the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Assessing future impacts of tropical cyclones on global banana production
Abstract. Tropical cyclones (TCs) are projected to increase in intensity globally, impacting human lives, infrastructure, and important agricultural activities, such as banana production. Banana production is already impacted by TCs in several parts of the world, leading to price volatility and impacted livelihoods of banana producers. While many potential impacts on banana production have already been quantified on a local scale, it remains unclear how bananas could be impacted by TCs across the globe under future climate conditions. To address this, we first looked at the documented impacts of cyclones on banana production from different places all around the world. Using spatially explicit data on banana producing regions and future TC occurrence and magnitude, we then identify the spatial distribution and extent of areas where TCs could impact banana production. Our results suggest that considerable portions of global banana production are at risk to be impacted by TCs under future climate conditions, and we show this for different return periods (RP).
Globally, at the 100-year return period, 24.3 % of all bananas producing areas will be majorly or completely damaged under present climate conditions and 26.5 % under future climate conditions. When looking at production, we see that 30.1 % of global production is projected to be majorly or completely damaged at the 100-year RP. The regions predominantly affected by future TCs are Asia and the Caribbean, experiencing substantial disruption in banana production. Our results therefore indicate, that considerable efforts in climate change mitigation and adaptation need to be made in order to ensure the stability of global banana supply chains.
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RC1: 'Comment on nhess-2023-182', Anonymous Referee #1, 03 Jan 2024
Dear authors,
Thank you very much for your work on this manuscript. I think the direction of the study is very important: TCs and bananas are a key research topic, and your work here fills an important research gap. I do have several comments to help to improve your manuscript, as there are several aspects of the manuscript that need work. For example, you mention expert knowledge, but refer instead to a meta-analysis, and this is also referred to as empirical work? There are also several inconsistencies and the discussion is far too broad to be impactful. Who are you writing for? Who would you like these results to aid? While the results are relevant I struggle to see an effort to make a connection to readers or stakeholders. For example, there is only one sentence that describes the actual impact of a hurricane on banana production in Honduras. Taking a risk-based approach, there is certainly greater exposure and vulnerability to TCs in the Western North Pacific Basin, where the Philippines is a major grower and greatly affected by TCs annually, with some of them making severe impacts to banana production (e.g. Typhoon Bopha). I also make a point to be more geographically specific in your analysis. Saying that "Asia" is more impacted is an extremely broad statement, as it is a diverse continent. Which countries in Asia are banana growers, and which ones will be impacted?
While I appreciate the scientific and technical work behind this paper, please see my comments as hopefully helpful revisions to improve the presentation of your results. What are the steps forward for banana growing? How can adaptation efforts utilize these modelling studies?
Thank you for your work, and I’m available to revise your work again.
Minor text notes: Reference style is somewhat inconsistent (with commas, no commas, semicolon, etc.). Please make this consistent throughout the document. Also, I would suggest line numbers rather than paragraph numbers to aid the reviewer.
Abstract
- Please minimise the use of acronyms in the abstract to aid the unfamiliar reader
- What does ‘majorly’ mean in this context? Is there a way to quantify this in the abstract?
- ‘Asia’ is a whole continent, not a region (e.g. compared to the Caribbean region). Be more specific here.
Text
- Para 25: I would suggest that the text opens with the importance of bananas as a crop first, before going to climate change affecting it.
- Para 25: Coumou 2012 reference – is this not an outdated reference, considering that the IPCC released a synthesis report in 2023? There has also been significantly more literature on tropical cyclone projections since. This may need an update as it appears several times in the introduction.
- Para 25: “Particularly…” is not a complete sentence.
- Para 25: categories?
- Para 25: “CC”?
- Paras 35 and 40: I would also emphasise the socio-economic importance of the crop, and for farmers’ or communities’ livelihoods more than just consumer prices. This appears briefly in Para 55, 110, 115. I think the introduction section could be tightened up in terms of its flow and writing as the information presented is a bit scattered throughout the first few sections.
- Para 45: Recent analyses from the Philippines shows more data to support these paragraphs on major TC damages to banana production, and that recovery can be up to 5 years post-TC: e.g. https://doi.org/10.18783/cddj.v005.i01.a05; https://journalofnaturestudies.org/files/JNS19-2/62-83_Damasa-Macandog_Assessment_Impacts_Flashflood.pdf; https://www.ijisrt.com/assets/upload/files/IJISRT21DEC732.pdf
- Para 120/125: What are the limitations of this assumption re: equal vulnerability of all banana cultivars? Do your datasets differentiate between different types of banana cultivars? As you are using plantation data, this are likely to be monocultures of the Cavendish variety. Please elaborate on this assumption as it is important to distinguish what farm type is considered in the analysis.
- Para 130: A reference missing for the final sentence.
- Para 155: it is unclear if you, in this work, employed expert opinion. Relying on a review of literature is not the same as soliciting expert opinion. (cf. para 180). This has impacts on your description of methods to determine damage categories (cf Table 2). You also later describe this is as a ‘meta-analysis’ (cf. Figure 1).
- Para 230. ‘s.’?
- Para 230-235 ‘areas’ – banana growing areas? Areas in general? What is a ‘banana area’? Be more specific.
- Figure 2, Table 5: future climates implies several scenarios, but I believe you only used SSP585. Please clarify throughout the text.
- Figure 2: why is the map cropped? Please show the whole map. There are also banana-growing regions in the subtropics, and I don’t know (or you haven’t described) if the IFPRI dataset is limited to tropical areas only
- Table 4: what is a ‘globally damaged banana producing area’?
- Para 255: as with the abstract, please be more specific with your language. Southeast Asia versus ‘Asia’ broadly allows for a more accurate representation of banana growing in the region, which is highly concentrated in the Philippines at the moment – this is also a country highly vulnerable to TCs. I think it would be helpful to ground your analysis (or maybe just introduction) in more practical examples of TCs and their impacts.
- Para 270: what does this first sentence mean, exactly?
- Para 280, 315: ‘We found out’, ‘especially valid’ are quite journalistic phrasing – please make this more a report of results. Also, same comment about broad reporting of the ‘Asia’ region. This paper would be more valuable if you named the specific countries rather than the whole continent.
- Para 315: banana supply chains implies the whole system of food supply, including transport, storage, and distribution. Do you mean this? Or just production?
- Para 325: pests and diseases such as…? Banana pests and diseases are a major research point in banana production, and it is only briefly mentioned in passing here.
- Para 335: “The IPCC (Koks et al. 2019) concluded that global modelling errors are associated with limitations in parametrizations.” – what are you trying to say by adding this citation here? I think your discussion of modeling limitations in this paragraph is very valuable, but this statement feels like a blunt addition, and could be made more specific in the context of your study limitations.
- Para 350: I would revise and review this paragraph. Was it an empirical approach? Was it expert knowledge? Which experts were consulted? Or was it a meta-analysis? The lack of clarity in methods on this point weakens the paper.
- Para 360: “This genotype is less vulnerable to TCs because of their short stems and recovery period.” – I’m not sure about this. What is your reference here? Cavendish bananas are typically planted in monocultures and the landscape homogeneity can contribute to its vulnerability to hazards.
- Para 360: “An example of this“ – an example of what, sorry?
- Para 370: what do you mean by “the susceptibility of a country”? Some of these statements are unfortunately exceptionally broad.
- Paras 370-390: These statements/ citations are simply placed together, with little additional insight. Why is there a comparison to Australia? Why are parameter limitations re-discussed here? How can the results of the study help to inform adaptation in agricultural production? Can they be connected to other efforts to understand food security under changing TCs?
Citation: https://doi.org/10.5194/nhess-2023-182-RC1 -
RC2: 'Comment on nhess-2023-182', Anonymous Referee #2, 18 May 2024
This is an interesting paper looking at the impacts of tropical cyclones on banana production under climate change. The most novel aspect is the vulnerability curve; I think how it was obtained needs to be explained better. Another major technical concern is that it appears that the maximum sustained wind speed is assumed to be experienced at the plantation when surely that is not generally the case (and if it was not done this way, then the methodology is not explained adequately) --- this affects the vulnerability calculation as well as the impacts projections. I have some other comments listed below. I think the paper needs major revision.
Major comments:
The main innovation here seems to be the development of the vulnerability curve. Given this, it is not described in enough detail. The reader should be able to reproduce it if they wish to. Data and code should be provided. What is the functional form assumed for the curve? How are the values interpolated between the small number of categories for which damage was calculated explicitly? Etc.
Along with the above, some representation of uncertainty should be given. The results are stated to a high degree of precision, 2 significant figures in the percentages. Surely this level of precision is not justified given the many uncertainties.
In supplemental table 1 only the maximum sustained wind speed for the storm is listed. Was it assumed that this wind speed was experienced at the banana plantation? Surely this is not correct unless the storm hits very directly, and maybe not even then. A parametric wind profile should be used to estimate the wind speed at the plantation. Please explain and justify better what was done. This goes both for the development of the vulnerability curve and the subsequent calculation of impacts.
One comment that is not about the results themselves, but how the results are communicated: there are many statements (including in the abstract) of the form that X percent of banana producing areas will experience some level of damage at 100-year return period. I think this is misleading. I believe what is mean that X percent will be damaged if they experience a 100-year event at their location. But the way it is stated sounds like a 100-year event for the planet will see X percent of banana production damaged at once --- which is not true, because the different areas will not experience 100-year storms at the same time. Please clarify this everywhere it comes up, including the abstract.
P14: the area around the Bay of Bengal seems important to these results. My understanding of the STORM dataset though is that it has a poor representation of storms in this region due to its neglect of wind shear. Please clarify if this is the case and caveat appropriately.
The discussion of caveats at the end is very long and detailed, more so than the explanation of the calculation of vulnerability itself (which is surely a source of great uncertainty). This seems a bit unbalanced.
The last paragraph of the paper is a bunch of boilerplate statements that seem unnecessary. I suggest sticking to summarizing the findings of the research itself.
Minor/editorial comments:
P1, l2 of main text: Coumou, 2012 reference for the global mean warming is a bit odd. It’s 12 years old, and an 0.5 degree uncertainty seems way too large. Please use an updated reference and a more precise number, this is a very well-studied quantity.
P1, last line: what does “these categories” refer to?
Some references (e.g., Baldwin, 2023) are not in the reference list. Others (e.g., Robinson) seem to have incomplete information. Please do a detailed check on all of them.
P2, l30: but this decrease in Walker circulation and trend towards El Niño has not been observed, and there is currently a very active debate about it, so it seems inappropriate to cite it uncritically.
P2, l34: what is “CC”? This needs more explanation.
P2, l45: is this really true? How does the FAO determine this? It seems quite surprising indeed given how many buildings TCs destroy, etc.
P2, l57: what does “these indices” refer to? And is “mitigation or adaptation” really meant seriously? Surely whatever banana growers can do to mitigate climate change (i.e., reduce their own emissions) will have a negligible impact on their own impacts from climate change, and any real direct benefit to them can only come through adaptation. This is repeated again in the conclusions, line 396.
P4, l103: there may be little difference between scenarios by 2050, but it becomes much larger later. This should be made clear.
P6, l153: this citation to Yum (2021) is not sufficient, please explain exactly what was done (see major comments above).
P7, l183: as in major comments, please clarify how wind speed at each plantation was obtained. It appears here that it was assumed to be the maximum sustained wind for the storm, but surely this is incorrect.
Table 2: please give units for wind speed (presumably m/s).
Citation: https://doi.org/10.5194/nhess-2023-182-RC2
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