The study is contained in Nature magazine, which says these effects of global warming have been largely overlooked.

If other rainforests follow suit as world temperatures rise, important carbon stores such as the pristine old-growth forests of the Amazon could conceivably stop storing carbon, said Ken Feeley of Harvard University’s Arnold Arboretum in Boston, who presented the research at the annual meeting of the Ecological Society of America in San Jose, California.

The amount of carbon a forest stores depends on the balance between the rate it draws carbon dioxide from the atmosphere through photosynthesis, and the rate it gives carbon dioxide back through respiration. In carbon sinks, mostly found at high latitudes, photosynthesis outstrips respiration and the amount of carbon storage increases.