This is the first forecast of marine circulation and biogeochemistry for the Ascension Island Marine Protected Area (MPA). MPAs are a key management tools used to safeguard ocean biodiversity from human impacts, but their efficacy is increasingly threatened by anthropogenic climate change. To assess the vulnerability of individual MPAs to climate change and predict biological responses, it is first necessary to forecast how local marine environments will change. We found that the MPA will become warmer, more saline, more acidic, with less nutrients, less chlorophyll and less primary production by the mid-century. A weakening of the Atlantic equatorial undercurrent is forecast in all scenarios. In most cases, these changes are more extreme in the scenarios with higher greenhouse gases emissions and more significant climate change. The mean rise in temperature is between 0.9 \degree C and 1.2 \degree C over the first half of the 21st century. The integrated primary production and nutrients are forecast to decline in the MPA, but there is less consistency between models in projections of salinity, surface chlorophyll, and dissolved oxygen concentration at 500m depth. The combined effects of these projections may lead to changes in ecosystem services around Ascension Island. The effects of the model outputs were interpreted for three key ecosystem service providing habitats: biogenic deep sea habitats, intertidal sand and intertidal rocky shores. The outcomes were then used to assess potential effects on eight marine and coastal ecosystem services and information was compared to current ecosystem service levels.