Today is Earth Day, a worldwide annual event that spreads awareness about how we can protect our planet from issues such as pollution, deforestation and global warming.
Last year, global leaders attended the United Nations Climate Change Conference (widely known as COP26) to discuss how the world can increase action to tackle the climate crisis, a key talking point of which was how to limit greenhouse gas emissions.
Carbon dioxide and other greenhouse gases, such as methane, cause heat to become trapped in Earth’s atmosphere, leading to a warming effect.
Levels of carbon dioxide in our atmosphere are more than 50% higher than before the Industrial Revolution, according to statistics from the Met Office.
In 2020, the global average temperature stood at 1.2C above pre-industrial levels, according to the World Meteorological Organisation’s State of the Global Climate 2020 report.
196 countries are currently signed up to the The Paris Agreement, which is a legally binding international treaty on climate change. The goal is that collectively we will cut emissions to help limit global warming to preferably 1.5C, compared to pre-industrial levels.
The 1.5C figure is considered important, because above that level of rise, there will be more heatwaves, extreme weather events and droughts – leading to economic losses, forced migration and loss of human life.
Carbon dioxide accounts for roughly 76% of carbon emissions, followed by methane (mostly from agriculture) at 16%, according to America’s Environmental Protection Agency.
But CO2 emissions vary widely by country, as well as by industry, with 60% of global CO2 emissions coming from the power and industry sector, according to the UN’s Intergovernmental Panel on Climate Change.
Which countries emit the most greenhouse gases?
China emitted 11.58 billion tonnes of CO2 in 2016, compared to the US's 5.83 billion tonnes, according to data from Our World in Data and the World Resources Institute.
India emitted 3.24 billion tonnes, and Russia emitted 2.39 billion tonnes (see chart below).
China, India, Saudi Arabia and Turkey are together responsible for around a third of global emissions and have not yet come forward with new emissions goals.
Which countries emit the most greenhouse gas per capita?
While China, which has the world’s largest population, is the biggest overall emitter, it is not in the top 10 countries with the highest emissions per capita.
The world’s largest per capita CO2 emitters tend to be major oil-producing countries, particularly those with small populations such as Qatar and Kuwait.
Guyana has become the world’s greatest per capita emitter after the discovery of a major offshore oil and gas field.
Guyana's petroleum development is just beginning, although politicians in the country claim the revenue from the oil will help investment in renewable and alternative energy sources.
In terms of total carbon emitted over time, China is in second place to the US, according to research by Carbon Brief.
Carbon Brief’s analysis of total carbon emissions by countries around the world since 1850 shows that the US is the biggest polluter in history, with China close behind.
The UK ranks in eighth place.
Carbon Brief found that humans have pumped a total around 2,500 billion tonnes of CO2 into the atmosphere since 1850 (taking into account both industrial emissions and emissions due to changes in land use) – with the US responsible for 20% of this total.
Which industries emit the most carbon dioxide?
Three-quarters of greenhouse gas emissions come from the energy sector (including energy for transport, heating buildings and use in industry), according to statistics from Our World in Data and the World Resources Institute.
Transport represents 16.2% of greenhouse gas emissions, with 1.9% from the aviation sector alone, mostly in the form of CO2.
In agriculture (responsible for 18.4% of global emissions), 4.1% of total global emissions comes from agricultural soils, where nitrous oxide (a greenhouse gas) is emitted when nitrogen fertilisers are applied to soils.
Another 5.8% of the global total comes from livestock and manure, from animals such as cattle and sheep that produce large amounts of methane as they digest grass.