A large international study has found that, on average, trees across the Amazon are increasing in size by just over three percent every ten years. Scientists often call the rainforest the “lungs of the planet” because it absorbs carbon dioxide and releases oxygen, and this new finding shows that those lungs may be expanding.

The research team, made up of nearly one hundred scientists from more than sixty universities across South America, the United Kingdom, and beyond, studied trees in 188 permanent forest plots. Their measurements revealed that the average tree size across the Amazon has risen by 3.2 percent per decade, a change that closely mirrors the rise in atmospheric carbon dioxide.

The study also found that this trend has been happening for at least three decades, and that both small and large trees are growing thicker trunks. Co-author Professor Beatriz Marimon from Universidade do Mato Grosso described the results as “a good news story.” She noted that while the world often hears about the dangers climate change poses to the Amazon, the trees in intact forests have continued to thrive. “Even the largest trees have grown bigger despite these threats,” she said.

But the scientists behind the research were careful not to suggest the forest is out of danger. Deforestation, fire, and climate extremes still threaten the region. Professor Tim Baker from the University of Leeds explained that the total amount of carbon stored in intact Amazon forests has increased, but this growth depends on protecting those ecosystems. “What this new study shows,” he said, “is that all sizes of tree have grown larger over the same period. The whole forest has changed.”

The results highlight how resilient the Amazon can be when left undisturbed, but they also serve as a reminder that this balance is fragile. The rainforest may be getting stronger, but it still needs protection to keep breathing life into the planet.