In addition to the most well-known greenhouse gas, carbon dioxide (CO2), there are other substances, such as methane and nitrous oxide, that significantly contribute to global warming and climate change on Earth. CO2 accounts for roughly two-thirds of the warming caused by greenhouse gases.

Methane (CH4) is the second most important greenhouse gas caused by human activity. About 40 % of methane comes from nature, mainly wetlands, but the remaining 60 % is produced by human activities such as agriculture, fossil fuel use and waste treatment. Methane has a warming effect that is more than 80 times stronger than CO2 over a 20-year period, but its lifetime in the atmosphere is shorter. This makes it a strategic target in efforts to limit short-term global warming. Reducing methane emissions could have a significant immediate cooling effect if its concentrations in the atmosphere were to fall. Despite global commitments from many countries, including the EU and the US, current emission trends are not optimistic. An international team of scientists led by the Global Carbon Project said that methane levels are rising faster than any other major greenhouse gas and are now 2.6 times higher than in pre-industrial times.

Nitrous oxide (N2O) is the third-largest greenhouse gas, with a warming potential almost 300 times greater than that of CO2. Nitrous oxide emissions come mainly from the use of synthetic fertilizers and manure in agriculture, but also from industrial activities, wastewater, and fossil fuels, as well as from natural sources such as soil and oceans. According to a study published in the journal Nature in 2020, global nitrous oxide emissions from human activities, primarily the application of nitrogen to agricultural land, have increased by 30 % over the past 40 years. An effective solution to the problem lies in increasing the efficiency of fertilizer use. Reductions in N2O emissions could be achieved by reducing fertilizer use to just 20 % of the world's arable land, especially in humid subtropical regions.

Fluorinated gases (PFCs, HFCs and SF6), found in refrigerators, air conditioners and electrical substations, have an extremely high greenhouse effect even in small quantities. SF6, used in electrical transformers, has a greenhouse effect 24,000 times stronger than CO2 over a 100-year period. The Montreal Protocol of 1987, ratified by 195 countries, has already significantly reduced the amount of CFCs in the atmosphere, another fluorinated gas that threatens the ozone layer. In 2016, the Kigali Agreement also agreed to phase out HFCs. Last year, the EU committed to gradually banning the sale of equipment containing fluorinated gases such as HFCs by 2050. (Co2AI )