# Climate effects of aerosols reduce economic inequality

## Abstract

The climate effects of anthropogenic aerosols have masked some of the warming induced by GHGs1 along with some impacts of that warming2. These temperature effects may be beneficial but are almost certainly overwhelmed by aerosols’ negative health impacts3. Recent analyses of economic impacts have concluded that warming harms economies in warm climates, but provides economic benefits in cold climates4. Here we investigate whether aerosol-induced cooling would have a positive effect on less wealthy economies in hotter regions and a negative effect on wealthier economies in colder regions. Climate simulations over the historical period both with and without anthropogenic aerosol emissions, using a fully coupled ocean and atmosphere climate model, indicate that in year 2010 anthropogenic aerosol emissions were cooling the Earth by 0.72 ± 0.02 °C relative to a scenario without such emissions. Due to opposing economic impacts in different regions, the net economic impact of aerosol-induced cooling is likely to be small at the global scale. However, these results suggest that the cooling effects of anthropogenic aerosols benefit developing tropical economies while harming developed high-latitude economies, and thus the temperature effects of past aerosol emissions have probably diminished global economic inequality.

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### Extended Data Fig. 8 GDP increment introduced by aerosol-induced cooling among the G20 nations.

(a) Median estimates (of ~8,000 realizations, see Methods) on changes in GDP in 2010 introduced by anthropogenic aerosols; (b) median estimates (of ~8,000 realizations, see Methods) on percentage changes in GDP in 2010 introduced by anthropogenic aerosols. Positive values indicate net benefits in GDP induced by the cooling effects of anthropogenic aerosols. Bars are shaded by the year 2010 population-weighted temperature of each country (derived from the ERA-Interim Reanalysis dataset, see Methods).

### Extended Data Fig. 9 Impact of aerosol-induced cooling on country-level economic inequality.

Changes in global economic inequality were calculated as the percentage changes in the ratio of per capita GDP between the top and bottom population-weighted deciles (that is, 90:10 ratio) and quintiles (that is, 80:20 ratio) relative to the counterfactual world without anthropogenic aerosols. For example, the 50% line in the left box means that half of the ~8,000 combinations of response function parameters and model simulation ensemble members have >1% reduction in the ratio of country-level per-capita-GDP of the (population-weighted) 10% richest to 10% poorest countries – indicating that aerosol-induced cooling tend to reduce global inequality.

### Extended Data Fig. 10 Impact of sulfate-induced cooling on country-level economic inequality.

Changes in global economic inequality were calculated as the percentage changes in the ratio of per capita GDP between the top and bottom population-weighted deciles (that is, 90:10 ratio) and quintiles (that is, 80:20 ratio) relative to the counterfactual world without anthropogenic sulfate aerosols. For example, the 50% line in the left box means that half of the ~8,000 combinations of response function parameters and model simulation ensemble members have >0.5% reduction in the ratio of country-level per-capita-GDP of the (population-weighted) 10% richest to 10% poorest countries – indicating that sulfate-induced cooling tend to reduce global inequality.

## Supplementary information

### Supplementary Information

Supplementary Discussion 1 and 2, Figs. 1–7 and Table 1.

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