Is CO2 the only greenhouse gas causing global warming?

When it comes to global warming and the climate crisis, CO2 _is the first thing that comes to mind. In fact, it is just one of the greenhouse gases that cause the Earth to heat up.

Carbon dioxide (CO ₂ ) accounts for about 70% of global greenhouse gas emissions, the rest being methane (CH ₄ ), nitrous oxide (N ₂ O) and fluorinated gases (F-gas).

Methane

Methane is the second most important greenhouse gas for global warming after carbon dioxide.

About 40% of methane comes from natural sources, mostly from wetlands, and 60% comes from human activities such as agriculture (livestock and rice farming), fossil fuels, and waste.

The global warming potential (gwp) of CH ₄ is on average 28 times higher than that of CO ₂ , but its lifetime in the atmosphere is shorter. Therefore, it is of great interest in short-term global warming mitigation efforts.

_{Reducing CH 4} emissions is very effective for cooling the Earth in the short term because the concentration of CH ₄ in the atmosphere will decrease rapidly, said researcher Mathijs Harmsen at the Netherlands Environmental Assessment Agency .

However, despite the global commitment to reduce greenhouse gas emissions that many countries, including the US and the European Union, have signed, the situation is not positive.

In a research report from the Global Carbon Project, scientists found that CH4 is increasing faster than other greenhouse gases and is now 2.6 times higher than pre-industrial levels.

Currently, greenhouse gas emissions are mainly caused by humans, most of which are from the use of fossil fuels (Illustration: Getty).

Nitrous oxide

The global warming potential of N ₂ O is nearly 300 times greater than that of CO ₂ .

_{N 2} O emissions are mainly from synthetic nitrogen fertilizers and manures used in agriculture. Other sources include human activities (chemical industry, wastewater, fossil fuel use) and natural sources (soil and ocean).

The key to solving the problem is to use fertilizers more efficiently. The potential to reduce climate change-related N ₂ O emissions could be improved by two-thirds if we reduced fertilizer use on just 20% of the world's cropland, especially in subtropical agricultural regions.

Fluoritizing gases

F-gases include: PFCs, HFCs, CFCs and SF6 , used in refrigeration (refrigerators and freezers), heat pumps, air conditioning and electrical networks.

Although the amount used is very small, these gases have an extremely strong greenhouse effect. For example, SF6, used in power transformers, has a harmful effect 24,000 times that of CO2 over a period of 100 years.

In 1987, 195 countries ratified the Montreal Protocol with the main goal of significantly reducing CFCs in the atmosphere.

In 2016, the Kigali Agreement also aimed to phase out the use of HFCs. And most recently, in 2023, the European Union signed a treaty to phase out the sale of appliances containing F-gas, with a view to completely eliminating these products by 2050.