I came across the term 'carbon footprint' for the very first time when I attended a seminar on wastewater treatment technologies and design. It was one of the seminars I attended inline with my first ever job - a researcher in an environmental research and consulting company.
One of the speakers half jokingly said that the only way we can stop polluting the earth is by being non-existent. To illustrate, he mentioned about carbon footprint and that every activity we do has an impact to the environment.
After the seminar, I read about carbon footprint in the internet and learned that jet-setting is one of the activities with the highest greenhouse gas emissions. That made me think twice about traveling and riding airplanes.