Carbon dioxide levels increase by record amount to new highs in 2024

• Carbon dioxide (CO2) levels in the atmosphere soared by a record amount to new highs in 2024, according to a new report from the World Meteorological Organisation (WMO).

• Continued emissions of CO2 from human activities and an upsurge from wildfires were responsible, as well as reduced CO2 absorption by “sinks” such as land ecosystems and the ocean – in what threatens to be a vicious climate cycle.

• Carbon sink is any system that absorbs more carbon than it emits.

• Carbon dioxide is the single most important greenhouse gas in the atmosphere.

• About half of the total CO2 emitted each year remains in the atmosphere and the rest is absorbed by Earth’s land ecosystems and oceans. 

• However, this storage is not permanent. As global temperature rises, the oceans absorb less CO2 because of decreased solubility at higher temperatures, whilst land sinks are impacted in a number of ways, including the potential for more persistent drought.  

• Growth rates of CO2 have tripled since the 1960s, accelerating from an annual average increase of 0.8 ppm per year to 2.4 ppm per year in the decade from 2011 to 2020. 

• From 2023 to 2024, the global average concentration of CO2 surged by 3.5 ppm, the largest increase since modern measurements started in 1957.

• The likely reason for the record growth between 2023 and 2024 was a large contribution from wildfire emissions and a reduced uptake of CO2 by land and the ocean in 2024 — the warmest year on record, with a strong El Nino. 

• During El Nino years, CO2 levels tend to rise because the efficiency of land carbon sinks is reduced by drier vegetation and forest fires — as was the case with exceptional drought and fires in the Amazon and southern Africa in 2024. 

• Today’s CO2 emissions to the atmosphere not only impact global climate today, but will do so for hundreds of years because of its long lifetime in the atmosphere. 

Methane and Nitrous oxide 

• Concentrations of methane and nitrous oxide — the second and third most important long-lived greenhouse gases related to human activities — have also risen to record levels. 

• Methane accounts for about 16 per cent of the warming effect on our climate by long-lived greenhouse gases and has a lifetime of about nine years. 

• Approximately 40 per cent of methane is emitted into the atmosphere by natural sources (for example, wetlands) which are sensitive to climate as well, and about 60 per cent comes from anthropogenic sources such as cattle, rice farming, fossil fuel exploitation, landfills and biomass burning.

• Nitrous oxide is the third most important long-lived greenhouse gas and comes from both natural sources and due to human activities such as biomass burning, fertilizer use and various industrial processes.