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Inquiry questions
How do global systems rely on interactions in chemical spheres?
Why is the carbon cycle important?
How does the Earth stay warm to sustain life?
Chapter introduction
In 1946, a rocket captured the first glimpse of Earth from space. In 1968, Apollo 8 provided a detailed view of Earth, prompting a new understanding of it as a global system.
We discuss the Earth's interconnected spheres, how humans are disrupting them, and scientists' ability to predict the future. The interactions between Earth's systems have shaped its past and will continue to shape its future.
Spheres of the Earth
Spheres of the Earth
Everything in Earth's system can be placed into one of four major subsystems: land, water, living things, or air. These four subsystems are called "spheres." Specifically, they are the "lithosphere" (land), "hydrosphere" (water), "biosphere" (living things), and "atmosphere" (air).
Activity - Complete the Earth Sphere Graphic Organiser in your books
The atmosphere
The atmosphere consists of all the gases above Earth’s surface – without it there would be no life on Earth. Two main gases make up our atmosphere: nitrogen and oxygen. There are also smaller proportions of other gases.
The composition of gases in Earth’s atmosphere
Our atmosphere in total is about 500 km thick and contains five layers: the troposphere, stratosphere, mesosphere, thermosphere and exosphere. The layers of most importance to us and other life on Earth are the troposphere and the stratosphere.
The five layers of Earth’s atmosphere
Layers in the Atmosphere
Troposphere: 6-17 km thick bottom layer of atmosphere, contains most of the air, where weather occurs
Stratosphere: extends up to 50 km, contains ozone layer, blocks harmful UV rays
Mesosphere: sits above stratosphere, colder temperature, meteors burn up due to friction
Thermosphere: largest layer, space shuttles and some satellites orbit here, ionosphere reflects radio signals and causes aurora, gases ionized by energy from the Sun
Exosphere: top layer, merges with space, communication satellites orbit here.
The biosphere
The biosphere consists of all areas of Earth and its atmosphere that contain life. It comprises all the living organisms on the planet, including plants, animals (including humans), fungi and microscopic organisms such as bacteria.
The hydrosphere
The hydrosphere is made up of all the water on Earth. This includes the oceans, rivers, lakes, glaciers, rain, water vapour, underground basins and even puddles.
Elephants, as living organisms, are part of the biosphere. Fox Glacier in New Zealand is part of the hydrosphere.
The lithosphere
The lithosphere consists of the Earth’s geological material, such as magma, lava, rocks and minerals located in the Earth’s crust and upper part of the mantle.
Uluru is part of the lithosphere.
The lithosphere is constantly in motion due to the many processes involved in the rock cycle.
The lithosphere is broken up into tectonic plates which float on top of the mantle – most earthquakes and volcanoes occur at boundaries between tectonic plates.
Natural events affecting chemical spheres
Natural events such as earthquakes and volcanoes influence the interactions between the chemical spheres.
How do natural events like volcanic eruptions and earthquakes impact the Earth's spheres and the global systems that rely on their interactions?
What are some current issues affecting society resulting from human activity on global systems, and how can scientific evidence be evaluated to address these issues?
What are some technological developments that have improved our understanding of Earth's systems and helped us make predictions about its future?
What is the significance of international agreements relating to biodiversity and climate change, and how have they impacted society and the environment?
How do ocean currents regulate global climate and marine life, and what are the key features of the El Niño and La Niña cycle?
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