International audienceThe Paris Climate Agreement is an important step for international climate policy, but the compensation for negative effects of climate change based on clear assignment of responsibilities remains highly debated. From both a policy and a science perspective, it is unclear how responsibilities should be defined and on what evidence base. We explore different normative principles of justice relevant to climate change impacts, and ask how different forms of causal evidence of impacts drawn from detection and attribution research could inform policy approaches in accordance with justice considerations. We reveal a procedural injustice based on the imbalance of observations and knowledge of impacts between developed and developing countries. This type of injustice needs to be considered in policy negotiations and decisions, and efforts strengthened to reduce it

Abstract. Evidence of observed negative impacts on natural and human systems from anthropogenic climate change is increasing. However, human systems in particular are dynamic and influenced by multiple drivers and hence identifying an anthropogenic climate signal is challenging. Here we analyze the case of lake Palcacocha in the Andes of Peru, which offers a representative model for other glacier lakes and related risks around the world because it features a dynamic evolution of flood risk driven by physical and socioeconomic factors and processes. Furthermore, it is the object of a prominent climate litigation case, wherein a local Peruvian citizen sued a large German energy producer over risk of flooding from lake Palcacocha. Adopting a conceptual model of cascading impacts and multiple drivers of risk, we first study climatic and other geophysical drivers of flood risk. We find that an anthropogenic signal from flood risk to greenhouse gas emissions is traceable. In parallel, flood risk has been strongly shaped (and increased) by interacting socioeconomic, institutional and cultural processes over the past few decades. The case raises important questions about the differentiation of responsibilities relating to flood risk of both global and local agents, which are, however, difficult to address in cases like Palcacocha, where we reveal a complex network of interlinked global, national and local drivers. Following from this, we outline a normative framework with a differentiated perspective on responsibility, implying that global emitters commit to support strengthening capacities in affected regions and localities and that local institutions and societies engage in local risk reduction measures and policies in collaboration with and driven by local communities.

This paper suggests a way to elaborate the ethical implications of the Warsaw International Mechanism (WIM) as decided at COP 19 from the perspective of justice. It advocates three pro-posals. First, in order to fully understand the responsibilities and liabilities implied in the WIM, adaptation needs to be distinguished from loss and damage (LD) on the basis of the different goals which should be attributed to adaptation and to LD approaches. Second, the primary concern of the WIM should be compensatory justice. In case of climate LD, three aspects of compensatory justice should be kept separate: corrective liability, remedial responsibility, and with regard to the resources available, fair remedy. Third, it is crucial to distinguish between recov-erable damage and irrecoverable or at least not fully recoverable loss. This distinction is crucial because it informs the principles of fair remedy and because damage and loss may differ in their relevance for the stability and functioning of a human system. Abstract: This paper suggests a way to elaborate the ethical implications of the Warsaw International Mechanism (WIM) as decided at COP 19 from the perspective of justice. It advocates three proposals. First, in order to fully understand the responsibilities and liabilities implied in the WIM, adaptation needs to be distinguished from loss and damage (L&D) on the basis of the different goals which should be attributed to adaptation and to L&D approaches. Second, the primary concern of the WIM should be compensatory justice. In case of climate L&D, three aspects of compensatory justice should be kept separate: corrective liability, remedial responsibility, and with regard to the resources available, fair remedy. Third, it is crucial to distinguish between recoverable damage and irrecoverable or at least not fully recoverable loss. This distinction is crucial because it informs the principles of fair remedy and because damage and loss may differ in their relevance for the stability and functioning of a human system.

Abstract. Evidence of observed negative impacts on natural and human systems from anthropogenic climate change is increasing. However, human systems in particular are dynamic and influenced by multiple drivers, and hence identifying an anthropogenic climate signal is challenging. Here we analyze the case of lake Palcacocha in the Andes of Peru which offers a representative model for other glacier lakes and related risks around the world because it features a dynamic evolution of flood risk driven by physical and socio-economic factors and processes. Furthermore, it is the object of a prominent climate litigation case where a local Peruvian citizen sued a large German energy producer over risk of flooding from lake Palcacocha. Adopting a conceptual model of cascading impacts and multiple drivers of risk we first study climatic and other geophysical drivers of flood risk. We find that an anthropogenic signal related to greenhouse gas emissions is traceable. In parallel, flood risk has been strongly shaped (and increased) by interacting socio-economic, institutional and cultural processes over the past decades. The case raises important questions of responsibility for flood risk of global and local agents which, however, are difficult to address in cases like Palcacocha where we reveal a complex network of interlinked global, national and local drivers. Following from this we outline a normative framework with a differentiated perspective on responsibility, implying that global emitters commit to support strengthening capacities in affected regions and localities, and local institutions and societies engage in local risk reduction measures and policies.