Interaction between the natural environment and the human society
- Very complex
- In the 21st century,
this cause-and-effect chain cannot be ignored:
carbon dioxide emission from fossil fuel use"
-> climate change (global warming)"
-> impacts on human society
Time lag, not simple delay, but time-integral, exists.
- Carbon cycle: stock and flow of (mass of) carbon atoms
- Emission from fossil fuel is a flow component.
- Other natural flow components exist, and their quantities may be modified.
- (For policymaking) mass of carbon dioxide in the atmosphere is the stock to be mainly considered.
- Other major stocks: mass of organic matter on land (plants, soil etc.), and mass of carbonates in the ocean, etc.
- Climate system: stock and flow of energy
- Radiative forcing is the major flow term.
- Changes in atmospheric CO2 content modifies radiative forcing.
There is no appreciable time lag here.
- (For century time scale) heat content of the upper (wind-driven) ocean is the major stock.
- Human society: (probably many)
(Correlation between "cause" and "effect" time series is not usually very good.)