Other greenhouse gases warming the planet

While carbon dioxide or CO₂is the most well-known greenhouse gas, several others, including methane and nitrous oxide, also cause global warming and change the Earth’s climate.

Methane

CON₂ accounts for about two-thirds of the warming attributed to greenhouse gases, said Piers Forster, an expert at the University of Leeds and author of reports by the IPCC, the UN panel on climate science.

Methane, or CH4, is the second most important greenhouse gas associated with human activity after CO₂.

About 40 percent of methane comes from natural sources, especially wetlands, but most (about 60 percent) is linked to human activities such as agriculture (ruminant farming and rice farming), fossil fuels and waste.

Its warming power is more than 80 times greater over 20 years than CO₂but its lifespan is shorter, making it an important lever in trying to limit global warming in the short term.

Reducing methane emissions “would have a strong, short-term cooling effect because methane concentrations in the atmosphere would drop rapidly,” said Mathijs Harmsen, a researcher at the Netherlands Environmental Assessment Agency PBL.

Policy should “focus on taking advantage of the low-hanging fruit, which means very low-cost measures such as reducing natural gas leaks,” he said.

Despite the global commitment to reduce greenhouse gas emissions signed by many countries, including the European Union and the United States, the trend is not positive.

“Methane is growing faster in relative terms than any major greenhouse gas and is now 2.6 times higher than in pre-industrial times,” said an international group of researchers under the aegis of the Global Carbon Project in a study published in the academic journal Journal Environmental research letters.

Nitrous oxide

Nitrous oxide or nitrous oxide (N₂O) is the third major greenhouse gas, almost 300 times more potent than CO₂.

It is emitted mainly by synthetic nitrogen fertilizers and manure used in agriculture.

Other emissions come from human activities (chemical industries, wastewater, fossil fuels) or from natural sources (soil and oceans).

“Global human-caused emissions, dominated by the addition of nitrogen to croplands, have increased by 30 percent over the past four decades,” concluded a large study published in the journal Nature in 2020

The key to solving the problem is to use fertilizers more efficiently.

“Two-thirds of the climate change mitigation potential of N₂O could be achieved by reducing fertilizers on just 20 percent of the world’s cropland, especially in humid subtropical agricultural regions,” wrote French researcher Philippe Ciais in 2021.

Fluorinated gases

Fluorinated greenhouse gases (PFC, HFC and SF6) are found in refrigerators and freezers, heat pumps, air conditioners and electrical networks.

Even in small quantities, they have an exceptionally high heating capacity.

For example, SF6 found in electrical transformers has a greenhouse effect 24,000 times greater than CO₂ over 100 years.

The Montreal Protocol, signed in 1987 and ratified by 195 countries, has already significantly reduced the presence of CFCs in the atmosphere – another fluorinated gas that depletes the ozone layer.

The 2016 Kigali Agreement also included the phase-out of HFCs.

Last year, the EU signed a pact to gradually ban the sale of equipment containing fluorinated gases, in particular HFCs, with the aim of eliminating them completely by 2050.

© 2024 AFP