Corrigendum: Groundwater depletion embedded in international food trade.

This corrects the article DOI: 10.1038/nature21403.

Unexpectedly large impact of forest management and grazing on global vegetation biomass.

Carbon stocks in vegetation have a key role in the climate system. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53-58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42-47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.

Groundwater depletion embedded in international food trade.

Recent hydrological modelling and Earth observations have located and quantified alarming rates of groundwater depletion worldwide. This depletion is primarily due to water withdrawals for irrigation, but its connection with the main driver of irrigation, global food consumption, has not yet been explored. Here we show that approximately eleven per cent of non-renewable groundwater use for irrigation is embedded in international food trade, of which two-thirds are exported by Pakistan, the USA and India alone. Our quantification of groundwater depletion embedded in the world's food trade is based on a combination of global, crop-specific estimates of non-renewable groundwater abstraction and international food trade data. A vast majority of the world's population lives in countries sourcing nearly all their staple crop imports from partners who deplete groundwater to produce these crops, highlighting risks for global food and water security. Some countries, such as the USA, Mexico, Iran and China, are particularly exposed to these risks because they both produce and import food irrigated from rapidly depleting aquifers. Our results could help to improve the sustainability of global food production and groundwater resource management by identifying priority regions and agricultural products at risk as well as the end consumers of these products.

Land use intensification increasingly drives the spatiotemporal patterns of the global human appropriation of net primary production in the last century.

Land use has greatly transformed Earth's surface. While spatial reconstructions of how the extent of land cover and land-use types have changed during the last century are available, much less information exists about changes in land-use intensity. In particular, global reconstructions that consistently cover land-use intensity across land-use types and ecosystems are missing. We, therefore, lack understanding of how changes in land-use intensity interfere with the natural processes in land systems. To address this research gap, we map land-cover and land-use intensity changes between 1910 and 2010 for 9 points in time. We rely on the indicator framework of human appropriation of net primary production (HANPP) to quantify and map land-use-induced alterations of the carbon flows in ecosystems. We find that, while at the global aggregate level HANPP growth slowed down during the century, the spatial dynamics of changes in HANPP were increasing, with the highest change rates observed in the most recent past. Across all biomes, the importance of changes in land-use areas has declined, with the exception of the tropical biomes. In contrast, increases in land-use intensity became the most important driver of HANPP across all biomes and settings. We conducted uncertainty analyses by modulating input data and assumptions, which indicate that the spatial patterns of land use and potential net primary production are the most critical factors, while spatial allocation rules and uncertainties in overall harvest values play a smaller role. Highlighting the increasing role of land-use intensity compared to changes in the areal extent of land uses, our study supports calls for better integration of the intensity dimension into global analyses and models. On top of that, we provide important empirical input for further analyses of the sustainability of the global land system.

Quantifying and attributing land use-induced carbon emissions to biomass consumption: A critical assessment of existing approaches.

Biomass production generates land use impacts in the form of emissions from Forestry and Other Land Use (FOLU), i.e. due to changes in ecosystem carbon stocks. Recently, consumption-based accounting (CBA) approaches have emerged as alternatives to conventional production-based accounts, quantifying FOLU emissions associated with biomass consumption, for example, of particular territories. However, the quantification and allocation of FOLU emissions to individual biomass products, a fundamental part of CBA approaches, is a complex endeavour. Existing studies make diverging methodological choices, which are rarely critically discussed. In this study, we provide a structured overview of existing CBA approaches to estimating FOLU emissions. We cluster the literature in a two-by-two grid, distinguishing the primary element under investigation (impacts of changing consumption patterns in a region vs. impacts of consumption on production landscapes) and the analytical lens (prospective vs retrospective). Further, we identify three distinct dimensions which characterise the way in which different studies allocate FOLU emissions to biomass products: the choice of reference system and the spatial and temporal scales. Finally, we identify three frontiers that require future attention: (1) overcoming structural biases which underestimate FOLU emissions from territories that experienced deforestation in the distant past, (2) explicitly tackling the interdependence of proximate causes and ultimate drivers of land use change, and (3) assessing uncertainties and understanding the effects of land management. In this way, we enable a critical assessment of appropriate methods, support a nuanced interpretation of results from particular approaches as well as enhance the informative value of CBA approaches related to FOLU emissions. Our analysis contributes to discussions on sustainable land use practices with respect to biomass consumption and has implications for informing international climate policy in scenarios where consumption-based approaches are adopted in practice.

Global changes in diets and the consequences for land requirements for food.

Provision of food is a prerequisite for the functioning of human society. Cropland where food and feed are grown is the central, limiting resource for food production. The amount of cropland needed depends on population numbers, average food consumption patterns, and output per unit of land. Around the globe, these factors show large differences. We use data from the Food and Agriculture Organization to consistently assess subcontinental dynamics of how much land was needed to supply the prevailing diets during a span of 46 y, from 1961 to 2007. We find that, in most regions, diets became richer while the land needed to feed one person decreased. A decomposition approach is used to quantify the contributions of the main drivers of cropland requirements for food: changes in population, agricultural technology, and diet. We compare the impact of these drivers for different subcontinents and find that potential land savings through yield increases were offset by a combination of population growth and dietary change. The dynamics of the three factors were the largest in developing regions and emerging economies. The results indicate an inverse relationship between the two main drivers behind increased land requirements for food: with socioeconomic development, population growth decreases and, at the same time, diets become richer. In many regions, dietary change may override population growth as major driver behind land requirements for food in the near future.

Comparison of dysplastic and benign endocervical polyps.

OBJECTIVE: This study aimed to estimate dysplasia rate in histologically evaluated endocervical polyps and to compare histological and clinical characteristics of dysplastic (D) polyps with those displaying representative benign changes. MATERIALS AND METHODS: Endocervical polyps removed at Mayo Clinic from January 1994 to December 2010 were categorized as polyp without other descriptors, benign polyp variants, adenomatous or reactive atypical (AR) polyps, and D polyps. Clinical characteristics, cervical cytological result, and polyp histological result of patients in the latter 2 categories were compared. RESULTS: Among the 4,328 patients with endocervical polyps, 3,656 were classified as polyp without other descriptors, 628 as benign polyp variants, 34 as AR polyps, and 9 as D polyps. Dysplasia was mild in 4 polyps, moderate in 1 polyp, and severe in 4 polyps. Overall risk of dysplasia was 0.2%. Patients with D polyps were younger (mean = 40.3 vs. 49.8 years, p = .009) and more likely to have abnormal cervical cytological result before polyp removal (67% vs. 21%, p = .014) as compared with those with AR. Patients with D polyps tended to have a polyp greater than 20 mm (44% vs. 15%, p = .074) compared with those with AR polyps. Associated endometrial pathological diagnosis was limited to a prolapsed endometrial polyp in 1 patient and submucosal endometriosis in 1 patient. CONCLUSIONS: Patients with D polyps were younger and had a greater likelihood of abnormal cytological result before polyp removal. No polyp size threshold below which dysplasia could be excluded was identified. No primary cervical cancer, endometrial hyperplasia, or cancer was identified.

Trade-induced displacement of impacts of global crop production on oxygen depletion in marine ecosystems.

In our globalized world, local impacts of agricultural production are increasingly driven by consumption in geographically distant places. Current agricultural systems strongly rely on nitrogen (N) fertilization to increase soil fertility and crop yields. Yet, a large portion of N added to cropland is lost through leaching / runoff potentially leading to eutrophication in coastal ecosystems. By coupling data on global production and N fertilization for 152 crops with a Life Cycle Assessment (LCA)-based model, we first estimated the extent of oxygen depletion occurring in 66 Large Marine Ecosystems (LMEs) due to agricultural production in the watersheds draining into these LMEs. We then linked this information to crop trade data to assess the displacement from consuming to producing countries, in terms of oxygen depletion impacts associated to our food systems. In this way, we characterized how impacts are distributed between traded and domestically sourced agricultural products. We found that few countries dominate global impacts and that cereal and oil crop production accounts for the bulk of oxygen depletion impacts. Globally, 15.9 % of total oxygen depletion impacts of crop production are ascribable to export-driven production. However, for exporting countries like Canada, Argentina or Malaysia this share is much higher, often up to three-quarters of their production impacts. In some importing countries, trade contributes to reduce pressure on already highly affected coastal ecosystems. This is the case for countries whose domestic crop production is associated with high oxygen depletion intensities, i.e. the impact per kcal produced, such as Japan or South Korea. Next to these positive effects trade can play in lowering overall environmental burdens, our results also highlight the importance of a holistic food system perspective when aiming to reduce the oxygen depletion impacts of crop production.

Multi-model assessment identifies livestock grazing as a major contributor to variation in European Union land and water footprints.

Food systems are the largest users of land and water resources worldwide. Using a multi-model approach to track food through the global trade network, we calculated the land footprint (LF) and water footprint (WF) of food consumption in the European Union (EU). We estimated the EU LF as 140-222 Mha yr-1 and WF as 569-918 km3 yr-1. These amounts are 5-7% of the global LF and 6-10% of the global WF of agriculture, with the EU representing 6% of the global population. We also calculated the global LF of livestock grazing, accounting only for grass eaten, to be 1,411-1,657 Mha yr-1, and the global LF of agriculture to be 2,809-3,014 Mha yr-1, which is about two-thirds of what the Food and Agriculture Organization Statistics (FAOSTAT) database reports. We discuss here the different methods for calculating the LF for livestock grazing, underscoring the need for a consistent methodology when monitoring the food LF and WF reduction goals set by the EU's Farm To Fork Strategy.

The environmental footprints of the feeds used by the EU chicken meat industry.

Chicken meat production in the European Union (EU) causes environmental pressures within and beyond the EU, mostly due to feed consumption. The expected dietary shift from red to poultry meat will drive changes in the demand for chicken feeds and the associated environmental impacts, calling for a renewed attention on this supply chain. By performing a break-down analysis based on material flow accounting, this paper assesses the annual environmental burden caused within and outside of the EU by each single feed consumed by the EU chicken meat industry from 2007 to 2018. The increased feed demand required to support the growth of the EU chicken meat industry over the analyzed period caused a 17 % increase in cropland use - 6.7 million hectares in 2018. Instead, CO2 emissions linked to feed demand decreased by ~45 % over the same period. Despite an overall improvement in resource and impact intensity, chicken meat production was not decoupled from environmental burden. In 2018, 0.40 Mt. of nitrogen, 0.28 Mt. of phosphorous, and 0.28 Mt. of potassium inorganic fertilizers were implied. Our findings indicate that the sector is not yet compliant with the EU sustainability targets defined in the Farm To Fork Strategy, calling for an urgent need to fill existing policy implementation gaps. The EU chicken meat industry's environmental footprints were driven by endogenous factors such as the feed use efficiency at the chicken farming stage and the feed cultivation efficiency within the EU, as well as by exogenous factors such as the import of feed via international trade. Limitations on the use of alternative feed sources, as well as the exclusion of the imports from the EU legal framework constitute a crucial gap, which hamper fully leveraging existing solutions.

Product level dataset on embodied human appropriation of net primary production.

This dataset includes data on the embodied human appropriation of net primary production (eHANPP) associated with products derived from agriculture and forestry. The human appropriation of net primary production (HANPP) is an indicator of changes in the yearly availability of biomass energy from photosynthesis that remains available in terrestrial ecosystems after harvest, under current land use, compared to the net primary production of the potential natural vegetation. HANPP is an indicator of land-use intensity that is relevant for biodiversity and biogeochemical cycles. The eHANPP indicator allocates HANPP to products and allows tracing trade flows from origin (the country where production takes place) to consumption (the country where products are consumed), thereby underpinning research into the telecouplings in global land use. The datasets described in this article trace eHANPP associated with the bilateral trade flows between 222 countries. It covers 161 primary crops, 13 primary animal products and 4 primary forestry products, as well as the end uses of these products for the years 1986 to 2013.

The global biodiversity footprint of urban consumption: A spatially explicit assessment for the city of Vienna.

With ongoing global urbanization processes and consumption patterns increasingly recognized as key determinants of environmental change, a better understanding of the links between urban consumption and biodiversity loss is paramount. Here we quantify the global biodiversity footprint (BDF) of Vienna's (Austria) biomass consumption. We present a state-of-the-art product specific approach to (a) locate the production areas required for Vienna's consumption and map Vienna's BDF by (b) linking them with data taken from a previously published countryside Species-Area-Relationship (cSAR) model with a representation of land-use intensity. We found that food has the largest share in Vienna's BDF (58 %), followed by biomass for material applications (28 %) and bioenergy (13 %). The total BDF occurs predominantly within Austria and in its neighbouring countries, with ~20 % located outside Europe. Although the per capita biomass consumption in Vienna is above the global average, global and Viennese per capita BDFs are roughly equal, indicating that Vienna sources its products from high-yield regions with efficient production systems and comparatively low native species richness. We conclude that, among others, dietary changes offer a key leverage point for reducing the urban BDF, while expanding the use of biomass for material and energy use may increase the BDF and requires appropriate monitoring.

Physical and virtual nutrient flows in global telecoupled agricultural trade networks.

Global agricultural trade creates multiple telecoupled flows of nitrogen (N) and phosphorus (P). The flows of physical and virtual nutrients along with trade have discrepant effects on natural resources in different countries. However, existing literature has not quantified or analyzed such effects yet. Here we quantified the physical and virtual N and P flows embedded in the global agricultural trade networks from 1997 to 2016 and elaborated components of the telecoupling framework. The N and P flows both increased continuously and more than 25% of global consumption of nutrients in agricultural products were related to physical nutrient flows, while virtual nutrient flows were equivalent to one-third of the nutrients inputs into global agricultural system. These flows have positive telecoupling effects on saving N and P resources at the global scale. Reducing inefficient trade flows will enhance resource conservation, environmental sustainability in the hyper-globalized world.

Outcomes in women age 40 years and older with cytologically benign endometrial cells.

OBJECTIVE: We sought to estimate cytologically benign endometrial cell (CBEC)-associated endometrial hyperplasia and cancer rates, and describe clinical and histologic outcomes. STUDY DESIGN: Medical records of women age >40 years with CBEC in 2005 through 2010 were reviewed for clinical characteristics; assessment with endometrial biopsy, ultrasound, or hysteroscopy; and consequent outcomes. RESULTS: Of 658 women, 281 (42.7%) were assessed: 39.4% of 330 premenopausal, and 46.0% of 328 postmenopausal women. Among these, cancer rate was 3.6% and differed between premenopausal (0.8%) and postmenopausal (6.0%) women (P = .019). Hyperplasia rate was similar in premenopausal (3.9%) and postmenopausal (3.3%) women. Of 20 assessed women with endometrial pathology, 4 (1 premenopausal) women with cancer and 4 (2 premenopausal) women with hyperplasia had no abnormal bleeding. CONCLUSION: Cancer was more common in postmenopausal women with assessed CBEC while hyperplasia was comparably distributed between premenopausal and postmenopausal women. Findings support CBEC assessment regardless of menopausal status or abnormal bleeding.

Global effects of national biomass production and consumption: Austria's embodied HANPP related to agricultural biomass in the year 2000.

Global trade of biomass-related products is growing exponentially, resulting in increasing 'teleconnections' between producing and consuming regions. Sustainable management of the earth's lands requires indicators to monitor these connections across regions and scales. The 'embodied human appropriation of NPP' (eHANPP) allows one to consistently attribute the HANPP resulting from production chains to consumers. HANPP is the sum of land-use induced NPP changes and biomass harvest. We present the first national-level assessment of embodied HANPP related to agriculture based on a calculation using bilateral trade matrices. The dataset allows (1) the tracing of the biomass-based products consumed in Austria in the year 2000 to their countries of origin and quantifying the HANPP caused in production, and (2) the assigning of the national-level HANPP on Austria's territory to the consumers of the products on the national level. The dataset is constructed along a consistent system boundary between society and ecosystems and can be used to assess Austria's physical trade balance in terms of eHANPP. Austria's eHANPP-trade balance is slightly negative (imports are larger than exports); import and export flows are large in relation to national HANPP. Our findings show how the eHANPP approach can be used for quantifying and mapping the teleconnections related to a nation's biomass metabolism.

Long-term trajectories of the human appropriation of net primary production: Lessons from six national case studies.

The 'human appropriation of net primary production' (HANPP) is an integrated socio-ecological indicator measuring effects of land use on ecological biomass flows. Based on published data for Austria, Hungary, the Philippines, South Africa, Spain and the UK, this paper investigates long-term trends in aboveground HANPP and discusses the relations between population, economic growth, changes in biomass use and land-use intensity and their influences on national HANPP trajectories. During early stages of industrialization, population growth and increasing demand for biomass drive land-cover change, often resulting in deforestation, which raises HANPP. During later stages, industrialization of agriculture boosts agricultural yields often faster than biomass demand grows, resulting in stable or even declining HANPP. Technological change improves agricultural area-efficiency (biomass provision per unit area), thereby decoupling population and economic growth from HANPP. However, these efficiency gains require large inputs of fossil fuels and agrochemicals resulting in pressures on ecosystems and emissions. Our findings corroborate the argument that HANPP alone cannot - as sometimes suggested - be used as a simple measure of carrying capacity. Nevertheless, analyses of long-term HANPP trajectories in combination with accounts of material and energy flows can provide important insights into the sustainability of land use, thereby helping to understand limits to growth.

Changes in Climate Vulnerability and Projected Water Stress of The Gambia's Food Supply Between 1988 and 2018: Trading With Trade-Offs.

Background: The coexistence of under- and overnutrition is of increasing public health concern in The Gambia. Fruits, vegetables and pulses are essential to healthy and sustainable diets, preventing micronutrient deficiencies and non-communicable diseases, while cereals significantly contribute to energy intake. However, environmental changes are predicted to intensify, reducing future yields of these crops if agricultural productivity and resilience are not improved. The Gambia is highly climate-vulnerable and import-dependent, but the extent of its reliance on other climate-vulnerable countries for its supply of nutritionally important crops is currently unknown. Methods: We used United Nations Food and Agriculture Organization data, with novel origin-tracing algorithms applied, to analyse The Gambia's supply of cereals, fruits, vegetables and pulses between 1988 and 2018. The climate vulnerability of countries was assessed using Notre Dame Global Adaptation Initiative (ND-GAIN) index scores, and projected water stress (2040) assessed using World Resources Institute (WRI) scores. Multilevel generalized linear mixed-effects models were used to identify changes in the overall climate vulnerability and projected water stress of supply. Results: Between 1988 and 2018, The Gambia's supply of cereals, fruits, vegetables and pulses diversified, with the proportion domestically produced falling (Cereals: 61.4%-27.7%; Fruits: 93.0%-55.7%; Vegetables: 24.6%-16.3%; Pulses: 100.0%-76.0%). The weighted-average ND-GAIN scores improved (indicating less climate vulnerability) for supply of all crops except cereals, but the weighted-average WRI score for supply deteriorated (indicating increased projected water stress) for all crops except vegetables. When just considering imports, weighted-average ND-GAIN scores deteriorated for fruits and cereals while showing no significant change for other food groups, and the WRI score deteriorated for cereals only. Conclusions: Despite some notable improvements in the environmental vulnerability of The Gambia's supply of nutritionally important crops (particularly vegetables), considerable, and in some cases increasing, proportions of their supply are produced in countries that are vulnerable to climate change and future water stress. This may have implications for the availability, affordability, and hence consumption of these crops in The Gambia, ultimately exacerbating existing nutritional challenges. Exploring the options to strengthen supply resilience-such as altering trade patterns, agricultural techniques and diets-should be prioritized.

Assessing the contribution of mobility in the European Union to rubber expansion.

Nearly three-quarters of global natural rubber production is used to produce tyres, supporting mobility around the globe. The projected increase in mobility could contribute to further expansion of rubber plantations and impact tropical ecosystems. We quantified the use of natural rubber in tyres in the European Union (EU), the corresponding land footprint, and explored drivers of tyre use using country-specific transport statistics and trade registers of rubber goods. Five percent of the world's natural rubber is consumed in tyres used in the EU, using up to a quarter of the area under rubber plantations in some producing countries. Car use is responsible for 58% of this consumption, due to car-dependent lifestyles that are associated with economic prosperity and spatial planning paradigms. While the EU's transport policy focuses on reducing dependence on fossil-fuels, cross-cutting policies are needed to address car-dependency and reduce the EU's land footprint in tropical landscapes without compromising progress towards decarbonisation.

Relative effects of land conversion and land-use intensity on terrestrial vertebrate diversity.

Land-use has transformed ecosystems over three quarters of the terrestrial surface, with massive repercussions on biodiversity. Land-use intensity is known to contribute to the effects of land-use on biodiversity, but the magnitude of this contribution remains uncertain. Here, we use a modified countryside species-area model to compute a global account of the impending biodiversity loss caused by current land-use patterns, explicitly addressing the role of land-use intensity based on two sets of intensity indicators. We find that land-use entails the loss of ~15% of terrestrial vertebrate species from the average 5 × 5 arcmin-landscape outside remaining wilderness areas and ~14% of their average native area-of-habitat, with a risk of global extinction for 556 individual species. Given the large fraction of global land currently used under low land-use intensity, we find its contribution to biodiversity loss to be substantial (~25%). While both sets of intensity indicators yield similar global average results, we find regional differences between them and discuss data gaps. Our results support calls for improved sustainable intensification strategies and demand-side actions to reduce trade-offs between food security and biodiversity conservation.