Jennifer Burney, Geeta G Persad, Jonathan Proctor, Eran Bendavid, Marshall Burke, Sam Heft-Neal

The magnitude and distribution of physical and societal impacts from long-lived greenhouse gases are insensitive to the emission source location; the same is not true for major co-emitted short-lived pollutants like aerosols. Here we combine novel global climate model simulations with established response functions to show that identical aerosols emitted from different regions (Brazil, China, East Africa, Western Europe, India, Indonesia, USA, and South Africa) produce divergent air quality and climate changes and associated human system impacts, both locally and globally. The marginal global damages to infant mortality, crop productivity, and economic growth from aerosol emissions and their climate effects differ by more than an order of magnitude depending on source region, with certain regions---particularly developed regions in the northern mid-latitudes---creating global external climate changes and impacts much larger than those felt locally. Importantly, these aerosol impacts arise from region-specific aerosol-climate interactions, are magnified by the geography and vulnerability of underlying human systems, and drastically increase both local and remote benefits to reducing emissions from human activity, particularly in the emerging economies assessed. These findings provide quantitative evidence that a social cost calculation incorporating geographically-resolved climate and air quality impacts from both long- and short-lived emissions would both increase incentives for mitigation and strongly differentiate between source regions, potentially stimulating coordination between regions with interlinked damages.