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38 Seiten, Note: 1,7
Table of content
Index of Abbreviations
1. The Planetary Boundary framework and the Planetary Nitrogen Boundary
1.1 The Planetary Boundary framework
1.2 The Planetary Nitrogen Boundary
1.2.1 Foundation of the Planetary Nitrogen Boundary
1.2.2 Definition and quantification of the Planetary Nitrogen Boundary
2. Operationalization of the Planetary Nitrogen Boundary for Germany
2.2 Current literature
2.3 Opportunities vs. critique
2.3.1 Boundaries for production based Nr
2.3.2 Boundaries for consumption based Nr
3. Germany’s internal and external contribution to the transgression of the Planetary Nitrogen Boundary
3.1 Research questions
3.2 Research design
3.3.2 Accounting principles and terminology
3.3.3 MRIO analysis
3.3.4 Legume BNF
3.3.5 Downscaling the PB N and assessing the transgression
Mineral N-fertilizer application and biological nitrogen fixation by legumes (“BNF”) are main anthropogenic sources of reactive N (“Nr”), biophysical drivers of the disruption of the N-cycle and indicate the transgression of the Planetary Nitrogen Boundary (“PB N”, Rockström et al. 2009, Bodirsky et al. 2014). To answer the question of Germany’s contribution to these agricultural Nr sources, through the total consumption of products and services, environmentally-extended multi-regional input-output (“MRIO”) analysis is applied to track and account, direct and indirect, N-fertilizer use through international supply chains in 2007. From the resulting 31 kg N/cap consumption based N-fertilizer use, 60% are embodied in imports and 40 % used internally. Comparing consumption based and production based values shows, that Germany is a net-importing country of embodied N-fertilizer use with + 9 kg N/cap. The total amount of N-fertilizer used for domestic production, imports and exports is 41 kg N/cap. Due to low long-term storage of Nr in the agricultural system, Nr sources correspond approximately to Nr losses (Rockström et al. 2009, Bodirsky et al. 2014) that can cause (multiple; but not linearly-dependent) environmental impacts (Galloway et al. 2003, Bodirsky et al. 2014). Complexities from the nitrogen cascade (Galloway et al. 2008) and social-economic dynamics puts also locally manifested N- boundary processes on a global scale (Häyhä et al. 2014, 7), challenging (consumption based) national bottom up boundaries in view of external N-flows. A “footprint”/boundary perspective that compares current national consumption based shoe sizes, per capita, with an equal, per capita, share of the PB N could provide a relevant estimation of the needed reductions to return to the safe operating space. For Germany a transgression of 270-310%, of which approximately two thirds is external, and one third internal Nr from human intended fixation processes, is found. It can be concluded that German consumption drives substantial local nitrogen pollution in other countries and mitigation, especially through sufficiency approaches, is necessary to return to the safe operating space.
Hiermit möchte ich insbesondere meinen Betreuern Dr. Holger Hoff, Prof. Dr. Dieter Gerten und Dr. Timm Zwickel für Ihre Unterstützung danken. Mein Dank geht auch an das Potsdam Institut für Klimafolgenforschung für die Möglichkeit eines Gastforscherstatus an Ihrer Einrichtung.
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The Planetary Boundary (PB) framework focuses on the biophysical constraints of the Earth system in a Holocene-like state (Steffen et al. 2009). Planetary Boundaries are human-determined values for those control variable of Earth system processes, that are crucial for the Earth system’s self-regulation capacity and Holocene-like state (ibid.). They are set at a (proposed) safe distance from dangerous levels or, if it exists, from its global threshold. Thresholds are defined following Schellnhuber (2002) as non-linear transitions in the functioning of coupled human-environmental systems (ibid.).
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Figure 1: The updated Planetary Boundaries (Steffen et al. 2015)
The original nine PB’s, published in 2009 were updated 2015 and include now: Biogeochemical flows (nitrogen and phosphorus), Biosphere integrity (Functional diversity and Genetic diversity), Land-system change, Climate Change, Ocean acidification, Stratospheric ozone depletion, Freshwater use, Atmospheric aerosol loading and Novel entities. Five boundaries are already exceeded: for three of them, Nitrogen, Phosphorus and Genetic diversity, scientific knowledge on current levels suggests, that there is a high risk of a “change to the functioning of the Earth system that could potentially be devastating for human societies” (Steffen et al. 2015, 2). They are therefore rated to be in the high risk zone. The other exceeded boundaries, Climate change and Land system change, are in the “increasing risk zone” (ibid.), whereas Atmospheric aerosol loading, Functional diversity and Novel entities are not yet quantified. Furthermore, the Planetary boundaries are interdependent , “because transgressing one may both shift the position of other boundaries or cause them to be transgressed.” (Steffen 2009, 1).
The Planetary Boundary framework has received widespread attention by scientists and is discussed at the interface of science and policy (Hoff et al. 2014, 2015, Nykvist et al. 2013, Pisano & Berger 2013). Related research topics, that also this thesis is close to, include the Operationalization of the Planetary Boundaries for national and regional applications, downscaling, benchmarking, policy mapping & mainstreaming (Planetary Boundary Research Lab 2016). On international level the PB concept has been used and referred to in UN reports and by the UN secretary; also in the context of the sustainable development goals (Pisano & Berger 2013). On EU level the concept is increasingly considered in reports of the EU commission and council of the EU. In Germany, especially the Enquete-Kommission Wachstum, Wohlstand, Lebensqualität, the WBGU- Wissenschaftlicher Beirat der Bundesregierung Globale Umweltveränderungen and the EEAC- European Advisory and Sustainable Development Councils recognized the concept (SRU 2015).
The nitrogen system change is to a large extend influenced by Human actions (Gruber & Galloway 2008, Fowler et al. 2013). One of its key drivers is the anthropogenic conversion of atmospheric N2 to reactive Nitrogen Nr via the Haber Bosch process (ibid., Erisman et al. 2015). For the terrestrial sphere, humanity has more than doubled these Nr inputs (Gruber & Galloway 2008). Further agricultural human-induced sources of Nr are the biological nitrogen fixation (BNF) of crops and Nr from soil organic matter depletion through land management practices (Bodirski et al. 2014). Also, human unintended N fixation is a source of Nr through nitrous oxides (NOx) from transport and industry (Rockström et al. 2009). From the introduction of new Nr a Nitrogen cascade through different environmental compartments starts (Galloway et al. 2003) with different consequences: First most of the Nr passes various terrestrial and freshwater ecosystems posing threats for soil quality and terrestrial biodiversity, air quality, greenhouse gas “balance”, fresh water quality and biodiversity (Galloway et al. 2003, Sutton 2011). The changes can have threshold character at local scales in lake systems (Steffen et al. 2009). Reaching coastal and marine ecosystems reactive N flows are related to hypoxic and even anoxic events and zones, a severe form of Eutrophication, as for example described for the Baltic sea (Carstensen 2014, Zillen 2008). Here threshold like shifts (ibid., Villnäs et al. 2012) occur, and important ecosystem services are effected, with major changes in fauna and species, biomass and abundance (Carstensen 2014). These zones are also named dead zones (i.e. Mee 2006) and are rapidly increasing globally (Selman 2008). Rockström et al. (2009, 13) conclude : “N and P flows at regional to global scales may cause undesired non-linear change in terrestrial, aquatic, and marine systems, while simultaneously functioning as a slow driver influencing anthropogenic climate change at the planetary level.”
Although N- flows itself have no global threshold (Steffen et al. 2015) or have one, that is difficult to determine with certainty (Rockström et al. 2009, Dao et al. 2015) its processes at local and regional scales can generate feedbacks for processes that have planetary thresholds (Steffen et al. 2015) and have local and regional thresholds. An examples of the dynamical interactions (Westley et al. 2011) are the relation between the N- and C-cycle with positive and negative feedbacks: While nutrients accelerate biomass growth and can induce (at least) a temporary carbon sink, fauna (diversity) can be fundamentally altered with possible detrimental effects for climate change adaptation (Gruber & Galloway 2008). Also interactions with the water cycle are noticeable (SRU 2015). There is limited scientific understanding on the total dynamics with their temporal component; often dynamics can only be made plausible but cannot be predicted (ibid.). Also the societal-economic effects of the N-systems change remain unclear and call for the application of the precautionary principle, that is part of the Planetary Boundary concept (ibid.)
Due to efforts later in this thesis to measure Germany’s performance towards the Planetary Nitrogen Boundary its control variable and method of quantification are described with the exact terminology used by the authors.
Given the sectoral and temporal complexity of the N cascade the Planetary Nitrogen Boundary was defined at driver level (Rockström et al. 2009, 13), originally with the control variable “human fixation of N2from the atmosphere”. Because environmental pressures occur in later steps of the Nitrogen cascade, the term foot print for an account of the human fixation of N2 from the atmosphere is not a perfect analogy and the term “shoe size” (Pfister & Hellweg 2009) will be adopted, here. In the updated Planetary Boundaries paper De Vries et al. (2013) definition of “the combined input of N from intended human fixation processes” (Steffen et al. 2015b, 4) has been adopted as the control variable for the Planetary Nitrogen Boundary. They state, generally, that included in the PB N is “the anthropogenic industrial fixation of nitrogen from atmospheric N2 via the Haber-Bosch process” and “intended biological N fixation”. Excluded is “(iii) unintended N fixation due to the emission of nitrogen oxides (NOx) from transport and industry” (ibid.).
In more detail De Vries et al. (2013) and Steffen et al. (2015) use the application rate of intentionally fixed reactive N to the agricultural system:
“However, again for pragmatic reasons we adopt the application rate of intentionally fixed reactive N to the agricultural system. This control variable is easier to measure and track, and is more directly amenable to policy and management interventions.” (Steffen et al. 2015, SI, 5). De Vries et al. (2013, 3) formulate it slightly different: “intended biological and chemical N fixation mainly for use in agriculture.”. The focus on agriculture is proposed, given that it reduces data and complexity and because “the unintended N2 anthropogenic fixation (i.e. industrial N fixation and combustion processes) amounts to 29% of anthropogenic fixation and is considered almost constant over time” (Dao et al. 2015, 39).
Then, in the actual calculation of the Planetary Boundary value, De Vries et al. (2013) use data on N fertilizer application rates and biological N fixation of legumes (excluding for example sugar cane (Bodirsky 2016, pers. comm., 21 June; Boddey 1995) and rice cultivation, that also induce higher values of biological nitrogen fixation than other crops and vegetation (Smil 1999).
In De Vries et al. (2013) critical limits were set for four environmental threat indicators: atmospheric NH3 concentrations in view of adverse biodiversity, radiative forcing in view of climate change, NO3-concentrations in ground water related to health effects and the eutrophication and acidification potential of dissolved inorganic N concentrations in surface water.
Except for Radiative Forcing this was followed by back-calculating critical N losses (that would respect the critical limits), while accounting for spatial variability and current exceedance. Thirdly De Vries et al. (2013) back-calculated the critical N fixation rates, that would lead to the critical N-losses, considering N-fertilizer application rates and biological N fixation of legumes. For the calculation De Vries et al. (2013) reduced present N-losses in agricultural areas, where the N-indicator is currently exceeded and kept N-addition in all other areas without elevations. The Boundary is therefore likely an underestimate if optimal allocation of N would be achieved (Steffen et al. 2015, SI). But even if optimal allocation was achieved, current levels of N application (150 Tg N y-1) would exceed this conservative boundary value (ibid.). De Vries et al. (2013) arrive at following global limit values for N losses and fixation:
Table 1: Limit values in terms of N-losses and N-fixation computed by De Vries et al. (2013) (in Dao et al. 2015; in Tg N/y)
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The calculations are described by the authors as example calculations in a first approximate approach (ibid.). Since Radiative Forcing is already covered by the climate change boundary, Steffen et al. (2015) take the next lower value: 62 Tg N y-1 as the Planetary Nitrogen Boundary. This is the N- fixation limit for the eutrophication and acidification potential of N runoff to surface water with a critical value of 1 mg l-1 (De Vries et al. 2013). The uncertainty range is set at 62-82Tg, to include the result obtained, when using a higher critical value of 2.5 mg l-1. Steffen et al. (2015) state, that this compares well with calculations of De Vries et al. (2013) and Bodirsky et al. (2014) of the N fixation needed for sufficient nutrition of the global population. There have also been other PB N boundary calculations, for example by Dao et al. (2015) for the N losses boundary, that could be operationalized to the national level.
Part of the original Planetary Boundary concept is the comparison of current levels of the globally aggregated PB control variable with the PB value itself (by some authors referred to as “benchmarking”, cf. Fang et al. 2015). As a result, the PBs are rated to be transgressed and in the high risk zone or zone of uncertainty; or not transgressed and in the below boundary zone (cf. chapter 1).
A research questions of this thesis is, to what extend German consumption of goods and services contributes to the PB N’s earth system processes and transgression. Advancements in the answering of this question can positively contribute to recent research questions regarding consumption based benchmarking of the PB N (Nykvist et al. 2013, Hoff et al. 2015) and also potentially provide knowledge for the goal 2b of the SDSN- Sustainable Development Solutions Network’s : Reporting of national contribution towards the PB’s (Pisano & Berger 2013). This target is part of the SDSN’s second priority challenge– Achieve Development within Planetary Boundaries. It suggests that “all countries have a right to development that respects planetary boundaries, ensures sustainable production and consumption patterns […] by mid-century” (SDSN 2013, ix).
An important part of the overarching research questions is how an individual or national “share” of the Planetary Boundary can be quantified (“downscaling”) and how environmental N- indicators are allocated to a country. Hoff et al. (2015) differentiates three different approaches of downscaling and allocating:
1) Total country values with regard to country area, agricultural area or yield
2) Production based per capita values and
3) Consumption based per capita values
A production based approach includes Nr from domestic production and exports, while the consumption based approach, includes Nr from domestic production and imports. Summed over all countries the production based and consumption based values are equal (Kanemoto et al. 2012). Although usually environmental data for countries is provided in production based figures, Peters (2008) shows that both consumption based and production based accounting are legitimate and have policy value. The operationalization of the nitrogen boundary is furthermore discussed at the interface of science and policy. Hoff (2015, 1) describes and follows a “bridging science and policy” approach, focusing on the Future Earth concept of “co-design and co-production” of knowledge, in which scientists, policymakers and stakeholders work closely together in an iterative process to generate policy-relevant knowledge (ibid.).
There are a number of German and EU policies regarding Nitrogen pollution already in place (Hoff et al. 2015). Many of the environmental and sustainability goals, however, are not met (ibid.). Since the first quarter of 2016 Germany is being taken to the Court of Justice of the EU “for failing to take stronger measures to combat water pollution caused by nitrates” (Environmental Technology 2016, 1), while currently the German national nitrogen sustainability strategy is being revised, that is supposed to provide a long-term perspective of 2030 and beyond. Pisano & Berger (2013, 21) researched the viewpoints of national policy makers on the Planetary Boundary concept: “InGermany, the BMU (Federal Ministry for the Environment, Nature Conservation and Nuclear Safety) considers the PB concept to be “potentially very important for putting the social and economic condition of sound ecological systems on the scientific and political agendas”; moreover, they say, “its scientific grounding combined with its intuitive rationale makes it highly attractive”. Regarding future actions, they note for Germany, that in the current program of the federal ministry, the PB concept could play a relevant role; but still questions, on the formulation and interpretation of the Planetary Boundary concept to the national scale and questions towards the method of defining national environmental goals and targets, are unanswered (ibid.).
Recent studies focused on the operationalization of the PB concept for the national and regional level with different approaches (i.e. Dao et al. 2015, Häyha et al. 2016, Hoff et al. 2015, Nykvist et al. 2013). Dao et al. (2015) assessed the Swiss environmental performance against a downscaled, N-losses Planetary Boundary, accounting in their hybrid-allocation downscaling method also for historic emissions. They report that global N-losses in 2000 transgressed the Planetary N-losses Boundary of 47.8 Tg N/a by 17%. For 2011 Swiss consumption based N-losses transgressed the Swiss per capita limit of 6.9 kg by almost 100%. N-losses for Swiss imports were about double as high as N-losses of exports and (since 2007) almost as high as N-losses for domestic production. N-losses for domestic production have been decreasing over the last 15 years by approx. 6%, while N-losses for imports have been growing more rapidly than those for exports (ibid., 53). To calculate their consumption based N-losses, environmentally- extended multi-regional input-output (MRIO) analysis was applied. Being able to identify both the direct and indirect international N-losses for national consumption, MRIO analysis can be an important methodology to enhance the operationalization of the Planetary Nitrogen Boundary. Wiedmann & Barrett (2013), as well as Peters (2008) underline the positive policy implication that MRIO based data can have.
Nykvist et al. (2013) analyzed the production based performance of many countries towards the 2009 version of the Planetary Nitrogen Boundary with an equal share downscaling approach and points at missing consumption based figures for nitrogen.
Häyha et al. (2016) offer a systematic for the operationalization and downscaling process, considering the biophysical, social-economical and ethical dimensions in bridge across scales and making the concept compatible with policy at smaller than global scales. They highlight the role of consumption-based analysis to show national responsibility, also in the “spatially heterogeneous, systemically connected processes [that] have only recently been seen as global problems through scientific insights about Earth system dynamics and global social economic connectivity.” (ibid., 13).
Hoff (2015) assesses the opportunities, that the Planetary Boundary framework offers for the current revision of the German nitrogen sustainability strategy. He summarizes, that the PB framework can support the vertical integration of the German sustainability strategy with international and global environmental goals, as well as international cooperation. Hoff (2015) concludes that the PB concept indicates, that current national policy is likely to be not ambitious enough in view of external N-shoe sizes and impacts. Hoff (2015), Nykvist et al. (2013, 88) and Häyhä et al. (2015, 15) formulate the need for consumption based accounts; also for benchmarking the downscaled Planetary Boundary.
Opportunities are being assessed how the planetary boundary framework can be operationalized for Germany (Hoff et al. 2015). Generally, the PB framework can have a signal function to fill national implementation gaps and develop more ambitious and vertically integrated policy, by referring to bigger scale environmental effects of N-pollution and a transgressed planetary boundary (ibid.).
German N- policy almost exclusively targets Nr from a production point of view (Jung et al. 2016). The consistency and efficiency measures Germany applies here are, in all probability, not sufficient to return to a safe operating space for nitrogen (SRU 2015, 66). They could also worsen the risk of shifting environmental impacts to other countries (ibid., Hoff et al. 2015 ). or leave already high external Nr- shoe sizes (cf. Chapter 3.4) and footprints unchanged, if not complemented by consistent sufficiency policy (SRU 2015, 66) and further production based measures (cf. Bodirsky et al. 2014). Sufficiency measures explicitly deal with the consumption perspective (Fischer & Grießhammer 2013, 10). The development of consumption based data and knowledge can support these efforts.
In the following two sub- chapters the opportunities of the Planetary Boundary to provide a boundary-shoe size (boundary-footprint) perspective for production-based and consumption-based data is discussed.
Using the Planetary Boundary to propose national Nr-budgets via downscaling can be criticized, because such budgets can be more accurately calculated via bottom-up- approaches (SRU 2015) (i.e. similar to the PB N calculation; cf. chapter 22.214.171.124). This bottom-up national limit can then be used to provide a shoe size- (cf. chapter 3.2) or footprint – boundary perspective, that can potentially be useful for policy. Erisman et al. (2011) for instance, recommend a 50%-70% reduction of Dutch Nr- production on the basis of such an assessment.
Likely such reductions are not sufficient, when also considering the external N-flows from, and connected to domestic and export production (Hoff et al. 2015; i.e. from riverine Nr transport to other countries, export of manure or livestock feed). It is complex to assess the external N-flow’s (multiple) contribution(s) to the actual external transgressions of various, local, critical loads, making it difficult to integrate in bottom-up approaches. The downscaled per-capita Planetary Boundary can possibly complement the bottom-up approaches in providing an orientation for a limit here: It indicates the acceptable Nr fixation for the individual’s share of the worlds ecosystems, in which no transgression of critical loads in critical zones and no additional footprints in the other zones is induced (cf. De Vries et al. 2013) and therefore has a more comprehensive system boundary (Feng et al. 2011). Furthermore, it can be useful in the context of international cumulative environmental effects, like Nr-pollution of the Baltic or North Sea and climate change (Hoff et al. 2015, 7).
Sufficiency measures explicitly deal with the consumption perspective (Fischer & Grießhammer 2013, 10). The consumption perspective allocates internal and external Nr from domestic and (international) imports production to the importing country. While there is currently a lack of consistent sufficiency policy (Hünecke et al. 2010, SRU 2012 in Jung et al. 2016), it has a big potential to substantially reduce N-pollution in various environmental compartments and regions inside and outside of Germany (cf. Jung et al. 2016, SRU 2015).
Knowledge on consumption based N-flows is limited and uses different methodologies; although it could be a good foundation for sufficiency measures: Oita et al. (2015) sum up N- “emissions” of households, industry and agriculture to the environment, abroad and internally, for the total national consumption of goods and services. For Germany they account with their top-down, MRIO-trade analysis, almost 50 kg N/capita; of which 35 kg are N20, NH3 and N-portable to water bodies and about 13 kg are NOx emissions. Additionally, they identify important trade routes of embodied N-emissions. Because of the summation over all N-flows of different stages of the N-cycle, it is difficult to determine from the data, how much new reactive N is originally introduced from the consumption activities, because of double-counting. Leach et al. (2011) use a bottom-up methodology and calculate consumption based reactive N- losses to the environment via the average food and protein supply data from FAOSTAT. Advantages of the Oita et al. (2015) trade analysis (like including country specific N-fertilizer rates; or inclusion of indirect N-flows in the supply chains) are missing and the virtual N-factors used, do not give information of the loss route or -form (Leach et al. 2011)). They calculate about 23 kg N/cap for all consumption sectors and about 20 kg N/cap for food consumption and production.
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