Preprints
https://doi.org/10.5194/egusphere-2022-960
https://doi.org/10.5194/egusphere-2022-960
 
04 Oct 2022
04 Oct 2022

Persistent La Niña’s favor joint soybean harvest failures in North and South America

Raed Hamed1, Sem Vijverberg1, Anne F. Van Loon1, Jeroen Aerts1,2, and Dim Coumou1,3 Raed Hamed et al.
  • 1Department of Water and Climate Risk, Institute for Environmental Studies (IVM), Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
  • 2Deltares Institute, Delft, the Netherlands
  • 3Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands

Abstract. Around 80% of global soybean supply is produced in southeast South America (SESA), central Brazil (CB) and the United States (US) alone. This concentration of production in few regions makes global soybean supply sensitive to spatially compounding harvest failures. Weather variability is a key driver of soybean yield variability, with soybean especially vulnerable to hot and dry conditions during the reproductive growth stage in summer. El Niño Southern Oscillation (ENSO) teleconnections can influence summer weather conditions across the Americas presenting potential risks for spatially compounding harvest failures. Here, we develop causal structural models to quantify the influence of ENSO on crop yields via mediating variables like local weather conditions and extratropical sea-surface temperatures (SST). We show that soybean yields are predominately driven by soil moisture conditions in summer explaining ~50 %, 18 % and 40 % of yield variability in SESA, CB and US respectively. Summer soil moisture is strongly driven by spring soil moisture as well as remote extra-tropical SST patterns in both hemispheres. Both of these soil moisture drivers are again influenced by ENSO. Our causal models show that persistent negative ENSO anomalies of -1.5 standard deviation (SD) lead to a -0.4 SD soybean reductions in the US and SESA. When spring soil moisture and extratropical SST precursors are pronouncedly negative (-1.5 SD), then estimated soybean losses increase to -0.9 SD for US and SESA. Thus, by influencing extratropical SSTs and spring soil moisture, persistent La Niña’s can trigger substantial soybean losses in both the US and SESA, with only minor potential gains in CB. Our findings highlight the physical pathways by which ENSO conditions can drive spatially compounding events. Such information may increase preparedness against climate related global soybean supply shocks.

Raed Hamed et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-960', Anonymous Referee #1, 31 Oct 2022
  • RC2: 'Comment on egusphere-2022-960', Anonymous Referee #2, 14 Nov 2022
  • EC1: 'Comment on egusphere-2022-960', Olivia Martius, 16 Nov 2022

Raed Hamed et al.

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Short summary
Spatially compounding soy harvest failures can have important global impacts. Using causal networks, we show that soy yields are predominately driven by summer soil moisture conditions in North and South America. Summer soil moisture is effected by antecedent soil moisture as well as remote extra-tropical SST patterns in both hemispheres. Both of these soil moisture drivers are again influenced by ENSO. Our results highlight physical pathways by which ENSO can drive spatially compounding events.