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A paper published in Scientific Reports looks at economic damages due to climate driven sea level rise.
Dr Robin Lamboll, Research Fellow at the Centre for Environmental Policy at Imperial College London, said:
“This paper convincingly shows that sea level rise is more damaging than simple national-level estimates might imply. However it is a shame that they use an implausibly high emissions scenario as their reference point and assume no adaptation. This means the headline figure is very likely a substantial overestimate. They also don’t calculate what fraction of this loss is already unavoidable.”
Prof Richard Allan, Professor of Climate Science, University of Reading, said:
“Sea level rise is a catastrophe emerging slowly and inexorably now that will worsen substantially into the far future. Low lying coastal regions that including many populous cities such as Miami, Mumbai, Shanghai and Tokyo will be affected during this century and many centuries in the future. It takes many hundreds of years for a warming climate to melt giant ice sheets like Greenland that add water to the oceans and for the deep sea to feel the heat of global surface warming and expand in volume.
“The current research considers a very high greenhouse gas emissions scenario out to the end of this century that has been questioned as being inconsistent with current policies, though the levels of warming considered are not inconceivable and even much more ambitious cuts in greenhouse gas emissions than currently planned would only moderate rather than remove the future costs of coastal inundation and the scale of sea defences required. A tiny benefit for inland areas due to relocation of coastal economies would be dwarfed by the overall losses.
“For the far future it seems inevitable that massive adaptation to rising seas will be essential and only by rapidly achieving net zero carbon emissions can the costs and scale of adaptation to the creeping ocean be tempered.”
Prof Chris Hilson, Director of the Centre for Climate and Justice at the University of Reading, said:
“This study is useful for showing how the increasing threat from climate-induced sea level rise plays out in an economically uneven way. While the hit to national GDP may or may not be high in particular countries, their data reveals that within those overall national figures, particular coastal regions and sectors may be particularly badly hit. In Italy for example, they reveal that an already high 4.43% national GDP loss masks a much more significant regional loss of 20.84% in the Veneto area.
“However, the authors miss an important climate justice element that also needs to be considered. In making cost-benefit analysis-based assessments on where to focus country climate adaptation spending, there is a danger that the money will all be directed at wealthy, high GDP areas. But, as academic scholarship on managed retreat has shown1, the risk is that poorer communities will be the ones singled out for relocation inland. In other words, the already marginalised become further marginalised. The recent judicial review challenge to the government’s National Adaptation Programme by Friends of the Earth and a resident of the village of Hemsby on the Norfolk coast is illustrative of this.”
1 e.g. Siders AR (2019) Social justice implications of US managed retreat buyout programs. Climatic Change 152:239-257. https://doi.org/10.1007/s10584-018-2272-5)
Quotes from SMC Germany:
Prof Ben Marzeion, Professor of Climate Geography at the University of Bremen, Germany, said:
“I think it is very important to also quantify the economic consequences of climate change. That’s why I’m pleased that the topic is increasingly being discussed from this perspective. There is a frequent misunderstanding that climate mitigation measures are too expensive – which ignores the fact that having no mitigation measures will also have a high price.”
“The projection of sea level rise which the paper uses appears to be based on the climate projections of only one climate model (HadGEM2-ES). This procedure is appropriate for an exploratory study. For a robust assessment, however, it is essential to take the uncertainty of such climate projections into account. This is usually done by at least using an ensemble of many different climate models.”
“It is also important to emphasize that the sea level projections used are not a ‘worst case’. Even though a scenario with high greenhouse gas emissions was chosen (RCP8.5), the range of possible sea level developments must first be determined. Only then can one decide which rise in sea level is unlikely but possible – that is, which scenario would be the ‘worst case’.”
“As I do not consider the modelling of the sea level rise to be robust – as described above – I also do not consider the other results to be quantitatively reliable. However, it is possible that the study represents a substantial advance in economic modelling, but I have no expertise to assess this.”
Prof Athanasios Vafeidis, Head of the working group “Coastal Risks and Sea-Level Rise” at Christian-Albrechts-university Kiel, Germany, said:
“The study provides new insights on the potential direct and indirect impacts of sea level rise and specifically how these impacts would be distributed regionally and for different sectors. Previous work has provided results at the national level, which in some cases may mask the true extent of impacts for specific subregions or sectors. The results show that sea level rise can have very significant direct and indirect impacts at the local level and for specific sectors – these impacts can be positive in some cases, particularly for land-locked regions. This indicates where adaptation may be more urgently required.”
“The study is limited, among other things, in that, first, it does not consider that adaptation will be taking place throughout the century, which is a rather unrealistic assumption. Second, it considers only one, high-end, scenario and therefore does not really account for the range of uncertainty that surrounds the provided estimates with respect to potential sea level rise and socio-economic development. Third, it accounts for socio-economic development in a very narrow way as it assumes that the GDP increases by a set amount and only at the national – instead of regional – level. The assumptions regarding population development are not clearly stated.”
“In the context of the above points, results should rather be interpreted as indicative of potential relative temporal and spatial trends. Therefore, deriving conclusions about the actual costs – in terms of GDP – should be done with extreme caution. However, the results can be indicative of potential hotspot locations or particularly vulnerable sectors in a relative and qualitative manner.”
“In general, the assessment of the economic impacts of sea level rise and the estimation of costs are developing fast due to increasing availability of information and the availability of new models. These can provide useful input for policy decisions. Nevertheless, responses – which are usually taken at local level – can considerably affect these estimates. Therefore, such assessments should be accompanied with further analysis to provide information for specific locations or sectors.”
Dr Rosanne Martyr-Koller, Senior scientist on coastal vulnerability and adaptation, Climate Analytics, Berlin, Germany, said:
“The study provides a necessary addition to current estimates of economic damages from sea level rise by covering two sides of economic loss: the direct economic costs from physical damage to assets such as homes, schools, commercial buildings, transport, and energy infrastructure, and indirect economic losses from reduced revenue, interruptions to supply chains, and increasing prices.
“This work addresses a critique of prior work on climate costs: considering only the direct economic damages of climate hazards, as well as national level impacts, masks the full extent of economic impacts, and is not granular enough to inform policy- decisions.
“The study’s results on regional economic losses from a worst-case emissions scenario with sea level rise – compared to a baseline scenario with two per cent GDP growth and no sea level rise – reflect research at the global scale: economic impacts are not borne equally across countries. Rather, certain countries and certain regions within countries will bear the brunt of economic impacts from sea level rise.
“The study focuses on a worst-case emissions scenario with the largest potential for SLR and a baseline scenario assuming two per cent economic growth and no sea level. Meanwhile, there are other scenarios, such as those in line with the current climate pledges (such as scenario SSP2-RCP4.5) or with the Paris Agreement’s commitment to keep global warming well below 2 degrees (such as SSP1-RCP1.9), which would have been at least as informative for comparing potential futures. These scenarios are in line with current global commitments to reduce global warming, making them more plausible than the high-emissions SSP5-RCP8.5 scenario. These scenarios also have much less uncertainty than the worst-case scenario, in which the sea level rise by 2100 shows an uncertainty range of several meters.
“The costs of sea level rise don’t only occur from the slow encroachment of the sea onto land, but the combination of the mean sea level at a particular region, tides, and other wave conditions that can occur during storms such as storm surge and extreme waves. These pieces all contribute to coastal flooding which causes the direct economic damages in a local area, and the indirect regional effects.
“It is not clear whether the study considers the many contributors to coastal flooding and how sea level rise can amplify them. As such, the study may still be underestimating the regional economic damages caused by sea level rise.
“The study provides several avenues for next steps: one is around adaptation, as no adaptation measures after 2015 are considered in this study. However, we can expect that adaptation measures will be undertaken into the future, especially as countries consider their national adaptation plans and strategies, along with local contexts.
“Further research on the costs of adaptation, the potential of measures to avert economic damages, as well as their effectiveness and limits under different climate scenarios, will be needed for regions to make decisions on which adaptation measures to implement, where to implement them, and which sectors can be prioritized.”
Dr Jochen Hinkel, Head of the department for adaptation and social learning, Global Climate Forum, Berlin, said:
“The study is methodologically sound, within the chosen approach of computable general equilibrium modelling. However, a major disadvantage of these approaches is that they generally only take into account the annual average damage caused by the higher extreme water levels resulting from sea level rise. In reality, however, the less frequent extreme flooding events – such as the 100-year or 1000-year floods – cause the damage that affect the economy1.”
On the question of whether the worst-case scenario that was considered is informative:
“Yes. Worst-case scenarios are particularly important when adapting to sea level rise. They help to think through what a threatened region could do in a worst-case. As the sea level rise is a slow process, you have time to adapt step by step. In the first step, you don’t need to implement worst-case adaptation measures, but you need to be sure that you have measures in mind for subsequent steps in 20, 40 or 80 years’ time that protect against the worst-case scenario2.”
“The conclusions that can be drawn from this study are very limited, as it does not take into account future adaptation to sea level rise. In other words, it assumes that although coastal populations will experience ever greater damage from storm surges, they will not act. This is highly unrealistic. In many parts of the world, including Germany, people have adapted to up to several metres of sea level rise caused by land subsidence over the past 100 years or more3. Furthermore, it is also relatively ‘cheap’ for cities, which are potentially facing the greatest damage from coastal flooding to adapt by building dykes, for example, because the adaptation costs are two to three orders of magnitude lower than the flood damage without adaptation1.”
“Uncertainties in the modelling of climate costs are generally large. One reason for this is that the uncertainties add up across the cascade of models used – from the climate model to the climate impact models to the economic model. However, this type of long-term economic assessment is not about whether gross domestic product changes by 1.2 or 1.3 percent, but about orders of magnitude and relative changes. This means, for example, it is about assessing for which regions the damage is around 0.1 per cent of gross domestic product or 1 per cent or 10 per cent1.”
1 Hinkel J et al. (2021): Uncertainty and Bias in Global to Regional Scale Assessments of Current and Future Coastal Flood Risk. Earth’s Future. DOI: 10.1029/2020EF001882.
2 Völz V et al. (2023): Sea Level Rise Learning Scenarios for Adaptive Decision-Making Based on IPCC AR6. Earth’s Future. DOI: 10.1029/2023EF003662.
3 Nicholls RJ et al. (2023): A global analysis of subsidence, relative sea-level change and coastal flood exposure. Nature Climate Change. DOI: https://doi.org/10.1038/s41558-021-00993-z.
‘Distribution of economic damages due to climate‑driven sea‑level rise across European regions and sectors’ by Ignasi Cortés Arbués et al. was published in Scientific Reports at 4pm UK TIME on Thursday 18 January 2024.
DOI: https://doi.org/10.1038/s41598-023-48136-y
Declared interests
Richard Allan: no interests to declare
Ben Marzeion: “I have no conflict of interest regarding this publication.”
Athanasios Vafeidis: “I declare that there are no potential conflicts of interest.”
Jochen Hinkel: “I am currently working with some of the study authors on a related modelling study. Here, I am speaking independently of this collaboration.”
For all other experts, no reply to our request for DOIs was received.