Detection and attribution of an anomaly in terrestrial photosynthesis in Europe during the COVID-19 lockdown

• DOI: 10.1016/j.scitotenv.2023.166149
• Publication Date: 2023-08-10T00:37:20Z
• Authors: Angela Che Ing Tang; Christophe R. Fle...; Nicola Arriga; Dario Papale; Paul C. Stoy; Nina Buchmann; Matthias Cuntz; John Douros; Silvano Fares; Alexander Knohl; Ladislav Šigut; Guillaume Simioni; Renske Timmermans; Thomas Grünwald; Andreas Ibrom; Benjamin Loubet; Ivan Mammarella; Luca Belelli Marc...; Mats Nilsson; Matthias Peichl; Corinna Rebmann; Marius Schmidt; Christian Bernhofer; Daniel Berveiller; Edoardo Cremonese; Tarek S. El-Madany; Mana Gharun; Damiano Gianelle; Lukas Hörtnagl; Marilyn Roland; Andrej Varlagin; Zheng Fu; Bernard Heinesch; Ivan Janssens; Natalia Kowalska; Jiří Dušek; Giacomo Gerosa; Meelis Mölder; Eeva-Stiina Tuittila; Denis Loustau
• Keywords: Terrestrial ecosystem; Carbon sink

Carbon dioxide (CO2) uptake by plant photosynthesis, referred to as gross primary production (GPP) at the ecosystem level, is sensitive environmental factors, including pollutant exposure, uptake, and changes in scattering of solar shortwave irradiance (SWin) - energy source for photosynthesis. The 2020 spring lockdown due COVID-19 resulted improved air quality atmospheric transparency, providing a unique opportunity assess impact pollutants on terrestrial functioning. However, detecting these effects can be challenging GPP influenced other meteorological drivers management practices. Based data collected from 44 European ecosystem-scale CO2 flux monitoring stations, we observed significant 34 sites during compared 2015-2019. Among these, 14 showed an increase associated with higher SWin, 10 had lower linked soil dryness, seven were subjected remaining three exhibited varying dynamics, one experiencing colder rainier weather resulting GPP, two showing earlier melts. Analysis using regional chemical transport model (LOTOS-EUROS) indicated that ozone (O3) concentration remained relatively unchanged research sites, making it unlikely O3 exposure was dominant factor driving anomaly. In contrast, SWin increased 9.4 % 36 suggesting enhanced possibly reduced aerosol optical depth cloudiness. Our findings indicate pollution cloudiness may weaken carbon sink up 16 %. Accurate continuous ground-based observations are crucial attributing subtle functioning response anthropogenic drivers.