Columbia Climate School
June 12, 2026
Highlights- Researchers found that oak forests can continue taking up carbon after their seasonal wood growth has ended.
- Aridity and heat limit tree growth more strongly than photosynthesis.
- As the climate warms, forests may keep absorbing carbon without storing as much of it in wood.
- The findings suggest climate models may overstate the long-term carbon sink provided by forests.
It’s intuitive to think that if a tree is photosynthesizing, it’s also growing. But that’s not necessarily so—and a
new study of oak trees, published in the journal
Science Advances, found that even as they photosynthesize late into the year, their growth stops by mid-summer.
Much of the long-term carbon storage that forests provide depends on trees converting the carbon they absorb through photosynthesis into new wood. Many researchers have predicted that rising atmospheric carbon dioxide (CO2) levels will enhance photosynthesis and stimulate tree growth, putting some of that planet-warming carbon into long-term storage inside wood. However, the observed decoupling of photosynthesis from growth suggests that increased carbon uptake does not necessarily translate into greater wood production. Instead, some of the absorbed carbon may be used to produce foliage or used in short-lived metabolic processes rather than being locked away long term, reducing the amount of carbon stored in forests compared with previous expectations.
…
“Right now, most models assume that if you have photosynthesis, you have growth. We find that’s not the case,” says lead author Mukund Palat Rao, an ecoclimatologist at Lamont-Doherty Earth Observatory, which is part of the Columbia Climate School. “Just because there is more photosynthesis might not necessarily mean more tree growth in the future.”
…
Mukund Palat Rao
et al. ,Decoupled carbon assimilation and growth responses to aridity in temperate deciduous oaks.
Sci. Adv. 12,eady7139(2026).DOI:
10.1126/sciadv.ady7139
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