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Understanding what carbon dioxide (CO2) emissions are ‒ and above all where they come from ‒ is key to understanding the global debate about climate change and how governments, companies, and individuals can contribute to the fight against global warming.
CO2 emissions are created from burning fossil fuels coal, oil and natural gas needed for activities like transportation, heating, and industry. Carbon emissions make up nearly all the greenhouse gas emissions from human activity that cause global warming.
Let’s look at carbon emissions by source, sector by sector. Overall, the biggest chunk of greenhouse gases – about two thirds – come from burning fossil fuels for any and all purposes.
In the United States, the biggest source of carbon emissions in 2019 was transportation by car, truck, ship, train and airplane, which accounted for 29% of the total, according to the Environmental Protection Agency (EPA), the U.S. regulatory agency. Electricity generation followed closely in second place, with 25%. Approximately 62% of electricity consumed in the United States is produced by burning fossil fuels, mostly coal and natural gas, the EPA said. Industry accounted for 23%; while commercial and residential use (mostly for heating) generated 13% of the total. Agriculture generated 10% of carbon emissions, and land use produced 12% since even managed forests can consume more C02 than they produce.
Globally, the biggest source of greenhouse gas emissions in 2016 by activity was manufacturing and construction, accounting for 24.3% the total, according Earth Charts based on data from the IEA and Climate Watch. Road transport accounted for 12.1% (with total transport rising to 16.5%). Agriculture and residential uses were similar, at 11.9% and 11% respectively. These figures do not strip out the energy sector, however. For the Intergovernmental Panel on Climate Change, energy accounted for 29.3% of global greenhouse gas emissions in 2014, followed by 19.5% for transport and 19% for industry.
Most of the world’s carbon emissions come from relatively few countries, says the Center for Climate and Energy Solutions (C2ES). The biggest three emitters are the United States, China, and the countries of the European Union. The other three of the top “big six” emitters are Russia, India and Japan. Only the EU, however, has set targets to reduce its C02 emissions to at least 55% below 1990 levels by 2030. Most other countries have set C02 reduction targets for 2050.
Per capita, the United States (at nearly 19 tons) and Russia (at nearly 18 tons) had the highest per capita production of greenhouse gas emissions in 2018 – compared to a global average of 6 tons, according to the C2ES. The EU, Japan and China all hovered just above the average, at around 8 tons per person. Keep in mind that in order to meet the Paris Agreement goal of under 1.5 C rise in temperature by 2050, average per person emissions would need to be around 2 tons by 2030, said the UN’s 2020 Emissions Gap Report.
The topic of emissions by country is complex, because it is impacted by history. In terms of cumulative emissions from 1751 to 2017, the United States and the EU-28 top the charts with 25% and 22% of the total, respectively, according to a chart from Our World in Data. If you add in Turkey and Russia to the EU total, it comes to 33%. Asia accounts for a total of 29%, of which China’s share is by far the largest with 12.7%.
If you look instead at the growth in absolute emissions as measured by tons in 2019, China, Russia and India are increasing their emissions, while emissions are falling in the EU, the US and Japan. Reducing carbon emissions is a global endeavor involving complex agreements negotiated annually by hundreds of counties in a process known as Conference of the Parties, or COP. The economies of China and Russia are more dependent on fossil fuels, and argue they need more time to meet C02 reduction targets.
Given that fossil fuels are the largest contributor to world carbon emissions by energy source, the energy transition from fossil fuels to renewable sources is crucial to guaranteeing a sustainable growth and a future with fewer extreme weather events caused by global warming. About one fifth of the world’s 2,000 largest publicly-listed companies have set some sort of net-zero carbon emissions target to become carbon-neutral by 2050, according to a 2021 report by UK-based Energy and Climate Intelligence Unit (ECIU) and Oxford Net Zero ‒ even though there is some debate about how to measure those pledges. The increase in natural gas prices in 2022 may help drive the energy transition to renewable sources, along with evidence that climate change puts life as we know it today increasingly at risk.