Changes in anthropogenic aerosols during the first wave of COVID-19 lockdowns in the context of long-term historical trends at 51 AERONET stations

TL;DR

This study analyzes aerosol levels during COVID-19 lockdowns across 51 European stations, finding no significant deviation from long-term trends and questioning the global climate mitigation potential of such localized reductions.

Contribution

It provides a long-term context for aerosol changes during COVID-19, showing that short-term reductions are not statistically significant compared to historical trends.

Findings

Aerosol levels in 2020 are within one standard deviation of long-term trends.

Localized reductions during lockdowns do not significantly alter global aerosol levels.

Lifestyle changes like lockdowns have limited potential for climate change mitigation.

Abstract

A quasi-consensus has steadily formed in the scientific literature on the fact that the prevention measures implemented by most countries to curb the 2020 COVID-19 pandemic have led to significant reductions in pollution levels around the world, especially in urban environments. Fewer studies have looked at the how these reductions at ground level translate into variations in the whole atmosphere. In this study, we examine the columnar values of aerosols at 51 mainland European stations of the Aerosol Robotic Network (AERONET). We show that when considered in the context of the long-term trend over the last decade, the columnar aerosol levels for 2020, at the regional level, do not appear exceptional. Both the yearly means and the number of episodes with extreme values for this period are within the one standard deviation of the long-term trends. We conclude that the spatially and temporally very localized reductions do not add up to statistically significant reductions in the global levels of aerosols. Furthermore, considering that pandemic lockdowns can be thought of as a simulation of a climate change mitigation scenario, we conclude that such lifestyle-based changes present a very low potential as a global climate change mitigation strategy.