Past climatic changes were caused by a slowdown of the thermohaline circulation. We use results from experiments with three climate models to show that the expected cooling due to a slowdown of the thermohaline circulation is less in magnitude than the expected warming due to increasing greenhouse gas concentrations. The integrated assessment model FUND and a meta-analysis of climate impacts are used to evaluate the change in human welfare. We find modest but by and large positive effects on human welfare since a slowdown of the thermohaline circulation implies decelerated warming.