What is carbon footprint?

A carbon footprint is basically the total amount of greenhouse gas emissions that anything -- a person, organization, event or product -- has produced. Greenhouse gases are the gases in the atmosphere that produce the "greenhouse effect" and contribute to global warming and climate change.

So your carbon footprint a way to measure the environmental impact your lifestyle has. For example, if you drive to work every day your carbon footprint might be bigger than someone who relies on public transport because you're emitting more greenhouse gas.

How is it calculated?

It works by summing up the emissions from all your activities -- everything from what you eat to what setting you wash your clothes with.

It's all measured in CO2e, which stands for carbon dioxide equivalent and is a standard unit for measuring carbon footprints. It essentially takes any quantity or type of greenhouse gas and expresses it in the amount of CO2 that would have the equivalent global warming impact. It just allows us to easily compare impacts across different gases.

How do you know what your carbon footprint is?

There are a number of online calculators that can help you figure out your carbon footprint, including one by The Nature Conservancy and another from the US Environmental Protection Agency.

Once you know your carbon footprint, and what part of your lifestyle contributes the most to it, you can then find ways to lessen your impact.

What does it mean to be net zero?

Net zero means achieving a balance between the greenhouse gases put into the atmosphere and those taken out.

Think about it like a bath – turn on the taps and you add more water, pull out the plug and water flows out. The amount of water in the bath depends on both the input from the taps and the output via the plughole. To keep the amount of water in the bath at the same level, you need to make sure that the input and output are balanced.

Reaching net zero applies the same principal, requiring us to balance the amount of greenhouse gases we emit with the amount we remove. When what we add is no more than what we take away we reach net zero. This state is also referred to as carbon neutral; although zero emissions and zero carbon are slightly different, as they usually mean that no emissions were produced in the first place.
 

What’s the difference between gross zero and net zero?

Given the impact that carbon emissions have on our planet, you might wonder why we aren’t aiming for zero, or gross zero, rather than net zero. Gross zero would mean stopping all emissions, which isn’t realistically attainable across all sectors of our lives and industry. Even with best efforts to reduce them, there will still be some emissions.

Net zero looks at emissions overall, allowing for the removal of any unavoidable emissions, such as those from aviation or manufacturing. Removing greenhouse gases could be via nature, as trees take carbon dioxide from the atmosphere, or through new technology or changing industrial processes.

Sources 

https://edition.cnn.com/2019/09/08/us/carbon-footprint-facts-trnd/index.html

https://www.nationalgrid.com/stories/energy-explained/what-is-net-zero