1. Essential Question: How does the Earth work to be a system?
Earth as a System
Essential Question: How does the Earth work to be a system?

2. System
Definition: A group of interdependent parts enclosed within a certain boundary.
The objective of Earth System Science is to understand how the Earth is changing and the effects for life on Earth, with a focus on enabling prediction and alleviation of undesirable effects.
Within the boundary of the earth is a group of four interdependent parts called subsystems.

3. Biosphere
Definition: The part of the earth's crust, waters, and atmosphere that supports life.
Within the biosphere, living things form ecological communities based on the physical surroundings of an area. These communities are referred to as biomes.
The term "biosphere" was coined by geologist Eduard Suess in 1875, which he defined as; "The place on Earth's surface where life dwells.“ He like many other scientists engaged in the study of the biosphere, or ecology.

4. Geosphere
Definition: The solid portion of the earth (distinguished from atmosphere, hydrosphere).
The word "lithosphere" will be used in reference to all land in Earth's system.
The solid, semi-solid, and liquid land of the lithosphere form layers that are physically and chemically different.
The word "lithosphere" can take on different meanings depending on the speaker and the audience.

5. Hydrosphere
Definition: The watery part of the earth's surface, including oceans, lakes, water vapor in the atmosphere, etc.
Ninety-seven percent of Earth's water is salty. These large collections of salty water are referred to as oceans.
Some scientists place frozen water--glaciers, icecaps, and icebergs--in its own sphere called the "cryosphere."

6. Atmosphere
Definition: The gaseous envelope surrounding the earth; the air.
It extends from less than 1 m below the planet's surface to more than 10,000 km above the planet's surface.
The upper portion of the atmosphere protects the organisms of the biosphere from the sun's ultraviolet radiation.
It also absorbs and emits heat. When air temperature in the lower portion of this sphere changes, weather occurs.

7. Cryosphere
Definition: Some places on Earth are so cold that water is a solid—ice or snow. Scientists call these frozen places of our planet the "cryosphere."
The word "cryosphere" comes from the Greek word for cold, "kryos.“
Snow, ice, or both are key ingredients in every aspect of the cryosphere, including sea ice, glaciers, ice shelves, icebergs, and frozen ground.

8. Citations http://www.cotf.edu/ete/ESS/ESSmain.html
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