Earth As A SystemAdapted from: The Layered Earth

A1-1: Earth As A System

• The Earth is a complex structure that consists of many interrelated natural systems. We use the broad term Earth System to describe these subsystems and their relationships to one another. The Earth system consists of five natural subsystems. These subsystems are the atmosphere, hydrosphere, cryosphere, biosphere, and geosphere.

A1-1: Earth As A System

• All parts of the Earth system have a crucial role to play in the maintenance of the planet. Actions in one subsystem can often have unexpected repercussions in other subsystems. The actions of humans, for example, although only one component of the biosphere, can often end up affecting many, if not all, components of the Earth system.

A1-2: The Atmosphere

• The atmosphere is the subsystem that is best described as the gas envelope that surrounds our planet. It consists primarily of nitrogen (78%) and oxygen (21%), and extends to an altitude of approximately 100 kilometers (approximately 62 miles).

A1-2: The Atmosphere

The atmosphere is composed of the following gases:

1. Prepare a properly labeled pie graph illustrating the main components of the atmosphere.

2. Approximately what fraction of the atmosphere is composed of oxygen?

A1-3: The Hydrosphere

• The hydrosphere is the subsystem that includes all the non-frozen water on the Earth. Water covers 71% of the Earth’s surface. The Earth’s oceans account for 97% of the Earth’s water. The remaining 3% is found as freshwater in bodies such as lakes, rivers, and groundwater.

A1-3: The Hydrosphere

These stacked bar charts illustrate the distribution of the Earth’s water.

1. Where is the majority of freshwater stored?

2. The amount of freshwater in the world is estimated to be approximately 35,027,000 cubic kilometers (8,403,424 cubic miles). • Calculate the volume of water (in cubic

kilometers) stored in ice caps and glaciers.

• Calculate the approximate volume (in cubic kilometers) of freshwater stored in lakes.

A1-4: The Cryosphere

• The cryosphere is the subsystem that includes all of the Earth’s frozen water. This includes polar ice caps, glaciers, and snow.

A1-5: The Biosphere

• The biosphere is the subsystem composed of all living things on the Earth and their habitats. This includes all living organisms on land, in the water, and in the air. Not only does the biosphere include all animals, but it also encompasses the complete range of life from tiny, single-celled organisms like the amoeba up to, and including, giant living organisms like a Sequoia tree.

A1-6: The Geosphere

• The geosphere is the subsystem that includes all parts of the solid surface of the Earth right down to, and including the interior of the Earth. This includes not only materials visible in the Earth’s surface like rocks and mountains, but also materials inside the Earth right to the very center of the planet.

Lesson Summary

• The Earth system is composed of five interrelated subsystems.

• The atmosphere is the gas envelope that surrounds Earth.

• The hydrosphere includes all the non-frozen water on Earth.

• The cryosphere consists of all the frozen water on the Earth.

• The biosphere consists of all living organisms on the Earth and their habitats.

• The geosphere extends from the solid surface of the Earth to the Earth’s interior.

Vocabulary Review

• Earth System: the general term for a set of five interrelated natural subsystems (atmosphere, hydrosphere, cryosphere, biosphere, geosphere)

• Atmosphere: the subsystem that is the gas envelope surrounding our planet; it consists primarily of nitrogen and oxygen

• Hydrosphere: the subsystem that includes all the non-frozen water on Earth; it consists primarily of oceans, lakes, rivers, and groundwater

• Cryosphere: the subsystem that includes all of the Earth's frozen water including polar ice caps, glaciers, and snow

• Biosphere: the subsystem that includes all living organisms on the Earth whether they be on air, water, or land

• Geosphere: the subsystem that includes all parts of the solid Earth, and extends down to the Earth’s interior