Yet another report has cast doubt on the accuracy and reliability of the carbon credits companies and individuals purchase to offset their climate-polluting emissions. The first-of-its-kind peer-reviewed study, published in Frontiers in Forests and Global Change Tuesday, looked at almost 300 projects that made up 11 percent of the carbon credits on offer to date. It found that methods for calculating the carbon credits were often in conflict with scientific best-practices, which increased the risk of “significant over-estimation” of the amount of carbon a project might keep from the atmosphere. The report comes around two months after a major investigation found that 94 percent of the forest offset credits verified by top carbon credit certifier Verra did not truly offset any emissions.