CL3.2.6 | Earth resilience, tipping points and human-Earth system interactions in the Anthropocene
EDI
Earth resilience, tipping points and human-Earth system interactions in the Anthropocene
Co-organized by BG8/CR7/ERE1/NP8/OS1
Convener: Jonathan Donges | Co-conveners: Ricarda Winkelmann, David Armstrong McKay, Marina Hirota, Lan Wang-Erlandsson
Orals
| Fri, 28 Apr, 10:45–12:30 (CEST)
 
Room 0.31/32
Posters on site
| Attendance Fri, 28 Apr, 08:30–10:15 (CEST)
 
Hall X5
Posters virtual
| Attendance Fri, 28 Apr, 08:30–10:15 (CEST)
 
vHall CL
Orals |
Fri, 10:45
Fri, 08:30
Fri, 08:30
In 2015, the UN Sustainable Development Goals and the Paris Agreement on climate recognized the deteriorating resilience of the Earth system, with planetary-scale human impacts constituting a new geological epoch: the Anthropocene. Earth system resilience critically depends on the nonlinear interplay of positive and negative feedbacks of biophysical and increasingly also socio-economic processes. These include dynamics and interactions between the carbon cycle, the atmosphere, oceans, large-scale ecosystems, and the cryosphere, as well as the dynamics and perturbations associated with human activities.

With rising anthropogenic pressures, there is an increasing risk we might be hitting the ceiling of some of the self-regulating feedbacks of the Earth System, and cross tipping points which could trigger large-scale and partly irreversible impacts on the environment, and impact the livelihood of millions of people. Potential domino effects or tipping cascades could arise due to the interactions between these tipping elements and lead to a further decline of Earth resilience. At the same time, there is growing evidence supporting the potential of positive (social) tipping points that could propel rapid decarbonization and transformative change towards global sustainability.

In this session we invite contributions on all topics relating to tipping points in the Earth system, positive (social) tipping, as well as their interaction and domino effects. We are particularly interested in various methodological approaches, from Earth system modelling to conceptual modelling and data analysis of nonlinearities, tipping points and abrupt shifts in the Earth system.

Orals: Fri, 28 Apr | Room 0.31/32

Chairpersons: Jonathan Donges, Lan Wang-Erlandsson, David Armstrong McKay
10:45–10:50
Climate change & climate tipping points
10:50–11:00
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EGU23-3443
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Highlight
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On-site presentation
Andrew H. MacDougall, Josie Mallett, David Hohn, and Nadine Mengis

The Zero Emissions Commitment (ZEC) is the expected temperature change following the cessation of anthropogenic emissions of climate altering gases and aerosols. Recent model intercomparison work has suggested that global average ZEC for CO2 is close to zero. However there has thus far been no effort to explore how temperature is expected to change at spatial scales smaller than the global average. Here we analyze the output of nine full complexity Earth System Models which carried out standardized ZEC experiments to quantify the ZEC from CO2. The models suggest that substantial temperature change following cessation of emissions of CO2 can be expected at large and regional spatial scales. Large scale patterns of change closely follow long established patterns seen during modern climate change, while at the regional scale patterns of change are far more complex and show little consistency between different models. Analysis of model output suggest that for most models these changes far exceed pre-industrial internal variability, suggesting either higher climate variability, continuing changes to climate dynamics or both. Thus it appears likely that at the regional scale, where climate change is directly experienced, climate disruption will not end even as global temperature stabilizes. Such indefinite continued climate changes will test the resilience of local ecosystem and human societies long after economic decarbonization is complete. Overall substantial regional changes in climate are expected following cessation of CO2 emissions but the pattern, magnitude and sign of these changes remains highly uncertain.

How to cite: MacDougall, A. H., Mallett, J., Hohn, D., and Mengis, N.: Regional Climate Expected to Continue to Change Significantly After Net-Zero CO2 Emissions Reached, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3443, https://doi.org/10.5194/egusphere-egu23-3443, 2023.

11:00–11:10
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EGU23-10044
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ECS
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Highlight
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On-site presentation
Gideon Futerman and Claudia Wieners

The modification of the climate by Solar Radiation Modification (SRM) could be a potentially important human-Earth System interaction in the Anthropocene, having potentially beneficial and adverse impacts across climatic and human indices. SRM would likely interact with Earth system resilience in many ways, with our paper exploring SRM’s interaction with Earth System tipping point which has been extremely underexplored in the literature thus far.

SRM would likely be able to reduce global mean surface temperature quickly, although its broader climate imprint, especially on precipitation and local climatic conditions, is not the same as reversing greenhouse gas emissions. Its cooling effect suggests that SRM can help stop us from hitting those tipping elements that are most temperature-dependent, while the situation is more complex for tipping elements which strongly depend on other factors such as precipitation or regional climate changes. This more complex picture could have important implications for the role (or lack of) that SRM could and ought to play in improving Earth system resilience in the Anthropocene.

We review the available literature about the influence of SRM on the tipping elements and threshold free-feedbacks identified by McKay et al. (2022), as well as reviewing the impact of SRM on relevant climatic conditions that could contribute to tipping of each element, to give an assessment of the potential beneficial or adverse impact of SRM and identify key uncertainties and knowledge gaps. We will also briefly assess how these impacts may differ with different methods of deployment and with the termination of SRM.

How to cite: Futerman, G. and Wieners, C.: The Impact of Solar Radiation Modification on Earth System Tipping Points and Threshold Free Feedbacks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10044, https://doi.org/10.5194/egusphere-egu23-10044, 2023.

11:10–11:20
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EGU23-14530
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ECS
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On-site presentation
Early Eocene hyperthermals as carbon cycle tipping points?
(withdrawn)
Margot Cramwinckel, Shruti Setty, Anna von der Heydt, Tim Lenton, and Luc Lourens
11:20–11:30
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EGU23-17342
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ECS
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On-site presentation
Sina Loriani, Boris Sakschewski, Jonathan Donges, and Ricarda Winkelmann

Tipping elements constitute one high-risk aspect of anthropogenic climate change - after their critical thresholds are passed, self-amplifying feedbacks can drive parts of the Earth system into a different state, potentially abruptly and/or irreversibly. A variety of models of different complexity shows these dynamics in many systems, ranging from vegetation over ocean circulations to ice sheets. This growing body of evidence supports our understanding of  potential climate tipping points, their interactions and impacts.

However, a systematic assessment of Earth system tipping points and their uncertainties in a dedicated model intercomparison project is of yet missing. Here we illustrate the steps towards automatically detecting abrupt shifts and tipping points in model simulations, as well as a standardised evaluation scheme for the Tipping Point Model Intercomparison Project (TIPMIP). To this end, the model outputs of taylored numerical experiments are screened for potential tipping dynamics and spatially clustered in a bottom-up approach. The methodology is guided by the anticipated setup of the intercomparison project, and in turn contributes to the design of the TIPMIP protocol.

How to cite: Loriani, S., Sakschewski, B., Donges, J., and Winkelmann, R.: Systematic assessment of climate tipping points, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17342, https://doi.org/10.5194/egusphere-egu23-17342, 2023.

Biosphere & social-ecological tipping
11:30–11:40
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EGU23-3251
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On-site presentation
Axel Kleidon

Many aspects of anthropogenic global change, such as land cover change, biodiversity loss, and the intensification of agricultural production, threaten the natural biosphere. Implications of these specific aspects of environmental conditions are not immediately obvious, so it is hard to obtain a bigger picture of what these changes imply and distinguish beneficial from detrimental human impacts.  Here I describe a holistic approach that provides a bigger picture and use it to understand how the terrestrial biosphere can be sustained in the presence of increased human activities.  This approach focuses on the free energy generated by photosynthesis, the energy needed to sustain both the dissipative metabolic activity of ecosystems and human activities, with the generation rate being set by the physical constraints of the environment.  One can then distinguish two kinds of human impacts on the biosphere: detrimental effects caused by enhanced human consumption of this free energy, and empowering effects that allow for more photosynthetic activity and, therefore, more dissipative activity of the biosphere.  I use examples from the terrestrial biosphere to illustrate this view and global datasets to show how this can be estimated.  I then discuss how certain aspects of modern technology can enhance the free energy generation of the terrestrial biosphere, which can then safeguard its sustenance even as human activity increasingly shapes the functioning of the Earth system.

Note: Presentation is based on this manuscript (https://arxiv.org/abs/2210.09164), accepted for publication in the INSEE journal.

How to cite: Kleidon, A.: How to sustain the terrestrial biosphere in the Anthropocene? A thermodynamic Earth system perspective, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3251, https://doi.org/10.5194/egusphere-egu23-3251, 2023.

11:40–11:50
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EGU23-5722
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ECS
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Highlight
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On-site presentation
Nico Wunderling, Arie Staal, Frederik Wolf, Boris Sakschewski, Marina Hirota, Obbe A. Tuinenburg, Jonathan F. Donges, Henrique M.J. Barbosa, and Ricarda Winkelmann

Since the foundational paper by Lenton et al. (2008, PNAS), tipping elements in the climate system have attracted great attention within the scientific community and beyond. One of the most important tipping elements is the Amazon rainforest. Under ongoing global warming, it is suspected that extreme droughts such as those in 2005 and 2010 occur significantly more often, up to nine out of ten years from the mid to late 21st century onwards (e.g. Cox et al., 2008, Nature; Cook et al., 2020, Earth’s Future).

In this work, we quantify how climates ranging from normal rainfall conditions to extreme droughts may generate cascading tipping events through the coupled forest-climate system. For that purpose, we make use of methods from nonlinear dynamical systems theory and complex networks to create a conceptual model of the Amazon rainforest, which is dependent on itself through atmospheric moisture recycling.

We reveal that, even when the rainforest is adapted to past local conditions of rainfall and evaporation, parts of the rainforest may still tip when droughts intensify. We uncover that forest-induced moisture recycling exacerbates tipping events by causing tipping cascades that make up to one-third (mean+-s.d. = 35.9+-4.9%) of all tipping events. Our results imply that if the speed of climate change might exceed the adaptation capacity of the forest, knock-on effects through moisture recycling impede further adaptation to climate change.

Further, we use a network analysis method to compare the four main terrestrial moisture recycling hubs: the Amazon Basin, the Congo Rainforest, South Asia and the Indonesian Archipelago. By evaluating so-called network motifs, i.e. local-scale network structures, we quantify the fundamentally different functioning of these regions. Our results indicate that the moisture recycling streams in the Amazon Basin are more vulnerable to disturbances than in the three other main moisture recycling hubs.

How to cite: Wunderling, N., Staal, A., Wolf, F., Sakschewski, B., Hirota, M., Tuinenburg, O. A., Donges, J. F., Barbosa, H. M. J., and Winkelmann, R.: Recurrent droughts increase risk of cascading tipping events by outpacing adaptive capacities in the Amazon rainforest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5722, https://doi.org/10.5194/egusphere-egu23-5722, 2023.

11:50–12:00
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EGU23-13620
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On-site presentation
Benjamin Stuch, Rüdiger Schaldach, Regine Schönenberg, Katharina Meurer, Merel Jansen, Claudia Pinzon Cuellar, Shabeh Ul Hasson, Christopher Jung, Ellen Kynast, Jürgen Böhner, and Hermann Jungkunst

The Amazon rainforest is a tipping element of the global climate system due to its high carbon storage potential and its flying rivers providing rain for South America. Studies suggest that land use and land cover change (LUCC) in the Amazon, i.e. deforestation, strongly disturb regional convectional rain pattern, which could lead to an increase of drought frequencies and intensities. Under increasing drought stress, the evergreen tropical rainforest may transform into a seasonal forest or even a savannah ecosystem. Such a transformation would likely activate the Amazon tipping element and may affect global climate change by triggering other critical tipping elements of the global climate system.  

Here we present our transdisciplinary research approach in the Western Amazon rainforest developed in context of the PRODIGY research project. We apply a social-ecological system approach to account for the dynamic interactions and feedbacks between people and nature, which could either stabilize or self-enforce regional tipping cascades. For example, regional land users may suffer declining yield and net primary production from decreasing precipitation. Land users may compensate the drop in production/income e.g. by cultivating more land or seeking for other income sources. As a response, deforestation could increase which may drive a self-enforcing feedback loop that further decrease precipitation.

In a participatory process, together with regional stakeholders we develop land use related explorative scenarios. Preliminary results from the scenario exercise show that future agricultural production increases in all scenarios (crops between 20% and 200% and livestock between 0% and 300%). In the first modelling step, these  changes drive the regionally adjusted spatial land system model LandSHIFT. Simulation results indicate that deforestation increases in all scenarios depending on the production technology and the reflexivity of institutions establishing appropriate management options.

In an integrated modelling step, the calculated LUCC maps serve as input to a regional climate model (WRF), which simulates respective changes in regional temperature and precipitation. Then, temperature and precipitation changes are applied to the biogeochemical model CANDY to simulate the impact (of regional deforestation) on crop yields, Net Primary Production (NPP) and changes in soil C and N cycling. In an iterative process, the yield and NPP responses are fed back to the land-use change model to simulate the required land use adaptations, accordingly. By closing the feedback loop between deforestation, climate, yield and NPP as well as respective land use adaptation, we are able to simulate a cascade of endogenous key process in the regions social ecological system. The integrated modelling results will support the stakeholders in identifying key measures/options/policies that could increase resilience of the regional social-ecological system to prevent crossing destructive regional tipping points.

How to cite: Stuch, B., Schaldach, R., Schönenberg, R., Meurer, K., Jansen, M., Pinzon Cuellar, C., Ul Hasson, S., Jung, C., Kynast, E., Böhner, J., and Jungkunst, H.: The Western Amazon social-ecological system at risk of tipping: A transdisciplinary modelling approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13620, https://doi.org/10.5194/egusphere-egu23-13620, 2023.

Societal tipping points & human-Earth system Interactions
12:00–12:10
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EGU23-3151
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Highlight
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On-site presentation
Adam Izdebski

The current crisis state of the planet, commonly called the Anthropocene, emerged as the result of the Great Acceleration in human consumption and environmental impact which followed the Second World War in the middle of the 20th c. There is growing evidence suggesting that similar acceleration dynamics, characterised by exponential growth in human environmental impact, occurred locally or regionally at earlier stages in human history. It is, however, difficult to identify, quantify, and confirm such cases without high-resolution, well-dated historical or paleoenvironmental data. In this presentation, I review three cases of well-documented Anthropocene-like accelerations, from Roman Anatolia, medieval Poland, and early modern Greece. In all of these cases, it was political consolidation, even if short-lived, as well as economic integration, that created the social tipping point triggering exponential acceleration of human environmental impact. All of these acceleration phases also collapsed once the underlying social dynamics was no longer present.

How to cite: Izdebski, A.: Social tipping points of Anthropocene acceleration dynamics in European history, from Roman times to the Little Ice Age, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3151, https://doi.org/10.5194/egusphere-egu23-3151, 2023.

12:10–12:20
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EGU23-17457
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ECS
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Highlight
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Virtual presentation
Joshua E Buxton, Chris A Boulton, Jean-Francois Mercure, Aileen Lam, and Timothy M Lenton

Through innovation and wider socio-economic processes, large sections of the economy have been known to rapidly (and often irreversibly) transition to alternative states. One such sector currently undergoing a transition is the automotive industry, which is moving from a state dominated by internal combustion engines to one characterised by low-emission vehicles. While much research has focused on early warning signals of climate and ecological tipping points, there is much to be done on assessing the applicability of these methods to social systems. Here we focus on the potential for tipping points to occur in the sale of electrical vehicles in various markets, including Norway and the UK. Early indicators that this new state is being approached are considered through the use of novel data sources such as car sales, infrastructure announcements and online advert engagement. We then map out the socio-technical feedback loops which may drive these tipping points. Consideration is also given to the resilience of the wider automotive industry to previous economic shocks. 

How to cite: Buxton, J. E., Boulton, C. A., Mercure, J.-F., Lam, A., and Lenton, T. M.: Indicators of changing resilience and potential tipping points in the automotive industry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17457, https://doi.org/10.5194/egusphere-egu23-17457, 2023.

12:20–12:30
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EGU23-16944
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ECS
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On-site presentation
Saverio Perri, Simon Levin, Lars Hedin, Nico Wunderling, and Amilcare Porporato

Anthropogenic emissions of CO2 must soon approach net zero to stabilize the global mean temperature. Although several international agreements have advocated for coordinated climate actions, their implementation has remained below expectations. One of the main challenges of international cooperation is the different degrees of socio-political acceptance of decarbonization.

In this contribution, we interrogate a minimalistic model of the coupled human-natural system representing the impact of such socio-political acceptance on investments in clean energy and the path to net-zero emissions. Despite its simplicity, the model can reproduce complex interactions between human and natural systems, and it can disentangle the effects of climate policies from those of socio-political acceptance on the path to net zero. Although perfect coordination remains unlikely, as clean energy investments are limited by myopic economic strategies and a policy system that promotes free-riding, more realistic decentralized cooperation with partial efforts from each actor could still lead to significant emissions cuts.

Since the socio-political feedback on the path to net zero could influence the trajectories of the Earth System for decades to centuries and beyond, climate models need to incorporate better the dynamical bi-directional interactions between socio-political groups and the environment. Our model represents a first step for incorporating this feedback in describing complex coupled human and natural systems.

How to cite: Perri, S., Levin, S., Hedin, L., Wunderling, N., and Porporato, A.: Socio-Political Feedback on the Path to Net Zero, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16944, https://doi.org/10.5194/egusphere-egu23-16944, 2023.

Posters on site: Fri, 28 Apr, 08:30–10:15 | Hall X5

X5.176
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EGU23-1304
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ECS
Arim Yoon

Previous studies with coarse-resolution global climate models (GCMs) have widely shown that extensive deforestation in the Amazon leads to a reduction in precipitation, with a potential irremediable loss of the rainforest past a critical threshold. However, precipitation in the Amazon region is of convective nature and thus has to be parameterized in coarse-resolution GCMs, limiting confidence in the results of such studies. To bypass this limitation, this study aims to investigate the impact of Amazon deforestation on precipitation in global climate simulations that can explicitly represent convection. The simulations are conducted with the ICON-Sapphire atmosphere-only model configuration run with a grid spacing of 5 km for two years. To understand the impacts of Amazon deforestation, we compare the results of a complete deforestation simulation with a control simulation. Results show no significant change in precipitation during the wet season and a slight decrease of precipitation during the dry season in the deforested simulation. Precipitation decreases due to decreased evapotranspiration are compensated by enhanced moisture convergence.

How to cite: Yoon, A.: The impact of Amazon deforestation on rain system using a storm-resolving global climate model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1304, https://doi.org/10.5194/egusphere-egu23-1304, 2023.

X5.177
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EGU23-9387
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ECS
Vitus Benson, Jonathan F. Donges, Jürgen Vollmer, and Nico Wunderling

Critical slowing down has recently been detected as an indicator of reduced resilience in remotely sensed data of the Amazon rainforest [1]. Tropical rainforests are frequently hit by disturbances such as fire, windthrow, deforestation or drought, which are known to follow a heavy-tailed amplitude distribution. Early warning signals based on critical slowing down are theoretically grounded for systems under the influence of weak, Gaussian noise. Hence, it is not imminent that they are applicable also for systems like the Amazon rainforest, which are influenced by heavy-tailed noise. Here, we extended a conceptual model of the Amazon rainforest [2] to study the robustness of critical slowing down indicators to power-law extremes. These indicators are expected to increase before a critical transition. 

We find the way by which such an increase is detected is decisive for the recall of the early warning indicator (i.e. the proportion of critical transitions detected by the indicator). If a linear slope is taken, the recall of the early warning signal is reduced under power-law extremes. Instead, the Kendall-Tau rank correlation coefficient should be used because the recall remains high in this case. Other approaches to increase robustness, like a high-pass filter or the interquartile range, are less effective. In [1], reduced resilience of the Amazon rainforest was determined through an increase in the lag-1 autocorrelation measured by the Kendall-tau rank correlation. Hence, if there was a resilience loss, they can correctly detect it even in the presence of relatively strong power-law disturbances. However, we also quantify the false positive rate, that is, how often a resilience loss is measured if the model represents a stable rainforest. At a significance level of 5% (1%, 10%) for the early warning signal detection, the false positive rate is approximately 10% (5%, 15%). For strong heavy-tailed noise, this false positive rate can deteriorate to as high as 25% (15%, 35%). This indicates, that increasing critical slowing down may not always be caused by an approaching critical transition, a false positive detection is possible.

 

[1] Boulton, C.,  Lenton, T.  and Boers, N.: “Pronounced Loss of Amazon Rainforest Resilience since the Early 2000s”. Nature Climate Change 12-3 (2022).

[2] Van Nes, E., Hirota, M., Holmgren, M. and Scheffer, M.: “Tipping Points in Tropical Tree Cover”. Global Change Biology 20-3 (2014).

How to cite: Benson, V., Donges, J. F., Vollmer, J., and Wunderling, N.: Robustness of critical slowing down indicators to power-law extremes in an Amazon rainforest model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9387, https://doi.org/10.5194/egusphere-egu23-9387, 2023.

X5.178
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EGU23-5233
Likun Ai, Juzhi Hou, Haichao Xie, Yanbo Yu, and Fahu Chen

Spanning more than 6,400 kilometers across Eurasia, the Silk Road played a key role in facilitating exchanges in economy, culture, politics, and religions between East and West. The ancient Silk Road was one of the most important passages for trans-Eurasia exchange and human migrations, which could be traced back to 5000-4000 years before present. To deepen understanding of the effects of environmental changes in shaping the long-term trans-Eurasia exchanges and Silk Road civilization, the Trans-Eurasia Exchange and Silk-Road Civilization Development (ATES) was launched by a group of scientists with background of climate, hydrology, environment, archaeology in 2019. There are about 118 scientists from 10 countries that with different background have joined the ATES so far. ATES now has a President, and three coordinators in the secretariat, and all the alliance members are allocated to the 5 Working Groups (WG) based on their background and research interests. The main scientific issues for the ATES are: 1) Routes and driving forces of ancient human migrations across Eurasia in the Paleolithic; 2) Relationship between the food globalization, development of agro-pastoralism in Eurasia and human migration in the Neolithic; 3) Mechanisms of establishment, shift and demise of routes and key towns along the ancient Silk Road; 4) Effects of environmental changes on the rise and fall of the Silk Road civilization as to the trans-Eurasia exchanges in terms of economy, technology and culture. What does it tell us about the future of ongoing climate change? ATES aims to set an international platform to exchange multi-discipline knowledge and the latest research achievement on the ancient Silk Road, including exchanges of culture, science, and technology along the roads, perceptions of climate change, and socio-economic development in different historical periods along the Silk Road, and effects of environmental changes on the rise and fall of the Silk Road civilization.

ATES welcomes institutes and scientists worldwide to initiate and launch relevant research programs and projects with the ATES community. By establishing several joint research and education centers with partners, ATES facilitates and supports field observations, research, and capacity building. Training of Young Scientists is one of the main tasks for ATES capacity building, which includes the training workshops and field learnings organized by ATES and its partners. In order to strengthen the interaction of the ATES community, and to enhance the exchange of new achievements and insights of the interdisciplinary study on the evolution of trans-Eurasia exchanges and Silk Road civilization, the ATES Silk Road Civilization Forum invites a world-renowned scientist to give a special lecture on the focused topic every 3 months. ATES will organize parallel sessions and side meetings in the big events such as AGU, EGU, Conference of the Parties of the UNFCCC, UNCBD, ANSO conference, et al. ATES partners and other institutes are welcome to join in organizing the above meetings.

How to cite: Ai, L., Hou, J., Xie, H., Yu, Y., and Chen, F.: Association for Trans-Eurasia Exchange and Silk-Road Civilization Development, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5233, https://doi.org/10.5194/egusphere-egu23-5233, 2023.

X5.179
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EGU23-14772
Kira Rehfeld and the SPACY research group members

External forcings and feedback processes of the Earth system lead to timescale and state-dependent climate variability, causing substantial surface climate fluctuations in the past. Particularly relevant for future livelihoods, changing variability patterns could also modify the occurrence of extreme events. However, spatiotemporal mechanisms of climate variability are poorly understood. Likewise, the societal implications are weakly constrained, particularly variability’s potential to drive sustainable transformation. The SPACY project investigates climate variability from past cold and warm periods to future scenarios. One research focus is how forcing mediates climate fluctuations. Bridging the gap between Earth system models and palaeoclimate proxies, we study vegetation and water isotope changes. A second focus is exploring sustainable pathways under climate variability, addressing potential interactions between artificial carbon dioxide removal and surface climate, among others.

 

In particular, we validate the ability of climate models to represent potential climate variability changes. Here, we focus on isotope-enabled simulations with dynamic vegetation. We find that models exhibit less local temperature and water isotope variability than paleoclimate proxies on decadal and longer timescales. Simulations with natural forcing agree much better with proxy records than unforced ones. The mean local temperature variability decreases with warming. Furthermore, we analyze potentials and limitations of terrestrial hydroclimate proxies. This includes water isotopes in speleothems and ice cores and vegetation indicators derived from pollen assemblages.

Transferring our understanding to the future, we contribute to mitigation and sustainable transitions. Weather and climate extremes determine losses and damages, but their impact on socioeconomic development is poorly examined. We scrutinize damage parametrization of economic models regarding the ability to consider variability. While large-scale sequestration of atmospheric carbon dioxide is paramount to mitigation targets, its representation in climate models is insufficient. Accounting for feedbacks of carbon dioxide removal (CDR) requires model experiments with modified land surfaces. We develop CDR representations of “artificial photosynthesis” in Earth system models. Pollen records benchmark the simulated climate–carbon dioxide–vegetation interactions. This supports modeling endogenous societal land use decisions in the future.

Our work continues to improve the understanding of long-term climate predictability. The combined knowledge from past climate studies and comprehensive modeling for future scenarios underlines the relevance of changing boundary conditions for a future within planetary boundaries.

 

 

How to cite: Rehfeld, K. and the SPACY research group members: Sustainable Pathways under Climate Variability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14772, https://doi.org/10.5194/egusphere-egu23-14772, 2023.

X5.180
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EGU23-10864
Mariusz Lamentowicz, Sambor Czerwiński, Monika Karpińska-Kołaczek, Piotr Kołaczek, Mariusz Gałka, Piotr Guzowski, and Katarzyna Marcisz

During European states’ development, various past societies utilized natural resources, but their impact was not uniformly spatially and temporally distributed. Considerable changes resulted in landscape fragmentation, especially during the Middle Ages. Changes in state advances that affected the local economy significantly drove the trajectories of ecosystems’ development. The legacy of significant changes from pristine forests to farming is visible in natural archives as novel ecosystems. Here, we present two high‑resolution, densely dated multi‑proxy studies covering the last 1000 years from peatlands in CE Europe. In that case, the economic activity of medieval societies was related to the emerging Polish state and new rulers, the Piasts (in Greater Poland) and the Joannites (the Order of St. John of Jerusalem, Knights Hospitaller). Our research revealed rapid deforestation and subsequent critical land-use transition in the high and late Middle Ages and its consequences on the peatland ecosystem development. The shift from the old-growth forests correlates well with raising the local economy, deforestation and enhanced peat initiation. Along with the emerging landscape openness, the wetlands switched from wet fen with open water to terrestrial habitats. Both sites possess a different timing of the shift, but they also show that the catchment deforestation caused accelerated terrestrialization. Our data show how closely the ecological state of wetlands relates to forest microclimate. We identified a significant impact of economic development and the onset of intensive agriculture processes near the study sites. Our results revealed a surprisingly fast rate at which the feudal economy eliminated pristine nature from the studied area and led to intensive nature exploitation in the Anthropocene. In consequence, its activities led to the creation of novel peatlands types.

How to cite: Lamentowicz, M., Czerwiński, S., Karpińska-Kołaczek, M., Kołaczek, P., Gałka, M., Guzowski, P., and Marcisz, K.: Towards the Anthropocene peatlands and forests – old-growth forest loss in Western Poland initiated peat growth and peatland state shifts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10864, https://doi.org/10.5194/egusphere-egu23-10864, 2023.

X5.181
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EGU23-14360
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ECS
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Xiaotian Zhou and Aidong Ruan

Microbial communities in freshwater lake sediments play a crucial role in regulating geochemical cycles and controlling greenhouse gas emissions. Many of them exhibit a highly ordered structure along depth profile. Besides redox effect, sediment stratification could also reflect historical transition. Dam construction dramatically increased in the mid-20th century and is considered one of the most far-reaching anthropogenic modifications of aquatic ecosystems. Here we attempted to identify the effect of historical dam construction on sediment microbial zonation in Lake Chaohu, one of the major freshwater lakes in China. The damming event in AD 1962 was coincidentally labeled by the 137Cs peak. Physiochemical and sequencing analyses (16S amplicon and shotgun metagenomics) jointly showed a sharp transition occurred at the damming-labeled horizon which overlapped with the nitrate-methane transition zone (NMTZ) and controlled the depth of methane sequestration. At the transition zone, we observed significant taxonomic differentiation. Random forest algorithm identified Bathyarchaeota, Spirochaetes, and Patescibacteria as the damming-sensitive phyla, and Dehalococcoidia, Bathyarchaeia, Marine Benthic Group A, Spirochaetia, and Holophagae as the damming-sensitive classes. Phylogenetic null model analysis also revealed a pronounced shift in microbial community assembly process, from a selection-oriented deterministic community assembly down to a more stochastic, dispersal-limited one. These findings delineate a picture in which dam-induced changes to the lake trophic level and sedimentation rate generate great changes in sediment microbial community structure, energy metabolism, and assembly process.

How to cite: Zhou, X. and Ruan, A.: Dam construction as an important anthropogenic modification triggers abrupt shifts in microbial community assembly in freshwater lake sediments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14360, https://doi.org/10.5194/egusphere-egu23-14360, 2023.

X5.182
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EGU23-16699
Direct measurements can help to understand the changes in ecosystems: Amazonia a case study
(withdrawn)
Luciana Gatti, Camilla Cunha, Luciano Marani, Henrique Cassol, Cassiano Messias, Egidio Arai, Luciana Soler, Claudio Almeida, Alberto Setzer, Lucas Domingues, Scott Denning, John Miller, Manuel Gloor, Caio Correia, Stephane Crispim, Sergio Correa, Raiane Neves, Francine Silva, and Guilherme Machado
X5.183
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EGU23-9954
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ECS
Tessa Möller, Ernest Annika Högner, Samuel Bien, Carl-Friedrich Schleussner, Johan Rockström, Jonathan F. Donges, and Nico Wunderling

The risk of triggering multiple climate tipping points if global warming levels were to exceed 1.5°C has been heavily discussed in recent literature. Current climate policies are projected to result in 2.7°C warming above pre-industrial levels by the end of this century and will thereby at least temporarily overshoot the Paris Agreement temperature goal.

Here, we assess the risk of triggering climate tipping points under overshoot pathways derived from emission pathways and their uncertainties from the PROVIDE ensemble using PyCascades, a stylised network model of four interacting tipping elements including the Greenland Ice Sheet, the West Antarctic Ice Sheet, the Atlantic Meridional Overturning Circulation, and the Amazon Rainforest.

We show that up until 2300, when overshoots are limited to 2°C, the upper range of the Paris Agreement goal, the median risk of triggering at least one element would be less than 5%, although some critical thresholds may have been crossed temporarily. However, the risk of triggering at least one tipping element increases significantly for scenarios that peak above the Paris Agreement temperature range. For instance, we find a median tipping risk in 2300 of 46% for an emission scenario following current policies. Even if temperatures would stabilize at 1.5°C after having peaked at temperatures projected under current policies, the long-term median tipping risks would approach three-quarters.

To limit tipping risks beyond centennial scales, we find that it is crucial to constrain any temperature overshoot to 2°C of global warming and to stabilize global temperatures at 1.0°C or below in the long-term.

How to cite: Möller, T., Högner, E. A., Bien, S., Schleussner, C.-F., Rockström, J., Donges, J. F., and Wunderling, N.: Climate tipping risks under policy-relevant overshoot temperature pathways, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9954, https://doi.org/10.5194/egusphere-egu23-9954, 2023.

X5.184
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EGU23-7871
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Highlight
Euan Nisbet, Martin Manning, David Lowry, Rebecca Fisher, and James France

Atmospheric methane shows very sharp growth since 2006. Growing evidence for methane's main sink, atmospheric OH, being relatively stable implies a major increase in methane emissions is occurring. Methane's synchronous isotopic shift to more negative d13C(CH4) values means the increase is primarily driven by rapid growth in emissions from biogenic sources, such as natural wetlands and agriculture. Recent acceleration in the increase is also strong evidence that it is too large to be caused primarily by anthropogenic sources. Instead, much of the growth may come from large-scale climate-change feedbacks affecting the productivity and balance between methanogenic and methanotrophic processes in tropical and boreal wetlands. Emissions from tropical wetlands in particular may be larger and more influenced by climate shifts than hitherto realised. If so, even despite the Global Methane Pledge, achieving the goals of the UN Paris Agreement may be much harder than previously anticipated.

Modelling indicates that, for scale and speed, the biogenic feedback component of methane's growth and isotopic shift in the 16 years from 2006-2022 is comparable to (or greater than) phases of abrupt growth and isotopic shift during glacial/interglacial terminations, from Termination V (about 430 ka BP) to Termination I that initiated the Holocene. These were rapid global-scale climate shifts when the Earth system reorganised from cold glacial to warmer interglacial conditions.  Methane's recent 2006-2022 growth in biogenic sources may be within Holocene variability, but it is also a possibility that methane may be providing the first indication that a very large-scale end-of-Holocene reorganisation of the climate system is already under way: Termination Zero.

How to cite: Nisbet, E., Manning, M., Lowry, D., Fisher, R., and France, J.: Is the current methane growth event comparable to a glacial/interglacial Termination event?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7871, https://doi.org/10.5194/egusphere-egu23-7871, 2023.

Posters virtual: Fri, 28 Apr, 08:30–10:15 | vHall CL

vCL.1
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EGU23-17397
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ECS
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Jan Nitzbon, Thomas Schneider von Deimling, Sarah Chadburn, Guido Grosse, Sebastian Laboor, Hanna Lee, Norman Julius Steinert, Simone Maria Stuenzi, Sebastian Westermann, and Moritz Langer

Arctic permafrost is yet the largest non-seasonal component of Earth's cryosphere and has been proposed as a climate tipping element. Already today, permafrost thaw and ground ice loss have detrimental consequences for Arctic communities and are affecting the global climate via carbon-cycle–feedbacks. However, it is an open question whether climatic changes drive permafrost loss in a way that gives rise to a tipping point, crossing of which would imply abrupt acceleration of thaw and disproportional unfolding of its impacts.

Here, we address this question by geospatial analyses and a comprehensive literature review of the mechanisms and feedbacks driving permafrost thaw across spatial scales. We find that neither observation-constrained nor model-based projections of permafrost loss provide evidence for the existence of a global-scale tipping point, and instead suggest a quasi-linear response to global warming. We identify a range of processes that drive rapid permafrost thaw and irreversible ground ice loss on a local scale, but these do not accumulate to a non-linear response beyond regional scales.

We emphasize that it is precisely because of this overall linear response, that there is no „safe space“ for Arctic permafrost where its loss could be acceptable. Every additional amount of global warming will proportionally subject additional land areas underlain by permafrost to thaw, implying further local impacts and carbon emissions.

How to cite: Nitzbon, J., Schneider von Deimling, T., Chadburn, S., Grosse, G., Laboor, S., Lee, H., Steinert, N. J., Stuenzi, S. M., Westermann, S., and Langer, M.: Is Arctic Permafrost a Climate Tipping Element? – Potentials for Rapid Permafrost Loss Across Spatial Scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17397, https://doi.org/10.5194/egusphere-egu23-17397, 2023.

vCL.2
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EGU23-13587
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ECS
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Krishna Kumar S and Ashwin K Seshadri

The convective quasi-equilibrium (CQE) framework has been successfully employed in the past to build intermediate complexity models accounting for the interaction of convection and large-scale dynamics (Neelin and Zeng, 1999, JAS). As a consequence, these models find use in the study of monsoon circulations, which also experience abrupt onset among several other intriguing features. While some low-order simplifications of CQE based Quasi-equilibrium tropical circulation model (QTCM) yields insights into the mechanisms of monsoon dynamics, they are restricted in the range of processes accounted for. A hierarchy of models, on the other hand, would serve well to study monsoon dynamics and various influences. While the existence of bifurcations or 'tipping-points' in monsoon dynamics has been studied for certain simple models, a thorough investigation of this possibility across a hierarchy of models is absent. Such a hierarchy of models would provide an understanding of effects of different simplifying assumptions on dominant balances in the momentum and thermodynamic equations and resulting nonlinear dynamics, including the choice of precipitation parameterizations. This study explores a hierarchy of such models of varying complexity, based on the QTCM equations. The potential occurrence of bifurcation phenomena are considered, along with their sensitivity to various parameter changes, in the context of the role of different nonlinearities present in these models. The study builds on recent results interpreting the suppression of bifurcation phenomena in these models, as a result of shifts in equilibrium branches and consequently their physical relevance. The hierarchy of models approach, in this context, reconciles apparent contradictions between bifurcations being observed in the simplest models and the evidence from more complex models as well as observations, while identifying robust phenomena.

How to cite: Kumar S, K. and Seshadri, A. K.: Model hierarchies and bifurcations in QE monsoon models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13587, https://doi.org/10.5194/egusphere-egu23-13587, 2023.