Earthquakes jolt and shake us. Volcanoes erupt, shooting ash and hot gases into the atmosphere and pouring molten rock over the land. Great mountain ranges gradually inch upward, over the course of millennia.
Earth’s geosphere is constantly moving and changing, and the energy for all that movement comes from Earth’s internal heat.
On this page
- What is Earth's internal heat?
- Earth system models about Earth’s internal heat
- How human activities are influenced by Earth’s internal heat
- Explore the Earth System
- Links to Learn More
For the classroom:
Global Change Infographic
Earth’s internal heat contributes to the energy budget, specifically the energy available on Earth that drives system processes in the geosphere. Earth’s internal heat is an essential part of How the Earth System Works. Click the image on the left to open the Understanding Global Change Infographic. Locate the Earth’s internal heat icon and identify other Earth system processes and phenomena that cause changes to, or are affected by, Earth’s internal heat.
What is Earth's internal heat?
Adapted from the USGS
Most of Earth’s internal heat is left over from when our planet formed, about 4.5 billion years ago. Earth and the other planets in the solar system first began to take shape as countless smaller bodies collided and clumped together. The energy of those violent collisions transformed into heat energy. As the early Earth grew bigger, gravity began pulling matter toward the center. The intense compression of material deep inside the Earth increased internal heat even further.
Once temperatures were high enough, the element iron began to melt and sink toward the center, as less dense material rose towards the surface. The friction of the iron moving down through the other material generated even more heat. As denser material sank, layers formed inside the Earth: A core primarily made of iron, the less dense mantle, and even less dense crust (to learn more about the structure of the Earth, visit the plate tectonics page).
Since its formation, the Earth has been losing heat to space. Certain elements, known as radioactive elements such as potassium, uranium, and thorium, break down through a process known as radioactive decay, and release energy. This radioactive decay in Earth’s crust and mantle continuously adds heat and slows the cooling of the Earth.
After 4.5 billion years, the inside of the Earth is still very hot (in the core, approximately 3,800°C – 6,000°C), and we experience phenomena generated by this heat, including earthquakes, volcanoes, and mountain building.
While Earth’s internal heat is the energy sources for processes like plate tectonics and parts of the rock cycle, it provides only a fraction of a percent to the Earth’s average atmospheric temperature. Overall, Earth’s interior contributes heat to the atmosphere at a rate of about 0.05 watts per square meter while incoming solar radiation adds about 341.3 watts per square meter.
Earth system models about Earth’s internal heat
This Earth system model is one way to represent the essential processes that are related to the Earth’s internal heat, including plate tectonics and the rock cycle. Hover over the icons for brief explanations; click on the icons to learn more about each topic.
Download the Earth system models on this page.
Earth’s internal heat shapes global landforms and environments through processes in the geosphere. This model shows some of the phenomena that result from plate tectonics and the rock cycle, including mountain building, volcanism, and the distribution of continents and oceans. These phenomena, ultimately driven by Earth’s internal heat, have far-reaching effects on other parts of the Earth system, including wind patterns and airborne particles in the atmosphere, and species ranges in the biosphere.
How human activities are influenced by Earth’s internal heat
The use of Earth’s internal heat as a renewable energy source can decrease the burning of fossil fuels and the impact of humans on the Earth system. Hover over or click on the icons to learn more about these human causes of change and how they influence the Earth system.
Explore the Earth System
Click the icons and bolded terms on this page to learn more about these process and phenomena (e.g. plate tectonics, evolution, etc.). Alternatively, explore the Understanding Global Change Infographic and find new topics that are of interest and/or locally relevant to you.
To learn more about teaching Earth’s internal heat, visit the Teaching Resources page.