Researchers have developed a new technique to measure the carbon density above forests and have discovered that due to deforestation, degradation, and disturbance, tropical forests now emit more carbon than they can capture. They are no longer playing their traditional role of carbon sinks.

Previous studies have focused exclusively on large-scale deforestation but the new approach takes into account the subtle changes that natural and human activities can make to forests, in terms of degradation and disturbances. The researchers were also able to better track gains from forest growth.

The study, which is published in Science, states that there’s a critical window to protect these habitats, halt deforestation, and restore forests to areas where trees have already been cut down. Tropical forests across America, Asia, and Africa are some of the most incredible locations in terms of biodiversity and provide essential resources for millions worldwide. Their threatened status is bad news for us all.

"These findings provide the world with a wakeup call on forests," lead author Alessandro Baccini, from the Woods Hole Research Center, said in a statement. "If we're to keep global temperatures from rising to dangerous levels, we need to drastically reduce emissions and greatly increase forests' ability to absorb and store carbon. Forests are the only carbon capture and storage 'technology' we have in our grasp that is safe, proven, inexpensive, immediately available at scale, and capable of providing beneficial ripple effects – from regulating rainfall patterns to providing livelihoods to indigenous communities."

According to the study, if governments ended deforestation and forest degradation, there would be a reduction of at least 782 million tonnes (862 million US tons) of carbon dioxide which is about 8 percent of the annual global emission. Governments worldwide are planning strategies to meet the Paris Agreement goals and saving the forest should be a top priority for politicians.

"With this study, countries are now able not only to identify where degradation is taking place, but also, given the potential to now measure gains from growth, they can demonstrate their contribution to returning tropical forests to their more beneficial role as a carbon sink," Baccini said. "We envision this tool improving the way countries across the tropics tackle the challenges of deforestation and degradation."

The United Nation has a dedicated program called REDD+ (Reducing Emissions From Deforestation and Forest Degradation) which provide incentives for countries to keep their forest intact. These are the first step but more must be done.