week 1

• geosphere • hydrosphere • biosphere • atmosphere

need to keep the subject before the threshold to keep the planet safe and make the processes reversible

• beyond zone of uncertainty (high risk) • in zone of uncertainty (increasing risk) • below boundary (safe)

this means more research is needed to indicate in which zone the subject is.

before humans were interfering with the earth system.

Outer circle: planetary boundaries Inner circle: social boundaries

a collection of interdependent parts enclosed within a defined boundary. Within the boundary of the earth is a collection of four interdependent parts called spheres.

• all of the cold, hard, solid rock of the planet’s crust (surface) • the hot semi-solid rock that lies underneath the crust • the hot liquid rock near the center of the planet • the solid iron core (center) of the planet

solid, liquid and gaseous water

all of the planet’s living organisms

all of the planet’s air -> layer of gases surrounding the planet

closed system (energy: yes) (matter: hardly)

neither energy or matter is being exchanged.

change in one sphere often results in a change in one or more of the other spheres › such changes = events.

An event can cause changes to occur in one or more of the spheres, and/or an event can be the effect of changes in one or more of Earth’s four spheres.

two-way cause and effect relationship between an event and a sphere

› Sphere to event (causes) › Event to sphere (effects) › Sphere to sphere (effects)

alters the rate of change (positive/negative)

The components of a system can create emergent properties, for example flight patterns of a flock of birds.