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Understanding inequality in groundwater access and cropland ownership is critical for assessing the sustainability and equity of agricultural systems, especially in regions facing climatic and socioeconomic patterns such as drought and cropland consolidation. These two forms of access are deeply interconnected: for instance, cropland ownership often determines who can access and control groundwater. Due to data challenges, however, few studies have quantified groundwater access inequality in the same ways that land ownership has been quantified. Similarly, the regional scale of most analyses to date limits our understanding of factors that shape and modify these interconnections. Our study aims to address this gap by constructing a novel geospatial dataset by matching groundwater wells with cropland parcels across California’s Central Valley. We quantify the magnitude and spatial patterns of groundwater and cropland inequality and examine how it scales with land ownership, crop types, and surface water access. Our results indicate substantial inequality in both groundwater access and land ownership, with the top decile of well owners possessing 46.4% of the region’s total well capacity. These well owners are more likely to allocate groundwater to high-revenue, water-intensive perennials such as almonds and walnuts. Furthermore, large landholders tend to have far more wells, deeper and higher-capacity wells, and greater access to surface water resources. However, we observe consistently wider inequality in land ownership than water access, and larger landowners possess less well depth and capacity per hectare. We discuss the implications of these findings in the context of California’s historical lack of regulation on groundwater, particularly with respect to inequality in open access vs private property resources. We also consider possible lessons for future groundwater regulation and distribution mechanisms for groundwater rights under California’s Sustainable Groundwater Management Act. 

Wind erosion and dust emissions affect regions of the world with sparse vegetation cover or affected by agricultural practices that expose the soil surface to wind action. Research in this field has investigated the impact of soil moisture, land use, and land cover on soil susceptibility to wind erosion and dust emissions. The effect of soil salinity and sodicity, however, remains poorly appreciated. Salt accumulation in agricultural soils is a major concern in agroecosystems with high evaporative demand, shallow water tables or irrigated with water rich in dissolved solids. The understanding of how salts can affect aeolian processes in arid and hyper-arid landscapes remains incomplete. Recent studies focused on the effect of soil salinity on soil erodibility in dry atmospheric conditions, while the effect of soil sodicity and more humid conditions still needs to be investigated. Here we use wind tunnel tests to detect the effect of varying atmospheric humidity on wind erodibility and particulate matter emissions under saline and sodic conditions.Through a series of controlled wind tunnel experiments of soils treated with different concentrations of saline and sodic water, we find that the threshold velocity for wind erosion significantly increases with increasing soil salinity and sodicity, provided that the soil crust formed by soil salts is not disturbed. Indeed, with increasing soil salinity, the formation of a soil crust of increasing strength is observed, leading to an increase in the threshold wind velocity and a consequent decrease in particulate emissions. However, if the crust is destroyed by trampling, no significant changes in threshold velocity for wind erosion are found with increasing salinity and sodicity levels. Interestingly, after the threshold velocity was exceeded, soil crusts were readily ruptured by saltating sand grains resulting in comparable or sometimes even higher particulate matter emissions in saline and sodic soils compared to their untreated ('control') counterparts. Finally, understanding the role of atmospheric humidity under changing climate scenarios will help to modulate the wind erosion processes in saline-sodic soils and will help mitigate better dust emissions and soil management policies in arid and semi-arid climate zones. 

Virtual water describes water embedded in the production of goods and offers meaningful insights about the complex interplay between water, trade, and sustainability. In this Review, we examine the trends, major players, traded products, and key drivers of virtual water trade (VWT). Roughly 20% of water used in global food production is traded virtually rather than domestically consumed. As such, agriculture dominates VWT, with livestock products, wheat, maize, soybean, oil palm, coffee, and cocoa contributing over 70% of total VWT. These products are also driving VWT growth, the volume of which has increased 2.9 times from 1986 to 2022. However, the countries leading VWT contributions (with China, the United States, the Netherlands, Germany, and India, accounting for 34% of the global VWT in 2022) have remained relatively stable over time, albeit with China becoming an increasingly important importer. VWT can mitigate the effects of water scarcity and food insecurity, although there are concerns about the disconnect between consumers and the environmental impacts of their choices, and unsustainable resource exploitation. Indeed, approximately 16% of unsustainable water use and 11% of global groundwater depletion are virtually traded. Future VWT analyses must consider factors such as water renewability, water quality, climate change impacts, and socio-economic implications. 

Abstract Arid and semiarid ecosystems around the world are often prone to both soil salinization and accelerated soil erosion by wind. Soil salinization, the accumulation of salts in the shallow portions of the soil profile, is known for its ability to decreases soil fertility and inhibit plant growth. However, the effect of salts on soil erodibility by wind and the associated dust emissions in the early stages of soil salinization (low salinity conditions) remains poorly understood. Here we use wind tunnel tests to detect the effects of soil salinity on the threshold velocity for wind erosion and dust production in dry soils with different textures treated with salt‐enriched water at different concentrations. We find that the threshold velocity for wind erosion increases with soil salinity. We explain this finding as the result of salt‐induced (physical) aggregation and soil crust formation, and the increasing strength of surface soil crust with increasing soil salinity, depending on soil texture. Even though saline soils showed resistance to wind erosion in the absence of abraders, the salt crusts were readily ruptured by saltating sand grains resulting in comparable or sometimes even higher particulate matter emissions compared to non‐saline soils. Interestingly, the salinity of the emitted dust is found to be significantly higher (5–10 times more) than that of the parent soil, suggesting that soil salts are preferentially emitted, and airborne dust is enriched of salts. 

Abstract Agricultural transformations have significantly contributed to the global market’s year-round supply of capital-intensive greenhouse-grown crops. For instance, berry production in México is increasingly relying on greenhouse systems to meet the growing demand of international markets, particularly in the USA. It is still unclear to what extent these transformations are related to land tenure, as data on greenhouse distribution often do not exist, are incomplete, or lack spatial resolution. This paper presents a support vector machine learning algorithm tool to map greenhouse expansion using satellite images. The tool is applied to the major berry-growing region of Michoacán, México. Here agricultural areas are transforming to satisfy foreign demand for berries, altering local land and water resource use patterns. We use this tool and a unique land tenure dataset to investigate (a) the spatially explicit extent to which high-input commercial agriculture (mainly the production of berries) has expanded in this region since 1989; and (b) the extent to which smallholder ( ejidal ) land has been incorporated into the highly capitalized agro-export sector. We combine a national dataset on ejidal land (which includes both communal and parcel land) with geospatial agricultural data to quantify the land-use changes in six municipalities in the berry-growing region of Michoacán between 1989 and 2021. We find that the development of the greenhouse berry boom can be quantified and shown with spatially-explicit detail, growing from zero to over 9,500 ha over the period, using almost one-quarter of all regional agricultural land in 2020. We further find that the capital-intensive market-oriented berry industry has been widely integrated into smallholder ejidal lands, so much so that over half of greenhouses are found there. 

Abstract The ongoing agrarian transition from smallholder farming to large-scale commercial agriculture promoted by transnational large-scale land acquisitions (LSLAs) often aims to increase crop yields through the expansion of irrigation. LSLAs are playing an increasingly prominent role in this transition. Yet it remains unknown whether foreign LSLAs by agribusinesses target areas based on specific hydrological conditions and whether these investments compete with the water needs of existing local users. Here we combine process-based crop and hydrological modelling, agricultural statistics, and georeferenced information on individual transnational LSLAs to evaluate emergence of water scarcity associated with LSLAs. While conditions of blue water scarcity already existed prior to land acquisitions, these deals substantially exacerbate blue water scarcity through both the adoption of water-intensive crops and the expansion of irrigated cultivation. These effects lead to new rival water uses in 105 of the 160 studied LSLAs (67% of the acquired land). Combined with our findings that investors target land with preferential access to surface and groundwater resources to support irrigation, this suggests that LSLAs often appropriate water resources to the detriment of local users. 

Agriculture’s global environmental impacts are widely expected to continue expanding, driven by population and economic growth and dietary changes. This Review highlights climate change as an additional amplifier of agriculture’s environmental impacts, by reducing agricultural productivity, reducing the efficacy of agrochemicals, increasing soil erosion, accelerating the growth and expanding the range of crop diseases and pests, and increasing land clearing. We identify multiple pathways through which climate change intensifies agricultural greenhouse gas emissions, creating a potentially powerful climate change–reinforcing feedback loop. The challenges raised by climate change underscore the urgent need to transition to sustainable, climate-resilient agricultural systems. This requires investments that both accelerate adoption of proven solutions that provide multiple benefits, and that discover and scale new beneficial processes and food products. 

Abstract The spatial pattern of vegetation patchiness may follow universal characteristic rules when the system is close to critical transitions between alternative states, which improves the anticipation of ecosystem-level state changes which are currently difficult to detect in real systems. However, the spatial patterning of vegetation patches in temperature-driven ecosystems have not been investigated yet. Here, using high-resolution imagery from 1972 to 2013 and a stochastic cellular automata model, we show that in a North American coastal ecosystem where woody plant encroachment has been happening, the size distribution of woody patches follows a power law when the system approaches a critical transition, which is sustained by the local positive feedbacks between vegetation and the surrounding microclimate. Therefore, the observed power law distribution of woody vegetation patchiness may be suggestive of critical transitions associated with temperature-driven woody plant encroachment in coastal and potentially other ecosystems. 

Foreign investors have acquired approximately 90 million hectares of land for agriculture over the past two decades. The effects of these investments on local food security remain unknown. While additional cropland and intensified agriculture could potentially increase crop production, preferential targeting of prime agricultural land and transitions toward export-bound crops might affect local access to nutritious foods. We test these hypotheses in a global systematic analysis of the food security implications of existing land concessions. We combine agricultural, remote sensing, and household survey data (available in 11 sub-Saharan African countries) with georeferenced information on 160 land acquisitions in 39 countries. We find that the intended changes in cultivated crop types generally imply transitions toward energy-rich, but nutrient-poor, crops that are predominantly destined for export markets. Specific impacts on food production and access vary substantially across regions. Deals likely have little effect on food security in eastern Europe and Latin America, where they predominantly occur within agricultural areas with current export-oriented crops, and where agriculture would have both expanded and intensified regardless of the land deals. This contrasts with Asia and sub-Saharan Africa, where deals are associated with both an expansion and intensification (in Asia) of crop production. Deals in these regions also shift production away from local staples and coincide with a gradually decreasing dietary diversity among the surveyed households in sub-Saharan Africa. Together, these findings point to a paradox, where land deals can simultaneously increase crop production and threaten local food security.