Drought in Northeast Brazil: A review of agricultural and policy adaptation options for food security

Sediment flows dynamics (erosion, transport and deposition) have been disrupted in South America (SA), a continent with the highest erosion and sediment transport rates globally. However, the magnitude and spatial distribution of the main drivers of changes have been poorly identified and explored. Here, we performed simulations using a hydrological-hydrodynamic-sediment model to comprehensively estimate the spatial and temporal sediment changes and trends in SA from 1984 to 2019. We found that 51% of the main SA rivers experienced significant changes in simulated sediment transport (QST) over this period, with 36% due to Amazon deforestation and river damming and 15% due to precipitation changes. We also estimated a 10% reduction in the average sediment delivery to the oceans. Deforestation was responsible for QST changes above 80% in some Amazon sites, and hydropower expansion led to a greater reduction of sediment flows (as high as 80-100%) in the Tocantins, Uruguay, Upper Paraná, lower São Francisco, Desaguadero, and Negro rivers. In addition, our results suggest that reservoirs built in the Amazon region in the last decade are also affecting sediment transport. Our modeling outputs provide unprecedented information about the status of sediment dynamics in SA, and a means to develop evidence-based strategies and transboundary policies related to continental-wide sediment dynamics and the conservation and restoration of ecosystems.

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“…Amazon, Diodato et al, 2020), while others have experienced severe droughts in recent years (e.g. Northeast Brazil, Marengo et al, 2022).…”

Section: Study Areamentioning

confidence: 99%

Human-induced changes in South American sediment fluxes from 1984 to 2019

Fagundes

Fleischmann

Fan

et al. 2023

Preprint

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“…This is supported by other records from the western Amazon and the tropical Andes that document an intensified SASM during the LIA, fueled by the southern location of the ITCZ (e.g., Vuille et al, 2012;Apaéstegui et al, 2018), which is also very well recorded in other archives around the tropics (Leichleitner et al, 2017;Campos et al, 2019;Orrison et al, 2022;Steinmann et al, 2022). In NEB, the low water availability has been one of the major challenges faced by its people during the last centuries (Marengo and Bernasconi, 2015;Marengo et al, 2021;Lima and Magalhães, 2018). On the other hand, the last 500 years were the wettest of the last two millennia, according to our results (Fig 4).…”

Section: Paleoclimate Interpretationmentioning

confidence: 99%

Spatiotemporal ITCZ dynamics during the last three millennia in Northeastern Brazil and related impacts in modern human history

Utida

Cruz

Vuille

et al. 2023

Preprint

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Abstract. Changes in tropical precipitation over the past millennia have usually been associated with latitudinal displacements of the Intertropical Convergence Zone (ITCZ). Recent studies provide new evidence that contraction and expansion of the tropical rainbelt may also have contributed to ITCZ variability on centennial time scales. Over tropical South America few records point to a similar interpretation, which prevents a clear diagnosis of ITCZ changes in the region. In order to improve our understanding of the equatorial rainbelt variability, our study presents a reconstruction of precipitation for the last 3200 years from the Northeast Brazil (NEB) region, an area solely influenced by ITCZ precipitation. We analyze oxygen isotopes in speleothems that serve as a faithful proxy for the past location of the southern margin of the ITCZ. Our results, in comparison with other ITCZ proxies, indicate that the range of seasonal migration, contraction and expansion of the ITCZ was not symmetrical around the equator. A new NEB ITCZ pattern emerged based on the comparison between two distinct proxies that characterize the ITCZ behavior during the last 2500 years, with an ITCZ zonal pattern between NEB and the eastern Amazon. In NEB, the period related to the Medieval Climate Anomaly (MCA) was characterized by an abrupt transition from wet to dry conditions. These drier conditions persisted until the onset of the period corresponding to the Little Ice Age (LIA), representing the longest dry period over the last 3200 years in NEB. The ITCZ was apparently forced by teleconnections between Atlantic Multidecadal Variability and Pacific Decadal Variability that controlled the position, intensity and width of Walker cell over South America changing the ITCZ zonally, and sea surface temperature changes in both the Pacific and Atlantic, stretching/weaking the ITCZ-related rainfall meridionally over NEB. Wetter conditions started around 1500 CE in NEB. During the last 500 years, our speleothems document the occurrence of some of the strongest drought events for the last millennia, which drastically affected population and environment of NEB during the Portuguese colonial period. The historical droughts were able to affect the karst system, and led to significant impacts over the entire NEB region.

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“…The various interlinkages and trade-offs that need to be considered in use of water resources are acknowledged in European policy on the water, energy, food, and ecosystems (WEFE) nexus [123], as well as in recent research in this field [124][125][126][127]. Both general conflicts in demands concerning use of land and resources, and water scarcity, in particular, affect the arid and semi-arid regions of the MENA region.…”

Section: Water Conservation and Pollution Preventionmentioning

confidence: 99%

The Role of Organic Fertilizers in Transition to Sustainable Agriculture in the MENA Region

Avery¹

2022

New Generation of Organic Fertilizers

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Organic fertilizers can serve as an element of transitions to sustainable low-input agriculture in semi-arid regions of the MENA region. They play a key role in supporting soil biota and soil fertility. Yield improvements, availability and relatively low costs make organic fertilizers an attractive alternative for farmers. In semi-arid regions, important considerations are improved soil quality, which in turn affects soil water retention, while better root development helps crops resist heat and water stress. Organic fertilizers thus support climate adaptation and regional food security. Soil quality is crucial for carbon sequestration, at the same time that increased nutrient retention reduces impacts of agricultural runoff on groundwater and water bodies. Factors that impede the generalised use of organic fertilizers include lack of expertise, subsidy structures, constraints of the wider food and agricultural systems, and difficulties in transitioning from conventional agriculture. Such obstacles are aggravated in countries affected by security issues, financial volatility or restrictions in access to market. Against the background of both general and local constraints, the chapter examines possible pathways to benefit from organic fertilizers, in particular synergies with other sustainable agricultural practices, as well as improved access to expertise.

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Drought in Northeast Brazil: A review of agricultural and policy adaptation options for food security

Cited by 63 publications

References 70 publications

Human-induced changes in South American sediment fluxes from 1984 to 2019

Human-induced changes in South American sediment fluxes from 1984 to 2019

Spatiotemporal ITCZ dynamics during the last three millennia in Northeastern Brazil and related impacts in modern human history

The Role of Organic Fertilizers in Transition to Sustainable Agriculture in the MENA Region

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