Environmental Systems and Societies · Topic 4: Water

ES4.1 — Water systems

Environmental Systems and Societies · SL / HL · syllabus-mapped notes

1. Drivers and the cycle as a system

   Solar radiation and gravity drive water movement; the global hydrological cycle modelled as stores (boxes) and flows (arrows).

2. Stores and flows

   The six main stores and their relative proportions, and the thirteen named flows that transfer water between them.

3. Human impacts and steady state

   How agriculture, deforestation and urbanization alter flows and stores, and using input/output diagrams to find sustainable harvest rates.

4. Life-supporting properties of water

   Polarity, cohesion, adhesion, solvent action, transparency, specific heat capacity, temperature-dependent density and gas solubility.

5. Oceans as a carbon sink

   How oceans absorb and sequester atmospheric CO2, the short-term acidification pathway and the long-term seabed-biomass pathway.

6. Stratification, upwelling and circulation

   Thermal stratification and the thermocline, why warming intensifies it, upwelling, and the thermohaline ocean conveyor belt.