According to the UN, the world is on course for a catastrophic temperature rise of 2.7°C (4.9°F) if we don't change our habits fast. Despite targets to reduce our collective carbon footprint by 2030, many countries are still polluting the planet through fossil fuels and deforestation. But which are the worst offenders? As the COP26 climate conference begins, read on to discover the 20 most polluting countries, using 1850-2021 data from climate science website Carbon Brief.

In 20th place is Iran, which produced 21.6 billion tonnes of carbon dioxide emissions from 1850 to 2021. While 19.7 billion tonnes have come from fossil fuels, the remaining 1.9 billion tonnes have come from changes in land use. This includes deforestation, according to Carbon Brief. It's currently unclear whether the Iranian president Ebrahim Raisi will attend the COP26 climate summit.

COP26 co-host Italy has produced 23.4 billion tonnes of carbon dioxide emissions since 1850. And data from the online tool Energy Policy Tracker shows that the Italian government has invested at least $4.36 billion (£3.2bn) into fossil fuels since the start of the coronavirus pandemic in March 2020. However, this figure is dwarfed by the $49.09 billion (£35bn) it's pumped into clean energies. This includes a $3.7 billion (£2.6bn) investment into hydrogen technologies and a $1.3 billion (£942m) investment into agrivoltaics, the development of land for both agriculture and solar energy. 

For many westerners, Thailand is their idea of a tropical paradise – but the country is actually one of the most polluting, and polluted, places on earth. According to Carbon Brief, Thailand has produced 24.1 billion tonnes of carbon dioxide emissions since the start of industrialisation. Of this, 7.7 billion tonnes has come from fossil fuels while 16.4 billion tonnes has come from land use. Previous estimates haven't taken pollution from land use into consideration, but Carbon Brief's updated criteria have pushed Thailand into the top 20 for the first time ever. 

The 17th most polluting country is Poland, which has produced 28.1 billion tonnes of carbon dioxide emissions since 1850. It has the worst air quality of any country in Europe, mainly due to its longstanding reliance on coal. According to Energy Policy Tracker, the Polish government has invested at least $6.47 billion (£4.7bn) in fossil fuels since the start of the pandemic. But recent figures suggest the country is starting to diversify. It's also funnelled $7.64 billion (£5.5bn) into clean energy investments, while a draft document in June 2021 revealed plans to close Poland's most polluting power plant in Bełchatów by 2036. 

Having produced 28.5 billion tonnes of carbon dioxide since 1850, South Africa is the 16th most polluting country in the world. Unsurprisingly, the bulk of this has come from fossil fuels. South Africa is heavily dependant on coal, which is responsible for around 80% of its CO2 emissions, according to Carbon Brief. Energy Policy Tracker reports that the South African government has burnt through $637.41 million (£462m) to support the fossil fuel industry since the start of the pandemic, while it's committed no money to clean energies. 

Mexico has contributed 31.8 billion tonnes of CO2 to the atmosphere since 1850, with about two-thirds coming from fossil fuels and the remaining third coming from land use. According to an article in the Yucatan Times, Mexico's greenhouse gas emissions grew by 62% from 1990 to 2019, due in part to the country's electrical generators, high levels of traffic, and cattle and beef industry. Unfortunately, the situation isn't improving. Mexico's fossil fuel investments have outweighed its clean energy investments by over 800% since March 2020. 

Like Thailand, Argentina is a new addition to the top 20 list. The majority of its 32.3 billion tonnes of CO2 has come from land use, with just 8.6 billion tonnes generated by fossil fuels since 1850. Deforestation is one of the major environmental crises facing the country. According to a report by the World Wildlife Fund (WWF), Argentina boasted 105 million hectares (1.05m square kilometres) of forest in 1914. By 2000, there was just 28-45 million hectares (280k-450k square kilometres) left. In October, it was revealed that Argentinian officials had requested changes to the UN's recent climate report. An investigative study by Greenpeace showed that Argentina, one of the world's biggest beef-producing nations, wanted the UN to remove recommendations for a plant-based diet. 

Australia has generated 35 billion tonnes of carbon dioxide since 1850. The country has come under fire in the run up to COP26 due to its 'inadequate' climate targets, which aimed to reduce CO2 emissions by 26-28% from 2005 levels by 2030. Prime Minister Scott Morrison has now announced that Australia will achieve net-zero carbon emissions by 2050. But many have wondered how the country will manage this without closing its coal mines, which Morrison intends to keep open as long as possible. Like Argentina, Australia also requested changes to the UN's climate report, urging writers to "downplay" the need to move away from coal. 

Between 1850 and 2021, France has generated 38.5 billion tonnes of carbon dioxide emissions. All of this has come from fossil fuels. According to Carbon Brief, the country's changing land use has actually reduced its overall CO2 emissions by three billion tonnes. But although France is driving investment into nuclear energy as a renewable alternative to coal, oil, and gas, Energy Policy Tracker reveals that the French government has invested more money into fossil fuels than clean energy since March 2020. 

Ukraine is the 11th most polluting country in the world and the third most polluting in Europe, according to Carbon Brief's data. Ukraine has produced 40.6 billion tonnes of carbon dioxide over the last 170 years, 30 billion of which has come from fossil fuels and 10.6 of which has come from changing land use. And it's not just CO2 pollution that the country produces. Its industries also release large quantities of polluted water, oil, metal deposits, and toxic chemicals into the Black Sea. Estimates suggest that, in some areas, the Ukrainian water supply is 10 times more contaminated than is considered safe. 

Of all the countries on this list, Canada has the most equal distribution of CO2 emissions, with 31.3 billion tonnes coming from land use and 34.2 billion tonnes coming from fossil fuels. According to a study quoted in The Globe and Mail, coal that's produced for export accounts for a whopping 45% of Canada's carbon footprint. 

In Japan, 66.7 billion tonnes of carbon dioxide emissions have been produced from fossil fuels since 1850, while 1.3 billion tonnes have been produced from land use. This brings the country's total emissions to 68 billion tonnes. Japan was an early adopter of nuclear energy but lost confidence after the Fukushima disaster in 2011, halting its plans to generate 40% of its power from nuclear fusion. By 2030, it now hopes to have restored its nuclear capacity, generating 20% of its energy requirements from nuclear power plants. To this end, the Japanese government has invested a whopping $19.06 billion (£13.8bn) into clean energy since the start of the coronavirus pandemic. 

The UK is the eighth most polluting nation in the world, and all of its 74.9 billion tonnes of carbon dioxide emissions have come from fossil fuels. Despite co-hosting the COP26 climate summit with Italy, the UK has been pumping money into fossil fuels since March 2020. According to Energy Policy Tracker, the country has invested $27.86 billion (£20bn) into clean energies and $42.19 billion (£30.5bn) into fossil fuels. This includes a £139 billion ($191bn) investment to bail out Luton Airport.

According to the World Health Organization (WHO), 14 of the world's 15 most polluted cities are in India (the other is Hotan, China). The country is reliant on fossil fuels such as coal, which powers 70% of its energy requirements. By 2030, it aims to generate 40% of its energy from renewables and nuclear – but India has also told the UN that it won't abandon coal completely within the next few decades and has rejected net-zero emissions targets.

In sixth place is Germany, the most polluting country in Europe. Since 1850, Germany has contributed 88.5 billion tonnes of carbon dioxide to the atmosphere and is home to four of the five most polluting industrial plants in the EU, according to 2016 research by the European Commission. The German government has committed almost exactly the same amount of money to fossil fuels and clean energies since the start of the pandemic, with $27.05 billion (£19.6bn) for the former and $26.94 billion (£19.5bn) for the latter. 

Indonesia is the fifth most polluting country in the world, according to Carbon Brief. Previous lists haven't included Indonesia, but when carbon dioxide emissions from changing land use are considered, the country has been responsible for a massive 102.5 billion tonnes of CO2 since 1850. The country has given $6.54 billion (£4.7bn) to fossil fuel-using companies since the start of the pandemic, mainly to bail out its local airlines and oil and gas plants. By contrast, it's given just $240.02 million (£174bn) to clean energies, although the Indonesian government has said that it aims to reduce greenhouse gas emissions by 29% through its own efforts and 41% with international aid by 2030.

Like Indonesia, Brazil is a new addition to the top 20 most polluting countries. This is because the majority of its 112.9 billion tonnes of CO2 have come from changing land use and deforestation. Although much of the world saw carbon dioxide emissions decrease during the pandemic, Brazil's emissions rose by a whopping 9.5%, according to research published by Reuters. The study concluded that "deforestation continues to dominate [Brazil's] emissions". But although President Bolsonaro has promised to end illegal deforestation by 2030, it might not be quick enough. The country's catastrophic forest fires and soaring emissions now hospitalise 47,000 people every year due to wildfire air pollution. 

Since 1850, Russia has choked out 172.5 billion tonnes of carbon dioxide emissions. Water and air pollution are both rife in the country, with up to 60% of drinking water failing to meet sanitary standards. It's long been a problem – until 1991, studies suggest that the Soviet Union generated almost twice as much pollution per unit of gross national product (GNP) as the US. But the Russian government isn't doing enough to solve it. President Putin, who won't be attending COP26, has committed no money to clean energy since the start of the pandemic and $5.18 billion (£3.76bn) to fossil fuels. The country is heavily reliant on coal and gas and is one of the world's largest exporters, something the EU has accused it of "weaponising" during the ongoing energy crisis. 

 

With cumulative CO2 emissions of 284.4 billion tonnes since 1850, China is the world's second biggest polluter. Like Putin, President Xi won't be attending the COP26 climate summit in person. On 28 October, the country published its national plan to limit greenhouse gas emissions – but many believe its targets are too little too late. According to the plan, China's emissions will peak in 2030 and be reduced to net zero within the following three decades. An article in the Guardian claims that this plan of action is insufficient and doesn't support global aims to limit global warming by 1.5°C (2.7°F) above pre-industrial levels. 

By a landslide, America is the most polluting country in the world. Carbon Brief's data shows that the US has generated a staggering 509.1 billion tonnes of carbon dioxide since 1850, almost 225 billion tonnes more than China. The US is the only country that's committed more money to fossil fuels since March 2020 than the UK, having pledged an enormous $72.35 billion (£52.5bn). But with President Biden at the helm, clean energy is back on the agenda. Biden aims to cut America's greenhouse gas emissions by 50-52% by 2030, and the framework includes $555 billion (£403bn) of incentives to boost the renewable energy sector. 

Now see the countries facing an energy crisis