| 1. |
- Boysen, Lena R., et al.
(author)
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The limits to global-warming mitigation by terrestrial carbon removal
- 2017
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In: Earth's Future. - 2328-4277. ; 5:5, s. 463-474
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Journal article (peer-reviewed)abstract
- Massive near-term greenhouse gas emissions reduction is a precondition for staying well below 2 degrees C global warming as envisaged by the Paris Agreement. Furthermore, extensive terrestrial carbon dioxide removal (tCDR) through managed biomass growth and subsequent carbon capture and storage is required to avoid temperature overshoot in most pertinent scenarios. Here, we address two major issues: First, we calculate the extent of tCDR required to repair delayed or insufficient emissions reduction policies unable to prevent global mean temperature rise of 2.5 degrees C or even 4.5 degrees C above pre-industrial level. Our results show that those tCDR measures are unable to counteract business-as-usual emissions without eliminating virtually all natural ecosystems. Even if considerable (Representative Concentration Pathway 4.5 [RCP4.5]) emissions reductions are assumed, tCDR with 50% storage efficiency requires >1.1 Gha of the most productive agricultural areas or the elimination of > 50% of natural forests. In addition, > 100 MtN/yr fertilizers would be needed to remove the roughly 320 GtC foreseen in these scenarios. Such interventions would severely compromise food production and/or biosphere functioning. Second, we reanalyze the requirements for achieving the 160-190 GtC tCDR that would complement strong mitigation action (RCP2.6) in order to avoid 2 degrees C overshoot anytime. We find that a combination of high irrigation water input and/or more efficient conversion to stored carbon is necessary. In the face of severe trade-offs with society and the biosphere, we conclude that large-scale tCDR is not a viable alternative to aggressive emissions reduction. However, we argue that tCDR might serve as a valuable supporting actor for strong mitigation if sustainable schemes are established immediately. Plain Language Summary In 2015, parties agreed to limit global warming to well below 2 degrees C above pre-industrial levels. However, this requires not only massive near-term greenhouse gas emissions reductions but also the application of negative emission techniques that extract already emitted carbon dioxide from the atmosphere. Specifically, this could refer to the establishment of extensive plantations of fast-growing tree and grass species in combination with biomass conversion to carbon-saving products. Although such deployment is seen as promising, its carbon sequestration potentials and possible side-effects still remain to be studied in depth. In this study, we analyzed two feasibility aspects of such a negative emissions approach using biomass plantations and carbon utilization pathways. First, we show that biomass plantations with subsequent carbon immobilization are likely unable to repair insufficient emission reduction policies without compromising food production and biosphere functioning due to its space-consuming properties. Second, the requirements for a strong mitigation scenario staying below the 2 degrees C target would require a combination of high irrigation water input and development of highly effective carbon process chains. Although we find that this strategy of sequestering carbon is not a viable alternative to aggressive emission reductions, it could still support mitigation efforts if sustainably managed.
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| 2. |
- Gerten, Dieter, et al.
(author)
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Feeding ten billion people is possible within four terrestrial planetary boundaries
- 2020
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In: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 3:3, s. 200-208
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Journal article (peer-reviewed)abstract
- Global agriculture puts heavy pressure on planetary boundaries, posing the challenge to achieve future food security without compromising Earth system resilience. On the basis of process-detailed, spatially explicit representation of four interlinked planetary boundaries (biosphere integrity, land-system change, freshwater use, nitrogen flows) and agricultural systems in an internally consistent model framework, we here show that almost half of current global food production depends on planetary boundary transgressions. Hotspot regions, mainly in Asia, even face simultaneous transgression of multiple underlying local boundaries. If these boundaries were strictly respected, the present food system could provide a balanced diet (2,355 kcal per capita per day) for 3.4 billion people only. However, as we also demonstrate, transformation towards more sustainable production and consumption patterns could support 10.2 billion people within the planetary boundaries analysed. Key prerequisites are spatially redistributed cropland, improved water-nutrient management, food waste reduction and dietary changes. Agriculture transforms the Earth and risks crossing thresholds for a healthy planet. This study finds almost half of current food production crosses such boundaries, as for freshwater use, but that transformation towards more sustainable production and consumption could support 10.2 billion people.
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| 3. |
- Grinberg, Marianna, et al.
(author)
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Toxicogenomics directory of chemically exposed human hepatocytes
- 2014
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In: Archives of Toxicology. - : Springer Science and Business Media LLC. - 1432-0738 .- 0340-5761. ; 88:12, s. 2261-2287
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Journal article (peer-reviewed)abstract
- A long-term goal of numerous research projects is to identify biomarkers for in vitro systems predicting toxicity in vivo. Often, transcriptomics data are used to identify candidates for further evaluation. However, a systematic directory summarizing key features of chemically influenced genes in human hepatocytes is not yet available. To bridge this gap, we used the Open TG-GATES database with Affymetrix files of cultivated human hepatocytes incubated with chemicals, further sets of gene array data with hepatocytes from human donors generated in this study, and publicly available genome-wide datasets of human liver tissue from patients with non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular cancer (HCC). After a curation procedure, expression data of 143 chemicals were included into a comprehensive biostatistical analysis. The results are summarized in the publicly available toxicotranscriptomics directory (http://wiki.toxbank.net/toxicogenomics-map/) which provides information for all genes whether they are up- or downregulated by chemicals and, if yes, by which compounds. The directory also informs about the following key features of chemically influenced genes: (1) Stereotypical stress response. When chemicals induce strong expression alterations, this usually includes a complex but highly reproducible pattern named 'stereotypical response.' On the other hand, more specific expression responses exist that are induced only by individual compounds or small numbers of compounds. The directory differentiates if the gene is part of the stereotypical stress response or if it represents a more specific reaction. (2) Liver disease-associated genes. Approximately 20 % of the genes influenced by chemicals are up- or downregulated, also in liver disease. Liver disease genes deregulated in cirrhosis, HCC, and NASH that overlap with genes of the aforementioned stereotypical chemical stress response include CYP3A7, normally expressed in fetal liver; the phase II metabolizing enzyme SULT1C2; ALDH8A1, known to generate the ligand of RXR, one of the master regulators of gene expression in the liver; and several genes involved in normal liver functions: CPS1, PCK1, SLC2A2, CYP8B1, CYP4A11, ABCA8, and ADH4. (3) Unstable baseline genes. The process of isolating and the cultivation of hepatocytes was sufficient to induce some stress leading to alterations in the expression of genes, the so-called unstable baseline genes. (4) Biological function. Although more than 2,000 genes are transcriptionally influenced by chemicals, they can be assigned to a relatively small group of biological functions, including energy and lipid metabolism, inflammation and immune response, protein modification, endogenous and xenobiotic metabolism, cytoskeletal organization, stress response, and DNA repair. In conclusion, the introduced toxicotranscriptomics directory offers a basis for a rationale choice of candidate genes for biomarker evaluation studies and represents an easy to use source of background information on chemically influenced genes.
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| 4. |
- Heck, Vera, et al.
(author)
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Collateral transgression of planetary boundaries due to climate engineering by terrestrial carbon dioxide removal
- 2016
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In: Earth System Dynamics. - : Copernicus GmbH. - 2190-4979 .- 2190-4987. ; 7:4, s. 783-796
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Journal article (peer-reviewed)abstract
- The planetary boundaries framework provides guidelines for defining thresholds in environmental variables. Their transgression is likely to result in a shift in Earth system functioning away from the relatively stable Holocene state. As the climate system is approaching critical thresholds of atmospheric carbon, several climate engineering methods are discussed, aiming at a reduction of atmospheric carbon concentrations to control the Earth's energy balance. Terrestrial carbon dioxide removal (tCDR) via afforestation or bioenergy production with carbon capture and storage are part of most climate change mitigation scenarios that limit global warming to less than 2 degrees C. We analyse the co-evolutionary interaction of societal interventions via tCDR and the natural dynamics of the Earth's carbon cycle. Applying a conceptual modelling framework, we analyse how the degree of anticipation of the climate problem and the intensity of tCDR efforts with the aim of staying within a safe level of global warming might influence the state of the Earth system with respect to other carbon-related planetary boundaries. Within the scope of our approach, we show that societal management of atmospheric carbon via tCDR can lead to a collateral transgression of the planetary boundary of land system change. Our analysis indicates that the opportunities to remain in a desirable region within carbon-related planetary boundaries only exist for a small range of anticipation levels and depend critically on the underlying emission pathway. While tCDR has the potential to ensure the Earth system's persistence within a carbon-safe operating space under low-emission pathways, it is unlikely to succeed in a business-as-usual scenario.
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| 5. |
- Heck, Vera, et al.
(author)
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Land use options for staying within the Planetary Boundaries – Synergies and trade-offs between global and local sustainability goals
- 2018
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In: Global Environmental Change. - : Elsevier BV. - 0959-3780. ; 49, s. 73-84
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Journal article (peer-reviewed)abstract
- In this paper we develop and assess alternative global land use patterns, guided by the Planetary Boundaries framework, to quantify land use opportunities for staying within the safe environmental operating space. Through a simulation based multi-criteria land use optimisation procedure, we determine the potential upper bounds of improved terrestrial carbon storage and of biodiversity conservation, while also meeting the Planetary Boundaries of land and water use and ensuring improved food supply for a population of 9 billion people. We present alternative global land use scenarios that could simultaneously yield better outcomes on all of these goals, in particular if substantial increases in agricultural productivity are realised. Terrestrial carbon sequestration potentials reach 98 GtC, whereas the potential reduction of the risk to biodiversity is 53%. Furthermore, we analyse the potential synergies and trade-offs of these global land use scenarios with national- and local-level environmental and developmental goals such as those specified in the SDGs, e.g. related to nature conservation, afforestation, bioenergy, employment and equity. This model-based information on synergies and trade-offs between different sustainability goals at different scales can be used in scientific assessments of transformation pathways, in policy making, in support of improved horizontal and vertical policy coherence and multi-level institutional solutions, as well as in SDG implementation, sustainable production and consumption (SDG 12) and global partnership mechanisms (SDG 17).
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