A report by the World Meteorological Organisation (WMO) has raised alarm over the surge in greenhouse gases, committing the planet to rising temperatures for many years to come.

The WMO reported that carbon dioxide (CO2) is accumulating in the atmosphere at an unprecedented rate, rising by more than 10 per cent in just two decades.

The organisation’s annual Greenhouse Gas Bulletin, published on its website, revealed that during 2023, large vegetation fires, reduced carbon absorption by forests, and persistently high CO2 emissions from human and industrial activities contributed to the rise in greenhouse gases.

“The globally averaged surface concentration of CO2 reached 420.0 parts per million (ppm), methane 1,934 parts per billion (ppb), and nitrous oxide 336.9 ppb in 2023. These values represent 151%, 265%, and 125% of pre-industrial (before 1750) levels, respectively,” the report said. “The last time the Earth experienced a comparable CO2 concentration was 3-5 million years ago when temperatures were 2-3°C warmer, and sea levels were 10-20 meters higher than today.”

According to WMO Secretary-General Celeste Saulo, this should set alarm bells ringing among decision-makers. We are clearly off track to meet the Paris Agreement goal of limiting global warming to well below 2°C, aiming for 1.5°C above pre-industrial levels. These are more than just statistics—every part per million and every fraction of a degree increase has real impacts on our lives and our planet.”

The report highlighted that the increase in CO2 levels in 2023 exceeded that of 2022, with an annual rise of 2.3 ppm marking the 12th consecutive year of increases above 2 ppm.

The Greenhouse Gas Bulletin, one of the WMO’s flagship publications, was released in preparation for the upcoming UN Climate Change Conference (COP29) in Baku, Azerbaijan.

Analysis of the emissions data revealed that nearly half of CO2 emissions remain in the atmosphere, while just over a quarter is absorbed by the ocean and nearly 30% by land ecosystems. However, this absorption varies yearly due to natural phenomena like El Niño and La Niña.

The report explained that during El Niño years, greenhouse gas levels tend to rise as drier vegetation and forest fires reduce the efficiency of land carbon sinks.

It warned of a potential vicious cycle, noting that natural climate variability could exacerbate emissions. The report suggested that in the near future, climate change might cause ecosystems to emit more greenhouse gases.

WMO Deputy Secretary-General Ko Barrett noted that wildfires could release more carbon into the atmosphere, while warmer oceans might absorb less CO2. “Consequently, more CO2 could remain in the atmosphere, accelerating global warming. These climate feedbacks pose critical concerns for human society,” Barrett said.

The report also cited the National Oceanic and Atmospheric Administration’s Annual Greenhouse Gas Index, which shows that from 1990 to 2023, radiative forcing—the warming effect of long-lived greenhouse gases—increased by 51.5%, with CO2 accounting for about 81% of the rise.

The WMO warned that as long as emissions continue, greenhouse gases will keep accumulating, driving global temperatures higher. It further cautioned that due to the long lifespan of CO2 in the atmosphere, the current temperature levels will persist for several decades, even if emissions are rapidly reduced to net zero.