Claim: Climate Change is Making Amazon Rainforest Trees Fatter

Essay by Eric Worrall

Excepting those Amazon trees which were bulldozed for the COP30 climate conference of course.

Amazon rainforest trees are resisting climate change by getting fatter from CO2 in the atmosphere

By Sascha Pare 

Tree trunks in the Amazon are getting 3.3% thicker every decade as the plants absorb extra carbon dioxide, suggesting they are more resilient to global warming than previously thought.

Trees of all sizes across the Amazon rainforest are getting fatter due to climate change, a new study shows.

…

“We knew that the total amount of carbon stored in the trees of intact Amazonian forests has increased,” study co-author Tim Baker, a professor of tropical ecology and conservation at the University of Leeds in the U.K., said in a statement. “What this new study shows is that all sizes of trees have grown larger over the same period — the whole forest has changed.”

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Read more: https://www.livescience.com/planet-earth/climate-change/amazon-rainforest-trees-are-resisting-climate-change-by-getting-fatter-from-co2-in-the-atmosphere

I led with the “fat trees” article because it is an admirable attempt to spin this good news into something bad, because being fat is bad right?

The university press release also attempts to maintain the tension in the face of some very good news.

Average size of trees in Amazon has increased as CO₂ levels rise

SEPTEMBER 25, 2025

by University of Birmingham
edited by Sadie Harley, reviewed by Robert Egan

Average tree size across the Amazon has increased by 3.2% every decade, consistent with a response to rising carbon dioxide levels, a new study suggests.

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Co-author of the study, Professor Beatriz Marimon, from Universidade do Mato Grosso, who coordinated much of the Brazilian data collection in southern Amazonia, commented, “This is a good news story. We regularly hear how climate change and fragmentation is threatening Amazonian forests. But meanwhile, the trees in intact forests have grown bigger; even the largest trees have continued to thrive despite these threats.”

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Joint lead author of the RAINFOR paper Dr. Adriane Esquivel-Muelbert, from the University of Cambridge—who led the research while at the Universities of Birmingham and Leeds—commented, “Ahead of COP30 in Brazil later this year, these results underscore just how important tropical rainforests are in our ongoing efforts to mitigate against man-made climate change.

“Large trees are hugely beneficial for absorbing CO₂ from the atmosphere and this study confirms that. Despite concerns that climate change may negatively impact trees in the Amazon and undermine the carbon sink effect, the effect of CO₂ in stimulating growth is still there. This shows the remarkable resilience of these forests, at least for now.”

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According to Professor Oliver Phillips of the University of Leeds, “What happens to big trees—including how they deal with increasing climate threats and manage to disperse their seeds—is now mission-critical. The only way the giants will stay healthy is if the Amazon ecosystem stays connected. Deforestation is a huge threat-multiplier and will kill them if we let it.”

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Read more: https://phys.org/news/2025-09-average-size-trees-amazon-co8322.html

No soup for Professor Beatriz Marimon, “this is a good news story” gets you in trouble with the climate community.

The abstract of the study;

Increasing tree size across Amazonia

Adriane Esquivel-Muelbert,† Rebecca Banbury Morgan,† Roel Brienen,† Emanuel Gloor,  Simon L. Lewis,† Kyle G. Dexter,† Everton Almeida,† Edmar Almeida de Oliveira,† Esteban ¡lvarez-D·vila,† Atila Alves de Oliveira,† Ana Andrade,† Simone Aparecida Vieira,† Luiz Arag„o,† Alejandro Araujo-Murakami,† Eric Arets,† Luzmila Arroyo,† Gerardo Aymard-Corredor,† Olaf Banki,† Plinio Barbosa de Camargo,† Jorcely Barroso,† Lilian Blanc,† Foster Brown,† JosÈ LuÌs Camargo,† Wendeson Castro,† Victor Chama Moscoso,† JÈrÙme Chave,† Ezequiel Chavez,† James Comiskey,† AntÙnio Carlos Lola da Costa,† Jhon del Aguila Pasquel,† GÈraldine Derroire,† Anthony Di Fiore,† Sophie Fauset,† Ted R. Feldpausch,† Gerardo Flores Llampazo,† Rene Guillen Villaroel,† Rafael Herrera,† Niro Higuchi,† EurÌdice Honorio Coronado,† Isau Huamantupa-Chuquimaco,† Walter Huaraca Huasco,† Eliana Jimenez,† Timothy Killeen,† Susan Laurance,† William Laurance,† Aurora Levesley,† Gabriela Lopez-Gonzalez,† Yadvinder Malhi,† Beatriz Marimon,† Ben Hur Marimon Junior,† Simone Matias de Almeida Reis,† Casimiro Mendoza Bautista,† Irina Mendoza Polo,† Abel Monteagudo-Mendoza,† Paulo SÈrgio Morandi,† Adriano Nogueira Lima,† Percy N˙Òez Vargas,† Nadir Pallqui Camacho,† Alexander Parada Gutierrez,† Julie Peacock,† Maria Cristina PeÒuela-Mora,† Georgia Pickavance,† John Pipoly,† Nigel Pitman,† Adriana Prieto,† Carlos Quesada,† Freddy Ramirez Arevalo,† Maxime RÈjou-MÈchain,† Zorayda Restrepo Correa,† Rocio Rojas,† Lily Rodriguez Bayona,† Anand Roopsind,† Rafael Salom„o,† Natalino Silva,† Javier Silva Espejo,† Marcos Silveira,† Juliana Stropp,† Joey Talbot,† Hans ter Steege,† John Terborgh,† Raquel Thomas,† Luis Valenzuela Gamarra,† Peter van der Hout,† Rodolfo Vasquez Martinez,† Ima CÈlia Guimar„es Vieira,† Emilio Vilanova,† Roderick Zagt,† Timothy R. Baker&† Oliver L. Phillips†

Abstract

Climate change and increasing availability of resources such as carbon dioxide are modifying forest functioning worldwide, but the effects of these changes on forest structure are unclear. As additional resources become available, for example, through CO₂ fertilization or nitrogen deposition, large trees, with greater access to light, may be expected to gain further advantages. Conversely, smaller light-suppressed trees might benefit more if their light compensation point changes, while bigger trees may be the most negatively impacted by increasing heat and drought. We assessed recent changes in the structure of Earth’s largest tropical forest by analysing 30 years of Amazonian tree records across 188 mature forest plots. We find that, at a stand level, trees have become larger over time, with mean tree basal area increasing by 3.3% per decade (95% CI 2.4; 4.1). Larger trees have increased in both number and size, yet we observed similar rates of relative size gain in large and small trees. This evidence is consistent with a resource-driven boost for larger trees but also a reduction in suppression among smaller trees. These results, especially the persistence and consistency of tree size increases across Amazonian forest plots, communities and regions, indicate that any negative impacts of climate change on forests and large trees here have so far been mitigated by the positive effects of increased resources.

Read more: https://www.nature.com/articles/s41477-025-02097-4

Reading further, the study notes “The increase in tree size was observed across the whole community.“. All the trees benefited from additional CO2. It also noted that their findings are counter to the alarmist hypothesis that big trees should become rarer, because big trees are more susceptible to the ravages of climate change.

What can I say? Yet another alarmist climate claim bites the dust. All the dust bowl amazon claims are contradicted by observational evidence that trees not currently being chopped down for climate conferences are growing fatter and healthier. But I can’t say it’s much of a surprise that the noisy alarmists who keep claiming the Amazon is dying didn’t bother to actually check.