Earth Systems Overview

The Earth is 4.6 billion years old. It is the only planet presently known to support life. The Earth is a closed system. There is an exchange of energy, but only a small exchange of matter.

Earth Systems Overview

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Earth can sustain life because:

• it is the perfect distance from the sun. Not too hot, not too cold
• the light from the sun can be used for photosynthesis
• the Earth has a breathable atmosphere
• the Earth has water
• the Earth’s climate can support life

Earth Systems Overview

The Earth is a system consisting of four major interacting components (spheres):

• the atmosphere,
• the biosphere,
• the hydrosphere, and
• the geosphere

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Let’s examine each of these four spheres in detail………

Geosphere

The geosphere is the solid Earth that includes the continental and ocean crust as well the various layers of Earth’s interior.

• 94% of the Earth is composed of the elements oxygen, silicon, and magnesium.
• The geosphere is not static (unchanging). Its surface (crust) is in a constant state of motion.
• Mineral resources are mined from the geosphere.

Layers of the Geosphere

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The Primary layers of the geosphere are the

• core - composed iron and nickel
• mantle - a molten layer
• crust- the surface of the Earth

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Layers of the Geosphere

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What is the Lithosphere?

• The lithosphere is the outer part of the Earth consisting of the crust and the upper mantle.

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Hydrosphere

The hydrosphere contains all the water found on our planet.

• Water found on the surface of our planet includes the ocean as well as water from lakes and rivers, streams, and creeks.
• Water found under the surface of our planet includes water trapped in the soil and groundwater.
• Water found in our atmosphere includes water vapor.
• Frozen water on our planet includes ice caps and glaciers.
• Only about 3% of the water on Earth is “fresh” water, and about 70% of the fresh water is frozen in the form of glacial ice.

The Cryosphere

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The Cryosphere is all of the frozen water on our planet.

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The Atmosphere

The Earth is surrounded by a blanket of air, which we call the atmosphere.

• The atmosphere consists of four unique layers (the troposphere, the stratosphere, the mesosphere, and the thermosphere).
• The atmosphere reaches over 560 kilometers (348 miles) up from the surface of the Earth.
• The atmosphere is primarily composed of nitrogen (about 78%), oxygen (about 21%), argon (.9%), and carbon dioxide (0.04%). Other components exist in small quantities.

The Biosphere

The biosphere is the “life zone” of the Earth, and includes all living organisms (including humans), and all organic matter that has not yet decomposed.

• The biosphere is structured into a hierarchy known as the food chain (all life is dependant on the first tier – mainly the primary producers that are capable of photosynthesis).
• Energy and mass is transferred from one level of the food chain to the next.

Earth System Science

Earth System Science is the study of how the four spheres of the Earth system interact continually, each affecting the others.

Let’s look at a couple of examples of how a change in one system (or sphere) affects other Earth systems.

System Interactions

Volcanoes (geosphere) erupt, sending ash and gases into the air (atmosphere) and sending lava and ash down onto surrounding forests (biosphere) and human habitations (biosphere).

Geosphere

Atmosphere

Biosphere

System Interactions

Hurricanes (atmosphere) sweep across the ocean (hydrosphere) and onto the land (geosphere), damaging the dwellings of people (biosphere) who live along the coast.

Atmosphere

Hydrosphere

Geosphere

Biosphere

System Interactions

Earthquakes (geosphere) can damage buildings which may kill people (biosphere), as well as cause fires which release gases into the air (atmosphere). Earthquakes in the ocean may cause a tsunami (hydrosphere) which can eventually hit land and kill both animals and people (biosphere).

Geosphere

Biosphere

Atmosphere

Hydrosphere