● Express energy use and carbon emissions in understandable numbers.

There is a global need to reduce greenhouse gas emissions to limit the extent of climate change. A better understanding of how our own activities and lifestyle influence our energy use and carbon emissions can help us enable changes in activities that can lead to reductions in carbon emissions. Here we discuss an approach based on examining carbon emissions from the perspective of the unit C, where 1 C is the CO₂ from food a person would on average eat every day. This approach shows that total CO₂ emissions in China, normalized by the population, is 22.5 C while carbon emissions for a person in the US is 43.9 C. A better appreciation of our own energy use can be obtained by calculating carbon emissions from our own activities in units of C, for example for driving a car gasoline or electric vehicle a certain number of kilometers, using electricity for our homes, and eating different foods. With this information, we can see how our carbon emissions compare to national averages in different countries and make decisions that could lower our personal CO₂ emissions.