CL3.2.4
Tipping points, domino effects and resilience in the Earth system

CL3.2.4

Tipping points, domino effects and resilience in the Earth system
Co-organized by CR7/NP8/OS1
Convener: Ricarda Winkelmann | Co-conveners: Jonathan Donges, Victor Brovkin, Sarah Cornell, Timothy Lenton
Presentations
| Wed, 25 May, 11:05–11:47 (CEST)
 
Room 0.31/32, Wed, 25 May, 13:20–14:30 (CEST)
 
Room 0.49/50

Presentations: Wed, 25 May | Room 0.31/32

Chairpersons: Sina Loriani, Nico Wunderling
11:05–11:12
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EGU22-1482
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Virtual presentation
Pathways of resilience in complex systems. 
Max Rietkerk

The concept of tipping points and critical transitions helps inform our understanding of the catastrophic effects that global change may have on ecosystems, Earth system components, and the whole Earth system. The search for early warning indicators is ongoing, and spatial self-organization has been interpreted as one such signal. Here, we review how spatial self-organization can aid complex systems to evade tipping points and can therefore be a signal of resilience instead. Evading tipping points through various pathways of spatial pattern formation may be relevant for many ecosystems and Earth system components that hitherto have been identified as tipping prone, including for the entire Earth system.

M. Rietkerk, R. Bastiaansen, S. Banerjee, J. van de Koppel, M. Baudena and A. Doelman. 2021. Evasion of tipping in complex systems through spatial pattern formation. Science 374 (169): abj0359.

How to cite: Rietkerk, M.: Pathways of resilience in complex systems., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1482, https://doi.org/10.5194/egusphere-egu22-1482, 2022.

11:12–11:19
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EGU22-2198
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ECS
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Highlight
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On-site presentation
Partial tipping in a spatially heterogeneous world 
Robbin Bastiaansen, Henk Dijkstra, and Anna von der Heydt

Many climate subsystems are thought to be susceptible to tipping - and some might be close to a tipping point. The general belief and intuition, based on simple conceptual models of tipping elements, is that tipping leads to reorganization of the full (sub)system. Here, we explore tipping in conceptual, but spatially extended and spatially heterogenous models. These are extensions of conceptual models taken from all sorts of climate system components on multiple spatial scales. By analysis of the bifurcation structure of such systems, special stable equilibrium states are revealed: coexistence states with part of the spatial domain in one state, and part in another, with a spatial interface between these regions. These coexistence states critically depend on the size and the spatial heterogeneity of the (sub)system. In particular, in these systems a tipping point might lead to a partial tipping of the full (sub)system, in which only part of the spatial domain undergoes reorganization, limiting the impact of these events on the system's functioning.

How to cite: Bastiaansen, R., Dijkstra, H., and von der Heydt, A.: Partial tipping in a spatially heterogeneous world, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2198, https://doi.org/10.5194/egusphere-egu22-2198, 2022.

11:19–11:26
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EGU22-3830
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ECS
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Highlight
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On-site presentation
Cascading tipping in a coupled cryosphere-ocean model 
Sacha Sinet, Anna S. von der Heydt, and Henk A. Dijkstra
In the climate system, many different large-scale components have been identified as tipping elements, i.e., components that may pass a tipping point, with a substantial and definitive impact on earth and societies. These climate components do not stand on their own, but are dynamically coupled, which leads to the issue of cascading tipping. One important example of cascading involves the Greenland Ice Sheet (GIS), the West Antarctica Ice Sheet (WAIS) and the Atlantic Meridional Overturning Circulation (AMOC). While the destabilizing effect of a GIS decline on the AMOC is well established, the effect of a tipping WAIS is still unclear.
 
In this project, we aim at getting a better understanding of the global behaviour of this connected system, at a conceptual level. Accounting for the different nature of both ice sheets, we use two models including their most important feedbacks, namely, the marine ice sheet instability for the WAIS and the height-accumulation feedback for the GIS. The AMOC, depicted by the Rooth model, is coupled to both ice sheets through meltwater fluxes. Finally, we consider the Southern Ocean temperature as the main driver of the marine ice sheet instability.
With this conceptual interhemispheric model, we study the role of the AMOC as mediator of this potential cascading in hosing and/or climate change experiments, as well as the involved time scales. As a new result we find that, in this model, the stability of the AMOC depends on the ratio between the GIS and WAIS tipping rates, as well as their delay in time.

How to cite: Sinet, S., von der Heydt, A. S., and Dijkstra, H. A.: Cascading tipping in a coupled cryosphere-ocean model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3830, https://doi.org/10.5194/egusphere-egu22-3830, 2022.

11:26–11:33
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EGU22-4425
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ECS
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On-site presentation
Tipping risks due to temperature overshoots within the Paris range 
Nico Wunderling, Ricarda Winkelmann, Johan Rockström, Sina Loriani, David A. McKay, Paul Ritchie, Boris Sakschewski, and Jonathan F. Donges

Climate tipping elements potentially lead to accelerated and irreversible climate change once their critical temperature threshold is passed. Some of their critical thresholds (tipping points) are at risk to be transgressed already within the temperature guardrails of 1.5-2.0°C above pre-industrial levels. However, it has been suggested at the same time that global mean temperature levels are likely to temporarily overshoot these boundaries.

Therefore, we investigate the tipping risk for a set of four interacting climate tipping elements using a conceptual model. To this end, we study the impact of different peak and long-term saturation temperatures on the Greenland Ice Sheet, the West Antarctic Ice Sheet, the Atlantic Meridional Overturning Circulation (AMOC) and the Amazon rainforest.

We find that overshoot peak temperatures between 2.5-4.0°C increase the risk by 10-55% even if long-term global mean temperature levels are stabilized between 1.5-2.0°C. Furthermore, the interactions between the tipping elements increase tipping risks significantly already at modest to intermediate levels of interaction. Therefore our conceptual study suggests that safe overshoots are only possible for low peak temperatures of the overshoot as well as final saturation temperatures at or below today’s global warming levels.

How to cite: Wunderling, N., Winkelmann, R., Rockström, J., Loriani, S., McKay, D. A., Ritchie, P., Sakschewski, B., and Donges, J. F.: Tipping risks due to temperature overshoots within the Paris range, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4425, https://doi.org/10.5194/egusphere-egu22-4425, 2022.

11:33–11:40
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EGU22-4970
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ECS
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On-site presentation
Planetary limits to soil degradation 
Clarisse Kraamwinkel, Anne Beaulieu, Teresa Dias, and Ruth Howison

Soils are essential to life on Earth but are rapidly degrading worldwide due to unsustainable human activities. We argue that soil degradation constitutes a key Earth system process that should be added as 10th Earth system process to the planetary boundaries framework.

Soil degradation shares all key traits with the nine Earth system processes already present in the planetary boundaries framework. It is caused by human activity, has the potential to cause unacceptable environmental change, shows tipping point behavior when forced beyond a critical level, is relevant on both local and global scales, and is strongly interrelated with the other Earth system processes. 

Healthy soils have a level of resilience against disturbances but once forced beyond a critical level, they are at risk of entering into a downward spiral of degradation fuelled by strong positive feedback loops. Well-documented examples include the local feedback between loss of soil structure and soil biota and the large-scale feedback loop between soil erosion and climate change. The final degraded state of the soil is unable to sustain human life on earth. The fall of past civilizations has been related to their inability to protect the soil. At present, ~33% of the global soils are moderately to severely degraded as a direct result of human activities such as unsustainable agricultural practices, urban expansion, and industrialization. Estimates show that by 2050, 90% of our soils will be degraded, the majority of our ecosystems will be compromised and the entire human population will be affected.

Soils are essential to life on Earth through the provision of soil functions and ecosystem services such as biomass production (including ~95% of the food we eat), climate regulation, water storage and purification, habitat provision, and nutrient cycling. They play a key role in achieving many of the Sustainable Development Goals (SDGs) including SDG 15: life on land, SDG2: zero hunger, and SDG6: clean water and sanitation. Soil degradation leads to critical disruptions to biosphere integrity, biogeochemical flows, climate change, and land-system change, all processes that have already crossed their planetary boundaries. Hence, in order to improve the planetary boundaries framework and clearly signal the need to protect the soil, we call for soil degradation to be considered the 10th Earth system process in the planetary boundaries framework. 

How to cite: Kraamwinkel, C., Beaulieu, A., Dias, T., and Howison, R.: Planetary limits to soil degradation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4970, https://doi.org/10.5194/egusphere-egu22-4970, 2022.

11:40–11:47
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EGU22-5176
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ECS
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On-site presentation
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Reversibility experiments of present-day Antarctic grounding lines 
Benoit Urruty, Emily A. Hill, Ronja Reese, Julius Garbe, Olivier Gagliardini, Gael Durand, Fabien Gillet-Chaulet, G. Hilmar Gudmundsson, Ricarda Winkelmann, Mondher Chekki, David Chandler, and Petra Langebroek

The stability of the grounding lines of Antarctica is a fundamental question in glaciology, because current grounding lines are in some locations at the edge of large marine basins, and have been hypothesized to potentially undergo irreversible retreat in response to climate change. This could have global consequences and raise sea levels by several metres. However, their reversibility for the current geometry has not yet been questioned, i.e. if pushed very slightly, are they able to recover their former position? 


Here we approach this question using three state-of-the-art ice sheet models (Elmer\Ice, Úa and PISM) which we initialise to closely replicate the current state of Antarctic ice sheet using inverse methods or spin-up approaches and the latest observations. To assess the reversibility of the Antarctic grounding lines in their current position, we apply a small amplitude perturbation in ice shelf melt rates for 20 years, which leads to a numerically significant grounding line retreat, but does not fundamentally alter it. After reversing the forcing we examine the grounding line evolution over the following 80 to 480 years, which allows us to see the direction of the ice sheet trajectory after removing the perturbation, i.e. recovery or further retreat. However, since ice dynamics adjust over long timescales of millennia, in some cases up to 500 years are not sufficient for the grounding lines to fully recover to their initial positions. To complement these experiments and to investigate the long-term response to small perturbations, we run the lower resolved Parallel Ice Sheet Model towards equilibrium. In this case, the perturbation is the increase from 1850 to present-day climate, and the experiments indicate whether present-day climate can cause Antarctic grounding lines to retreat on the long-term.


This work is part of the TiPACCs project and complements two presentations focusing on the short-term (EGU22-7802) and long-term (EGU22-7885) reversibility experiments of present-day Antarctic grounding lines in more detail.

How to cite: Urruty, B., Hill, E. A., Reese, R., Garbe, J., Gagliardini, O., Durand, G., Gillet-Chaulet, F., Gudmundsson, G. H., Winkelmann, R., Chekki, M., Chandler, D., and Langebroek, P.: Reversibility experiments of present-day Antarctic grounding lines, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5176, https://doi.org/10.5194/egusphere-egu22-5176, 2022.

Lunch break

Presentations: Wed, 25 May | Room 0.49/50

Chairpersons: Nico Wunderling, Sina Loriani
13:20–13:27
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EGU22-5370
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On-site presentation
Revealing hidden tipping in spatially-resolved Earth system analysis 
Sina Loriani, Boris Sakschewski, Jesse F. Abrams, Markus Drüke, Timothy Lenton, Nico Wunderling, Caroline Zimm, and Ricarda Winkelmann
The assessment of potential tipping elements in the Earth system and their associated tipping thresholds is essential for understanding long-term Earth system change and describing a safe operating space. However, their identification in model outputs and observational data typically requires making assumptions about the spatial extent of individual elements. While the resulting regional to continental aggregates allow for the study of collective time series, they are potentially based on subjective judgement and could mask non-linear behaviour on smaller scales.

In this work, we present a novel method based on a timescale- and variable-independent metric to automatically identify potential tipping elements in the Earth system with a few or no free parameters. Gridded datasets are scanned for abrupt shifts on the grid-cell level, which are subsequently automatically clustered in space and time. This allows for the creation of maps with areas grouped and classified by their dynamical behaviour without an a-priori definition of connected regions.

Applying the presented method to various Earth System model outputs, we detect clusters with different nonlinear responses to future emission scenarios which are otherwise masked. Consequently, our bottom-up approach provides insight into the spatial structures and temporal processes of large-scale tipping elements, and sheds light on ‘hidden’ tipping of their subsystems.

 

How to cite: Loriani, S., Sakschewski, B., Abrams, J. F., Drüke, M., Lenton, T., Wunderling, N., Zimm, C., and Winkelmann, R.: Revealing hidden tipping in spatially-resolved Earth system analysis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5370, https://doi.org/10.5194/egusphere-egu22-5370, 2022.

13:27–13:34
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EGU22-6786
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ECS
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Virtual presentation
Estimating nonlinear stability from time series data 
Adrian van Kan, Jannes Jegminat, and Jonathan Donges

Basin stability (BS) is a measure of nonlinear stability in multistable dynamical systems. BS has previously been estimated using Monte-Carlo simulations, which requires the explicit knowledge of a dynamical model. We discuss the requirements for estimating BS from time series data in the presence of strong perturbations, and illustrate our approach for two simple models of climate tipping elements: the Amazon rain forest and the thermohaline ocean circulation. We discuss the applicability of our method to observational data as constrained by the relevant time scales of total observation time, typical return time of perturbations and internal convergence time scale of the system of interest and other factors.

How to cite: van Kan, A., Jegminat, J., and Donges, J.: Estimating nonlinear stability from time series data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6786, https://doi.org/10.5194/egusphere-egu22-6786, 2022.

13:34–13:41
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EGU22-7064
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ECS
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On-site presentation
Identification and management of climate change induced socio-economic tipping points 
Kees van Ginkel, Marjolijn Haasnoot, Elco Koks, and Wouter Botzen

Global warming may cause abrupt and non-linear climate tipping points, with large impacts to established socio-economic systems [1]. The socio-economic system itself also exhibits many non-linear change processes, and therefore may experience manifold unintentional climate-change induced socio-economic tipping points (SETPs) that could already follow from relatively small changes in climatic conditions. Examples are the gentrification of vulnerable groups or abrupt unplanned retreat from areas of increasing climate risk, abrupt transitions in financial markets, large-scale systematic malfunction of critical infrastructure networks during weather extremes, sudden reconfigurations of insurance markets and house price collapses. Such SETPs are defined as ‘a climate change induced, abrupt change of a socio-economic system, into a new, fundamentally different state’ [2]. It is important for spatial-economic planners and capital investors to know if and under what conditions SETPs may happen, and what can be done to anticipate and manage their causes and effects.

With three model-based case studies we demonstrate a stepwise approach to identify SETPs and to support adaptation and mitigation policy. The first is a house price collapse and radical transformation of long-term flood risk policy in a coastal city like Rotterdam, following rapid sea level rise due to Antarctic ice-sheet instability. Using a model that simulates flood risk, house prices and adaption integrally, we identify abrupt house price collapses in hundred-thousands possible futures spanning the uncertainty in sea level rise, storm surge and house market scenarios. We explicitly explore the long-term impacts of four dynamic adaptive strategies to anticipate flood risk and their successfulness in avoiding a SETP [3]. The second case is the financial collapse of the winter sports industry in the European Alps following a gradually retreating snowline [4]. The third is a large-scale systematic malfunction of national road networks of European countries due to increasing river flood hazards. The focus of our contribution is on showing how decision making can be supported despite the large uncertainties around SETPs. Finally, we discuss how the SETP-concept aligns with socio-ecological regime shifts [5] and deliberate positive social tipping points to achieve large mitigation and adaptation challenges [6,7].

Types of tipping points along the cause-effect chain from increasing GHG, to biophysical changes, to socioeconomic impacts and transformative adaptation and mitigation response. Source [2], CC-BY3.0 license.

Refs (doi): [1] 10.1073/pnas.2103081118; [2] 10.1088/1748-9326/ab6395; [3] 10.2139/ssrn.3935775; [4] 10.1016/j.envsci.2021.09.005; [5] 10.1088/1748-9326/aaaa75; [6] 10.1073/pnas.1900577117 [7] v10.1016/j.ecolecon.2021.107242

How to cite: van Ginkel, K., Haasnoot, M., Koks, E., and Botzen, W.: Identification and management of climate change induced socio-economic tipping points, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7064, https://doi.org/10.5194/egusphere-egu22-7064, 2022.

13:41–13:48
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EGU22-7867
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ECS
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On-site presentation
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Exploring the emergence of tipping points in the social-ecological system at the border of Peru, Brazil and Bolivia (MAP region) 
Alberto Andrino and the Prodigy Team

Soils are a key component of the Critical Zone of continental surfaces, ranging from the atmosphere to bedrock, guaranteeing the functioning of the Earth's ecosystems and ensuring the continuity of life on Earth. Our assumption is that highly biodiverse and functional soils provide the underpinning of indispensable services that ensure the basis for sustainable economic livelihoods and societies. Soils are susceptible to degradation through misuse, leading to a reduction in their functional diversity and redundancy. The adoption of a systemic approach, such as the social-ecological systems (SES) framework, may contribute to the identification of the adaptive capacities of societies to this expected reduction in soil functioning. In a SES framework, humans are embedded in natural systems and are understood to profoundly affect these system’s functions/services, interacting through feedbacks and cascading dynamics at different spatial and temporal scales. A SES framework is a suitable analytical tool that can provide insight on sensitive components and constellations of them, which likely may led to the crossing of a tipping point (TP), resulting in undesired alternative steady states of the system.

We aim to identify potential TPs, via an in-depth characterization and understanding of the SESs in the tri-national MAP region (Southwestern Amazon). For this purpose, we have delimited key underlying interconnected subsystems within the study region: the soil ecosystem, the livelihood system, the regional social system and the regional climate system. In our SES framework, we focus on relevant component’s functions for the tipping dynamics relating land use change and loss of ecosystem services. Our objective is to provide a set of early warning indicators of the impact and legacy damage of disturbances and the regulatory feedback dynamics between the different subsystems. Our hypothesis is that the crossing of a TP as consequence of reduced soil functions may exert pressure on livelihoods, as people shift to a new level of welfare or adapt their land use or income-generating activities. If this process leads to additional deforestation, it will likely lead to the amplification of regional drought events due to the loss of moisture convection that forests provide. Increasing drought due to the loss of forests will (self)amplify and lead to increased forest wildfires and more opportunities for illegal deforestation and land use change. Further, increasing livelihood and income insecurity, combined with insufficient provision of state services and regulation, as well as weak law enforcement, may exert pressure on social systems by e.g. making illegal and criminal activities more attractive, ultimately undermining social cohesion. In addition, a central aspect of our research is to investigate options for counteracting this cascade of detrimental/harmful and potentially self-amplifying positive feedbacks. This might be achieved by interfering with self-enhancing positive feedback loops, the stimulation of negative, stabilizing feedbacks, e.g. forest recovery or reflexive governance, especially on the local to regional level in order to prevent the crossing of TPs or even to stimulate non-linear dynamics towards positive TPs.

How to cite: Andrino, A. and the Prodigy Team: Exploring the emergence of tipping points in the social-ecological system at the border of Peru, Brazil and Bolivia (MAP region), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7867, https://doi.org/10.5194/egusphere-egu22-7867, 2022.

Vimeo: EGU22-7867-material-r0
13:48–13:55
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EGU22-11441
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ECS
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On-site presentation
Detecting ecosystem-relevant crossings of thresholds 
Friederike Fröb, Timothée Bourgeois, Nadine Goris, Jörg Schwinger, and Christoph Heinze

With ongoing climate change, multiple stressors including ocean warming, deoxygenation, ocean acidification and limited nutrient availability are expected to lead to considerable regime shifts within marine ecosystems [1]. However, distinguishing such abrupt shifts from long-term trends in physical and biogeochemical ocean variables may not only be obscured by the natural variability of the system, but also the complexity of the ecosystem itself. Moreover, species-dependent physiological tolerances are likely going to limit the detectability of crossing of thresholds or tipping points of the whole ecosystem. The metabolic index describes temperature-dependent hypoxic tolerances with respect to the oxygen supply [2]. Critical values of the metabolic index indicate the geographical limits of marine species, therefore it is a useful metric to describe the extent of a potential habitat. Here, we assess the spatio-temporal detectability of abrupt changes in such a potential habitat for selected marine species using an environmental time series changepoint detection routine developed by [3]. We compare the number and timing of these abrupt changes in different Shared Socioeconomic Pathways (SSPs) run with the fully coupled Norwegian Earth System Model version 2 (NorESM2), i.e., analysing the SSP1-26, SSP-5-34-OS, and SSP5-85 scenarios. Preliminary results reveal global, regional and local abrupt changes of lost metabolically viable potential habitat in relation to environmental stressors under different evolving climates.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 820989 (project COMFORT). The work reflects only the authors’ view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains.

 

[1] Heinze et al., 2020, The quiet crossing of tipping points, PNAS, 118(9)

[2] Deutsch et al., 2020, Metabolic trait diversity shapes marine biogeography, Nature, 585, 557-562

[3] Beaulieu and Killick, 2018, Distinguishing trends and shifts from memory in climate data, Journal of Climate, 31(23), 9519-9543

How to cite: Fröb, F., Bourgeois, T., Goris, N., Schwinger, J., and Heinze, C.: Detecting ecosystem-relevant crossings of thresholds, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11441, https://doi.org/10.5194/egusphere-egu22-11441, 2022.

13:55–14:02
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EGU22-12359
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On-site presentation
Spatial-temporal dynamics of positive social resilience to flood hazards 
Liang Emlyn Yang

Concerns are rising that the earth system may reach some critical tipping points in the coming decades. Though, growing evidence also supports the potential of positive social tipping points that could propel transformative changes towards global sustainability. The recently approved ERC Starting Grant “StoRes” (Spatial-Temporal Dynamics of Flood Resilience) proposed a systematic analysis on unique cases of flood resilience, which is expected to demonstrate such a positive perspective over various spatial and temporal scales.

The ERC project focuses on the historical Tea Horse Road area (THR), a mountainous region of the Southeast Tibetan Plateau with well-documented history going back over 600 years. The study first sets up a theoretical framework on the multi-spatial-temporal features of flood resilience at the THR region, which covers the spatial differences (household, community, city and region) over the past 600 years regarding the governance, technology, society, and culture perspectives of flood resilience. A set of quantitative proxy data, historical archives, literature re-analysis, statistical data, observation data and field survey data are integrated into both the empirical study in the case areas and the agent-based modelling across the cases. Preliminary results indicated that, various strong and smart social regulations (governance, institutions, plans, management, motivations, orders, donations, dedication, etc.) enabled a wise development of many water conservancy projects that consequently enhanced the resilience of local communities to hydrological hazards.

The study aims to further 1) establish a theoretical understanding of the spatial-temporal scales of flood resilience; 2) investigate the spatial patterns and temporal evolution of flood resilience at the THR cases; 3) model the spatial-temporal dynamics of flood resilience using agent-based models; 4) transfer and generalize the research findings of the THR cases to the Mekong River basin and beyond. By doing so, the project will present pioneering work to shape the emerging research field of flood resilience, offering new and multi-dimensional knowledge on the dynamic nature of flood-society relations, and providing crucial missing links to understand how flood resilience develops within complex human-environment contexts.

How to cite: Yang, L. E.: Spatial-temporal dynamics of positive social resilience to flood hazards, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12359, https://doi.org/10.5194/egusphere-egu22-12359, 2022.

14:02–14:09
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EGU22-12865
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ECS
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On-site presentation
Towards a green water planetary boundary 
Lan Wang-Erlandsson, Arne Tobian, Ruud van der Ent, Ingo Fetzer, Sofie te Wierik, Miina Porkka, Arie Staal, Fernando Jaramillo, Heindriken Dahlmann, Chandrakant Singh, Peter Greve, Dieter Gerten, Patrick Keys, Tom Gleeson, Sarah Cornell, Will Steffen, Xuemei Bai, and Johan Rockström

Green water - i.e., land precipitation, evaporation and soil moisture - is fundamental for the functioning of the biosphere and the Earth System, but is increasingly perturbed by continental-to-planetary scale human pressures on land, water and climate systems. The planetary boundaries (PB) framework demarcates a global safe operating space for humanity, but does hitherto not explicitly account for green water. Here, we propose a green-water boundary within the existing PB framework, of which a control variable could be defined as "the percentage of ice-free land area on which root-zone soil moisture deviates from Holocene variability for any month of the year". We provide provisional estimates of baseline departures based on CMIP6 data, and review the literature on soil-moisture induced deterioration in Earth System functioning. The evidences taken together suggest that the green water PB is already transgressed, implying that human modifications of green water need to come to a halt and be reversed. Future research needs to advance our understanding of root-zone water dynamics, including associated large-scale and potentially non-linear interactions with ecohydrology, hydroclimate, biogeochemistry and societies.

How to cite: Wang-Erlandsson, L., Tobian, A., van der Ent, R., Fetzer, I., te Wierik, S., Porkka, M., Staal, A., Jaramillo, F., Dahlmann, H., Singh, C., Greve, P., Gerten, D., Keys, P., Gleeson, T., Cornell, S., Steffen, W., Bai, X., and Rockström, J.: Towards a green water planetary boundary, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12865, https://doi.org/10.5194/egusphere-egu22-12865, 2022.

14:09–14:16
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EGU22-13474
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On-site presentation
Global blue and green water cycles exit from pre-industrial variation – freshwater change planetary boundary exceeded? 
Miina Porkka, Vili Virkki, Lan Wang-Erlandsson, Chinchu Mohan, Tom Gleeson, Dieter Gerten, and Matti Kummu
Cycling of water supports a wide array of Earth system functions ranging from ecosystem provision to regulating greenhouse gas fluxes. While justifiably included in the planetary boundaries framework, the current freshwater planetary boundary fails in recognising the interplay between local and global drivers modifying the water cycle. Building on recent conceptual work and considering an extended selection of Earth system functions, we propose quantitative indicators for blue and green water to measure and monitor water cycle modifications. These indicators can capture changes at local, regional, or planetary scales, offering a robust and easily measurable way of determining alterations in the water cycle.
 
Our data consisted of discharge (blue water) and root-zone soil moisture (green water) simulated by state-of-the-art gridded global hydrological models in ISIMIP 2b. Initiating our analysis at the 30-arcmin grid scale, we set cell-wise dry (5th percentile) and wet (95th percentile) local bounds based on pre-industrial (1681–1860) data, separately for blue and green water. We then determined cell-wise exits from these local bounds of baseline variability and aggregated them at the global scale. This resulted in a time series of the percentage of global land area where blue or green water anomalies exit local bounds of baseline variability. The 95th percentile of these global baseline departures was then set as the safe limit of water cycle modifications. Finally, to estimate the state of the water cycle, we compared the recent past (1881–2005) blue and green water conditions to the pre-industrial conditions. First, we determined cell-wise exits from the local bounds and then aggregated the global baseline departures to compare those with the safe limits.
 
We show that in all aspects - blue and green water and dry and wet anomalies - the global water cycle has undergone substantial changes and transgressed the safe limits. This is a result of a gradual change throughout the 20th century. For blue water, drying conditions dominate along the mid-latitudes, whereas for green water, large-scale wetting prevails in the Northern Hemisphere boreal regions. Major changes in both blue and green water conditions co-occur commonly around regions with the highest anthropogenic pressures. Overall, global changes especially towards drier blue water conditions and wetter green water conditions have gone far beyond the pre-industrial levels - therefore placing the water cycle in a state unknown to modern societies.
 
Our results underline the necessity and urgency to update the freshwater change planetary boundary. As both blue and green water cycles have entered an unprecedented state following a long and gradual change, Earth system functions upkept by the water cycle may already be or become compromised. While further studies are required to assess the status of the freshwater change planetary boundary alongside other boundaries to provide a comprehensive analysis on total Earth system resilience, our results clearly show that the global water cycle is changing towards the unknown.

How to cite: Porkka, M., Virkki, V., Wang-Erlandsson, L., Mohan, C., Gleeson, T., Gerten, D., and Kummu, M.: Global blue and green water cycles exit from pre-industrial variation – freshwater change planetary boundary exceeded?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13474, https://doi.org/10.5194/egusphere-egu22-13474, 2022.

14:16–14:23
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EGU22-13516
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Highlight
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Virtual presentation
Ten new insights in climate science 2021 – a horizon scan 
Maria A. Martin

Since 2017, the 10 new insights in climate science (10NICS, https://10insightsclimate.science/) annually summarize a set of the most critical aspects of Earth’s complex climate system – including physical, biogeochemical and socioeconomic/sociocultural dimensions.

Here we set the context of the 10NICS series as a joint project between Future Earth, the Earth League and the World Climate Research Programme (WCRP), and briefly visit each of the ten insights from the 2021 edition (Martin et al., 2021):  (1) the options to still keep global warming below 1.5 °C; (2) the impact of non-CO2 factors in global warming; (3) a new dimension of fire extremes forced by climate change; (4) the increasing pressure on interconnected climate tipping elements; (5) the dimensions of climate justice; (6) political challenges impeding the effectiveness of carbon pricing; (7) demandside solutions as vehicles of climate mitigation; (8) the potentials and caveats of nature-based solutions; (9) how building resilience of marine ecosystems is possible; and (10) that the costs of climate change mitigation policies can be more than justified by the benefits to the health of humans and nature.

The 10NICS topics are not intended to form a comprehensive scientific assessment. Intentionally limited to 10, each insight is succinct and does not try to cover entire fields.

Martin, M. A., Alcaraz Sendra, O., Bastos, A., Bauer, N., Bertram, C., Blenckner, T., … Woodcock, J. (2021). Ten new insights in climate science 2021: a horizon scan. Global Sustainability, 4(e25), 1–20. https://doi.org/10.1017/sus.2021.25

How to cite: Martin, M. A.: Ten new insights in climate science 2021 – a horizon scan, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13516, https://doi.org/10.5194/egusphere-egu22-13516, 2022.

14:23–14:30
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EGU22-13540
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Virtual presentation
Conceptualizing World-Earth System resilience: Exploring transformation pathways towards a safe and just operating space for humanity 
John M. Anderies, Wolfram Barfuss, Jonathan F. Donges, Ingo Fetzer, Jobst Heitzig, and Johan Rockström

We develop a framework within which to conceptualize World-Earth System resilience.  Our notion of World-Earth System resilience emphasizes the need to move beyond the basin of attraction notion of resilience as we are not in a basin we can stay in. We are on a trajectory to a new basin and we have to avoid falling into undesirable basins.  We thus focus on `pathway resilience', i.e. the relative number of paths that allow us to move from the transitional operating space we occupy now as we leave the Holocene basin  to a safe and just operating space in the Anthropocene. We develop a mathematical model to formalize this conceptualization and demonstrate how interactions between earth system resilience  (biophysical processes) and world system resilience (social processes) impact pathway resilience.  Our findings show that building earth system resilience is probably our only chance to reach a safe and just operating space.  We also illustrate the importance of world system dynamics by showing how the notion of fairness coupled with regional inequality affects pathway resilience. 

How to cite: Anderies, J. M., Barfuss, W., Donges, J. F., Fetzer, I., Heitzig, J., and Rockström, J.: Conceptualizing World-Earth System resilience: Exploring transformation pathways towards a safe and just operating space for humanity, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13540, https://doi.org/10.5194/egusphere-egu22-13540, 2022.