Key findings of the study: decreased aerosol loadings (left: lower AOD - "Aerosol Optical Depth" ) and increased climate warming (right: decreased TOA - "short wave flux at Top of the Atmosphere") due to less aerosol scattering of radiation back to space.

In a new publication, observational constraints showed that removing aerosol air pollution led to climate warming (from Greenhouse Gases, GHG) over South Asia (aerosol demasking of climate warming).

The international team, led by ACES Prof. Örjan Gustafsson and with PhD student Hari Nair as first author, used the COVID shutdown over India as a large-scale geophysical perturbation experiment (decreases in short-lived aerosols, <1% decrease in GHG loadings).

This and forthcoming (intended) mitigation is likely to give cleaner skies yet also measurable increases in heating when the net cooling aerosols are removed.  Upon mitigation, we can thus expect some transient decades of increased warming before the effect of decreasing GHG also kicks in.

This can lead to climate overshoot – that climate targets and thresholds are crossed. The study combined ground-based multi-year measurements at the Maldives Climate Observatory with large-scale remote sensing products and modelling.

The article was published in npj Climate and Atmospheric Science.

Link to article: https://www.nature.com/articles/s41612-023-00367-6

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