A study from the Columbia University, published by The Guardian, warns that trees might not store as much carbon as previously assumed. Researchers found that forests stop growing months before photosynthesis ends, which questions projections about the capacity for carbon dioxide absorption (CO₂).
The work, led by Mukund Palat Rao at the Lamont-Doherty Earth Observatory, analyzed 137 sites in the United States and revealed that photosynthesis does not always translate into wood growth, the key tissue for long-term carbon sequestration.
Photosynthesis vs. wood growth
Climate models often estimate carbon absorption based on photosynthesis, but the study shows that:
- In the eastern U.S., 36% of the annual carbon absorption occurs after the trees have stopped growing.
- In California, the proportion is 26%.
This means that much of the captured carbon is not fixed in wood but is allocated to other shorter-term processes.
Critical environmental conditions
Specific measurements at four sites demonstrated that wood growth only occurs under conditions of low aridity and moderate temperatures. In the face of droughts and heatwaves, growth stops almost instantly, although photosynthesis continues at a reduced rate.
This decoupling raises questions about the future stability of terrestrial carbon sinks, especially in a global warming scenario.
Implications for climate action
The finding suggests that tree planting, while valuable, might not be sufficient on its own to curb climate change. Carbon sequestration depends on the absorbed CO₂ being converted into durable biomass.
This reinforces the need for:
- More advanced carbon capture technologies.
- Conservation strategies that prioritize the health of existing forests.
- Policies that integrate climate variability into carbon absorption models.
Complementing with technological solutions
The study adds to reports warning about the urgency of accelerating carbon extraction through artificial technologies, even faster than the installation of solar panels. Currently, tree planting represents the majority of global efforts, while mechanical or chemical technologies barely reach 0.1% of CO₂ removal.
Columbia University’s work redefines how we understand the role of forests in the fight against climate change. Planting trees remains essential, but it does not guarantee stable and lasting carbon sequestration on its own.
The combination of healthy forests, conservation policies, and innovative technologies will be key to facing the climate challenge in the coming decades.
