Flávio Barbosa Justino

Potential forcing of CO2, technology and climate changes in maize (Zea mays) and bean (Phaseolus vulgaris) yield in southeast Brazil

Based upon sensitivity experiments, this study aims to investigate the impact of increased atmospheric CO2 concentration, climate changes, and ongoing technological advancements on bean (Phaseolus vulgaris) and maize (Zea mays) yield. This investigation assumes that the atmospheric CO2 concentration evolves according to the A2 scenario. For these analyses we have used climate data as projected by climate simulations conducted with the HadCM3 climate model for both present day and greenhouse warming conditions. The results demonstrated that warming conditions associated with increased greenhouse gases as delivered by the HadCM3 model lead to reductions in the potential productivity of maize and beans for the years 2050 and 2080 by up to 30%. This thermal response is, however, damped by the highly efficient CO2 fertilization effect which is expected to increase bean productivity as compared to present day conditions. A similar investigation for maize yield revealed a different picture. It has been found that the CO2 fertilization feedback is much weaker and cannot cancel out the thermal effect. We have found, therefore, that climate changes as simulated to occur in the future are not favorable for increasing the maize yield in southeast Brazil. By the inclusion of the third forcing evaluated, representing technological advancements, it is demonstrated that improvements in the crop system reduce the negative effect associated with warmer climate conditions for both crops. We conclude that appropriate soil and technological management as well as genetic improvements may very likely induce an increase in bean and maize yield despite the unfavorable future climate conditions.

Modeling the photosynthetically active radiation in South West Amazonia under all sky conditions

Accurate estimates of photosynthetically active radiation (PAR) are critical for the development of realistic models of plant productivity. However, in many areas such as the vast Amazon region of South America, there have been few empirical studies of PAR. Here, we analyzed the relationship between PAR and broadband solar irradiance (Rs) and formulated models to estimate PAR in two experimental sites (pasture and forest) in the Brazilian Amazon. Three different models of increasing complexity were developed based on information from Rs (model 1), Rs and clearness index (kt; model 2), and Rs, kt, and water vapor pressure (model 3). Estimates of PAR were generated for each season and for the entire year. All models had very high determination coefficients and indices of agreement for both pasture and forest sites. This strongly supports the use of Rs and kt to produce robust estimates of PAR. The results obtained by annual models were close than that found by seasonal models, demonstrating that a single annual model is able to estimate PAR, albeit with lower accuracy.

The influence of oceanic basins on drought and ecosystem dynamics in Northeast Brazil

The 2012 drought in Northeast Brazil was the harshest in decades, with potentially significant impacts on the vegetation of the unique semi-arid caatinga biome and on local livelihoods. Here, we use a coupled climate–vegetation model (CCM3-IBIS) to: (1) investigate the role of the Pacific and Atlantic oceans in the 2012 drought, and; (2) evaluate the response of the caatinga vegetation to the 2012 climate extreme. Our results indicate that anomalous sea surface temperatures (SSTs) in the Atlantic Ocean were the primary factor forcing the 2012 drought, with Pacific Ocean SST having a larger role in sustaining typical climatic conditions in the region. The drought strongly influenced net primary production in the caatinga, causing a reduction in annual net ecosystem exchange indicating a reduction in amount of CO2 released to the atmosphere.

Utilization of the cropgro-soybean model to estimate yield loss caused by Asian rust in cultivars with different cycle

In recent years, crop models have increasingly been used to simulate agricultural features. The DSSAT (Decision Support System for Agrotechnology Transfer) is an important tool in modeling growth; however, one of its limitations is related to the unac- counted-for effect of diseases. Therefore, the goals of this study were to calibrate and validate the CSM CROPGRO-Soybean for the soybean cultivars M-SOY 6101 and MG/BR 46 (Conquista), analyze the performance and the effect of Asian soybean rust on these cultivars under the environmental conditions of Vicosa, Minas Gerais, Brazil. The experimental data for the evaluation, testing, and adjustment of the genetic coefficients for the cultivars, M-SOY 6101 and MG/BR 46 (Conquista), were obtained during the 2006/2007, 2007/2008 and 2009/2010 growing seasons. GLUE (Generalized Likelihood Uncertainty Estimation) was used for the estimation of the genetic coefficients, and pedotransfer functions have been utilized to estimate the physical characteristics of the soil. For all of the sowing dates, the early season cultivar, M-SOY 6101, exhibited a lower variance in yield, which represents more stability with regard to the interannual climate variability, i.e., the farmers who use this cultivar will have in 50% of the crop years analyzed, a higher yield than a late-season cultivar. The MG/BR 46 (Conquista) cultivar demonstrated a greater probability of obtaining higher yield in years with favorable weather conditions. However, in the presence of the Asian soybean rust, yield is heavily affected. The early cultivar, M-SOY 6101, showed a lower risk of being affected by the rust and consequently exhibited less yield loss considering the scenario D90 (condensation on the leaf surface occurs when the relative humidity is greater than or equal to 90%), for a sowing date of November 14.

Variabilidade da precipitação no Sertão do São Francisco, estado de Alagoas

The objective of this paper was to study the homogeneity and the existence of trends in temporal distribution of rainfall for microregion of San Francisco in the State of Alagoas. The mean precipitation data used was divided in three climatological periods: 1931-1960, 1961-1990 and 1991-2011. For these time series the statistical tests of Pettitt-Mann-Kendal was applied and linear regression with the Student test for the slope of a line, respectively to identify the homogeneity and trend in the precipitation data. The temporal distribution of precipitation for the periods 1931-1960 and 1961-1990 did not show changes or trends, which were detected for the period of 1991-2011, with a significant trend of increased precipitation in seven months.

Suscetibilidade do ambiente a ocorrências de queimadas sob condições climáticas atuais e de futuro aquecimento global

Vegetation burning is the second source of greenhouse gas emissions into the atmosphere. An important step to reduce the climate impact of these emissions is to investigate the atmospheric susceptibility of a region for fire development (fire risk). This study aims to investigate the environmental susceptibility to fire development, based on the burning risk index: the Haines Index (HI). The study is carried out with data from the ECHAM5/MPI-OM climate model and the NCEP reanalysis data, to calculate the HI during two periods: present day (1980-2000) and climate projections for the end of the 21st century (2080-2100). Based upon the results, we concluded that the Haines index could reproduce properly the areas with the highest fire incidence under present conditions. Moreover, it has been found an enlargement in the fire risk area under global warming conditions, in particular for the Amazon region.

The Large-Scale Climate in Response to the Retreat of the West Antarctic Ice Sheet

AbstractBased upon coupled climate simulations driven by present-day conditions and conditions resembling the Marine Isotope Stage 31 (this simulation is called WICE-EXP), insofar as the West Antarctic Ice Sheet (WAIS) configuration is concerned, it is demonstrated that changes in the WAIS orography lead to noticeable changes in the oceanic and atmospheric circulations. Compared with the present-day climate, WICE-EXP is characterized by warmer conditions in the Southern Hemisphere (SH) by up to 5°C in the polar oceans and up to 2°C in the Northern Hemisphere (NH). These changes feed back on the atmospheric circulation weakening (strengthening) the extratropical westerlies in the SH (northern Atlantic). Calculations of the southern annular mode (SAM) show that modification of the WAIS induces warmer conditions and a northward shift of the westerly flow; in particular, there is a clear weakening of the polar jet. These changes lead to modification of the rate of deep water formation, reducing the magnitude ...

Influence of Antarctic ice sheet lowering on the Southern Hemisphere climate: modeling experiments mimicking the mid-Miocene

A coupled global atmosphere-ocean model is used to study the influence of the Antarctica ice sheet in a configuration that mimics that of the early Miocene on the atmospheric and oceanic circulations. Based on different climate simulations of the present day (CTR) and conducted with distinct Antarctic ice sheet topography (AIS-EXP), it is found that the reduction of the Antarctic ice sheet topography (AIS) induces warming of the Southern Hemisphere and reduces the meridional thermal gradient. Consequently, the atmospheric transient low level eddy heat flux

Efeitos do aumento da tensão de cisalhamento do vento no clima do Hemisfério Sul obtido do modelo acoplado SPEEDO

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