Mercury (Hg) is emitted into the atmosphere by both natural and anthropogenic sources, gets dispersed and deposited globally, and bioaccumulates to toxic levels in food webs. Periodic evaluation is required to assess the effectiveness of the global 2017 Minamata Convention, which addresses Hg emissions. Previous analyses that have relied on atmospheric models to estimate the impact of different regulatory strategies for future mercury deposition have not accounted for the possible future growth of legacy emissions--the recycling of previously deposited Hg. Using an integrated modeling approach, this study investigates how delays in implementing emissions reductions and the associated growing accumulation of legacy emissions impact deposition of Hg to ecosystems in different regions. On a global average, each 5-year delay leads to a 14% decrease in policy impacts on local-scale Hg deposition.