The carbon footprint of an event is the total increase in greenhouse gas emissions caused as a result of the event. The same can be defined for any activity, including your professional or personal activity. To bring it down to a number, carbon footprints are usually measured in some mass of equivalent carbon dioxide (e.g., 1 ton of CO₂e). Of course, this indicator is only relevant to the climate crisis, and should not obscure the many other environmental issues that we currently face.