Key Findings

In a world with global greenhouse gas emissions still on the rise, higher temperatures, more extreme weather and climate events, and multiple impacts of climate change, communities face big challenges. Adaptation to climate change is needed, but not all adaptation measures are sustainable; some even worsen conditions, especially in the long run. Sustainable climate change adaptation cannot be taken for granted since whether and how local communities succeed in enhancing resilience depends on a variety of social conditions. Based on nine case studies, the Hamburg Climate Futures Outlook 2024 identifies key conditions that influence the plausibility of achieving sustainable climate change adaptation and their connections to mitigation goals. The current Outlook provides a realistic assessment that sets expectations straight and helps to identify social conditions for effective climate action.

Our key findings are:

• The Social Plausibility Assessment confirms our previous finding that achieving deep decarbonization, that is, net-zero CO₂ emissions by 2050, is not plausible. No overall shift can be observed since the previous assessment in 2023. Therefore, meeting the Paris Agreement goal of limiting the temperature increase to 1.5°C remains not plausible. Currently, none of the 10 social drivers supports deep decarbonization by 2050, with only six social drivers supporting decarbonization. These are: UN climate governance, transnational cooperation, climate-related regulation, climate activism and social mobilization, climate litigation, and knowledge production. The media driver remains ambivalent as it sometimes supports and sometimes inhibits deep decarbonization. Since 2023, fossil-fuel divestment showed a significant change, from a social driver that supported decarbonization to one inhibiting deep decarbonization. This, along with corporate responses and consumption trends, makes three drivers that currently inhibit deep decarbonization by 2050.
  
  
• Social drivers relate to and affect each other in different ways. All social drivers offer empirical evidence for an increase in their dynamics contributing to climate action. This happens also by creating new resources for other drivers, for instance new court rulings, new forms of knowledge, and increased political pressure. Nevertheless, despite the plethora of new resources, there is less change affecting key structural and institutional context conditions of drivers, and therefore no qualitative transformative shift toward deep decarbonization can be observed. Some driver dynamics highlight that available resources may also be used to undermine or counteract climate action.
  
  
• Internal climate variability arises spontaneously and randomly within the climate system. The assessment emphasizes that it is essential to explicitly consider internal variability to better predict changes in extreme events. The quality of these predictions is affected by the uncertainties and limitations of climate models. Knowledge and understanding of these uncertainties and limitations are crucial for communities facing adaptation challenges to climate change. They need to adapt to extreme events, which are strongly influenced by internal climate variability. Such knowledge can make a difference in effective and sustainable climate change adaptation strategies to high-impact events with respect to time-horizons, plans, or expenses.

• The interplay of climate change and internal variability can lead to ecosystem and socio-economic disruptions with potentially devastating consequences. Adaptation strategies are needed, for example in compound extreme events in crop-growing regions that may threaten local and global food security, in costly precipitation extremes and severe floodings that damage infrastructure and cause fatalities, and in marine heatwaves that are powerful catalysts of ecosystem disruption, with severe consequences for local communities.
  
  
• The analysis of nine case studies emphasizes key conditions that affect the plausibility of achieving sustainable climate change adaptation. Long-standing political conflicts, social inequalities, and other structural problems ought to be addressed for sustainable adaption to become plausible. The same is true of increasing socio-cultural embedded capacities so as to bridge the gap between adaptive capacities and local climate vulnerabilities. Establishing climate-friendly laws, regulations, and adaptation plans are not sufficient unless the people who have to implement adaptation are involved, unless the measures are actively put into practice, and unless the plans are connected to clear indicators and measurable goals based on both scientific assessments and climate justice principles. It is essential to strengthen enabling conditions for sustainable climate change adaptation.
  
  
• Engaging social actors and communities through participatory, trustworthy, and mobilizing strategies is key to foster social involvement and to hold policymakers accountable for their commitments. There is significant potential for collective social action to co-produce knowledge and tackle challenges related to sustainable climate change adaptation. Leveraging past experiences and local knowledge in handling extreme events and climate risks can inform public policies that align climate change adaptation with socio-economic development, as well as the promotion of health and well-being.
  
  
• Sustainable climate change adaptation requires substantial changes on different levels. Key aspects include improving knowledge about interdependencies between mitigation and adaptation scenarios, and increasing considerations of localities and socio-cultural dimensions in the processes of designing and implementing climate adaptation strategies. Sustainable climate change adaptation further requires considering trade-offs and potential synergies as well as reconsidering current path dependencies in coping strategies that reproduce unsustainable adaptation practices, and an increase in the societal support for and political action toward structural transformations.

• The assessment underlines how ambition and implementation gaps are reproduced. For example, the integration of empirical findings shows how these gaps are the outcome of (1) existing power dynamics and inequalities, (2) different ways of understanding, interpreting, and translating cli - mate change-related norms and practices, (3) a lack of political coherence on different scales of climate governance, and (4) climate change mitigation and adaptation as multifaceted and wicked problems. In addition, uncertainty in social and physical dynamics as well as the interrelation of global and local dynamics affect the plausibility of sustainable climate change adaptation in different ways.
  
  There is never just one agreed climate goal or one way to achieve that goal. To increase the future plausibility of climate change mitigation and adaptation, it is just as important to fight back constraining conditions as it is to strengthen enabling conditions in order to achieve qualitative shifts. The integration of diverse ways of knowing, for instance from local communities or Indigenous Peoples, is crucial for mitigation and adaptation practices, as it is to reduce social inequalities, foster just negotiation processes, and create synergies toward effective climate action.