the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 30 Oct 2025
Brief communication: 'Multi-hazard-to-health-outcome' (MH2O) pathways: the known, the unknown, and ten most urgent priorities.
Abstract. Climate-driven hazards like heat and flooding have complex impacts on human health. Most research considers the impact of individual hazards (e.g., heatwaves) on discrete health outcomes (e.g., heatstroke). However, climate-driven hazards often precipitate additional hazards with cumulative health impacts, such as the compound effect of drought and heatwaves on the physical and mental health of farming communities. Little is known about ‘multi-hazard-to-health-outcome’ (MH2O) pathways. We engaged multi-sectorial and international stakeholders through the newly established MH2O Working Group and report our co-developed ten most urgent priorities for guiding research, policy and practice towards preparing our global One Community for future uncertainty.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
(433 KB)
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(433 KB) - Metadata XML
- BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-4062', Anonymous Referee #1, 21 Nov 2025
- AC1: 'Reply on RC1', Harriet Moore, 15 Dec 2025
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RC2: 'Comment on egusphere-2025-4062', Molly Gilmour, 23 Apr 2026
General comments
This paper addresses a critical and under-researched area at the intersection of hazards and health, and I’m glad to see much needed attention on this topic. The focus on multi-hazard to health outcome pathways is timely and the paper makes a useful contribution by foregrounding complexity, uncertainty and research priorities. The topic is clearly novel and of relevance to NHESS readers.
That said, some key concepts require further refinement and clarification to strengthen the paper’s analytical contribution. In particular, several terms and framings risk oversimplifying existing bodies of work on vulnerability, participation and knowledge production. Addressing these issues would make the paper more robust and more clearly situated within interdisciplinary hazard research.
Specific comments
- Use of the term “amenable health condition”
I am uncertain what is meant by “manageable health condition” in this context, for who/in what geography. If the intention is to refer to chronic or long-term illness, this should be stated more explicitly, or perhaps explain the term. For many people, particularly those living in rural settings or in low and middle income countries, illness often fluctuates between being manageable and unmanageable depending on environmental, social and infrastructural conditions. The current wording risks implying stability or access to consistent care that may not exist in practice. - Compounding, co-occurring and cascading impacts
The paper would benefit from a clearer distinction between hazards and health impacts that occur simultaneously, cascade from one another, or accumulate over time. Which typology is this paper focusing on. These distinctions are important for understanding preparedness, response and recovery, as well as the interrelated effects of repeated or overlapping hazards on health outcomes. Making this explicit would strengthen the framing. - Hazard inclusion criteria
It is unclear if or why hydrological and geophysical hazards are excluded from the conditions examined. Flooding and earthquakes, for example, are common globally and have well-documented health implications. Flooding in particular increases damp and mould exposure and is strongly linked to respiratory conditions such as asthma. Please explain the rationale for excluding these hazards, especially given the stated interest in multi-hazard pathways.
Relatedly, the paper appears to focus primarily on climate change related hazards. It would be helpful to clarify whether non-climate related geological hazards and their health impacts are considered within scope, and if not, why this boundary has been drawn.
- Participation and knowledge production
I would caution against the characterisation of participatory paradigms as a response to vaguely defined “complex phenomena defining human history”. Much of this work emerges from specific emancipatory struggles and calls for equity, including decolonial, anti-ableist and disability justice approaches. Framing participation in abstract or universal terms risks obscuring these political and historical roots.
Similarly, the suggestion that the current climate can be understood as a “natural process” (around line 100) is underdeveloped and could be misinterpreted, specifically relating to well-established arguments about anthropogenic climate change and responsibility.
Participatory and emancipatory approaches in health research often centre place-specific, non-scientific and/or Indigenous knowledges, rather than advocating for new scientific/academic hierarchic institutions. I was surprised when I read your argument, as it could be interpreted that you are framing this as otherwise. There is a move away from expert-led knowledge hierarchies and towards recognising lived and Indigenous knowledge as central to preparedness and recovery. Engaging more directly with this literature would strengthen the argument.
- Use of “vulnerable groups”
There is a substantial and growing body of evidence generated by ‘populations made vulnerable’ that challenges the use of the simplified term “vulnerable groups”. I would strongly encourage the authors to review and revise this language, to acknowledge the agency, expertise and resistance of these populations against the ‘structural vulnerabilities’ they are subject to. - Assumptions about data, synthesis and machine learning
The paper engages well with the available and need for more, large-scale quantitative data synthesis and machine learning approaches, as future priorities in the Urgent Priorities. While these methods are valuable, I would caution that they may also reinforce existing epistemic inequalities if used uncritically.
Although there is recognition of the need to work with communities, it remains unclear what kinds of knowledge these communities are understood to hold, and how such knowledge would be meaningfully synthesised with approaches such as machine learning. To critically move this argument forward, the ‘how’ feels underdeveloped - Is this synthesis the priority, or are/what other forms of knowledge production are equally valued? The paper would benefit from greater clarity and specificity on how space for different forms of knowledge will be ensured. At present, this section feels quite vague and requires more substance to be convincing.
Technical corrections
- Line 117: “fo” should be corrected to “for”
Citation: https://doi.org/10.5194/egusphere-2025-4062-RC2 - AC2: 'Reply on RC2', Harriet Moore, 11 May 2026
- Use of the term “amenable health condition”
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-4062', Anonymous Referee #1, 21 Nov 2025
Overall comment
I very much enjoyed reading this brief communication. It is well written and it brings forward a very important research avenue. I strongly suggest the authors to strengthen the multi-hazard risk element of their manuscript. A lot of work is done in this field, especially in recent years; also in bridging to diseases and health impacts, which is currently less recognized in the manuscript.
General comments
- While the manuscript seems to focus on “climate-driven hazards like heat and flood” many of the examples mention earthquakes and volcanic eruptions. I found this a bit confusing as these are not climate-driven.
- I also wondered what search terms were used. Many people working in the field of (multi-) natural hazards and disasters won’t refer to them as “environmental hazards”. Moreover, within the field of multi-hazards, a lot of other terminology is used (e.g. cascading hazards (see Pescaroli et al 2018), consecutive disasters (De Ruiter et al 2020), etc etc).
- In line 61 (but also P2 of Table 1), I wondered whether the authors truly meant (climate) mitigation or if they actually meant adaptation and/or risk reduction?
- Part of the argument made in this paper was also made in:
- Mora et al. 2022
- Sairam & De Ruiter (2025; also published in EGUsphere).
- Line 56 – 70: the authors could also refer to recent reports by the WHO and UNDRR and that make a similar pledge.
- Some sentences could use a bit more careful phrasing such as “while environmental scientists consider flooding and drought”. Maybe the term (socio-)hydrologists is more accurate?
- Line 70: the authors could consider reaching out to similar groups such as the RiskKAN working group on disasters, diseases and health (see also P4 of Table 1).
literature
- Instead of Bixler et al (L. 37) (and some of the subsequent references) there are a lot of studies that support this more broadly than a study that looks at a local case in Texas… I suggest the authors reflect a bit better on the field of multi-hazard risk. Eg but by no means limited to:
- AghaKouchak et al 2014, 2018
- Claassen et al., 2023, 2025
- De Ridder et al 2020
- De Ruiter et al 2020
- Gill & Malamud 2014, 2017
- Kappes et al. 2012
- Quintal et al (in discussion – egusphere)
- Scolobig et al. 2017
- Thieken et al. 2021
- Ward et al 2022
- Zscheischler et al 2017, 2018
Citation: https://doi.org/10.5194/egusphere-2025-4062-RC1 - AC1: 'Reply on RC1', Harriet Moore, 15 Dec 2025
-
RC2: 'Comment on egusphere-2025-4062', Molly Gilmour, 23 Apr 2026
General comments
This paper addresses a critical and under-researched area at the intersection of hazards and health, and I’m glad to see much needed attention on this topic. The focus on multi-hazard to health outcome pathways is timely and the paper makes a useful contribution by foregrounding complexity, uncertainty and research priorities. The topic is clearly novel and of relevance to NHESS readers.
That said, some key concepts require further refinement and clarification to strengthen the paper’s analytical contribution. In particular, several terms and framings risk oversimplifying existing bodies of work on vulnerability, participation and knowledge production. Addressing these issues would make the paper more robust and more clearly situated within interdisciplinary hazard research.
Specific comments
- Use of the term “amenable health condition”
I am uncertain what is meant by “manageable health condition” in this context, for who/in what geography. If the intention is to refer to chronic or long-term illness, this should be stated more explicitly, or perhaps explain the term. For many people, particularly those living in rural settings or in low and middle income countries, illness often fluctuates between being manageable and unmanageable depending on environmental, social and infrastructural conditions. The current wording risks implying stability or access to consistent care that may not exist in practice. - Compounding, co-occurring and cascading impacts
The paper would benefit from a clearer distinction between hazards and health impacts that occur simultaneously, cascade from one another, or accumulate over time. Which typology is this paper focusing on. These distinctions are important for understanding preparedness, response and recovery, as well as the interrelated effects of repeated or overlapping hazards on health outcomes. Making this explicit would strengthen the framing. - Hazard inclusion criteria
It is unclear if or why hydrological and geophysical hazards are excluded from the conditions examined. Flooding and earthquakes, for example, are common globally and have well-documented health implications. Flooding in particular increases damp and mould exposure and is strongly linked to respiratory conditions such as asthma. Please explain the rationale for excluding these hazards, especially given the stated interest in multi-hazard pathways.
Relatedly, the paper appears to focus primarily on climate change related hazards. It would be helpful to clarify whether non-climate related geological hazards and their health impacts are considered within scope, and if not, why this boundary has been drawn.
- Participation and knowledge production
I would caution against the characterisation of participatory paradigms as a response to vaguely defined “complex phenomena defining human history”. Much of this work emerges from specific emancipatory struggles and calls for equity, including decolonial, anti-ableist and disability justice approaches. Framing participation in abstract or universal terms risks obscuring these political and historical roots.
Similarly, the suggestion that the current climate can be understood as a “natural process” (around line 100) is underdeveloped and could be misinterpreted, specifically relating to well-established arguments about anthropogenic climate change and responsibility.
Participatory and emancipatory approaches in health research often centre place-specific, non-scientific and/or Indigenous knowledges, rather than advocating for new scientific/academic hierarchic institutions. I was surprised when I read your argument, as it could be interpreted that you are framing this as otherwise. There is a move away from expert-led knowledge hierarchies and towards recognising lived and Indigenous knowledge as central to preparedness and recovery. Engaging more directly with this literature would strengthen the argument.
- Use of “vulnerable groups”
There is a substantial and growing body of evidence generated by ‘populations made vulnerable’ that challenges the use of the simplified term “vulnerable groups”. I would strongly encourage the authors to review and revise this language, to acknowledge the agency, expertise and resistance of these populations against the ‘structural vulnerabilities’ they are subject to. - Assumptions about data, synthesis and machine learning
The paper engages well with the available and need for more, large-scale quantitative data synthesis and machine learning approaches, as future priorities in the Urgent Priorities. While these methods are valuable, I would caution that they may also reinforce existing epistemic inequalities if used uncritically.
Although there is recognition of the need to work with communities, it remains unclear what kinds of knowledge these communities are understood to hold, and how such knowledge would be meaningfully synthesised with approaches such as machine learning. To critically move this argument forward, the ‘how’ feels underdeveloped - Is this synthesis the priority, or are/what other forms of knowledge production are equally valued? The paper would benefit from greater clarity and specificity on how space for different forms of knowledge will be ensured. At present, this section feels quite vague and requires more substance to be convincing.
Technical corrections
- Line 117: “fo” should be corrected to “for”
Citation: https://doi.org/10.5194/egusphere-2025-4062-RC2 - AC2: 'Reply on RC2', Harriet Moore, 11 May 2026
- Use of the term “amenable health condition”
Peer review completion
Journal article(s) based on this preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(433 KB) - Metadata XML
Overall comment
I very much enjoyed reading this brief communication. It is well written and it brings forward a very important research avenue. I strongly suggest the authors to strengthen the multi-hazard risk element of their manuscript. A lot of work is done in this field, especially in recent years; also in bridging to diseases and health impacts, which is currently less recognized in the manuscript.
General comments
literature