Even if carbon emissions are reduced drastically in the next decade the amount of carbon already stored in the atmosphere would lead to the occurrence of extreme thermal events every three to four years between 2040 and 20801, 2. This time lag on the effect of reducing emissions suggests that the benefits of carbon emission reduction on the health of coral reefs will be noticeable only in the long term2, 3, 4. Here, we use a spatially explicit ecosystem model to compare the potential ecosystem benefits that Caribbean and Pacific reefs could gain from reductions in carbon emissions, and the timescale of these benefits. We found that whereas the effect of a reduction in emissions on Caribbean reefs will be modest and realized only in the long term (more than 60 years), Pacific reefs would start to show benefits within the first half of this century. Moreover, it seems that Pacific reefs have the potential to maintain their ecological integrity and ecosystem state in the mid- to long term if carbon emissions are reduced, but only if plate-like corals are present.