| 1. |
- Bondeau, Alberte, et al.
(författare)
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Modelling the role of agriculture for the 20th century global terrestrial carbon balance
- 2007
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 13:3, s. 679-706
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Forskningsöversikt (refereegranskat)abstract
- In order to better assess the role of agriculture within the global climate-vegetation system, we present a model of the managed planetary land surface, Lund-Potsdam-Jena managed Land (LPJmL), which simulates biophysical and biogeochemical processes as well as productivity and yield of the most important crops worldwide, using a concept of crop functional types (CFTs). Based on the LPJ-Dynamic Global Vegetation Model, LPJmL simulates the transient changes in carbon and water cycles due to land use, the specific phenology and seasonal CO2 fluxes of agricultural-dominated areas, and the production of crops and grazing land. It uses 13 CFTs (11 arable crops and two managed grass types), with specific parameterizations of phenology connected to leaf area development. Carbon is allocated daily towards four carbon pools, one being the yield-bearing storage organs. Management (irrigation, treatment of residues, intercropping) can be considered in order to capture their effect on productivity, on soil organic carbon and on carbon extracted from the ecosystem. For transient simulations for the 20th century, a global historical land use data set was developed, providing the annual cover fraction of the 13 CFTs, rain-fed and/or irrigated, within 0.5 degrees grid cells for the period 1901-2000, using published data on land use, crop distributions and irrigated areas. Several key results are compared with observations. The simulated spatial distribution of sowing dates for temperate cereals is comparable with the reported crop calendars. The simulated seasonal canopy development agrees better with satellite observations when actual cropland distribution is taken into account. Simulated yields for temperate cereals and maize compare well with FAO statistics. Monthly carbon fluxes measured at three agricultural sites also compare well with simulations. Global simulations indicate a similar to 24% (respectively similar to 10%) reduction in global vegetation (respectively soil) carbon due to agriculture, and 6-9 Pg C of yearly harvested biomass in the 1990s. In contrast to simulations of the potential natural vegetation showing the land biosphere to be an increasing carbon sink during the 20th century, LPJmL simulates a net carbon source until the 1970s (due to land use), and a small sink (mostly due to changing climate and CO2) after 1970. This is comparable with earlier LPJ simulations using a more simple land use scheme, and within the uncertainty range of estimates in the 1980s and 1990s. The fluxes attributed to land use change compare well with Houghton's estimates on the land use related fluxes until the 1970s, but then they begin to diverge, probably due to the different rates of deforestation considered. The simulated impacts of agriculture on the global water cycle for the 1990s are similar to 5% (respectively similar to 20%) reduction in transpiration (respectively interception), and similar to 44% increase in evaporation. Global runoff, which includes a simple irrigation scheme, is practically not affected.
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| 2. |
- Barfuss, Wolfram, et al.
(författare)
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Sustainable use of renewable resources in a stylized social-ecological network model under heterogeneous resource distribution
- 2017
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Ingår i: Earth System Dynamics. - : Copernicus GmbH. - 2190-4979 .- 2190-4987. ; 8:2, s. 255-264
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Tidskriftsartikel (refereegranskat)abstract
- Human societies depend on the resources ecosystems provide. Particularly since the last century, human activities have transformed the relationship between nature and society at a global scale. We study this coevolutionary relationship by utilizing a stylized model of private resource use and social learning on an adaptive network. The latter process is based on two social key dynamics beyond economic paradigms: boundedly rational imitation of resource use strategies and homophily in the formation of social network ties. The private and logistically growing resources are harvested with either a sustainable (small) or non-sustainable (large) effort. We show that these social processes can have a profound influence on the environmental state, such as determining whether the private renewable resources collapse from overuse or not. Additionally, we demonstrate that heterogeneously distributed regional resource capacities shift the critical social parameters where this resource extraction system collapses. We make these points to argue that, in more advanced coevolutionary models of the planetary social-ecological system, such socio-cultural phenomena as well as regional resource heterogeneities should receive attention in addition to the processes represented in established Earth system and integrated assessment models.
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| 3. |
- Boysen, Lena R., et al.
(författare)
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The limits to global-warming mitigation by terrestrial carbon removal
- 2017
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Ingår i: Earth's Future. - 2328-4277. ; 5:5, s. 463-474
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Donges, Jonathan F., et al.
(författare)
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Earth system modeling with endogenous and dynamic human societies : the copan
- 2020
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Ingår i: Earth System Dynamics. - : Copernicus GmbH. - 2190-4979 .- 2190-4987. ; 11:2, s. 395-413
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of Earth system dynamics in the Anthropocene requires explicitly taking into account the increasing magnitude of processes operating in human societies, their cultures, economies and technosphere and their growing feedback entanglement with those in the physical, chemical and biological systems of the planet. However, current state-of-the-art Earth system models do not represent dynamic human societies and their feedback interactions with the biogeophysical Earth system and macroeconomic integrated assessment models typically do so only with limited scope. This paper (i) proposes design principles for constructing world-Earth models (WEMs) for Earth system analysis of the Anthropocene, i.e., models of social (world)-ecological (Earth) coevolution on up to planetary scales, and (ii) presents the copan:CORE open simulation modeling framework for developing, composing and analyzing such WEMs based on the proposed principles. The framework provides a modular structure to flexibly construct and study WEMs. These can contain biophysical (e.g., carbon cycle dynamics), socio-metabolic or economic (e.g., economic growth or energy system changes), and sociocultural processes (e.g., voting on climate policies or changing social norms) and their feedback interactions, and they are based on elementary entity types, e.g., grid cells and social systems. Thereby, copan:CORE enables the epistemic flexibility needed for contributions towards Earth system analysis of the Anthropocene given the large diversity of competing theories and methodologies used for describing socio-metabolic or economic and sociocultural processes in the Earth system by various fields and schools of thought. To illustrate the capabilities of the framework, we present an exemplary and highly stylized WEM implemented in copan:CORE that illustrates how endogenizing sociocultural processes and feedbacks such as voting on climate policies based on socially learned environmental awareness could fundamentally change macroscopic model outcomes.
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| 5. |
- Donges, Jonathan, et al.
(författare)
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Taxonomies for structuring models for World-Earth systems analysis of the Anthropocene : subsystems, their interactions and social-ecological feedback loops
- 2021
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Ingår i: Earth System Dynamics. - : Copernicus GmbH. - 2190-4979 .- 2190-4987. ; 12:4, s. 1115-1137
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Tidskriftsartikel (refereegranskat)abstract
- In the Anthropocene, the social dynamics of human societies have become critical to understanding planetary-scale Earth system dynamics. The conceptual foundations of Earth system modelling have externalised social processes in ways that now hinder progress in understanding Earth resilience and informing governance of global environmental change. New approaches to global modelling of the human World are needed to address these challenges. The current modelling landscape is highly diverse and heterogeneous, ranging from purely biophysical Earth system models, to hybrid macro-economic integrated assessments models, to a plethora of models of socio-cultural dynamics. World-Earth models capable of simulating complex and entangled human-Earth system processes of the Anthropocene are currently not available. They will need to draw on and selectively integrate elements from the diverse range of fields and approaches; thus, future World-Earth modellers require a structured approach to identify, classify, select, combine and critique model components from multiple modelling traditions. Here, we develop taxonomies for ordering the multitude of societal and biophysical subsystems and their interactions. We suggest three taxa for modelled subsystems: (i) biophysical, where dynamics is usually represented by natural laws of physics, chemistry or ecology (i.e. the usual components of Earth system models); (ii) socio-cultural, dominated by processes of human behaviour, decision-making and collective social dynamics (e.g. politics, institutions, social networks and even science itself); and (iii) socio-metabolic, dealing with the material interactions of social and biophysical subsystems (e.g. human bodies, natural resources and agriculture). We show how higher-order taxonomies can be derived for classifying and describing the interactions between two or more subsystems. This then allows us to highlight the kinds of social-ecological feedback loops where new modelling efforts need to be directed. As an example, we apply the taxonomy to a stylised World-Earth system model that endogenises the socially transmitted choice of discount rates in a greenhouse gas emissions game to illustrate the effects of social-ecological feedback loops that are usually not considered in current modelling efforts. The proposed taxonomy can contribute to guiding the design and operational development of more comprehensive World-Earth models for understanding Earth resilience and charting sustainability transitions within planetary boundaries and other future trajectories in the Anthropocene.
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| 6. |
- Drüke, Markus, et al.
(författare)
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The long-term impact of transgressing planetary boundaries on biophysical atmosphere–land interactions
- 2024
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Ingår i: Earth System Dynamics. - 2190-4979 .- 2190-4987. ; 15:2, s. 467-483
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Tidskriftsartikel (refereegranskat)abstract
- Human activities have had a significant impact on Earth's systems and processes, leading to a transition of Earth's state from the relatively stable Holocene epoch to the Anthropocene. The planetary boundary framework characterizes major risks of destabilization, particularly in the core dimensions of climate and biosphere change. Land system change, including deforestation and urbanization, alters ecosystems and impacts the water and energy cycle between the land surface and atmosphere, while climate change can disrupt the balance of ecosystems and impact vegetation composition and soil carbon pools. These drivers also interact with each other, further exacerbating their impacts. Earth system models have been used recently to illustrate the risks and interacting effects of transgressing selected planetary boundaries, but a detailed analysis is still missing. Here, we study the impacts of long-term transgressions of the climate and land system change boundaries on the Earth system using an Earth system model with an incorporated detailed dynamic vegetation model. In our centennial-scale simulation analysis, we find that transgressing the land system change boundary results in increases in global temperatures and aridity. Furthermore, this transgression is associated with a substantial loss of vegetation carbon, exceeding 200 Pg C, in contrast to conditions considered safe. Concurrently, the influence of climate change becomes evident as temperatures surge by 2.7–3.1 °C depending on the region. Notably, carbon dynamics are most profoundly affected within the large carbon reservoirs of the boreal permafrost areas, where carbon emissions peak at 150 Pg C. While a restoration scenario to reduce human pressure to meet the planetary boundaries of climate change and land system change proves beneficial for carbon pools and global mean temperature, a transgression of these boundaries could lead to profoundly negative effects on the Earth system and the terrestrial biosphere. Our results suggest that respecting both boundaries is essential for safeguarding Holocene-like planetary conditions that characterize a resilient Earth system and are in accordance with the goals of the Paris Climate Agreement.
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| 7. |
- Gerten, Dieter, et al.
(författare)
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Feeding ten billion people is possible within four terrestrial planetary boundaries
- 2020
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Ingår i: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 3:3, s. 200-208
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Heck, Vera, et al.
(författare)
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Collateral transgression of planetary boundaries due to climate engineering by terrestrial carbon dioxide removal
- 2016
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Ingår i: Earth System Dynamics. - : Copernicus GmbH. - 2190-4979 .- 2190-4987. ; 7:4, s. 783-796
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Jans, Yvonne, 1978, et al.
(författare)
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Biomass production in plantations: Land constraints increase dependency on irrigation water
- 2018
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Ingår i: GCB Bioenergy. - : Wiley. - 1757-1707 .- 1757-1693. ; 10:9, s. 628-644
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Tidskriftsartikel (refereegranskat)abstract
- Integrated assessment model scenarios project rising deployment of biomass‐using energy systems in climate change mitigation scenarios. But there is concern that bioenergy deployment will increase competition for land and water resources and obstruct objectives such as nature protection, the preservation of carbon‐rich ecosystems, and food security. To study the relative importance of water and land availability as biophysical constraints to bioenergy deployment at a global scale, we use a process‐detailed, spatially explicit biosphere model to simulate rain‐fed and irrigated biomass plantation supply along with the corresponding water consumption for different scenarios concerning availability of land and water resources. We find that global plantation supplies are mainly limited by land availability and only secondarily by freshwater availability. As a theoretical upper limit, if all suitable lands on Earth, besides land currently used in agriculture, were available for bioenergy plantations (“Food first” scenario), total plantation supply would be in the range 2,010–2,300 EJ/year depending on water availability and use. Excluding all currently protected areas reduces the supply by 60%. Excluding also areas where conversion to biomass plantations causes carbon emis- sions that might be considered unacceptably high will reduce the total plantation supply further. For example, excluding all areas where soil and vegetation carbon stocks exceed 150 tC/ha (“Carbon threshold savanna” scenario) reduces the supply to 170–290 EJ/year. With decreasing land availability, the amount of water available for irrigation becomes vitally important. In the least restrictive land availability scenario (“Food first”), up to 77% of global plantation biomass supply is obtained without additional irrigation. This share is reduced to 31% for the most restrictive “Carbon threshold savanna” scenario. The results highlight the critical —and geographically varying—importance of co‐managing land and water resources if substantial contributions of bioenergy are to be reached in mitigation portfolios.
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| 10. |
- Otto, Ilona M., et al.
(författare)
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Human agency in the Anthropocene
- 2020
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Ingår i: Ecological Economics. - : Elsevier BV. - 0921-8009 .- 1873-6106. ; 167
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Tidskriftsartikel (refereegranskat)abstract
- The human species has been recognized as a new force that has pushed the Earth's system into a new geological epoch referred to as the Anthropocene. This human influence was not conscious, however, but an unintended effect of the consumption of fossil-fuels over the last 150 years. Do we, humans, have the agency to deliberately influence the fate of our species and the planet we inhabit? The rational choice paradigm that dominated social sciences in the 20th Century, and has heavily influenced the conceptualization of human societies in global human-environmental system modelling in the early 21st Century, suggests a very limited view of human agency. Humans seen as rational agents, coordinated through market forces, have only a very weak influence on the system rules. In this article we explore alternative concepts of human agency that emphasize its collective and strategic dimensions as well as we ask how human agency is distributed within the society. We also explore the concept of social structure as a manifestation of, and a constraint on, human agency. We discuss the implications for conceptualization of human agency in integrated assessment modelling efforts.
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