Learning Center

Earth’s Four Main Systems

Do you know what an ecosystem is?

An ecosystem is all of the living and non-living natural elements in a specific location. Every place has its own ecosystem. There is a distinct ecosystem in the region where you live that is different from one even a few miles away.

You might have heard about how important a healthy ecosystem is to the lives of everyone and everything living in it – we need clean air to breathe and water to drink, and that largely depends upon the condition of our local ecosystems. There are a lot of factors that influence what is in an ecosystem, but what makes different ecosystems healthy, functional, and unique are the Earth’s four main systems that work together to create the planet as we know it.

The health of the environment depends on how well we all treat these four systems. We protect these systems when we recycle plastic and other materials that build up in landfills, when we plant trees, when we use energy-efficient light bulbs, and when we make sure we don’t waste water. However, when we neglect to care for one part of the ecosystem – our forests, for example – there are environmental consequences that harm other parts of the ecosystem. When forests are destroyed, animals die because their habitats (homes) and food sources have been removed. Rains can flood surrounding towns and cities because the water isn’t being absorbed and redirected by forest trees and plants. Air quality (how clean the air is) can suffer because forests filter pollution from the air through the process of photosynthesis. (Photosynthesis is the chemical process green plants use to create nutrients from carbon dioxide.)

Many systems make the planet Earth a living, breathing environment, but four systems encompass every one of Earth’s characteristics. We call these systems “spheres” because, like the planet, they are round. While there are lots of smaller spheres within four main systems, the four main spheres are the biosphere (all living things including plants, animals, and microbes), the lithosphere (all rock formations on the solid outer portion of the Earth), the hydrosphere (all bodies of water on the surface of the Earth as well as in rainclouds), and the atmosphere (all of the gasses around the Earth).

There are also other systems related to the four main spheres, including the cryosphere (all frozen surfaces), the geosphere (all rock in the lithosphere and below the upper mantle), and the pedosphere (all soil and sand).

But… how do the Earth’s systems affect you?

No matter where you live, you are affected by the Earth’s systems. Even if you live in a big city surrounded by buildings, the Earth’s systems still influence your daily activities. The Earth’s systems create different weather conditions, so if you want to go for a walk and it suddenly starts raining, your plans have been affected by the systems.

And the health of the systems also has long-term effects on your life. It might not seem as though rock formations and lakes have anything to do with your lifestyle if you live in an apartment building hundreds of miles away from the nearest forest. However, you need water to live, and the quality of your water supply is influenced by the health of these systems.

If you want to understand just how the systems work and how they play a part in your daily life, here is a closer look at the four main systems and how they interact to create a healthy planet for all living things.


The biosphere consists of all parts of the planet where life can be found. This includes all life found in the air, the ocean, and on land. It is called the biosphere because the prefix, “bio,” means “life.”

Because the biosphere includes all living things, the system includes all of the places on the planet where life can grow and survive. Within the biosphere there are lots of ecosystems that support all different kinds of life. This is because the other spheres relate to each other in different ways throughout the planet. For example, the lithosphere, atmosphere, hydrosphere, and cryosphere (the frozen surfaces) affect regional temperatures, which create different environments that produce different life forms. If you live in the Pacific Northwest, the animals and plants you see in the wild near your home are very different from the animals and plants you would find in the Southeastern U.S. This is because the biosphere has been affected by the other spheres and created different conditions.

There has been a biosphere on Earth for approximately 3.5 billion years. The earliest life forms were called prokaryotes, which are single-celled organisms without a nucleus (bacteria are prokaryotes). While prokaryotes existed before oxygen entered the biosphere, far more complex organisms were able to evolve after oxygen was introduced.


The lithosphere consists of all the parts of the planet that contain minerals in the form of solid rock. This includes mountains that are tens of thousands of feet above sea level, and down through the Earth’s crust and into the upper mantle. The mantle is the part of the Earth that is right above the outer core near the center. It is called the lithosphere because the prefix “lithos” means “stone.”

The lithosphere is divided into two types: Oceanic lithosphere and continental lithosphere. Oceanic lithosphere is underneath the oceans, while continental lithosphere is underneath land. The oceanic lithosphere is slightly different from the continental lithosphere because the oceanic lithosphere is denser than the continental lithosphere, which means that the minerals that make up the rock are packed more tightly. Continental lithosphere is mainly granite rock, while oceanic lithosphere is mainly basalt.


The hydrosphere is all of the water on the planet. This includes the oceans, rivers, and lakes above ground, and the groundwater below ground. The hydrosphere also includes water in rainclouds and water vapor in the humid air. Can you guess why it’s called the hydrosphere? It’s because “hydro” means water!

All of the water on the planet travels through what is called the water cycle. The water cycle is the evaporation of water that collects in rain clouds. When the rain or snow falls, it then collects in our oceans, rivers, and lakes. The heat from the sun causes it to evaporate, and the process begins again.

The frozen parts of the Earth have their own sphere, too. The frozen portion of the hydrosphere is called the cryosphere. The cryosphere includes permafrost, which is frozen ground, as well as frozen sheets of ice, snowpack’s, and glaciers. The two largest ice sheets in the world are on Greenland and Antarctica. Ice sheets are important environmental resources because they have an effect on global climate – the ice reflects solar radiation away from the Earth and back into outer space, helping to keep the planet cool.


The atmosphere is the collection of gasses that surround the Earth. These gasses are mostly oxygen and nitrogen, but also include carbon dioxide, argon, and helium, as well as very small amounts of other gasses. “Atmos” means “vapor” in Greek.

Keeping the atmosphere healthy and intact is very important for all life on the planet. In addition to supplying essential oxygen, the atmosphere filters out most of the dangerous ultraviolet radiation from the sun while allowing the warmth to penetrate. While sunshine is essential for all life forms, ultraviolet radiation is extremely harmful, and is the cause of sunburn as well as skin cancer.

All of these spheres are essential to the health of the planet. They all interact and change each other, resulting in differences in temperature and land formation, and can either help or hurt living creatures’ ability to survive in different environments.

How do Earth’s Main Systems Interact?

The four spheres – the biosphere, lithosphere, hydrosphere, and atmosphere – are constantly interacting. We can see some of these interactions daily during our normal routines. Some, like rainfall, occur constantly. Others, like the formation of rivers and streams, occur slowly over hundreds of thousands of years. Here are some of the ways the Earth’s spheres interact.

The Hydrosphere and Atmosphere Create Weather

Have you ever seen satellite pictures of a hurricane over the ocean? If so, you’re seeing the violent interaction between the hydrosphere and the atmosphere. Hurricanes only occur over tropical oceans when there are high winds. When the ocean and the atmosphere are warm, the water evaporates into the atmosphere and becomes water vapor. The water vapor condenses (turns from vapor back into liquid) and releases heat that causes more evaporation, and more water to condense. This interaction between the hydrosphere and atmosphere fuels the storm.

Rainfall is the far milder result of the hydrosphere interacting with the atmosphere. When the energy of the sun causes water from the ocean to evaporate, the water molecules move into the atmosphere. Once in the atmosphere, the water molecules continue to collect and condense into clouds until they become too heavy to remain suspended. They then fall to the Earth as rain.

In the rainforests, the biosphere also interacts with the hydrosphere and atmosphere to create rainfall. The forests in the Amazon absorb water from the soil and release water vapor stored in their leaves during photosynthesis, which creates low rainclouds and rain. Rainforests are unique because they experience almost continuous rainfall – their annual rainfall can be as much as 14 feet.

The Hydrosphere and Biosphere Create Life

The biosphere and hydrosphere intersect constantly – all living things need a water supply to survive. Some organisms have a constant water supply from lakes or rivers, while others need to absorb water from the plants and animals they eat.

The ocean is also the interconnection between the hydrosphere and biosphere. There is a diverse assortment of life forms in the oceans, and the type of life that flourishes depends upon the environmental conditions within the hydrosphere.

The Biosphere and Lithosphere Make Things Grow

The biosphere and lithosphere interact through soil systems (soils and sands are their own sphere, called the pedosphere). Not only does the soil and sand provide an anchor for the plant, the soil and sand store minerals that the plants absorb. Soil type and quality influence the organisms that live within the soil, as well as the type of plants that can grow. Additionally, the landscape also influences the type of life that can flourish – a slope will have different kinds of plants growing on it than a flat surface, for example.

The Lithosphere and Hydrosphere Create Bodies of Water

The hydrosphere influences the lithosphere most clearly in rivers and streams. The force and amount of water create channels within rock formations, creating rivers, inlets, lakes, and waterfalls. The grinding of the rocks also creates sand and sediment which deposit on riverbanks and shores.

The Atmosphere and Lithosphere Create Volcanoes

Volcanic activity is an interaction between the atmosphere and lithosphere. Eruptions occur within the lithosphere when the mantle melts into magma (molten rock) underneath the Earth. The pressure causes the magma to push up to the surface where it spills out as lava. The eruption releases carbon dioxide, sulfur dioxide, steam, and ash into the atmosphere.

The Biosphere and Atmosphere Create Oxygen

Plants and trees in forests use energy from the sun and absorb carbon dioxide from the atmosphere during photosynthesis. Forests also release oxygen into the atmosphere – the Amazon rainforest releases nearly 30 percent of the global oxygen.

How Humans Affect Interaction Between Spheres

Human activity affects all of the spheres, and very often it affects them in negative ways. When humans cut down forests, it creates a chain reaction affecting ecological diversity (the variety of living things) and climate across the globe. Deforestation increases the volume of carbon dioxide (CO2) in the atmosphere, which when combined with other atmospheric gasses causes the global climate to increase. When climate increases, the temperature becomes too high in certain regions for the living organisms to survive.

Deforestation also affects the water supply. Forests help control storm runoff. Thick forests contain rainwater by preventing it from falling directly on the ground – water falls through dense tree cover and slowly makes its way down to the soil where it is gradually absorbed. When there is no tree cover, all of the water overwhelms the soil and creates flooding and runoff. This erodes the terrain and washes dirt and sediment into water supplies.

Although the spheres influence each other, humans can also influence the health of the spheres. When we damage the environment by releasing pollution into the atmosphere, drill for resources in the lithosphere, spill oil into the hydrosphere, and destroy trees in the biosphere, we risk the health of the planet and all living things.

Saving our forests can help protect all of the major spheres since the trees in forests help to reduce erosion (breaking apart) of the lithosphere and filter pollutants from the hydrosphere and atmosphere. If we want to keep the Earth’s spheres functioning properly, we must work to restore global forest cover. At Forest Founders, we are dedicated to protecting the world’s forests, which are disappearing quickly due to deforestation, natural disasters, and human interference. To learn how you can help protect the world’s forests, please visit the ForestFounders.org information page.

How do the Earth’s Spheres Interact?
  • Hydrosphere and Atmosphere: The hydrosphere and atmosphere interact to create rainfall. The heat from the sun evaporates water from the oceans which is condensed into rainclouds. When the water molecules become too heavy to remain suspended, they fall as raindrops.
  • Hydrosphere and Biosphere: All living organisms need a water supply to survive, either from lakes and rivers, or from stores of water within the plants and animals they eat.
  • Biosphere and Lithosphere: Plants grow in sand and soil, which are a part of the lithosphere called the pedosphere.
  • Lithosphere and Hydrosphere: The hydrosphere influences the lithosphere by forming rivers and streams. The force and pressure of water carve channels into rocks which become waterways.
  • Atmosphere and Lithosphere: Volcanic activity is the interaction between the atmosphere and lithosphere. When the mantle melts and gas bubbles create pressure underneath the Earth, it erupts as lava, and releases sulfur dioxide, carbon dioxide, steam, and ash into the atmosphere.
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