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https://www.theguardian.com/environment/2026/jun/13/trees-store-less-carbon-than-thought-study>
"Trees may not be able to store as much planet-heating carbon as hoped, a study
suggests, with researchers finding photosynthesis does not always lead to wood
growth.
Scientists studied 137 sites across the US and found trees stopped growing
months before the point in the year at which photosynthesis stopped.
Forests are a vital defence against climate breakdown but their power depends
in part on how much carbon dioxide they can convert into wood, which keeps the
planet-heating molecule out of the atmosphere for decades and centuries. Other
uses of carbon are typically shorter lasting.
As fossil fuel emissions leave more carbon dioxide in the atmosphere for trees
to absorb, climate scientists expect the land-based carbon sink to remain
stable or grow over the 21st century. But many of the models estimate the
uptake using the levels of photosynthesis, rather than actual wood growth.
“Right now, most models assume that if you have photosynthesis, you have
growth. We find that’s not the case,” said Mukund Palat Rao, a carbon cycle
scientist at the Lamont-Doherty Earth Observatory at Columbia University and
lead author of the study. “Just because there is more photosynthesis might not
necessarily mean more tree growth in the future.”
At sites in the eastern US, the researchers found about 36% of yearly carbon
uptake occurred after the tree growth stopped in late summer. At sites in
California, it was about 26%.
More detailed measurements at four sites showed wood growth was restricted to
periods of low aridity and temperature, which are becoming rarer as the global
rise in temperature makes heatwaves and droughts more common.
Rao said:“The moment you have dry and hot conditions, growth activity stops
pretty instantly, while photosynthesis seems to continue at a slightly
decreased rate.”"
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
