Forests and other land ecosystems failed to mitigate climate change in 2023, as severe drought in the Amazon rainforest and record wildfires in Canada hindered their natural capacity to absorb carbon dioxide, according to a new study released on July 30.

The combination of fires and drought in the Amazon led to a record amount of CO2 entering Earth's atmosphere last year, when these forests should have been taking gigatonnes of CO2 out of the atmosphere, the researchers reported.

Plant life plays a crucial role in combating climate change by absorbing large amounts of CO2, the primary greenhouse gas (GHG) driving global warming. Typically, forests and other land ecosystems fix nearly a third of annual emissions from fossil fuels, industry and other human activities, or approximately 7.6 gigatonnes of CO2 compared with the circa 40 gigatonnes humanity is currently producing a year.

Removing the absorption of CO2 by plant life will accelerate the depletion of the carbon budget that was allotted by the Paris Agreement in 2015 and make it less likely that temperature increases can be limited to the 1.5C goal. As bne IntelliNews reported, the trees are already coughing due to heat stress and drought and fixing less CO2 than normal. Wildfires obvious only make the situation worse.

But in 2023, that carbon sink collapsed, according to study co-author Philippe Ciais of the Laboratory for Climate and Environmental Sciences (LSCE), a French research organisation.

"The sink is a pump, and we are pumping less carbon from the atmosphere into the land," Ciais explained in an interview cited by the Japan Times. "Suddenly the pump is choking, and it's pumping less."

As a consequence, the growth rate of CO2 in the atmosphere surged by 86% in 2023 compared to the previous year, the researchers found.

Other research as estimated that the Canadian wildfires last year emitted a total of 2.8 gigatons of CO2 – a bit less than half of all the CO2 trees normally absorb – and this year the total of CO2 already released is up to 3 gigatonnes. If the wildfires blazing in Russia and North America are added then the entire annual stock of carbon that trees normally absorb is believed to have been used up and the fires have been a net contributor to CO2 levels this year, accelerating the Climate Crisis.

The study, conducted by scientists from Tsinghua University in China, the University of Exeter in England and LSCE, was presented at the International Carbon Dioxide Conference in Manaus, Brazil. It identified record high global temperatures as a major factor contributing to the wildfires.

High temperatures have left vegetation tinder dry in the Amazon and other rainforests. Drought also reduces plants ability to take up carbon.

"Imagine your plants at home: If you don't water them, they're not very productive, they don't grow, they don't take up carbon," said Stephen Sitch, a co-author of the study and a carbon expert at the University of Exeter. "Put that on a big scale like the Amazon forest," Sitch added during the conference.

Although the study is still undergoing peer review, three independent scientists confirmed its conclusions as credible. They noted that reductions in land carbon sinks are more common during years influenced by the El Niño climate phenomenon, as was the case in 2023. However, the record high temperatures driven by climate change made the reduction particularly severe.

Moreover, the consequences are more dire now as human activities are emitting more CO2 than ever before; emissions are currently at an all-time high. The scientists cautioned that while fluctuations in the Earth's carbon sink are typical, the 2023 observations are concerning if they become a trend.