Compounding, Cascading, and Cumulative Risks: Research-to-practice storylines

Compounding and cascading hazards, and their associated physical-societal interactions, affect every U.S. region, posing serious challenges to our collective ability to respond, recover, and build for community resilience. The workshop will bring together scientists, impacts/adaptation researchers, practitioners, and stakeholders, using interdisciplinary storyline approaches to identify and explore 1) compounding and cascading risks to communities in rural, urban, coastal, and mountain areas of the U.S., and 2) different strategies to exchange and deepen knowledge for reducing harm to communities within these geographies. Through structured discussions about key community-centered themes, capabilities, constraints, and unsolved problems, the workshop aims to:

• enhance connections between research and practice,
• identify research priorities to support resilience measures, and
• inspire innovative approaches for understanding and managing complex, intensifying risks.

Through structured discussions about key community-centered themes, capabilities, constraints, and unsolved problems, the workshop aims to:

• enhance connections between research and practice,
• identify research priorities to support resilience measures, and
• inspire innovative approaches for understanding and managing complex, intensifying risks.

Motivation

Compound events – interactions among hazards across space, time, and hazard type – are an increasing global challenge because of their potential to impose greater harm than isolated events on physical infrastructure, water resources, public health, ecosystems, and critical interconnected sectors such as food, energy, and consumer goods. Back-to-back or co-occurring extremes strain communities and resources, affecting recovery and adaptation, while complex combinations of hazards heighten both the impacts and the associated scientific and management challenges. In fall 2020, for example, several hurricanes affected the Southeast U.S. in quick succession. Combined with the storms’ strength and pre-existing societal vulnerabilities, this situation heightened the severity and duration of impacts to infrastructure and public health as well as delayed recovery timelines.

Additionally, the impacts were accentuated by the need to devote personnel and equipment to other simultaneous hazards, including multiple large wildfires across the U.S. West and the global COVID-19 pandemic. Vulnerable communities (e.g. agricultural workers, low-income communities, rural communities, and tribal and indigenous peoples) are often hit hardest due to higher exposure to hazards, socioeconomic factors that contribute to higher baseline vulnerability, and lower financial and infrastructural resources.

Increasingly severe hazards such as heatwaves, droughts, floods, and wildfires, are already posing serious threats to lives and property in the U.S. and abroad. Far from a simple temperature-based scaling, the magnitudes and ramifications of extreme events may be highly intricate and dependent upon a host of physical and societal contexts.

Communities in every U.S. region are experiencing the impacts of compound events, with many critical sectors and systems at risk. Yet there is high potential for investments to be based primarily on understanding of univariate hazards, aligning poorly with true community needs in both the short- and long-run.

Therefore, there is growing recognition that effective knowledge, planning, and preparedness for such risks must account for potential interactions between combinations of physical hazards and societal vulnerabilities. Hindering progress, however, is the reality that many of the relevant research and practice communities rarely interact in meaningful ways in the U.S.. Application-oriented research in the U.S. is often limited to siloed efforts within disciplines and agencies, leading to fewer innovative insights around understanding and managing these events. Cross-disciplinary workshops in the U.S. would improve research coordination around many of the most thorny and important compounding events facing the country: droughts, floods, heat waves, hurricanes, and wildfires.

This situation creates a pressing need to more accurately assess and plan for the risks that compound events pose to the U.S. population and economy. Workshop participants will span research in the atmospheric, hydrological, and land-surface domains, as well as governance, human geography, insurance, public health, energy utilities, water resources, and agriculture. Participants will be tasked to:

• Identify plausible and important compound, cascading, and cumulative events and scenarios that may have been overlooked
• Understanding leading practices and challenges for managing risks in communities, private sector, local govts
• Develop a broad-based and transferable framework for designing research on these events
Identify mechanisms to facilitate more effective information exchange with affected communities to reduce risks and apply lessons learned

Outcomes will be designed to meet the growing institutional-level demand for understanding, interpreting, and funding adaptation and mitigation efforts targeted specifically for compound hazards. Outcomes will be refined and consolidated by workshop co-chairs in a summary report, to be disseminated through agency contacts and research networks.

Impact & Outputs

Compound events (when a combination of hazards occur concurrently) contribute to societal impacts that are often severe and extensive. The workshop aims to organize and connect disparate strands of ongoing research, as well as catalyze new ones in a space where there is much interest but comparatively few efforts to arrange cross-cutting discussions. We believe that building and strengthening connections across disciplines and with sectors outside academia is essential to understanding and identifying stakeholder needs and thus to true success in mitigating impacts of compound-event hazards.

Additionally, a special focus on U.S. communities in exposed geographies (rural, urban, coastal, mountain areas) is integral to our workshop concept. The most unexpected, dramatic and damaging effects of hazards often stem from the intersection of physical-system and societal-system dynamics, precisely the sorts of effects that workshop participants will be interrogating. The contours of the discussions and preliminary outcomes will be made publicly accessible to facilitate further work to advance exchanges between research and applications, and inform decision-making.

Following the workshop, we will create a public website illustrating annotated storylines of key risks from each of the session themes, summarizing the characteristics of affected communities, methodological considerations, practical limitations, and any ultimate consensus on the research and translation needs for devising effective approaches. These latter will be laid out in more detail through a set of statements, perhaps also consolidated into a white paper, about recommended frameworks for conceptually and practically identifying and tackling the risks examined, and generalizable principles that flow from them.

The ultimate goal is to provide guidance, relevant at the level of local communities, on where and how best to focus research attention – across a variety of scientific disciplines – over the short-term future to comprehensively characterize societal risks from changing compound hazards, and to minimize their harms. These storylines and frameworks can also serve as examples for researchers and practitioners to examine the risks associated with compound hazards in contexts other than those specifically covered here.