Trying to understand how this planet we call home works can seem confusing – there are so many things going on at once! Scientists break down the way the Earth system works to a number of subsystems – the atmosphere, biosphere, geosphere (or lithosphere) and hydrosphere.
Before we look at what all these subsystems do, it is important to remember that the subsystems do not work in isolation – each one depends on and interacts with the other three.
The atmosphere is the layer of gases that surround the Earth. In comparison to the size of the Earth, it is a thin layer, composed primarily of nitrogen and oxygen with small amounts of carbon dioxide and other gases. The atmosphere is important for a number of reasons – it protects the Earth from incoming solar rays, it circulates the gases that plants and animals need to survive and it is responsible for our weather.
The biosphere consists of all the living organisms on Earth. Their habitats extend from the upper areas of the atmosphere, to deep in the ground, to the bottom of the ocean – any place that life can exist.
The geosphere is the physical Earth – the rock, magma and soil. The geosphere extends from the centre of the Earth (the core, mantle and crust) to the dust in the atmosphere and even includes the sediments found in the oceans.
The hydrosphere is all the water held on the Earth – water molecules in the air, icebergs and glaciers, groundwater, lakes, rivers and oceans.
How do the subsystems interact?
This is a big question, and it would take many books to explain, but think about this example. We know weather happens in the atmosphere, but without the hydrosphere, there would be no water to evaporate and so no cloud or rain could form. Without oceans and land (hydrosphere and geosphere), there would be no wind (as winds are produced by differences of air temperature between the land and oceans).
Without the atmosphere (giving us air to breathe and protection from incoming solar rays), there would be no life on Earth. It would be as barren as the moon. Without water, life as we know it would cease to exist. Last of all, without the geosphere, there would be no world to live on!
Look at the changing landscape of Earth. Rivers erode the geosphere, changing the physical environment so that plants and animals have to adapt or die. Bad weather might increase the weathering of rocks (the way rocks are broken down) changing both the physical and chemical makeup of the rocks.
These are a few examples to show how the systems are interlinked. Upsetting one system can lead to serious consequences in the sustainability of another system. The article Earth systems and climate change looks at the holistic nature of the Earth system from scientific and te ao Māori perspectives.
Nature of science
This topic shows how science is a way of explaining the world and how scientists work together to do this. In studying this, students will be able ask questions, find evidence and share and examine knowledge.