A new study published in One Earth challenges a long held assumption about how forests and other ecosystems absorb carbon dioxide. Researchers found that plants are not adapting their photosynthesis to higher temperatures as previously thought. Instead, the increase in carbon uptake over the past two decades is mainly driven by greater leaf cover and improved water use efficiency. The optimal temperature for photosynthesis has changed very little, especially in dry and cold regions. This matters for climate predictions and carbon offset projects. If models rely too heavily on temperature adaptation, they may overestimate or underestimate future carbon absorption. The study suggests that water availability and canopy growth are more important factors. For project developers and carbon credit buyers, this means drought risk and long term water access need more attention when forecasting how much CO2 a forest will absorb. The lead researcher stressed that plants remain a critical tool for slowing global warming, but they cannot replace the need to cut emissions. The findings help refine how we estimate the natural carbon sink, which absorbs about a quarter of human CO2 emissions each year.
