This study advances the understanding and impacts of dry episodes on wheat, corn, and soybean yields over Argentina's core crop region. The production of these major crops is intense and is the main contribution to the country's gross domestic product. Our analysis focuses on the droughts' properties, including their magnitude, frequency at different timescales, duration, and severity. We analyzed 40 years of precipitation and soil moisture anomalies and their corresponding nonparametric standardized indices at timescales of 1, 3, and 6 months. The climate variables were complemented with 40 years of the crops' yield data. The percentage of drought occurrence in northeastern Argentina ranges between 12 % and 18 %, with the larger values located towards the core crop region's eastern–northeastern sector. An analysis of drought duration suggests that most cases tend to occur for periods shorter than 3 months, while a few can extend up to 1 year, and even fewer can last longer. More importantly, regardless of the duration, droughts have larger impacts during the crops' critical growth period. Corn and soybean have their critical growth periods during summer and are more sensitive to precipitation and soil moisture deficits than wheat, which has its critical growth period during spring. Quantification of the relation between the droughts' indicators during the crops' critical periods and detrended annual crop yields was performed. Large drought severity values during the crop-sensitive months result in significant crop yield losses. Results suggest that shorter-scale indicators during sensitive periods are more appropriate for predicting crop yield losses than the longer-scale indicators. This new approach can be helpful for regional decision-making systems that support planning by water managers and agricultural stakeholders.

This study examines the joint variability of precipitation, river streamflow and temperature over northeastern Argentina; advances the understanding of their links with global SST forcing; and discusses their impacts on water resources, agriculture and human settlements. The leading patterns of variability, and their nonlinear trends and cycles are identified by means of a principal component analysis (PCA) complemented with a singular spectrum analysis (SSA). Interannual hydroclimatic variability centers on two broad frequency bands: one of 2.5–6.5 years corresponding to El Niño Southern Oscillation (ENSO) periodicities and the second of about 9 years. The higher frequencies of the precipitation variability (2.5–4 years) favored extreme events after 2000, even during moderate extreme phases of the ENSO. Minimum temperature is correlated with ENSO with a main frequency close to 3 years. Maximum temperature time series correlate well with SST variability over the South Atlantic, Indian and Pacific oceans with a 9-year frequency. Interdecadal variability is characterized by low-frequency trends and multidecadal oscillations that have induced a transition from dryer and cooler climate to wetter and warmer decades starting in the mid-twentieth century. The Paraná River streamflow is influenced by North and South Atlantic SSTs with bidecadal periodicities. The hydroclimate variability at all timescales had significant sectoral impacts. Frequent wet events between 1970 and 2005 favored floods that affected agricultural and livestock productivity and forced population displacements. On the other hand, agricultural droughts resulted in soil moisture deficits that affected crops at critical growth stages. Hydrological droughts affected surface water resources, causing water and food scarcity and stressing the capacity for hydropower generation. Lastly, increases in minimum temperature reduced wheat and barley yields.

The core crop region of the Humid Pampa is one of the most productive agricultural lands around the world and depends highly on climate conditions. This study assesses climate variability, climate extremes, and observed and projected climate changes there, using 1911–2019 observations and CMIP5 model simulations. Since 1970, the annual mean temperature has risen by 1 °C and the mean annual minimum and maximum temperatures by 2 and 0.5 °C, respectively. The frequency of warm days and nights increased, and cold days and nights decreased. Heatwaves became longer and more intense, and cold waves decreased with less frost events. Annual precipitation increased by 10% from 1911, mainly in summer, and years with excess precipitation outnumbered those with a deficit. Both intense precipitation events and consecutive dry days grew, suggesting more annual precipitation falling on fewer days. Projections show a warming of 1 °C by 2035, regardless of the scenario. From then on until 2100, mean temperature will increase by 2 and 3–3.5 °C in the RCP4.5 and RCP8.5 scenarios, respectively. Annual precipitation will grow 8 and 16% from current values by 2100 in the RCP4.5 and RCP8.5 scenarios, respectively. No major precipitation changes are projected in the RCP2.6 scenario.

The current study advances the documentation of dry episodes over Argentina’s Core Crop Region, where the production of major crops like wheat, corn, and soybean is most intense and represents the main contribution to the country’s Gross Domestic Product. Our analysis focuses on the properties of droughts that include their magnitude, frequency at different time scales, duration, and severity. It is of interest to assess the relationship between those properties and the crop yields. We analyzed 40 years of precipitation and soil moisture at resolutions suitable for regional studies. The analysis of precipitation and soil moisture anomalies is complemented with the corresponding standardized indices estimated at time scales of 3- and 6-months. Most droughts tend to occur for periods shorter than three months, but a few can extend up to one year and fewer even longer. However, if a multiyear drought experienced breaks, each period would be considered a separate case. Analysis of the frequency distribution indicates that cases of water deficit conditions are more common than instances of water excess. As relevant as the drought duration is its timing and severity. Even short dry spells may have large impacts if they occur at the time of the critical growth period of a given crop. In the core crop region, corn yield is the most sensitive to drought severity. For these reasons, the quantification of severity during the crop-sensitive months is an indicator of what crop yields could be on the next campaign.

This study examines the relation between hydroclimate variability (precipitation, river discharge, temperature) and water resources, agriculture and human settlements at different time scales in northeastern Argentina. It also discusses the impacts on these productive and socio-economic sectors. The leading patterns of variability, their nonlinear trends, and cycles are identified by means of a Principal Component Analysis (PCA) complemented with a Singular Spectrum Analysis (SSA). Interannual hydroclimatic variability centres on two broad frequency bands: one of 2.5–6.5 years corresponding to El Niño Southern Oscillation (ENSO) periodicities and the second of about 9 years. Interdecadal variability is characterized by low-frequency trends and multidecadal oscillations that have induced a transition to wetter and warmer climate starting in the mid-twentieth century. The hydroclimate variability at all time scales had significant sectoral impacts. Frequent wet events between 1970 and 2005 favoured floods that affected agricultural and livestock productivity and forced population displacements. On the other hand, agricultural droughts produced soil moisture deficits affecting crops at critical growth periods. Hydrological droughts affected surface water resources causing water and food scarcity and stressed the capacity for hydropower generation. Lastly, increases in minimum temperature reduced wheat and barley yields.