Periodic Reporting for period 1 - CriticalEarth (Multiscales and Critical Transitions in the Earth System)
Periodo di rendicontazione: 2021-03-01 al 2023-02-28
CriticalEarth is a research consortium focused on understanding tipping elements (TEs) in the climate system. TEs are components of the climate system that have the potential to undergo abrupt transitions, such as the Atlantic Meridional Overturning Circulation (AMOC), ice sheets, rainforests, and permafrost. The consortium aims to develop advanced statistical tools to monitor TEs and identify early-warning signals for tipping. They will also investigate the interaction between different TEs and the possibility of cascading tipping events. The research requires a truly interdisciplinary effort, combining paleoclimatic records, recent observations, and Earth System Models (ESMs). We train 15 early stage researchers (ESRs) to develop new methods for assessing the mechanisms and associated risks of critical transitions in the climate. The goal is to better understand the thresholds for irreversible climate change and develop early warning systems and safe operating spaces to avoid it.
It is important for society to understand climate tipping points because they pose a significant threat to human well-being and the sustainability. By identifying and understanding these tipping points, we can take action to avoid crossing them and prevent catastrophic climate change.
This requires developing advanced statistical tools, monitoring Tipping Elements (TEs) in the climate system, and investigating the interaction between different TEs. By doing so, we can better predict and prepare for potential climate changes, develop early warning systems, and identify safe operating spaces to avoid irreversible climate change.
The research objectives are:
1 Explore stochastic multiscale models in climate science and develop the theory of fast-slow systems and the relationship to classical bifurcation theory. Provide the theoretical basis for cascading tipping points in high-dimensional complex systems.
2 Dynamical analysis: Investigate and identify critical transitions in stochastic and deterministic dynamical models, such as state-of-the-art ESMs and compute safe operating spaces and transition probabilities. Develop the methodology and the mathematics of rare event algorithms with models of intermediate complexity.
3 Physical processes: Quantify the TEs and the interaction between different TEs in the Earth system.
4 Connect the paleoclimatic recordings of abrupt changes with the theories of critical transitions and identify useful early warning signals for future abrupt changes.
5 Develop a self-consistent framework for abrupt changes from observations and the model-hierarchy from low order to high-dimensional complex climate models.
6 Develop a theory of climate response in the presence of tipping points that goes beyond linear and equilibrium concepts, and specifically beyond equilibrium climate sensitivity.
It is important for society to understand climate tipping points because they pose a significant threat to human well-being and the sustainability. By identifying and understanding these tipping points, we can take action to avoid crossing them and prevent catastrophic climate change.
This requires developing advanced statistical tools, monitoring Tipping Elements (TEs) in the climate system, and investigating the interaction between different TEs. By doing so, we can better predict and prepare for potential climate changes, develop early warning systems, and identify safe operating spaces to avoid irreversible climate change.
The research objectives are:
1 Explore stochastic multiscale models in climate science and develop the theory of fast-slow systems and the relationship to classical bifurcation theory. Provide the theoretical basis for cascading tipping points in high-dimensional complex systems.
2 Dynamical analysis: Investigate and identify critical transitions in stochastic and deterministic dynamical models, such as state-of-the-art ESMs and compute safe operating spaces and transition probabilities. Develop the methodology and the mathematics of rare event algorithms with models of intermediate complexity.
3 Physical processes: Quantify the TEs and the interaction between different TEs in the Earth system.
4 Connect the paleoclimatic recordings of abrupt changes with the theories of critical transitions and identify useful early warning signals for future abrupt changes.
5 Develop a self-consistent framework for abrupt changes from observations and the model-hierarchy from low order to high-dimensional complex climate models.
6 Develop a theory of climate response in the presence of tipping points that goes beyond linear and equilibrium concepts, and specifically beyond equilibrium climate sensitivity.
• Concerning "Mathematical basis for critical transitions and tipping points," we find even in these systems we can study early-warnings signs for bifurcations and establish variance scaling laws. For noise-induced tipping, it is crucial to understand the path, how to transition between different attractors of the system. We have established an algorithm to calculate these paths.
• "Transitions and rare events in climate models": (i) the applicability of rare event algorithms was extended to be able to efficiently deal with high-dimensional climate models through improved score functions. (ii) we developed new mathematical /numerical approaches to determine transition pathways and rates associated with tipping. (iii) Novel methods were applied to understand transitions in the coupled Arctic-Atlantic system.
• We have investigated B- and R-tipping in individual Earth System components as part of ‘Tipping Elements in the climate’. Multistability and distinct low frequency variability in the ocean-atmosphere flow were assessed in a reduced order ocean-atmosphere coupled model. Where multistabilities exist for fixed parameters, the possibility for tipping between solutions was investigated.
• "Tipping points in observations and paleo-records:" we have (i) compared speleothem proxy records, evidencing tipping in precipitation regimes with corresponding simulations from a comprehensive ESMl to study the global impacts of the DO events. (ii) investigated precursor signals based on critical slowing down (CSD) for a future AMOC collapse in CMIP6 models. .
• "Bifurcations and the model hierarchy;" we have focussed on i) understanding similarities and differences between critical transitions in dynamical models of the individual tipping events using multiple models of varying resolution and complexity. Higher resolution models are not always better; they may include simplifying assumptions that preclude nonlinear feedbacks (ii) understanding interactions between tipping elements for different systems within the hierarchy.
• "Response theory" allows for predicting how the statistical properties of a complex system change as a result of a perturbation impacting its dynamics, and our work has established that there is a one-to-one correspondence between divergence of the response operators and proximity of tipping points. When considering the impact of stochastic perturbations on multiscale systems, we have clarified the mechanisms of noise-induced transitions between competing states.
• "Transitions and rare events in climate models": (i) the applicability of rare event algorithms was extended to be able to efficiently deal with high-dimensional climate models through improved score functions. (ii) we developed new mathematical /numerical approaches to determine transition pathways and rates associated with tipping. (iii) Novel methods were applied to understand transitions in the coupled Arctic-Atlantic system.
• We have investigated B- and R-tipping in individual Earth System components as part of ‘Tipping Elements in the climate’. Multistability and distinct low frequency variability in the ocean-atmosphere flow were assessed in a reduced order ocean-atmosphere coupled model. Where multistabilities exist for fixed parameters, the possibility for tipping between solutions was investigated.
• "Tipping points in observations and paleo-records:" we have (i) compared speleothem proxy records, evidencing tipping in precipitation regimes with corresponding simulations from a comprehensive ESMl to study the global impacts of the DO events. (ii) investigated precursor signals based on critical slowing down (CSD) for a future AMOC collapse in CMIP6 models. .
• "Bifurcations and the model hierarchy;" we have focussed on i) understanding similarities and differences between critical transitions in dynamical models of the individual tipping events using multiple models of varying resolution and complexity. Higher resolution models are not always better; they may include simplifying assumptions that preclude nonlinear feedbacks (ii) understanding interactions between tipping elements for different systems within the hierarchy.
• "Response theory" allows for predicting how the statistical properties of a complex system change as a result of a perturbation impacting its dynamics, and our work has established that there is a one-to-one correspondence between divergence of the response operators and proximity of tipping points. When considering the impact of stochastic perturbations on multiscale systems, we have clarified the mechanisms of noise-induced transitions between competing states.
The scientific work has been focussed on exploring fast-slow systems with stochastic components. Critical transitions in stochastic and deterministic dynamical models, such as state-of-the-art ESMs are being investigated. Especially rare event algorithms are used to assess safe operating spaces and risks of extreme events.TEs and the interaction between different TEs in the Earth system are being identified. Development of useful early warning signals for future abrupt changes are tested against the paleoclimatic recordings of past abrupt changes.
An expected outcome is the development of a self-consistent framework for abrupt changes from observations and the model-hierarchy from low order to high-dimensional complex climate models.
Progress has also been achieved in development of a theory of climate response in the presence of tipping points that goes beyond linear and equilibrium concepts, and specifically beyond equilibrium climate sensitivity.
The societal impacts of this research are significant, as it has the potential to inform policy decisions and actions related to climate change. By identifying TEs and assessing the risks of abrupt changes, the research can help guide efforts to mitigate and adapt to climate change.
The development of a self-consistent framework for abrupt changes from observations and models can provide a more accurate understanding of the potential impacts of climate change, allowing policymakers to make informed decisions about mitigation and adaptation strategies.
The development of a theory of climate response in the presence of tipping points that goes beyond linear and equilibrium concepts can also provide a more comprehensive understanding of the impacts of climate change, including the potential for cascading tipping events. This can help guide efforts to develop early warning systems and safe operating spaces to avoid irreversible climate change.
An expected outcome is the development of a self-consistent framework for abrupt changes from observations and the model-hierarchy from low order to high-dimensional complex climate models.
Progress has also been achieved in development of a theory of climate response in the presence of tipping points that goes beyond linear and equilibrium concepts, and specifically beyond equilibrium climate sensitivity.
The societal impacts of this research are significant, as it has the potential to inform policy decisions and actions related to climate change. By identifying TEs and assessing the risks of abrupt changes, the research can help guide efforts to mitigate and adapt to climate change.
The development of a self-consistent framework for abrupt changes from observations and models can provide a more accurate understanding of the potential impacts of climate change, allowing policymakers to make informed decisions about mitigation and adaptation strategies.
The development of a theory of climate response in the presence of tipping points that goes beyond linear and equilibrium concepts can also provide a more comprehensive understanding of the impacts of climate change, including the potential for cascading tipping events. This can help guide efforts to develop early warning systems and safe operating spaces to avoid irreversible climate change.