Oak Study Finds 36% of Carbon Uptake Continues After Growth Stops, Weakening Forest Sink Estimates
Updated
Updated · Columbia University · Jun 13
Oak Study Finds 36% of Carbon Uptake Continues After Growth Stops, Weakening Forest Sink Estimates
3 articles · Updated · Columbia University · Jun 13
Summary
Researchers tracking oak forests at 137 U.S. sites found trees kept photosynthesizing long after wood growth ended, with 36% of eastern U.S. carbon uptake and 26% in California occurring after growth ceased.
Hot, dry conditions shut down growth faster than photosynthesis because trees lose the internal water pressure needed to add wood, leaving absorbed carbon to support leaves, roots and metabolism instead.
The study, published in Science Advances, suggests forests may keep removing CO2 from the air without locking as much of it into long-lived woody biomass.
That gap means climate models that treat photosynthesis and growth as tightly linked may overstate forests' long-term carbon sink, especially as warming brings more variable wet-dry extremes.
Are our carbon offset markets built on a flawed promise from the world's forests?
If trees are weaker climate allies than we believed, is the 1.5°C goal already lost?
Should we now protect old forests instead of planting billions of new, less reliable trees?
Decoupling Photosynthesis and Wood Growth: Implications for Forest Carbon Storage and Climate Policy
Overview
Forests are vital for climate change mitigation because they absorb carbon dioxide and store it in their woody biomass, keeping carbon locked away for long periods. Traditionally, it was believed that the more trees photosynthesize, the more they grow and store carbon in wood. However, new research has found a significant decoupling between photosynthesis and wood growth, meaning trees may absorb carbon but not store as much in durable wood as previously thought. This discovery challenges long-held assumptions about forests as carbon sinks and has important implications for climate models and carbon offset strategies.