3.2 Earth's Systems

Interacting Systems

Lesson 3.2 Systems in Environmental Science

•Inputs into Earth’s interconnected systems include energy, information, and matter.

•Feedback loops regulate systems.

•Negative feedback
loops: Result in
stabilization
of a system

•Positive feedback
loops: Result in a
system moving
to an extreme

Did You Know?Predator-prey cycles are negative feedback loops. If prey populations rise, predator populations can rise in response, causing prey populations to fall. Then predator populations may decline, allowing prey populations to rise again, and so on.

Negative feedback loop

Spheres of Function

•Earth can be divided into spheres that are defined
according to their location and function.

Lesson 3.2 Systems in Environmental Science

The Geosphere

•Crust: Thin, cool, rocky outer “skin”

•Mantle: Very hot and mostly solid

•Core: Outer core is molten metal, inner core
is solid metal

Lesson 3.3 Earth’s Spheres

•Rocks and minerals on and below Earth’s surface:

•Biosphere: The part of Earth in which living and
nonliving things interact

•Atmosphere: Contains the gases that organisms
need, such as oxygen; keeps Earth warm enough
to support life

The Biosphere and Atmosphere

Lesson 3.3 Earth’s Spheres

The Hydrosphere

•Consists of Earth’s water

•Most of Earth’s water (97.5%) is salt water.

•Only 0.5% of Earth’s water is unfrozen fresh water
usable for drinking or irrigation.

•Earth’s available fresh water includes surface water
and ground water.

Lesson 3.3 Earth’s Spheres

Did You Know?If it is depleted, groundwater can
take hundreds or even thousands of years to
recharge completely.