Global climate change is often thought of as a steady and approximately predictable physical response to increasing forcings, which then requires commensurate adaptation. But adaptation has practical, cultural and biological limits, and climate change may pose unanticipated global hazards, sudden changes or other surprises, as may societal adaptation and mitigation responses. We outline a strategy for better accommodating these challenges by making climate science more integrative, in order to identify and quantify known and novel physical risks even–or especially–when they are highly uncertain, and to explore risks and opportunities associated with mitigation and adaptation responses by engaging across disciplines. This improves the chances of anticipating potential surprises and identifying and communicating “safe landing” pathways that meet UN Sustainable Development Goals and guide humanity toward a better future.

The concept of climate tipping points in socio-environmental systems is increasingly being used to describe nonlinear climate change impacts and encourage social transformations in response to climate change. However, the processes that lead to these tipping points and their impacts are highly complex and deeply uncertain. This is due to numerous interacting environmental and societal system components, constant system evolution, and uncertainty in the relationships between events and their consequences. In the face of this complexity and uncertainty, this research presents a conceptual framework that describes systemic processes that could lead to tipping points socio-environmental systems, with a focus on coastal communities facing sea level rise. Within this context, we propose an organizational framework for system description that consists of elements, state variables, links, internal processes, and exogenous influences. This framework is then used to describe three mechanisms by which socio-environmental tipping could occur: feedback processes, cascading linkages, and nonlinear relationships. We presented this conceptual framework to an expert panel of coastal practitioners and found that it has potential to characterize the effects of secondary climatic impacts that are rarely the focus of coastal risk analyses. Finally, we identify salient areas for further research that can build upon the proposed conceptual framework to inform practical efforts that support climate adaptation and resilience.

Saltmarsh habitats sequester significant amounts of carbon from the atmosphere and provide vital habitats for various bird species but are eroding at increasingly rapid rates due to ongoing sea level rise. Yet, in some regions where space and topography permit, saltmarshes are transgressing into adjacent uplands, counterbalancing the lost area. In these areas, a greater proportion of saltmarsh is relatively young but it remains uncertain whether younger marshes support the same plant and animal communities as older ones. We compared soil organic matter (SOM), plant communities, and bird occupancy at 133 marsh patches on the Delmarva Peninsula, Virginia, USA. Marshes that converted from uplands since the early to mid-20th century exhibited lower SOM levels, were more closely situated to trees and snags, and were less likely to support obligate saltmarsh nesting bird species. Areas with past agricultural activity, characterized by features like berms and ditches, exhibited higher SOM levels, supported fewer of the most salt-tolerant plants and more of the least salt-tolerant species, and were more likely to support saltmarsh obligate bird species. We expect areas where a high proportion of relatively young marsh to shift away from the most salt-tolerant plants and birds, especially where an agricultural legacy can be found. We hypothesize that elevated organic carbon content found in formerly farmed fields may result from decreased inorganic sediment input, facilitated by restricted tidal flooding, rather than an enhanced capacity for carbon sequestration. However, further investigation is necessary to conclusively address this issue.