Once a vital planetary safeguard against climate change, the Amazon rainforest is showing troubling signs of reversal. Scientists using satellite-based carbon tracking have confirmed that large areas of the forest are now releasing more carbon than they absorb, signaling a dangerous shift in the world’s largest tropical carbon sink. This new understanding comes from the European Space Agency’s (ESA) advanced RECCAP-2 project, which uses satellite data to map carbon flows between land and atmosphere with unprecedented accuracy. The findings carry global implications: if the Amazon continues losing its ability to store carbon, the world’s pathway to meeting the Paris Agreement’s 1.5°C target could narrow faster than expected.

From Carbon Sponge to Carbon Source

For decades, the Amazon acted as one of Earth’s most efficient carbon sinks, absorbing around 14% of all plant-based carbon uptake annually. But between 2010 and 2020, the forest lost 370 million tons of carbon, most of it concentrated in its southeastern regions areas heavily impacted by deforestation, fires, and prolonged drought. The shift is not just an environmental setback; it represents the approach of a tipping point, where damaged forest ecosystems could transition irreversibly into savanna-like conditions. Once this happens, the Amazon’s carbon storage capacity and its role in stabilizing the global climate could collapse.

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Satellites Bring Clarity from Above

Traditional methods for tracking carbon rely heavily on national estimates calculating emissions from fuel use, forest cover, and land management. These activity-based reports, while useful, often miss subtle but crucial on-the-ground changes. Satellite-based observation offers a clearer, independent perspective. Through ESA’s Earth observation programs, scientists now track carbon fluxes directly, detecting where carbon is emitted or absorbed with regional precision. The RECCAP-2 (REgional Carbon Cycle Assessment and Processes) initiative merges satellite readings, field data, and atmospheric modeling to create regional carbon budgets. These budgets allow comparisons with national inventories, helping governments verify whether their climate mitigation policies are actually working.

“Comparing inversion results with national greenhouse gas inventories can be applied regularly to monitor the effectiveness of mitigation policy,” said Simonetta Cheli, ESA’s Director of Earth Observation Programs.

Shrinking Carbon Sinks Worldwide

The Amazon is not alone in decline. ESA data show that boreal and temperate forests which make up 41% of global forest area have also begun releasing more carbon than they store. Droughts, insect outbreaks, and record wildfires across North America, Europe, and Siberia are accelerating this reversal.In the European Union, forests once absorbed about 10% of the region’s total greenhouse gas emissions, but that figure is falling sharply. Over-harvesting, aging tree populations, disease, and heat stress are steadily reducing Europe’s forest carbon sink, challenging its target of climate neutrality by 2050. ESA’s analysis also revealed that the visible, living part of forests the trees themselves store only 6% of the carbon absorbed by land between 1992 and 2019. The remaining 94% resides in soils, roots, and dead wood, the so-called “hidden carbon stores” that are rarely measured but vital for long-term stability.

The Carbon Budget Tightens

According to ESA’s January 2025 estimate, the remaining global carbon budget stands at roughly 235 gigatons of CO₂ before surpassing the 1.5°C threshold. At current emission rates, that limit could be breached within six years. The loss of forest carbon sinks compounds the challenge. Even small regional changes such as forest dieback or degradation smaller than five acres can cause outsized impacts. Between 1990 and 2020, nearly 90% of global biomass carbon loss came from small-scale disturbances covering only 15% of the affected land area.

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Protecting Old Growth and Restoring Balance

New trees can grow back, but recovery is limited. Research cited by ESA shows that regrown forests recapture only about a quarter of the carbon lost when the original trees are cleared or burned. Protecting old-growth forests, therefore, remains one of the most powerful climate strategies available. ESA scientists emphasize that national greenhouse gas inventories must now integrate satellite-based verification. This dual system combining human-reported and machine-measured data offers greater accuracy and accountability, ensuring that mitigation promises translate into real atmospheric impact.

A Wake-Up Call from Space

The latest RECCAP-2 findings turn the Amazon’s carbon decline into a planetary warning. The world’s largest tropical forest, once humanity’s best natural ally against climate change is now showing the limits of resilience under relentless pressure. As the forest releases what it once absorbed, the message from orbit is clear: the planet’s carbon safety net is unraveling, and the time to restore it is rapidly running out.

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