Thermal Expansion Definition

by Laurent Cousineau

Thermal expansion can be defined as the increase in volume of matter when it is exposed to an increase in temperature.

This phenomenon occurs because particles move at higher speeds during higher temperatures and hence will take up more space.

Thermal Expansion and Climate Change

When discussing climate change, the term thermal expansion refers to the increase in volume (and simultaneous decrease in density) that occurs when water becomes warmer.

As a result, global warming will expand the ocean volume which will lead to an increase in sea levels.

Often, people will neglect thermal expansion when discussing the rise of sea level due to global warming.

However, it is important to realize that the melting of polar ice caps (and the glaciers of Greenland) will not be the only factors responsible for rising sea levels worldwide.

Therefore, scientists will need to take thermal expansion into account when they make predictions. In other words, climate change could raise sea levels even more than previously expected.


Thermal originates from the New Latin word thermalis, which comes from the Ancient Greek word θέρμη meaning “heat.”

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