Laura Scherer

Modelling spatially explicit impacts from phosphorus emissions in agriculture

PurposeExcess phosphorus from fertilizer application and mobilised soil phosphorus from erosion are partially lost to the aquatic environment where they might cause eutrophication. Phosphorus emissions vary spatially and it is the goal of this study to broaden the scope of the existing inventory to the global scale and to increase the spatial resolution by accounting for relevant environmental processes.MethodsPhosphorus emissions were estimated globally at a resolution of 5 arc-minutes for 169 crops. Two models were coupled for that purpose. First, the Universal Soil Loss Equation (USLE) model was used to determine soil erosion which is the dominant process inducing phosphorus emissions. Second, the Swiss Agricultural Life Cycle Analysis (SALCA) model was applied to estimate the phosphorus emissions from four different processes with erosion being one of them. The emissions as inventory were compared to the ecoinvent database and subsequently translated into environmental impacts on biodiversity via characterisation factors. Additionally, sensitivity and contribution to variance analyses were carried out.Results and discussionOur results suggest that the data in the ecoinvent database, which is widely used for life cycle assessments, underestimate phosphorus emissions by up to an order of magnitude. Furthermore, the contribution to variance analysis highlighted the importance of regionalising both, inventory results and characterisation factors.ConclusionsSince the ecoinvent database provides a poor representation of global conditions, we highly recommend using regionalised estimates of phosphorus emissions provided in this study.

Global Biodiversity Loss by Freshwater Consumption and Eutrophication from Swiss Food Consumption

We investigated water-related resource use, emissions and ecosystem impacts of food consumed in Switzerland. To do so, we coupled LCA methodologies on freshwater consumption, freshwater eutrophication and the consequent local and global biodiversity impacts with Swiss customs data and multiregional input-output analysis. Most of the resource use, emissions and impacts occur outside the national boundaries which illustrates the extent of environmental outsourcing facilitated by international trade. Countries that are severely affected by Swiss food consumption include Spain, the United States and Ecuador. Cocoa, coffee, and almonds stood out as products with high impacts. By identifying spatial hotspots and impactful products, awareness of policy-makers as well as individual consumers can be raised and efforts of detailed assessments can be streamlined. However, political and economic constraints and the resistance by individual consumers limit the high potential of changes in diets and trade relations to decrease the environmental impacts of food.

Large-scale hydrological modeling for calculating water stress indices: Implications of improved spatiotemporal resolution, surface-groundwater differentiation, and uncertainty characterization

Physical water scarcities can be described by water stress indices. These are often determined at an annual scale and a watershed level; however, such scales mask seasonal fluctuations and spatial heterogeneity within a watershed. In order to account for this level of detail, first and foremost, water availability estimates must be improved and refined. State-of-the-art global hydrological models such as WaterGAP and UNH/GRDC have previously been unable to reliably reflect water availability at the subbasin scale. In this study, the Soil and Water Assessment Tool (SWAT) was tested as an alternative to global models, using the case study of the Mississippi watershed. While SWAT clearly outperformed the global models at the scale of a large watershed, it was judged to be unsuitable for global scale simulations due to the high calibration efforts required. The results obtained in this study show that global assessments miss out on key aspects related to upstream/downstream relations and monthly fluctuations, which are important both for the characterization of water scarcity in the Mississippi watershed and for water footprints. Especially in arid regions, where scarcity is high, these models provide unsatisfying results.

Hydropower's Biogenic Carbon Footprint

Global warming is accelerating and the world urgently needs a shift to clean and renewable energy. Hydropower is currently the largest renewable source of electricity, but its contribution to climate change mitigation is not yet fully understood. Hydroelectric reservoirs are a source of biogenic greenhouse gases and in individual cases can reach the same emission rates as thermal power plants. Little is known about the severity of their emissions at the global scale. Here we show that the carbon footprint of hydropower is far higher than previously assumed, with a global average of 173 kg CO2 and 2.95 kg CH4 emitted per MWh of electricity produced. This results in a combined average carbon footprint of 273 kg CO2e/MWh when using the global warming potential over a time horizon of 100 years (GWP100). Nonetheless, this is still below that of fossil energy sources without the use of carbon capture and sequestration technologies. We identified the dams most promising for capturing methane for use as alternative energy source. The spread among the ~1500 hydropower plants analysed in this study is large and highlights the importance of case-by-case examinations.

Dealing with uncertainty in water scarcity footprints

Water scarcity adversely affects ecosystems, human well-being and the economy. It can be described by water scarcity indices (WSIs) which we calculated globally for the decades 1981–1990 and 2001–2010. Based on a model ensemble, we calculated the WSI for both decades including uncertainties. While there is a slight tendency of increased water scarcity in 2001–2010, the likelihood of the increase is rather low (53%). Climate change played only a minor role, but increased water consumption is more decisive. In the last decade, a large share of the global population already lived under highly water scarce conditions with a global average monthly WSI of 0.51 (on a scale from 0 to 1). Considering that globally there are enough water resources to satisfy all our needs, this highlights the need for regional optimization of water consumption. In addition, crop choices within a food group can help reduce humanitys water scarcity footprint without reducing its nutritional value.

Linking country level food supply to global land and water use and biodiversity impacts: The case of Finland.

The agricultural products consumed in Finland are increasingly grown on foreign farms. We analyze the Finnish imports of food and feed crops from 1986 to 2011 by products and by their geographic origin drawing a link to environmental impacts. The share of foreign crops consumed in Finland nearly doubled in the study period. The imports increased especially with commodities that could also be produced domestically. While the production of food increasingly shifted abroad, also the exports from Finland increased. >90% of the blue water of the Finnish crop supply came from foreign water resources. We map the results of land and water use together with their impacts on global biodiversity, and show that most of the land and water use related biodiversity impacts (>93%) associated with the Finnish food consumption are related to the imports and therefore taken place outside the Finnish borders. The use of multiple environmental indicators can help identifying products and spatial hotspots associated with the most severe environmental impacts of the Finnish crop imports contributing to a more holistic decision-making and the promoting of sustainable food consumption both domestically and globally.

Mapping and linking supply- and demand-side measures in climate-smart agriculture. A review

Climate change and food security are two of humanity’s greatest challenges and are highly interlinked. On the one hand, climate change puts pressure on food security. On the other hand, farming significantly contributes to anthropogenic greenhouse gas emissions. This calls for climate-smart agriculture—agriculture that helps to mitigate and adapt to climate change. Climate-smart agriculture measures are diverse and include emission reductions, sink enhancements, and fossil fuel offsets for mitigation. Adaptation measures include technological advancements, adaptive farming practices, and financial management. Here, we review the potentials and trade-offs of climate-smart agricultural measures by producers and consumers. Our two main findings are as follows: (1) The benefits of measures are often site-dependent and differ according to agricultural practices (e.g., fertilizer use), environmental conditions (e.g., carbon sequestration potential), or the production and consumption of specific products (e.g., rice and meat). (2) Climate-smart agricultural measures on the supply side are likely to be insufficient or ineffective if not accompanied by changes in consumer behavior, as climate-smart agriculture will affect the supply of agricultural commodities and require changes on the demand side in response. Such linkages between demand and supply require simultaneous policy and market incentives. It, therefore, requires interdisciplinary cooperation to meet the twin challenge of climate change and food security. The link to consumer behavior is often neglected in research but regarded as an essential component of climate-smart agriculture. We argue for not solely focusing research and implementation on one-sided measures but designing good, site-specific combinations of both demand- and supply-side measures to use the potential of agriculture more effectively to mitigate and adapt to climate change.

Expanding kenya's protected areas under the convention on biological diversity to maximize coverage of plant diversity.

Biodiversity is highly valuable and critically threatened by anthropogenic degradation of the natural environment. In response, governments have pledged enhanced protected-area coverage, which requires scarce biological data to identify conservation priorities. To assist this effort, we mapped conservation priorities in Kenya based on maximizing alpha (species richness) and beta diversity (species turnover) of plant communities while minimizing economic costs. We used plant-cover percentages from vegetation surveys of over 2000 plots to build separate models for each type of diversity. Opportunity and management costs were based on literature data and interviews with conservation organizations. Species richness was predicted to be highest in a belt from Lake Turkana through Mount Kenya and in a belt parallel to the coast, and species turnover was predicted to be highest in western Kenya and along the coast. Our results suggest the expanding reserve network should focus on the coast and northeastern provinces of Kenya, where new biological surveys would also fill biological data gaps. Meeting the Convention on Biological Diversity target of 17% terrestrial coverage by 2020 would increase representation of Kenyas plant communities by 75%. However, this would require about 50 times more funds than Kenya has received thus far from the Global Environment Facility.

A Multimedia Hydrological Fate Modeling Framework To Assess Water Consumption Impacts in Life Cycle Assessment

Many new methods have recently been developed to address environmental consequences of water consumption in life cycle assessment (LCA). However, such methods can only partially be compared and combined, because their modeling structure and metrics are inconsistent. Moreover, they focus on specific water sources (e.g., river) and miss description of transport flows between water compartments (e.g., from river to atmosphere via evaporation) and regions (e.g., atmospheric advection). Consequently, they provide a partial regard of the local and global hydrological cycle and derived impacts on the environment. This paper proposes consensus-based guidelines for a harmonized development of the next generation of water consumption LCA indicators, with a focus on consequences of water consumption on ecosystem quality. To include the consideration of the multimedia water fate between compartments of the water cycle, we provide spatial regionalization and temporal specification guidance. The principles and recommendations of the paper are applied to an illustrative case study. The guidelines set the basis of a more accurate, novel way of modeling water consumption impacts in LCA. The environmental relevance of this LCA impact category will improve, yet much research is needed to make the guidelines operational.

Erratum to: Modelling spatially explicit impacts from phosphorus emissions in agriculture

Purpose Excess phosphorus from fertilizer application and mobilised soil phosphorus from erosion are partially lost to the aquatic environment where they might cause eutrophication. Phosphorus emissions vary spatially and it is the goal of this study to broaden the scope of the existing inventory to the global scale and to increase the spatial resolution by accounting for relevant environmental processes. Methods Phosphorus emissions were estimated globally at a resolution of 5 arc-minutes for 169 crops. Two models were coupled for that purpose. First, the Universal Soil Loss Equation (USLE) model was used to determine soil erosion which is the dominant process inducing phosphorus emissions. Second, the Swiss Agricultural Life Cycle Analysis (SALCA) model was applied to estimate the phosphorus emissions from four different processes with erosion being one of them. The emissions as inventory were compared to the ecoinvent database and subsequently translated into environmental impacts on biodiversity via characterisation factors. Additionally, sensitivity and contribution to variance analyses were carried out. Results and discussion Our results suggest that the data in the ecoinvent database, which is widely used for life cycle assessments, underestimate phosphorus emissions by up to an order of magnitude. Furthermore, the contribution to variance analysis highlighted the importance of regionalising both, inventory results and characterisation factors. Conclusions Since the ecoinvent database provides a poor representation of global conditions, we highly recommend using regionalised estimates of phosphorus emissions provided in this study.