Observed and Projected Changes in Temperature and Precipitation in the Core Crop Region of the Humid Pampa, Argentina
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climate Article Observed and Projected Changes in Temperature and Precipitation in the Core Crop Region of the Humid Pampa, Argentina Gabriela V. Müller 1,2,* , Miguel A. Lovino 1,2 and Leandro C. Sgroi 2 1 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires 1425, Argentina; [email protected] 2 Centro de Estudios de Variabilidad y Cambio Climático (CEVARCAM), Facultad de Ingeniería y Ciencias Hídricas, Universidad Nacional del Litoral, Santa Fe 3000, Argentina; [email protected] * Correspondence: gvmuller@fich.unl.edu.ar Abstract: 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 Citation: Müller, G.V.; Lovino, M.A.; in the RCP2.6 scenario. Sgroi, L.C. Observed and Projected Changes in Temperature and Precipitation in the Core Crop Region Keywords: climate variability; climate extremes; climate change; Humid Pampa; global climate of the Humid Pampa, Argentina. models; future scenarios Climate 2021, 9, 40. https://doi.org/ 10.3390/cli9030040 Received: 2 January 2021 1. Introduction Accepted: 19 February 2021 Global warming brings increased occurrences of extreme weather and climate world- Published: 27 February 2021 wide [1]. Significant intensification of heavy precipitation can be seen on global and continental scales [2,3]. Consistently, southeastern South America (SSA) tends towards Publisher’s Note: MDPI stays neutral warmer and moister conditions, with a noticeable increase in the magnitude and frequency with regard to jurisdictional claims in of extreme temperatures and heavy rainfall (e.g., [4,5]). In particular, central-northeastern published maps and institutional affil- Argentina has been experiencing these significant climate changes since the 1960s [6,7]. iations. The continuous increase in frequency and in intensity of heavy rainfall has caused great losses in agro-industrial production, severely damaged water management, and affected the urban centers in the region [8,9]. However, human activities are also impacted by increased occurrence of consecutive dry days, which lead to more seasonal droughts [10,11] Copyright: © 2021 by the authors. as well as by extreme—maximum and minimum—temperature events, which have grown Licensee MDPI, Basel, Switzerland. in frequency, intensity, and duration [12]. This article is an open access article The Humid Pampa extends over central-northeastern Argentina, and its core crop distributed under the terms and region is centered in the southern half of the province of Santa Fe (see Figure1). The conditions of the Creative Commons core crop region is acknowledged as one of the most productive agricultural lands in Attribution (CC BY) license (https:// the world, thanks to the combination of its climate and the characteristics of soil sedi- creativecommons.org/licenses/by/ ments. Lovino et al. [13] have reported enhanced annual precipitation since the 1960s and 4.0/). Climate 2021, 9, 40. https://doi.org/10.3390/cli9030040 https://www.mdpi.com/journal/climate Climate 2021, 9, 40 2 of 24 a considerable increase in the frequency and magnitude of heavy rainfalls throughout the province of Santa Fe. According to Llano and Vargas [14], the days with extreme precipitation are mostly associated to convective precipitation patterns all over the region. However, the distribution of observed precipitation changes is not uniform throughout the province [13]. Records from weather stations in the north and center indicate that annual precipitation has grown by 15% from 1960. This upward trend seems to have stabilized after 1990; however, the number of consecutive dry days has also grown significantly in recent decades [13]. On the other hand, observations in the core crop region indicate an increase in annual precipitation and in the frequency of heavy rainfall events with upward trends to present days. Figure 1. Central-northeastern region of Argentina delimited by 36◦ S–26◦ S latitude and 65◦ W–58◦ W longitude and its main rivers. Extreme precipitation may lead to floods and droughts that have strong negative impacts on human activities and the environment. Floods occurred in the core crop region in 2018–2019. Immediately following the flooding period, a severe drought started in 2019 and lasted during 2020. This drought took place over a large part of SSA and caused extraordinarily low water levels in the Parana River [15,16]. The Rosario Stock Exchange (BCR) estimated a loss of USD 244 million in the agro-export sector of Rosario in the first quarter of 2020 [17,18]. The sector had already faced losses of USD 230 million as a consequence of the 2018–2019 flood [19]. Moreover, low water in the Paraná River also affected the river ecosystem and other essential activities such as fishing and water purification [17]. This study examines climate variability, climate extremes as well as observed and projected climate changes in the core crop region of the Humid Pampa in the 20th and 21st centuries. The resulting information might contribute to estimate the impacts of climate variability and change aiming at reducing disaster risks and implementing appropriate management policies and adaptation actions in the affected sectors. The final goal is to make science-based information available to policy and decision makers in the public and private sectors for the development of policies, actions, and plans aimed at reducing the vulnerability of the region to extreme hydroclimatic events. To fulfill this objective, we analyzed the variability and changes in temperature and precipitation using high-quality meteorological records and future climate projections for the core crop region of the Humid Pampa. The paper is organized as follows; Section2 describes the methods and the data used. The observed changes in temperature and precipitation from the beginning of the Climate 2021, 9, 40 3 of 24 20th century to present are described in Section 3.1. For the same period, we identified and examined climate extremes using different indices, mainly focused on intense precipitation and extreme temperature events, which are in Section 3.2. Future climate projections in the short-, medium-, and long-term for the 21st century are presented in Section 3.3. The conclusions of the study are in Section4. 2. Study Region, Data, and Methodology 2.1. The Relevance of the Core Crop Region The Humid Pampa is an extensive region in central-northeastern Argentina. Its core crop region includes the center and south of Santa Fe province, east of Córdoba province, and north of Buenos Aires province (see Figure1). The Humid Pampa presents a flat landscape with dominance of Quaternary aeolian sediments. Its prairie-like ecosystem develops in humid to sub-humid temperate to subtropical climates (North Pampa, [20]). The southeast of the Santa Fe province extends over the Pampean loessic belt [21,22], which is the most extensive in the Southern Hemisphere and one of the thickest loess deposits in the world [22]. The characteristics of the Pampean loess and the present climate make soils of the region highly productive and known worldwide for their fertility [21,22]. The Paraná River, which drains the second largest basin (2,600,000 km2) in South America, flows across the Humid Pampa. The city of Rosario is located in the southeast of Santa Fe, on the right margin of the Paraná River, i.e., the core crop region of the Humid Pampa (see Figure1). Rosario rests over a complex floodplain extending 600 km in the heart of the inland lowlands of the continent [22]. Tributaries to the Paraná River in the area of Rosario are the Carcarañá and the Saladillo Rivers (see Figure1). Rosario has a privileged location both from the geographic and environmental perspectives. It is the most important city in the core crop region and one of the most important in Argentina, as it is a major industrial, trade, and financial center [23], with 43% of the province population. It is also the main agro-industrial and port hub in the region, and in recent years, it became the largest soybean and by-product export node in the world, with 78% of Argentina’s installed capacity [24]. The port of Rosario is connected to the north with Mercosur countries through the Parana–Paraguay waterway, which is the primary communication corridor with southern Brazil and Paraguay [25]. 2.2. Observed Data Temperature and precipitation were examined using a long-term record of observa- tions from Rosario Aero meteorological station (32.92◦ S, 60.78◦ W) of the National Weather Service of Argentina. This station, located in the core crop region of the Humid Pampa, is the only weather station in the region with long, complete, and reliable records of observa- tions. These observations started in the first decades of the 20th century, thus allowing an analysis of long-term variability and historical changes.