A carbon footprint is a measure of the total volume of greenhouse gas (primarily carbon dioxide and methane) emissions produced by an individual, community, event, organisation, service, product, or country.
A greenhouse gas (GHG) is a gas that absorbs and emits radiant heat, creating a “greenhouse effect” that traps heat near the Earth's surface and ultimately warms the planet.
Greenhouse gases are important for maintaining a habitable temperature on Earth. However, an excess of greenhouse gases in the atmosphere can disrupt the Earth's carbon cycle and accelerate global warming. This is the scenario currently taking place, with the main source of greenhouse gases being emissions generated by excessive fossil fuel consumption. When discussing emissions on a national or global scale, carbon dioxide emissions are usually expressed in CO2 units – typically metric tonnes (1,000 kg/2,205 lb = 1 t), millions of tonnes (1,000,000 t = 1 Mt), or gigatonnes (1 billion metric tonnes/1,000 Mt = 1 GT).
Reducing the carbon footprint
Generally, developed countries have a larger carbon dioxide footprint and higher CO2 emissions per country. This is largely due to their more robust energy sectors, which burn vast amounts of fossil fuels to provide electricity, as well as a higher proportion of citizens who own their own vehicles, significantly increasing emissions. Industrial sectors such as manufacturing and meat production are also major contributors to emissions.
Countries can reduce carbon dioxide emissions in many ways. Commonly used methods include generating electricity from renewable energy sources (solar, wind, hydroelectric) rather than fossil fuels, improving energy efficiency, promoting the use of biofuels in transport, reducing CO2 emissions from vehicles, capturing greenhouse gases like methane from landfills and flue gases, applying a carbon tax to industries that generate greenhouse gas emissions, and halting deforestation.
Many countries have committed to using these and other measures to become carbon neutral, which means they absorb as much CO2 as they emit. In fact, some countries have managed to become carbon-negative nations, removing even more CO2 from the air than they add. Individuals can also reduce their carbon dioxide emissions by choosing to walk, cycle, car-share, or use public transport instead of driving a car, using reusable containers or bottles rather than single-use plastic bottles, reducing overall electricity consumption, and eating less red meat.
Carbon footprint by country
According to data from the European Union's Joint Research Centre, total global CO2 emissions rose from 34.1 GT in 2010 to 37.9 GT – a record high by 2019. The C19 pandemic and associated travel and transport restrictions caused a decrease to 35.962 GT in 2020, but emissions are expected to start rising again once the full 2021 data is available. China is the world's largest CO2 emitter, releasing 11,680 Mt (11.680 GT) of carbon dioxide in 2020. This is slightly more than 32% of the world's total emissions in 2020. The second-largest volume of carbon dioxide emissions comes from the United States, at 4.535 GT or approximately 12.6% of total global emissions.
Top ten countries producing the highest global CO2 emissions (total CO2 volume in Mt) – EU JRC 2020
China – 11,680.42
USA – 4,535.30
India – 2,411.73
Russia – 1,674.23
Japan – 1,061.77
Iran – 690.24
Germany – 636.88
South Korea – 621.47
Saudi Arabia – 588.81
Indonesia – 568.27
However, total emissions do not tell the whole story. For instance, keen observers may note that the three largest emitters are also three of the most densely populated countries on Earth, so it is logical that their emissions will be higher than countries with only a fraction of their population. To more accurately assess whether a country's policy is successfully or unsuccessfully reducing CO2 emissions, it is often useful to examine not only total emissions but also CO2 emissions per capita.
15 countries with the highest CO2 emissions per capita (t) – EU JRC 2020
Palau – 55.29
Qatar – 35.64
Trinidad and Tobago – 21.97
Bahrain – 21.60
Kuwait – 20.91
United Arab Emirates – 20.70
Brunei – 17.95
Saudi Arabia – 16.96
Oman – 16.9
Australia – 15.22
Canada – 14.43
Kazakhstan – 14.22
United States – 13.68
Turkmenistan – 13.37
Luxembourg – 13.24
According to this metric, the USA is the thirteenth highest emitter per capita (13.68 tonnes), while Russia is in 20th place (11.64), Japan in 26th place (8.39), China in 28th place (8.20), and India is in 110th place with only 1.74 tonnes per capita. Meanwhile, several developing countries occupy the top spots, primarily due to less regulated energy, industrial, and transport sectors.