Forests are substantial carbon sinks, capable of absorbing one-fourth of the planet’s annual carbon emissions. But how sustainable is this? A seven-year-study conducted by researchers at the Marine Biological Laboratory in Woods Hole, Mass., attempted to answer this question—and we may not like the answer. Here’s the thing. There are two countervailing processes at work vis-à-vis forests and carbon: warming (i.e., climate change) hastens decomposition of dead vegetation, releasing CO₂. But at the same time, that decomposition releases ammonium which acts as a fertilizer and helps trees grow faster and—ergo—absorb more carbon. The purpose of the MBL study was to determine which of these two processes dominates in the long term. Discover takes it from here:

The growth rate of trees is limited, unlike the rise in temperatures. Once that growth rate tails off, additional carbon released from the ground will enter the atmosphere and make the planet even warmer. “If we continue with business as usual,” Melillo says, “plants’ ability to store carbon will be maxed out.”