ence ci & C S l h im rt a a t E i c Lacerda et al., J Earth Sci Clim Change 2015, 6:8 f o C l h a a n n http://dx.doi.org/10.4172/2157-7617.1000296 r g u e o J Earth Science & Climatic Change ISSN: 2157-7617 Research Article Article OpenOpen Access Access Long-term Temperature and Rainfall Trends over Northeast Brazil and Cape Verde Lacerda FF1, Nobre P2, Sobral MC3, Lopes GMB1*, Chou SC2, Assad ED4 and Brito E5 1Agronomic Institute of Pernambuco – IPA, Brazil 2National Institute for Space Research – INPE, Brazil 3Federal University of Pernambuco – UFPE, Brazil 4Brazilian Agricultural Research Corporation – Embrapa, Brazil 5National Meteorology and Geophysics Institute – INMG, Cape Verde Abstract This study investigates long-term climate trends in Pernambuco, Northeast Brazil (Nordeste), and in the Tropical Atlantic islands of Fernando de Noronha and Cape Verde. The study is based on meteorological station time series and model simulations of present and future climates. Past trends are compared with numerical simulations of present and future climate scenarios for the periods of 1960-2000 and 2010-2050. Both the station data analyses and numerical simulations revealed trends of increasing temperature maxima and diminishing precipitation. While station data analyses showed modest warming in Fernando de Noronha they revealed strong warming and drying trends in Cape Verde similar to the trends detected over the semiarid Nordeste. The water-balance calculations for the study sites showed reduced soil moisture availability and total rainfall in all areas. The observed temperature and precipitation trends are indicative that aridification processes are underway in Pernambuco and Cape Verde. The atmospheric model simulations were consistent with the station data regarding the present warming; the climate change scenarios for 2010-2050 indicated a faster increase of daily temperature maxima over Nordeste compared to that simulated for the recent past. Keywords: Anthropogenic origin; Global temperature; Meteorological; studies have documented a decrease in the total annual rainfall over Rainfall; Temperature the tropics and an increase in the occurrence of intense precipitation episodes [13,14]. However, the consequences of global warming in Introduction the tropics are basically an increase in the temperature, evaporation, Climate change scenarios have been published by numerous and evapotranspiration, with possible impacts on the hydrological research centers around the world and were summarized in the cycle and water availability [15]. The climate change scenario in Brazil Intergovernmental Panel on Climate Change annual reports [1,2]. is similar [9,16]. In terms of climate simulations, the Eta regional Such scenarios show coherent positive trends in global temperature atmospheric model has been used to downscale global climate change and less coherent changes in rainfall patterns; these trends are scenarios in South America [6,10,17]. The model has been modified for attributed with great certainty to human activities due to the burning long-term decadal integrations and has reproduced the present climate of fossil fuels and deforestation of tropical forests. Recent studies reasonably well when forced by HadCM3 global outputs [18]; the on global warming and food security in Brazil indicate that climate model is able to generate high-resolution downscaled climate change change might affect national food production and extend the areas at scenarios for future climates [9]. risk [3,4]. Studies on the impacts of climate change on the stability of A description of the same regional models and the diverse aspects Brazilian biomes revealed that the Caatinga biome of Northeast Brazil of their simulated climatology are provided in Chou et al. [18]; (Nordeste) is highly vulnerable to rising global temperatures [5]. The Marengo et al. [9] and Solman et al. [19]. The code, including an region is on alert because the effects of climate change represent an additional pressure regarding the aridification of anthropogenic origin updated version is available for download at the NCEP website [20]. [6]. In the long term, this factor alone can trigger the replacement of Marengo et al. [19] described regionalized future climate scenarios existing biomes by those adapted to drier climates. Such replacements (2071-2100) for South America. The scenarios were derived from are exemplified in the work of Nobre and Assad [7], Nobre et al. [8] Eta-CCS, RegCM3 and HadRM3 at a spatial resolution of 50 km and in which savannas replaced forests, Caatinga replaced savannas, and were forced by the outputs of the global atmospheric model HadAM3 semi-deserts replaced Caatinga, respectively. Marengo et al. [9] showed for extreme emission scenarios A2 and B2 of IPCC AR4. In the A2 that the semiarid Nordeste will be more greatly affected by climate scenario, temperatures increase by 2°C to 4°C and rainfall decreases by change. With the risk of accelerated desertification, the region may 15-20% (2-4 mm/day) in the semiarid Nordeste by the end of the XXI become unsuitable for most currently cultivated crops, particularly cassava and maize [10]. To decelerate this process while still offering food alternatives for people and livestock, several researchers have *Corresponding author: Geraldo Majella B Lopes, Agronomic Institute of argued that the solution lies in cultures of Caatinga [5]. In the case of Pernambuco, IPA, Av. General San Martin, 1371 - Jiquiá, PE, Brazil, Tel: +55 81 3184-7200, E-mail: [email protected] semiarid Pernambuco, there is evidence of an increase in short-lived torrential rains [11]. Additionally, a higher frequency of consecutive Received July 30, 2015; Accepted August 28, 2015; Published September 08, 2015 dry days and heat waves is expected to increase the frequency of dry Citation: Lacerda FF, Nobre P, Sobral MC, Lopes GMB, Chou SC (2015) Long- spells in the region [9]. This process, besides threatening species (plant term Temperature and Rainfall Trends over Northeast Brazil and Cape Verde. J Earth Sci Clim Change. 6: 296. doi:10.4172/2157-7617.1000296 and animal) and ecosystems, threatens water security of populations, particularly those inhabiting semiarid regions; these people may Copyright: © 2015 Lacerda FF, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits become climate refugees and may head toward large urban centers. unrestricted use, distribution, and reproduction in any medium, provided the Therefore, more areas will have high climatic risks [12]. Observational original author and source are credited. J Earth Sci Clim Change ISSN:2157-7617 JESCC, an open access journal Volume 6 • Issue 8 • 1000296 Citation: Lacerda FF, Nobre P, Sobral MC, Lopes GMB, Chou SC (2015) Long-term Temperature and Rainfall Trends over Northeast Brazil and Cape Verde. J Earth Sci Clim Change. 6: 296. doi:10.4172/2157-7617.1000296 Page 2 of 8 century. In the B2 scenario, the warming is 1-3°C and the rain decreases distribution of probabilities, with a zero mean and a unit standard by 10-15% (1-2 mm/day). Therefore, the aims of this study were to (1) deviation, providing an average time series from distinct stations. This identify temperature and precipitation trends over the Nordeste of normalization method has already been used by Back [25]; Jin and Brazil and over the tropical Atlantic islands using station time series Chow [26]. and (2) formulate climate change scenarios over the Nordeste using a regional atmospheric model. Water balance analysis The second step was the calculation of the annual water balances Materials and Methods [27] at five meteorological stations (Araripina, Petrolina, Caruaru, Station data time series Vitoria, and Recife) by considering the daily precipitation and temperature data over 40 years. The water-balance monthly output The station data used in this study are daily time series of rainfall variables are potential evapotranspiration (PET) and water storage in and temperature for 1911 to 2011. Because of the scarcity of continuous the soil (ARM). historical station data for temperature, time series of varying lengths were used (Table 1). Six locations with data from 1950-1965 to 2010, namely, Simulations for the present and future climates the Araripina (40.42°S; 7.46°W), Petrolina (40.33°S; 9.08°W), Caruaru The third methodological step consisted of numerical simulations (35.92°S; 8.24°W), Vitória de Santo Antão (35.30°S; 8.13°W), and for the present and future climates using the Eta Regional Atmospheric Recife (34.92S; 8.05°W) stations in the State of Pernambuco, Fernando Model [6,19] nested in two global climate models, HadCM3 and BESM, de Noronha Archipelago (32.42°S, 3.85°W), in the western equatorial described below. Atlantic, and the Cape Verde Islands Station (15.11°N, 23.62°W) in the northeastern Tropical Atlantic were used for the temperature analyses. Regional scenarios were generated for the Nordeste, with a spatial For the rainfall analyses, 33 stations with time series of at least 45 years resolution of 40 km over the entire tropical Atlantic Ocean and the (within 1960-2004) and 22 stations with 70+ year time series (within tropical portion of South America. The experiments with the Eta model 1911-2011) were used to enhance the spatial representativeness of the were used for two atmospheric CO2 concentrations: 380 ppmv (1960 to rainfall trends1 in Pernambuco. Data time series consistency checks 2000) and 760 ppmv (2010-2050). Simulations for the present climate were performed at multiple levels. First, each station’s metadata (e.g., (1960-2000 with 380 ppmv) and future scenarios (2010-2050 with 760 thermometer location, sensor changes, and outliers due to digitation ppmv) were conducted using atmospheric lateral boundary conditions errors) were used to determine data gaps and outliers, checked against from the global climate model HadCM3, as also used in previous the original data sheets and manually corrected in the digital database.