Deforestation and greenhouse gas emissions could arise when replacing palm oil with other vegetable oils.

Oil crops are among the main drivers of global land use changes. Palm oil is possibly the most criticized, as a driver of primary tropical forests loss. This has generated two different reactions in its use in various sectors (e.g., food, feed, biodiesel, surfactant applications, etc.): from one side there is a growing claim for deforestation-free palm oil, whereas on the other side the attention raised towards other vegetable oils as possible substitutes, such as soybean, rapeseed and sunflower oil. We assess potential land use changes and consequent greenhouse gas (GHG) emissions for switching from palm oil to other oils and compare this solution to deforestation-free palm oils. We consider three scenarios of 25 %, 50 % and 100 % palm oil replacement in the eight major oil crop producing countries. Total GHG emissions account for anthropogenic emissions generated along the life cycle of the field production process and potential forest carbon stock losses from land use change for oil crops expansion. Replacing palm oil with other oils would have a worthless effect in terms of global emissions reduction since GHG emissions remain approximatively stable across the three scenarios, whereas it would produce a deforestation increase of 28.2 to 51.9 Mha worldwide (or 7 to 21.5 Mha if excluding the unlikely deforestation in USA, Russia, Ukraine and the offset deforestation in China, India). Conversely, if the global palm oil production becomes deforestation-free, its GHG emissions would be reduced by 92 %, switching from the current 371 to 29 Mt CO2eq per year. Although highlighting the historical unsustainability of oil palm plantations, results show that replacing them with other oil crops almost never represents a more sustainable solution, thus potentially questioning sustainability claims of palm oil free products with respect to deforestation-free palm oil.

Preserving global land and water resources through the replacement of livestock feed crops with agricultural by-products.

While animal-source foods contribute to 16% of the global food supply and are an important protein source in human diets, their production uses a disproportionately large fraction of agricultural land and water resources. Therefore, a global comprehensive understanding of the extent to which livestock production competes directly or indirectly with food crops is needed. Here we use an agro-hydrological model combined with crop-specific yield data to investigate to what extent the replacement of some substitutable feed crops with available agricultural by-products would spare agricultural land and water resources that could be reallocated to other uses, including food crop production. We show that replacing 11-16% of energy-rich feed crops (that is, cereals and cassava) with agricultural by-products would allow for the saving of approximately 15.4-27.8 Mha of land, and 3-19.6 km3 and 74.2-137.8 km3 of blue and green water, respectively, for the growth of other food crops, thus providing a suitable strategy to reduce unsustainable use of natural resources both locally or through virtual land and water trade.

Using drivers and transmission pathways to identify SARS-like coronavirus spillover risk hotspots.

The emergence of SARS-like coronaviruses is a multi-stage process from wildlife reservoirs to people. Here we characterize multiple drivers-landscape change, host distribution, and human exposure-associated with the risk of spillover of zoonotic SARS-like coronaviruses to help inform surveillance and mitigation activities. We consider direct and indirect transmission pathways by modeling four scenarios with livestock and mammalian wildlife as potential and known reservoirs before examining how access to healthcare varies within clusters and scenarios. We found 19 clusters with differing risk factor contributions within a single country (N = 9) or transboundary (N = 10). High-risk areas were mainly closer (11-20%) rather than far ( < 1%) from healthcare. Areas far from healthcare reveal healthcare access inequalities, especially Scenario 3, which includes wild mammals and not livestock as secondary hosts. China (N = 2) and Indonesia (N = 1) had clusters with the highest risk. Our findings can help stakeholders in land use planning, integrating healthcare implementation and One Health actions.

Will war in Ukraine escalate the global land rush?

Land grabbing typically leads to social and environmental harms.

Modeling snowmelt influence on shallow landslides in Tartano valley, Italian Alps.

Shallow landslides (SLs) are rapid soil mass movements, typically occurring in the mountain areas, involving the most superficial soil layers up to 5 to 10 m in depth. Damages, and casualties due to shallow landslides are recorded globally, and in literature a variety of models to study landslides have been implemented hitherto. Often times, shallow landslides occur in the wake of snowfall events, when sudden temperature increase triggers fast snow thaw, and soil moisture increases thereby. Several models studied the influence of intensity, and duration of rainfall upon shallow landslides, but the effect of snow melt in spring/summer was little considered so far. Thus, we developed a simple but robust, and parameter-wise parsimonious model, that mimics the triggering mechanism of SLs, accounting for the combined effect of precipitation duration and intensity, and snowmelt at thaw. The model is here applied to the case study of the high altitude Tartano basin, paradigmatic of SLs in the Alps of Lombardia. Our results showed that about 26 % of the Tartano basin slopes display unstable conditions. Using a traditional (i.e. rainfall-based) approach, the occurrence of shallow landslides was predicted in ca. 19 % of the basin, mainly during storms in October and November. In contrast, when snowmelt was included, the model was able to mimic potential SLs even during April and May, when snow melt rate is the highest, and may increase SLs triggering potential, to ca. 26 % of the treated area. With better spatial and temporal description of slope failure as achieved here, validated against observed failures, a public authority may be prepared to implement emergency plans, to prevent injuries, causalities, and damages to infrastructures even during springtime, when shallow landslides may occur in response to fast snowmelt, even during dry, clear sky days, and with scarce/null precipitation.

Hydrological implications of large-scale afforestation in tropical biomes for climate change mitigation.

Rising interest in large-scale afforestation and reforestation as a strategy for climate change mitigation has recently motivated research efforts aiming at the identification of areas suitable for the plantation of trees. An often-overlooked aspect of agroforestry projects for carbon sequestration is their impact on water resources. It is often unclear to what extent the establishment of forest vegetation would be limited by water availability, whether it would engender competition with other local water uses or induce water scarcity. Here we use global water models to study the hydrologic constraints and impacts of afforestation in tropical biomes. We find that 36% of total suitable and available afforestation areas are in areas where the rain alone can meet just up to the 40% of total plant water requirement. Planting trees will substantially increase water scarcity and possible dispossession (green water grab) especially in dryland regions of Africa and Oceania. Moreover, the combination of tree restoration and irrigation expansion to rainfed agricultural areas is expected to further exacerbate water scarcity, with about half of the global suitable areas for tree restoration experiencing water scarcity at least 7 months per year. Thus, the unavailability of water can overall limit climate change adaptation strategies. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'.

Present and future distribution of bat hosts of sarbecoviruses: implications for conservation and public health.

Global changes in response to human encroachment into natural habitats and carbon emissions are driving the biodiversity extinction crisis and increasing disease emergence risk. Host distributions are one critical component to identify areas at risk of viral spillover, and bats act as reservoirs of diverse viruses. We developed a reproducible ecological niche modelling pipeline for bat hosts of SARS-like viruses (subgenus Sarbecovirus), given that several closely related viruses have been discovered and sarbecovirus-host interactions have gained attention since SARS-CoV-2 emergence. We assessed sampling biases and modelled current distributions of bats based on climate and landscape relationships and project future scenarios for host hotspots. The most important predictors of species distributions were temperature seasonality and cave availability. We identified concentrated host hotspots in Myanmar and projected range contractions for most species by 2100. Our projections indicate hotspots will shift east in Southeast Asia in locations greater than 2°C hotter in a fossil-fuelled development future. Hotspot shifts have implications for conservation and public health, as loss of population connectivity can lead to local extinctions, and remaining hotspots may concentrate near human populations.

Low Adherence to the EAT-Lancet Sustainable Reference Diet in the Brazilian Population: Findings from the National Dietary Survey 2017-2018.

Diets are simultaneously connected with population health and environment. The EAT-Lancet Commission proposed a sustainable reference diet to improve population health and respect the planetary boundaries. Recently, the Planetary Health Diet Index (PHDI) has been developed to assess the adherence to this reference diet. In the present study, we aimed to evaluate the adherence to the EAT-Lancet diet through the PHDI in a nationwide population-based study carried out in Brazil. We used data from the National Dietary Survey conducted through the Household Budget Survey in 2017-2018, with 46,164 Brazilians aged over 10 years old. Food consumption was evaluated with a 24 h dietary recall. The average PHDI total score in the Brazilian population was 45.9 points (95% CI 45.6:46.1) on a total score that can range from 0 to 150 points. The adherence to EAT-Lancet diet was low among all Brazilian regions. Women, elderly, those overweighed/obese, with higher per capita income and living in the urban area had higher scores in the PHDI. In general, the Brazilian population presented low adherence to a healthy and sustainable dietary pattern and seems far from meeting the EAT-Lancet recommendations.

Competition for water induced by transnational land acquisitions for agriculture.

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.

Socio-environmental impacts of diamond mining areas in the Democratic Republic of Congo.

The mining industry of the Democratic Republic of the Congo (DRC) represents the most important sector of the country's economy, and the DRC belongs to the world top five diamond producers. Artisanal small-scale mining (ASM) of alluvial diamonds represents an important source of alternative income for subsistence farmers, but it also leads to several socio-environmental impacts: deforestation, river pollution, water resources exploitation, unhealthy, unregulated and sometimes dangerous work environments. We perform a data-driven comprehensive analysis of the impact of the diamond mining industry on natural resources and assess the potential relevance of these resources to the DRC food system. To this end, we evaluate land and water resources consumption associated with diamond mining from 2001 to 2018, cross-referencing high-resolution data on mines, land use and tree cover, and using a dynamic and spatially distributed agro-hydrological model. We leverage disaggregated agrological data to provide alternative resources allocation scenarios, and use subnational development indicators and spatially explicit conflict data to frame our analysis within the socio-economic context. We find that, despite the richness in natural resources of the DRC, the impact of diamond mining is relevant because of its effects on ecology, economy, and society. Resources and efforts currently put into the mining industry may have the potential to alleviate the malnourishment crisis in DRC if diverted towards the construction of a more structured and resilient food system. Phenomena such as the illicit trafficking of diamonds and their use to finance wars contribute to nullify the potential of mining as an alternative source of income for subsistence farmers.

Bedrock erosion in subglacial channels.

The Labyrinth in the McMurdo Dry Valleys of Antarctica is characterized by large bedrock channels emerging from beneath the margin of Wright Upper Glacier. To study the morphodynamics of large subglacial channels cut into bedrock, we develop herein a numerical model based on the classical theory of subglacial channels and recent results on bedrock abrasion by saltating bed load. Model results show that bedrock abrasion in subglacial channels with pressurized flow reaches a maximum at an intermediate distance up-ice from the glacier snout for a wide range of sediment grain sizes and sediment loads. Close to the snout, the velocity is too low and the sediment particles cannot be mobilized. Far from the snout, the flow accelerates and sediment is transported in suspension, thus limiting particle impacts at the channel bottom and reducing abrasion. This non-monotonic relationship between subglacial flow and bedrock abrasion produces concave up bottom profiles in subglacial channels and potential cross-section constrictions after channel confluences. Both landforms are present in the bedrock channels of the Labyrinth. We therefore conclude that these geomorphic features are a possible signature of bedrock abrasion, rather than glacial scour, and reflect the complex interplay between transport rate, sediment load, and transport capacity in subglacial channels.

Energy implications of the 21st century agrarian transition.

The ongoing agrarian transition from small-holder farming to large-scale commercial agriculture is reshaping systems of production and human well-being in many regions. A fundamental part of this global transition is manifested in large-scale land acquisitions (LSLAs) by agribusinesses. Its energy implications, however, remain poorly understood. Here, we assess the multi-dimensional changes in fossil-fuel-based energy demand resulting from this agrarian transition. We focus on LSLAs by comparing two scenarios of low-input and high-input agricultural practices, exemplifying systems of production in place before and after the agrarian transition. A shift to high-input crop production requires industrial fertilizer application, mechanization of farming practices and irrigation, which increases by ~5 times fossil-fuel-based energy consumption compared to low-input agriculture. Given the high energy and carbon footprints of LSLAs and concerns over local energy access, our analysis highlights the need for an approach that prioritizes local resource access and incorporates energy-intensity analyses in land use governance.

Impact of transnational land acquisitions on local food security and dietary diversity.

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.

Land-use change and the livestock revolution increase the risk of zoonotic coronavirus transmission from rhinolophid bats.

The extent to which humans facilitate zoonotic transmission of infectious diseases is unclear. Human encroachment into wildlife habitats as a consequence of expanding urbanization, cropland area and intensive animal farming is hypothesized to favour the emergence of zoonotic diseases. Here we analyse comprehensive, high-resolution datasets on forest cover, cropland distribution, livestock density, human population, human settlements, bat species' distribution and land-use changes in regions populated by Asian horseshoe bats (>28.5 million km2)-the species that most commonly carry severe acute respiratory syndrome (SARS)-related coronaviruses. We identify areas at risk of SARS-related coronavirus outbreaks, showing that areas in China populated by horseshoe bats exhibit higher forest fragmentation and concentrations of livestock and humans than other countries. Our findings indicate that human-livestock-wildlife interactions in China may form hotspots with the potential to increase SARS-related coronavirus transmission from animals to humans.

Potential for sustainable irrigation expansion in a 3 °C warmer climate.

Climate change is expected to affect crop production worldwide, particularly in rain-fed agricultural regions. It is still unknown how irrigation water needs will change in a warmer planet and where freshwater will be locally available to expand irrigation without depleting freshwater resources. Here, we identify the rain-fed cropping systems that hold the greatest potential for investment in irrigation expansion because water will likely be available to suffice irrigation water demand. Using projections of renewable water availability and irrigation water demand under warming scenarios, we identify target regions where irrigation expansion may sustain crop production under climate change. Our results also show that global rain-fed croplands hold significant potential for sustainable irrigation expansion and that different irrigation strategies have different irrigation expansion potentials. Under a 3 °C warming, we find that a soft-path irrigation expansion with small monthly water storage and deficit irrigation has the potential to expand irrigated land by 70 million hectares and feed 300 million more people globally. We also find that a hard-path irrigation expansion with large annual water storage can sustainably expand irrigation up to 350 million hectares, while producing food for 1.4 billion more people globally. By identifying where irrigation can be expanded under a warmer climate, this work may serve as a starting point for investigating socioeconomic factors of irrigation expansion and may guide future research and resources toward those agricultural communities and water management institutions that will most need to adapt to climate change.

The global value of water in agriculture.

Major environmental functions and human needs critically depend on water. In regions of the world affected by water scarcity economic activities can be constrained by water availability, leading to competition both among sectors and between human uses and environmental needs. While the commodification of water remains a contentious political issue, the valuation of this natural resource is sometime viewed as a strategy to avoid water waste. Likewise, water markets have been invoked as a mechanism to allocate water to economically most efficient uses. The value of water, however, remains difficult to estimate because water markets and market prices exist only in few regions of the world. Despite numerous attempts at estimating the value of water in the absence of markets (i.e., the "shadow price"), a global spatially explicit assessment of the value of water in agriculture is still missing. Here we propose a data-parsimonious biophysical framework to determine the value generated by water in irrigated agriculture and highlight its global spatiotemporal patterns. We find that in much of the world the actual crop distribution does not maximize agricultural water value.

The green and blue crop water requirement WATNEEDS model and its global gridded outputs.

Accurately assessing green and blue water requirements from croplands is fundamental to promote sustainable water management. In the last decade, global hydrological models have provided important insights into global patterns of water requirements for crop production. As important as these models are, they do not provide monthly crop-specific and year-specific data of green and blue water requirements. Gridded crop-specific products are therefore needed to better understand the spatial and temporal evolution of water demand. Here, we present a global gridded database of monthly crop-specific green (rain-fed) and blue (irrigated) water requirements for 23 main crops and 3 crop groups obtained using our WATNEEDS model. For the time periods in which our dataset matched, these estimates are validated against existing global products and satellite based datasets of evapotranspiration. The data are publicly available and can be used by practitioners in the water-energy-food nexus to assess the water sustainability of our food and energy systems at multiple spatial (local to global) and temporal (seasonal to multi-year) scales.

Global agricultural economic water scarcity.

Water scarcity raises major concerns on the sustainable future of humanity and the conservation of important ecosystem functions. To meet the increasing food demand without expanding cultivated areas, agriculture will likely need to introduce irrigation in croplands that are currently rain-fed but where enough water would be available for irrigation. "Agricultural economic water scarcity" is, here, defined as lack of irrigation due to limited institutional and economic capacity instead of hydrologic constraints. To date, the location and productivity potential of economically water scarce croplands remain unknown. We develop a monthly agrohydrological analysis to map agricultural regions affected by agricultural economic water scarcity. We find these regions account for up to 25% of the global croplands, mostly across Sub-Saharan Africa, Eastern Europe, and Central Asia. Sustainable irrigation of economically water scarce croplands could feed an additional 840 million people while preventing further aggravation of blue water scarcity.

Coupling the water footprint accounting of crops and in-stream monitoring activities at the catchment scale.

In this work, a simple approach for calibrating the water footprint (WF) accounting of crops with in-stream measurements at the catchment scale was developed. The green and blue components of the WF were evaluated by performing a soil-water balance at a 10-day time-interval. The surface runoff was calibrated based on continuous streamflow measurements. Meanwhile, the grey component of the WF related to nitrogen use was quantified by means of the results from the in-stream monitoring activities. The methodology can be applied to any catchment where soil, land use, weather, agricultural practices, nitrogen balance and stream data are available. This methodological approach can support local authorities in the decision-making process for effective agricultural policy setting and water planning. •The WF accounting for an agricultural catchment is coupled with surface-water monitoring results•The green and blue WF are assessed by performing a soil-water balance•Surface runoff and grey water accounts are based on in-stream monitoring activities.