The term "global average" refers to an overall measure or calculation that takes into account data from various sources, regions, or time periods. In other words, it is a statistical representation of the world as a whole, based on information gathered from different parts of the globe.
When used in the context of climate change, "global average temperature" refers to an annual measure of the Earth's surface temperature, taking into account readings from weather stations, ships and buoys at sea, and remote sensing data from satellites. This global average temperature is a key indicator of how our planet is responding to increasing levels of greenhouse gases in the atmosphere.
In summary, "global average" refers to an overall measure or calculation that takes into account various sources, regions, or time periods, providing a snapshot of the world as a whole.