A new study titled “Increasing Tree Size Across Amazonia” has found that trees in the Amazon rainforest are growing larger as a result of rising atmospheric carbon dioxide (CO₂) concentrations. 

About the Study

• Research Collaboration: Conducted by about 100 scientists from 60 universities across South America, Europe, and the United Kingdom.
• Duration: Observation periods varied by region, with some datasets spanning over 30 years.
• Key Findings:
• • Average tree diameter (in Amazon forest) increased by around 3.3% per decade.
  • In mature forests, tree size usually remains stable as new saplings replace fallen trees; the observed deviation indicating an external factor influencing growth.
  • The study attributes this anomaly to the rise in atmospheric CO₂, which has increased by nearly 20% over the last three decades.
  • The findings confirm that CO₂ acts “as a fertiliser, increasing tree growth,” which is reassuring since wood serves as a globally significant carbon sink.

Cause: The Carbon Fertilisation Effect

• The main factor behind this phenomenon is the increase in atmospheric CO₂ concentration, which has risen by nearly 20% over the past three decades.
• Mechanism: Higher CO₂ enhances photosynthesis, accelerating plant growth and biomass accumulation.
• Impact: Larger trees absorb and store more carbon, thereby increasing the Amazon’s contribution as a global carbon sink.
• Researchers confirmed that rising CO₂ levels act as a “fertiliser” for tree growth, strengthening the forest’s carbon-absorbing capacity.

Significance of the Findings

• Increased Carbon Absorption: Larger can trees enhance the forest’s capacity to sequester carbon, offering limited mitigation against greenhouse gas buildup.
• Positive but Limited Impact: The study suggests some compensatory benefit against climate change but warns against overestimating this effect.
• Value of Old-Growth Forests: The study underscores that the benefits of mature forests cannot be replicated by new plantations, since large tropical trees take centuries to mature and sustain biodiversity.
• Deforestation Concerns: Despite CO₂-driven growth, ongoing deforestation and forest degradation continue to erode the Amazon’s ability to regulate climate and support ecosystems

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