Jake Spring
SAO PAULO (Reuters) – Severe drought in the Amazon rainforest and record wildfires in Canada have undermined the natural ability of forests and other terrestrial ecosystems to absorb carbon dioxide, causing climate change to fail to curb by 2023, a study published on Monday showed.
This means a record amount of carbon dioxide entered Earth’s atmosphere last year, further contributing to global warming, researchers said.
Plants help slow climate change by absorbing large amounts of carbon dioxide, the main cause of global warming. On average, forests and other terrestrial ecosystems absorb nearly one-third of annual emissions from fossil fuels, industry and other human-induced causes.
But that carbon sink will collapse by 2023, according to study co-author Philippe Scias of the French research institute Laboratory of Climate and Environmental Sciences (LSCE).
“Carbon sinks are pumps, and they’re reducing the amount of carbon being released from the atmosphere onto land,” Siais said in an interview. “All of a sudden the pump gets clogged, and less is being released.”
As a result, the rate of increase in atmospheric carbon dioxide was 86% higher in 2023 compared to 2022, the researchers said.
The study to understand what’s causing this change was led by scientists from China’s Tsinghua University, the University of Exeter in the UK, and the LSCE, and was presented at the International Carbon Dioxide Conference in Manaus, Brazil.
The main contributing factors, the study said, were record-high temperatures around the world, drying out vegetation in the Amazon and other rainforests, preventing them from absorbing carbon, and causing record fires in Canada.
“Think about plants in your home: if you don’t water them, they’re less productive, they don’t grow as well, and they don’t absorb as much carbon,” said Stephen Sitch, a carbon expert at the University of Exeter and co-author of the study.
“Let’s make it on a massive scale, like the Amazon forest,” Sitch told Reuters on the sidelines of the meeting.
The study is still undergoing peer review by an academic journal, but three scientists not involved in the work told Reuters the findings were sound.
They say declines in land-based carbon sinks tend to occur in years affected by El Niño weather, such as 2023. But last year’s decline was particularly extreme due to record high temperatures caused by climate change.
And because humans are emitting more carbon dioxide than ever before, the effects of falling temperatures are more severe than in the past.
Scientists warned that Earth’s carbon sink varies widely from year to year and one year alone would not spell doom, but they added that what was observed in 2023 would be cause for concern if it became a trend.
“This is a warning,” said Richard Bardsey of the Woodwell Climate Research Center in the United States, who was not involved in the study. “Years like 2023 are likely to become more frequent in the future.”
The less carbon terrestrial ecosystems can absorb, the less fossil fuel the world can burn before humanity exceeds global climate targets, said Anthony Walker, an ecosystem modeller at Oak Ridge National Laboratory in the US, who was not involved in the study.
“We can’t count on ecosystems to save us in the future,” said Trevor Keenan, an ecosystem scientist at the University of California, Berkeley, who was not involved in the study.
(Reporting by Jake Spring; Additional reporting by Bruno Kelly in Manaus, Brazil; Editing by Will Dunham)
