Humid tropical forests, vital in global efforts to limit rising temperatures, are under threat as a result of changes in land use and climate. Now, researchers reporting in the journal One Earth on July 23 have developed a new way to keep tabs on the vulnerability of these forests on a global scale using satellite data. Called the tropical forest vulnerability index (TFVI), the hope is that this method will serve as an early warning for areas that are under the greatest threat to enable actions aimed at protecting these forests before it's too late.