Greenhouse gas (GHG) levels surged to a new record in 2023, committing the planet to rising temperatures for many years to come, according to a report from the UN’s World Meteorological Organisation (WMO).

In fact, CO₂ is building up in the atmosphere faster than any time previously, accelerating by more than 11% in two decades. CO2 concentrations have increased 11.4 % in just 20 years, said WMO.

The organisation said that the long lifetime of CO2 in atmosphere “locks in future temperature increase”.

The weather phenomenon El Niño and wildfires have fuelled the surge in the second of of 2023.

Global carbon dioxide emissions from forest fires have surged by 60% since 2001, with emissions nearly tripling in some of the most climate-sensitive boreal forests, said a study published in the journal Science earlier in October.

The effectiveness of carbon sinks such as forests cannot be taken for granted, cautioned WMO, while an improved understanding of carbon-climate feedbacks is needed.

The globally-averaged surface concentration of CO₂ reached 420.0 parts per million (ppm), methane reached 1,934 parts per billion and nitrous oxide 336.9 ppb in 2023, said WMO.

These values are 151%, 265% and 125% of pre-industrial or 1750 levels, it said.

“Another year. Another record. 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 and 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 temperature increase has a real impact on our lives and our planet,” said WMO Secretary-General Celeste Saulo.

The 2023 increase of CO₂ in the atmosphere was higher than that of 2022, although lower than that of the three years before that. The annual increase of 2.3 ppm marked the 12th consecutive year with an increase greater than 2 ppm, said WMO.

The WMO Greenhouse Gas Bulletin is one of WMO’s flagship publications, and is released to inform the UN Climate Change conference, COP. Later in November, COP29 will start in Baku, Azerbaijan.

During that time the CO₂ level has increased by 11.4 % (42.9 ppm) above the level of 377.1 ppm recorded in 2004 by WMO’s Global Atmosphere Watch network of monitoring stations.

The Greenhouse Gas Bulletin reports on greenhouse gas concentrations, rather than on emission levels. Analysis of data shows that just under half of CO₂ emissions remain in the atmosphere. Just over one quarter are absorbed by the ocean and just under 30% by land ecosystems – although there is considerable year-to-year variability in this because of naturally occurring phenomena like El Niño and La Niña.

The Greenhouse Gas Bulletin complements the UN Environment Programme’s just-released Emissions Gap report.

“The Bulletin warns that we face a potential vicious cycle. Natural climate variability plays a big role in carbon cycle. But in the near future, climate change itself could cause ecosystems to become larger sources of greenhouse gases. Wildfires could release more carbon emissions into the atmosphere, whilst the warmer ocean might absorb less CO₂. Consequently, more CO₂ could stay in the atmosphere to accelerate global warming. These climate feedbacks are critical concerns to human society,” said WMO Deputy Secretary-General Ko Barrett.