coast. They sought ivory, gold and slaves.
Slavery started as early as ~650 ACE
- it stared from the by product of war to a primary industry for Europeans.
- Entire commercial economy of west Africa 16 C-19thC was organized to
capture, transport and sell slaves.