Greenhouse gases are key elements of global warming. Although carbon dioxide (CO2) remains the most publicized, other gases, less present in public discourse, play a significant role in the accumulation of heat in the atmosphere. Methane (CH4), nitrous oxide (N2O) and various fluorinated gases are added to the picture, each presenting particular properties and effects on the climate.
CO2 accounts for about two-thirds of the total warming effect caused by greenhouse gases, according to Piers Forster, an expert at the Intergovernmental Panel on Climate Change (IPCC). However, other gases, notably methane, also have a marked influence on global temperature, justifying increased attention to better understand and reduce their emissions.
Methane: a short-term lever
Methane is the second most widespread greenhouse gas, emitted mainly by human activities such as agriculture, fossil fuel exploitation and organic waste management. Around 60% of methane emissions are linked to these activities, with the rest coming from natural sources such as wetlands. This gas has a warming potential 84 to 87 times greater than that of CO2 over a 20-year period, although its lifetime in the atmosphere is relatively short. This gives methane strategic importance in efforts to reduce global warming in the short term.
Mathijs Harmsen, a researcher at the Netherlands Environmental Assessment Agency, points out that “reducing methane emissions could have a significant cooling effect, as atmospheric methane levels would fall quickly if gas leaks were reduced natural “. However, despite global commitments to reduce these emissions, including those from the United States and the European Union, methane concentrations continue to grow. The current level of methane in the atmosphere is about 2.6 times higher than in pre-industrial times, according to research by the Global Carbon Project.
Nitrous oxide: the role of nitrogen fertilizers
Nitrous oxide, also known as N2O, is a potent greenhouse gas with a warming potential nearly 300 times that of CO2 over a 100-year period. Mainly from nitrogen fertilizers used in agriculture, it is also produced by the chemical industry, wastewater treatment and the combustion of certain fossil fuels. Nitrogen inputs for crops have increased N2O emissions by 30% over the last four decades.
According to Philippe Ciais, a French researcher, better management of nitrogen fertilizers could significantly reduce nitrous oxide emissions. “A reduction in fertilizer use on just 20% of cultivated land in the humid subtropics could represent two-thirds of the climate reduction potential linked to N2O,” he explains.
Fluorinated gases: long-term effects
Fluorinated gases, although emitted in less quantity, have a particularly powerful impact on the climate. Used in refrigeration systems, air conditioners, heat pumps and electrical equipment, they include compounds like hydrofluorocarbons (HFCs) and sulfur hexafluoride (SF6), the latter having a warming effect 24,000 times greater than that of CO2 over a period of 100 years.
International agreements, such as the Montreal Protocol in 1987 and its Kigali amendment in 2016, have made it possible to reduce the use of certain fluorinated gases. The European Union also took steps last year to phase out equipment containing HFCs, aiming for a complete phase-out of these substances by 2050. These initiatives show the global desire to reduce the climate footprint of fluorinated gases, although their impact persists in the atmosphere for long periods.
As the fight against climate change intensifies, reducing greenhouse gas emissions beyond CO2 is becoming a priority. The challenge is based on concrete solutions to reduce the footprint of methane, nitrous oxide and fluorinated gases, with the aim of quickly mitigating global warming.
