Systems Dynamics: Climate System PDF

Systems Dynamics: Climate System System Dynamics – Systems Thinking What is a system? Comprised of interconnected parts Has a purpose or function Ex: human body, earth climate system, global economic system Not a system: a group of items without connections, a group of rand...

Systems Dynamics: Climate System System Dynamics – Systems Thinking What is a system? Comprised of interconnected parts Has a purpose or function Ex: human body, earth climate system, global economic system Not a system: a group of items without connections, a group of randomly scattered items Earth’s climate system System Dynamics – Systems Thinking What is a system? Comprised of interconnected parts Has a purpose or function Ex: human body, earth climate system, global economic system How do systems work? Information/material flows between parts, allowing systems to function How do systems change overtime? Feedbacks can cause changes in systems System Dynamics – Systems Thinking Stock – amount of stuff in a particular place in a system at a particular time Ex: Gtons C = giga-tonnes of carbon in the atmosphere today Stuff flows in, out, through a system System Dynamics – Systems Thinking Stuff flows in, out, through a system Inflow – rate at which stuff enters a system Outflow – rate at which stuff exits a system Ex: rate of carbon added to atmosphere = GtonsC/year Stocks at a particular time reflect the current and historical inflow/outflow System Dynamics – Systems Thinking Inflow STOCK Outflow If inflow = outflow, stock remains the same System Dynamics – Systems Thinking Inflow STOCK Outflow If outflow > inflow, stock decreases System Dynamics – Systems Thinking Inflow STOCK Outflow If inflow > outflow, stock increases Systems Dynamics – Systems Thinking Source: NOAA System Dynamics – Systems Thinking Flow influence stock Outflow > inflow = stock may decrease Outflow < inflow = stock may increase AND stock influences flow More stock means outflow may be higher Equilibrium = stock remains the same Inflow = Outflow System Dynamics – feedback Feedback can cause stock to influence inflow/outflow Amplifying feedback – a response to a perturbation that pushed system further in same direction Reinforces the perturbation Destabilizes the systems Can cause new system equilibrium which is irreversible Stabilizing/balancing feedback – brings system back to equilibrium System Dynamics – feedback Earth’s climate system Atmosphere: Gases + aerosols Hydrosphere: Water + ice Geosphere: Rocks Biosphere: Life System Dynamics – Lags Lags = delays Time between occurrence of action + effect of action New equilibrium takes longer t achieve Human deal well with short expected delays, not long unexpected Ex: temperature rises, ocean temperature rises, but we don’t feel the full effects of temperature rise. When will we feel it? LAGS add an higher level of uncertainty to all systems dynamics Learning Objectives Define stock, flow, and feedback Explain how the combined history of inflows and outflows determines a stock Predict what happens to stocks and flows of energy and materials when a system is perturbed Describe examples of both amplifying and stabilizing feedbacks Describe our climate system using systems dynamics