As awareness of climate change grows, so does the desire to do something about it. But the scale of the problems it causes—from wildfires to melting glaciers to droughts—can seem utterly overwhelming. It can be hard to make a connection between our everyday lives and the survival of polar bears, let alone how we as individuals can help turn the situation around.

One way to gain a quantifiable understanding of the impacts of our actions, for good and bad, is through what is known as a carbon footprint. But while the concept is gaining traction—Googling “How do I reduce my carbon footprint?” yields almost 27 million responses—it is not always fully understood.

So, what exactly is a