Which phenomenon describes the increase in Earth's average surface temperature?

Global warming refers specifically to the observed increase in the Earth's average surface temperature due to the accumulation of greenhouse gases in the atmosphere. This phenomenon is largely driven by human activities, such as the burning of fossil fuels and deforestation, which increase concentrations of carbon dioxide, methane, and other greenhouse gases. As these gases trap heat from the sun, they lead to a warming effect, resulting in climate changes with widespread impacts.

In contrast, climate variability encompasses variations in climate patterns over time that may not necessarily correlate with long-term trends in temperature. Ozone depletion pertains to the thinning of the ozone layer in the stratosphere, which is not directly related to surface temperature increases. The greenhouse effect describes the natural process by which certain gases trap heat, but it doesn’t specifically denote the recent and significant rise in global average temperatures, which is the central focus of global warming. Thus, global warming is the most precise term to describe the increase in Earth's average surface temperature.