Richard Condit, from the Smithsonian Tropical Research Institute, devised the analysis to interpret measurements from more than 600,000 trees belonging to 403 species.
"Rather than slowing down or ceasing growth and carbon uptake, as we previously assumed, most of the oldest trees in forests around the world actually grow faster, taking up more carbon," Condit said. "A large tree may put on weight equivalent to an entire small tree in a year."
Meanwhile, lead author and forest ecologist with the U.S. Geological Survey, Nate Stephenson said if human growth would accelerate at the same rate, we would weigh half a ton by middle age and well over a ton at retirement.
Whether accelerated growth of individual trees translates into greater carbon storage by aging forests remains to be seen.
The study is published in the journal Nature.