Extreme heatwaves reduce Earth's ability to absorb carbon: Study
A recent European Space Agency (ESA)-backed study has found that the extreme heatwaves of 2023 severely limited Earth's capacity to absorb atmospheric carbon. The heatwaves, which caused widespread wildfires and extreme droughts, also contributed to a record spike in atmospheric carbon dioxide (CO2) levels. Hawaii's Mauna Loa Observatory recorded an unprecedented 86% surge in atmospheric carbon concentrations last year, even as fossil fuel emissions rose by only ~0.6%.
Investigation into weakened carbon absorption
The study was conducted under ESA's Science for Society Near-Realtime Carbon Extremes project and Climate Change Initiative RECCAP-2 project. An international team of scientists employed global vegetation models and satellite data, to investigate the reasons behind this alarming rise in atmospheric carbon levels. The research indicated that factors other than fossil fuel emissions, such as a decline in carbon absorption by natural ecosystems, could be behind this spike.
2023 marked weakest land carbon sink performance in 20 years
The study discovered that Earth's CO2 absorption capacity dropped to merely one-fifth of its normal capacity in 2023. This is the worst land carbon sink performance in 20 years. Normally, land absorbs roughly one-third of human-made carbon dioxide emissions. Philippe Ciais of France's Laboratory for Climate and Environmental Sciences said, "30% of this decline was driven by the extreme heat of 2023," which sparked massive wildfires and caused extreme droughts in parts of the Amazon rainforest.
Wildfires and droughts weakened land's ability to absorb carbon
The 2023 wildfires and droughts caused a major loss of vegetation, further diminishing the land's capacity to absorb carbon dioxide. This was compounded by a particularly strong El Nino event, which historically decreases carbon absorption capacity in the Tropics. The wildfires across Canada and Amazon droughts last year emitted roughly as much carbon into the atmosphere as North America's entire fossil fuel emissions, underscoring climate change's devastating impact on natural ecosystems.
Amazon shows signs of long-term strain
The Amazon rainforest, one of the world's most important carbon sinks, is showing signs of long-term stress. Some areas are shifting from absorbing carbon to becoming net sources of carbon emissions. The researchers say this declining capacity may indicate that these natural carbon sinks are reaching their limits, and can no longer offer the mitigation service they have historically provided by absorbing almost half of human-induced CO2 emissions.
More ambitious emission reductions needed to combat climate change
Ciais emphasized that "achieving safe global warming limits will require even more ambitious emission reductions than previously anticipated." The study also suggests that current climate models may be underestimating the rapid pace and impact of extreme events like droughts and fires on these crucial carbon reservoirs. Stephen Plummer, ESA Earth Observation Applications scientist, stressed the importance of understanding the knock-on effects of climate change on the carbon cycle.
