Changes in net ecosystem exchange over Europe during the 2018 drought based on atmospheric observations

R. L. Thompson, G. Broquet, C. Gerbig, T. Koch, M. Lang, G. Monteil, S. Munassar, A. Nickless, M. Scholze, M. Ramonet, U. Karstens, E. van Schaik, Z. Wu, C. Rödenbeck

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Abstract

The 2018 drought was one of the worst European droughts of the 21st century in terms of its severity, extent and duration. The effects of the drought could be seen in a reduction in harvest yields in parts of Europe, as well as an unprecedented browning of vegetation in summer. Here, we quantify the effect of the drought on Net Ecosystem Exchange (NEE) using five independent regional atmospheric inversion frameworks. Using a network of atmospheric CO2 mole fraction observations, we estimate NEE with at least monthly and 0.5°×0.5° resolution for 2009-2018. We find that the annual NEE in 2018 was likely more positive (less CO2 uptake) in the temperate region of Europe by 0.09 ± 0.06 PgC y-1 (mean ± SD) compared to the mean of the last 10 years of -0.08 ± 0.17 PgC y-1, making the region close to carbon neutral in 2018. Similarly, we find a positive annual NEE anomaly for the northern region of Europe of 0.02 ± 0.02 PgC y-1 compared the 10-year mean of -0.04±0.05 PgC y-1. In both regions, this was largely owing to a reduction in the summer CO2 uptake. The positive NEE anomalies coincided spatially and temporally with negative anomalies in soil water. These anomalies were exceptional for the 10-year period of our study.
Original languageUndefined/Unknown
JournalPhilosophical Transactions of the Royal Society B: Biological Sciences
Early online date7 Sept 2020
DOIs
Publication statusPublished - 26 Oct 2020

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