Analysis finds extreme heat weakens land’s ability to absorb carbon

A new study supported by the European Space Agency shows that the extreme heatwave of 2023 that caused massive wildfires and severe drought also impaired land’s ability to absorb carbon from the atmosphere. . This reduction in carbon intake has pushed atmospheric carbon dioxide levels to new highs, fueling concerns about accelerating climate change.

Measurements from Hawaii’s Mauna Loa Observatory show atmospheric carbon levels rose 86% in 2023 from the previous year, the highest level since tracking began in 1958.

Despite this sharp increase, fossil fuel emissions only increased by about 0.6%, suggesting that other factors, such as weakening carbon uptake by natural ecosystems, may have caused the surge. are.

With support from ESA’s Science for Society’s Near Real-Time Carbon Extremes Project and the Climate Change Initiative’s RECCAP-2 project, an international team of scientists will analyze global vegetation models and satellite data to investigate the root causes. , quickly produced a 2023 carbon balance report.

Typically, land absorbs about one-third of the carbon dioxide emitted by humans. But the team’s study, published in the National Science Review, shows that by 2023, this capacity will fall to just one-fifth of normal levels, making land’s ability to absorb carbon dioxide the weakest it has been in 20 years. It became clear that

The graph above shows the decline in northern land carbon uptake (blue) and the change in tropical land fluxes (green) from 2015 to 2023. The solid line reflects analysis using a dynamic global vegetation model, and the dotted line is based on data from the NASA-JPL Orbiting Carbon Observatory 2 mission.

“Our research shows that 30% of this decline is due to the heat wave in 2023, which triggered massive wildfires and caused widespread damage in Canada,” said Philippe Sier of France’s Institute of Climate and Environmental Sciences. It destroyed vast areas of forest and caused severe drought in many places.” of the Amazon rainforest.

“These fires and droughts have caused significant vegetation loss and weakened the carbon absorption capacity of terrestrial ecosystems. This has been exacerbated by particularly strong El Niños, which have historically reduced the carbon absorption capacity of the tropics. did.”

Wildfires across Canada and drought in the Amazon in 2023 will release nearly as much carbon into the atmosphere as all of North America’s fossil fuel emissions, highlighting the serious impact of climate change on natural ecosystems. It became.

The Amazon, one of the world’s most important carbon sinks, is showing signs of long-term strain, with some regions moving from being carbon sinks to becoming net carbon emitters.

Researchers believe that the decline in the carbon absorption capacity of Earth’s terrestrial ecosystems means that these natural carbon sinks, which have historically provided up to half of anthropogenic carbon dioxide emissions by absorbing half of them, are nearing their limits. The authors suggest that this may indicate that they are no longer able to provide mitigation services.

“Achieving safe global warming limits will therefore require even more ambitious emissions cuts than previously anticipated,” said Philippe Siais.

The study also highlights that current climate models may underestimate the rapid pace and impact of extreme events such as droughts and fires on the degradation of these critical carbon reservoirs. There is.

ESA Earth Observation Applied Scientist Stephen Plummer said: “Understanding the knock-on effects of climate change on the carbon cycle is essential and two ESA research projects are developing methodologies to quickly assess the carbon cycle. “This demonstrates the importance of Earth observation in the world.” It affects all over the world. ”

Clement Albergel, Acting Head of ESA’s Actionable Climate Information Section, said: “Given the difficulty the world has in limiting warming to 1.5°C, as stipulated in the Paris Agreement, , these results are particularly worrying.”