Philip 2020 - Vulnerability, Exposure and Communication
Summary
The meteorological synthesis only concerns the hazard. Overall risk is hazard x exposure x vulnerability; the protocol attributes only the hazard quantitatively and treats trends in exposure and vulnerability in a separate, mostly qualitative, desk review with local partners. Communication produces a scientific report, a 1-2 page scientific summary, a 1-page policy summary and a press release.
Overview
Why separate: hazard attribution is a climate question; vulnerability and exposure change faster than the hazard (heat plans, population growth) and depend on local context, so mixing them makes the transfer function hard to defend.
Main Content
Risk components (Field et al. 2012, IPCC SREX)
Hazard: probability/intensity of the physical event (steps 1-6). Exposure: presence of people, livelihoods, infrastructure and assets in places that could be adversely affected. Vulnerability: propensity or predisposition to be affected. Risk = hazard x exposure x vulnerability.
Step 7 - vulnerability and exposure
- Real-time, location-specific; start from official disaster information (humanitarian, government, media): who or what was impacted and how (which also informs the event definition).
- Baseline of country-level vulnerability and exposure through existing metrics (e.g. the INFORM Index, now sub-national in eastern Africa); then a desk review of peer-reviewed and institutional literature (social, economic, geographic, demographic, cultural, institutional, governance, environmental factors), then description of trends, often qualitative, and consultation of in-country stakeholders (adds credibility).
- “Detailing the exposure and vulnerability context … is distinctly different from attempting to attribute the disaster impacts of an extreme event.”
- Example: São Paulo drought (Otto et al. 2015): no trend in the hazard of low precipitation over the catchment, but more people and higher per-capita water use exceeded system capacity.
Step 8 - communication
Four products: scientific report (always; traceability of numbers, data, methods; peer review where the reality of climate change is publicly contested; open access recommended), scientific summary (1-2 pages: event and impacts, definition, return period, model evaluation, separate model results, synthesised statement, vulnerability and exposure summary, relation to other studies; numbers with uncertainty), policy-relevant summary (1 page in non-scientific language with impacts, attribution statement, vulnerability/exposure and future outlook; local partners as contacts), press release. Information must be translated correctly along the chain.
Conclusions (Sec. 10)
The protocol is practical, validated by Otto et al. (2018a) and Philip et al. (2018b), ready for rapid and operational use; further research needed on model validation and synthesis (EUPHEME project). Storyline approaches could complement the probabilistic ones and sit under a common framework. Data for the reproduced figures are on the KNMI Climate Explorer.
Examples
Separate "hazard" from "outcome" in measurement
A marketing analogue: attributing an incremental lift to a campaign (the hazard-like causal effect) is separate from the business impact, which depends on exposure (audience size, inventory) and vulnerability (price sensitivity, competitor activity). Reporting incrementality as a probability/rate ratio with an uncertainty interval, and the exposure context separately, mirrors steps 6-8.
Connections
Decision Analysis (risk = probability x consequence), Philip 2020 - Probability Framing, Event Definition and Return Periods.