Generalized diagram of the Earth system Systems Notation

  • Slides: 26
Download presentation
Generalized diagram of the Earth system

Generalized diagram of the Earth system

Systems Notation = system component = positive coupling = negative coupling

Systems Notation = system component = positive coupling = negative coupling

Positive Coupling Car’s gas pedal Car’s speed Amount of food eaten Body weight A

Positive Coupling Car’s gas pedal Car’s speed Amount of food eaten Body weight A change in one component leads to a change of the same direction in the linked component

Positive Coupling Atmospheric CO 2 Greenhouse effect • An increase in atmospheric CO 2

Positive Coupling Atmospheric CO 2 Greenhouse effect • An increase in atmospheric CO 2 causes a corresponding increase in the greenhouse effect, and thus in Earth’s surface temperature • Conversely, a decrease in atmospheric CO 2 causes a decrease in the greenhouse effect

Negative Coupling Car’s break system Car’s speed Exercise Body weight A change in one

Negative Coupling Car’s break system Car’s speed Exercise Body weight A change in one component leads to a change of the opposite direction in the linked component

Negative Coupling Earth’s albedo (reflectivity) Earth’s surface temperature • An increase in Earth’s albedo

Negative Coupling Earth’s albedo (reflectivity) Earth’s surface temperature • An increase in Earth’s albedo causes a corresponding decrease in the Earth’s surface temperature by reflecting more sunlight back to space • Or, a decrease in albedo causes an increase in surface temperature

Increasing carbon dioxide: forcing (long term)

Increasing carbon dioxide: forcing (long term)

Volcanic eruption: perturbation (short term)

Volcanic eruption: perturbation (short term)

positive coupling parents’ anger childrens’ noise negative coupling

positive coupling parents’ anger childrens’ noise negative coupling

Negative Feedback Loops: Electric Blankets person A’s body temperature person A’s blanket temperature person

Negative Feedback Loops: Electric Blankets person A’s body temperature person A’s blanket temperature person B’s body temperature

A Positive Feedback Loop: Mixed-up Electric Blankets person A’s body temperature person A’s blanket

A Positive Feedback Loop: Mixed-up Electric Blankets person A’s body temperature person A’s blanket temperature person B’s body temperature

A simplified climate system: Daisyworld ü Average Temperature = 30 o. C ü No

A simplified climate system: Daisyworld ü Average Temperature = 30 o. C ü No clouds, no ocean ü Soil = light gray (absorbs some light) ü Life = white daisies (reflects all light) ü Sun = like Earth’s ü Daisy growth = changes with temperature

Albedo: measure of reflectivity of a surface, expressed as a % of reflected insolation

Albedo: measure of reflectivity of a surface, expressed as a % of reflected insolation to incoming insolation. (Christopherson, Elemental Geosystems, 2004)

albedo=0. 75 albedo = 0. 5

albedo=0. 75 albedo = 0. 5

Systems diagram explicitly including albedo

Systems diagram explicitly including albedo

Response of average surface temperature to daisy coverage Systems diagram

Response of average surface temperature to daisy coverage Systems diagram

completely covered planet 22. 5 °C 40 °C

completely covered planet 22. 5 °C 40 °C

Equilibrium States: Graphical Determination 1. Overlay the two graphs (this is the graphical way

Equilibrium States: Graphical Determination 1. Overlay the two graphs (this is the graphical way of setting them equal to each other). 2. The points where they meet are equilibrium points. 3. Draw a systems diagram to determine whether each one is stable or unstable.

The Faint Young Sun Problem More H 2 O Kasting et al. , Scientific

The Faint Young Sun Problem More H 2 O Kasting et al. , Scientific American (1988)

Response of average surface temperature to daisy coverage Systems diagram

Response of average surface temperature to daisy coverage Systems diagram

External Forcing: the response of Daisy World 1. Assume that the external forcing is

External Forcing: the response of Daisy World 1. Assume that the external forcing is an increase in solar luminosity 2. The effect of temperature on daisy coverage should not change (this depends on the physiology of daisies) 3. The effect of daisy coverage on temperature should change: for the same daisy coverage, higher temperature