# What does anthropogenic mean in terms of climate change?

Greenhouses gasses such as carbon dioxide $\left({\text{CO}}_{2}\right)$ or methane $\left({\text{CH}}_{4}\right)$ can be produced naturally in the environment through things like volcanoes or other geothermal sources. Throughout history, greenhouse gas concentrations have risen and fallen significantly over long periods of time.
The difference nowadays is that greenhouse gas emissions are increasing at a rate far beyond any sort of natural fluctuations. We know this by observing historical proxy data through things like ice core sampling, which allows us to compare historical data such as ${\text{CO}}_{2}$ concentrations with modern ${\text{CO}}_{2}$ levels.