The study looked at what caused changes in the number of carbon credits issued in voluntary carbon offset markets from 2006 to 2020. They found that more credits were issued for forestry and land use projects from 2006 to 2015, mainly due to increases in priority and scale of REDD+ projects. The reasons for these changes varied by region and project size. The increase in forestry credits raised concerns about governance and actual CO2 reduction outcomes. This suggests a need for policy changes to ensure the effectiveness of carbon offset programs.