Climate Sea Level Research Articles

Improved Sea Level Reconstruction from 1900 to 2019

Abstract Before the satellite era, global sea level reconstructions depended on tide gauge records and in situ hydrographic observations. However, the available global mean sea level (GMSL) reconstructions, using different methods, indicate a spread in sea level trend over 1900–2008 (1.3 ∼ 2.0 mm yr−1). With better understanding of the causes of sea level change, here we implement an improved sea level reconstruction, building upon previous work by Church and White, and include three additional factors: the sea level fingerprints, the sterodynamic sea level (SDSL) climate change patterns, and more complete local vertical land motion (VLM) estimates. The trend of new GMSL reconstruction is 1.6 ± 0.2 mm yr−1 (90% confidence level) over 1900–2019, consistent with the sum of observation-based sea level contributions of 1.5 ± 0.2 mm yr−1. The lower trend from the new reconstruction compared with the earlier Church and White result is mainly due to the updated VLM correction. The inclusion of sea level fingerprints and SDSL climate change patterns are the dominant contributors for the improved skill of regional reconstruction. Despite GMSL budget closure in terms of long-term trend since 1900, our study shows discrepancies between the trends from available GMSL reconstructions and the sum of independent observation-based contributions over different periods in the twentieth century, e.g., the discrepancy at the beginning of the twentieth century, which could be related to possible bias in the land ice component estimate. The reconstruction methodology developed here, as tested with synthetic sea level fields, could provide a promising way to identify potential biases in the individual sea level components constrained by available global tide gauge observations.

Expanding the Duty to Rescue to Climate Migration

Expanding the Duty to Rescue to Climate Migration

Local Knowledge of Coastal Population to Sea Level Rise and Climate Change – A Case Study in Fishermen Community, Kanyakumari District, Tamil Nadu, India

This research synthesises two evaluations of a local level climate change adaptation and planning process in the southernmost coastal region, Kanyakumari, India which was supported through community-based appraisals. First, understanding the public perception of climate change factors is crucial in generating support for climate change response. Second, generating enough grass-root level support from the local population to assess the long-term climate change impacts on decision-making to design the adaptation strategies for sea-level rise. These two results highlight the level of understanding and awareness of climate change’s impact by the local population in the coastal region of Kanyakumari. A well-designed questionnaire with structured interviews, to collect data on local knowledge and local perception of climate change and sea-level rise from 100 respondents was distributed each in 44 coastal villages in the study area. The finding showed that 20.7% of the local population have knowledge of climate change and its impacts and 18.4% of the population agreed that the impact of sea-level rise is experienced in the coastal region. This study is to provide insight into the communities’ knowledge of the adaptive capacity of the local population to cope with climate change towards the treaty of sea-level rise.

Sea Levels Dynamical Downscaling and Climate Change Projections at the Uruguayan Coast

This work implements a dynamical downscaling approach, based on a set of nested two-dimensional hydrodynamic models, to quantify the expected changes in the total sea level climate and its components for the Uruguayan coast, using surface wind and sea level pressure projections from global climate models generated during the Phase 5 of the Coupled Models Inter-Comparison Project, considering three time horizons: historical period (1986-2005), short term (2027-2045) and long term (2082-2100), and the future scenarios RCP 4.5 and RCP 8.5. It is concluded that the main contribution to the projected changes in the area is the regional mean sea level rise, followed in importance by the effect that the increase in the water depth has on the amplitude of the tidal components. Moreover, it is concluded that changes in the meteorological residuals (or surges), associated with potential changes in the atmospheric circulation patterns, are negligible in the study area. The obtained results reinforce the need to resort to dynamic downscaling for projecting total sea level changes in areas characterized by wide and shallow continental shelfs and estuaries, as this approach allows to resolve the interactions that may arise between tides, surges and the mean sea level rise, something that cannot addressed with an approach based solely on statistical downscaling.

PROCESSOS FLUVIOMARINHOS ASSOCIADOS À FORMAÇÃO DA ILHA RASA, SUL DA BAÍA DE MARAPATÁ, NORDESTE DO PARÁ, BRASIL

As ilhas assumem expressivo destaque na paisagem estuarina paraense; contudo, a maior parte delas apresenta gênese não claramente definida. A fim de investigar os fatores de formação da ilha Rasa, situada na foz do rio Tocantins, estuário do rio Pará, o presente trabalho se apoia em feições sedimentares identificadas em um testemunho de sedimento coletado no interior da ilha. Neste trabalho, a integração faciológica e a interpretação de seus ambientes deposicionais, em associação aos eventos climáticos reportados para a região, subsidiaram a proposição de modelo morfogenético. O modelo aqui proposto sugere que a ilha Rasa possui idade tardio-holocênica e consistia, incialmente, de barras arenosasque evoluíram sob o efeito de processos fluviais, inerentes à rede de drenagem e marinhos, articulados às mudanças no clima e nível do mar. Esses processos afetaram o suprimento de sedimento e a distribuição da cobertura vegetal, influenciando a configuração do setor estuarino e contribuindo para a formação de ilhas proximais.
 Palavras-chave: barra arenosa, estuário, nível relativo do mar, ambiente sedimentar, rioTocantins.

A coastally improved global dataset of wet tropospheric corrections for satellite altimetry

Abstract. The accuracy of satellite radar altimetry (RA) is known to deteriorate towards the coastal regions due to several reasons, amongst which the improper account for the wet path delay (WPD) can be pointed out. The most accurate WPDs for RA are derived from the on-board microwave radiometer (MWR) radiance measurements, acquired simultaneously as the altimeter ranges. In the coastal zone, however, the signal coming from the surrounding land contaminates these measurements and the water vapour retrieval from the MWR fails. As meteorological models do not handle coastal atmospheric variability correctly yet, the altimeter measurements are rejected whenever MWR observations are absent or invalid. The need to solve this RA issue in the coastal zone, simultaneously responding to the growing demand for data in these regions, motivated the development of the GNSS (Global Navigation Satellite System) derived Path Delay (GPD) algorithm. GPD combines WPD from several sources through objective analysis (OA) to estimate the WPD or the corresponding RA correction accounting for this effect, the wet tropospheric correction (WTC), for all along-track altimeter points for which this correction has been set as invalid or is not defined. The current GPD version (GPD Plus, GPD+) uses as data sources WPD from coastal and island GNSS stations, from satellites carrying microwave radiometers, and from valid on-board MWR measurements. GPD+ has been tuned to be applied to all, past and operational, RA missions, with or without an on-board MWR. The long-term stability of the WTC dataset is ensured by its inter-calibration with respect to the Special Sensor Microwave Imager (SSM/I) and SSM/I Sounder (SSMIS). The dataset is available for the TOPEX/Poseidon (T/P); Jason-1 and Jason-2 (NASA and CNES); Jason-3 (NASA and EUMETSAT); ERS-1, ERS-2, Envisat and CryoSat-2 (ESA); SARAL/AltiKa (ISRO and CNES); and GFO (US Navy) RA missions. The GPD+ WTC for Sentinel-3 (ESA and EUMETSAT) shall be released soon. The present paper describes the GPD+ database and its assessment through statistical analyses of sea level anomaly (SLA) datasets, calculated with GPD+, the ECMWF Reanalysis Interim (ERA-Interim) model or MWR-derived WTCs. Global results, as well as results for three regions (the North American and European coasts and the Indonesia region), are presented for ESA's recent Envisat Full Mission Reprocessing (FMR) V3.0. Global results show that the GPD+ WTC leads to a reduction in the SLA variance of 1–2 cm2 in the coastal zones, when used instead of the ERA WTC, which is one of the WTCs available in these products and can be adopted when the MWR-derived WTC is absent or invalid. The improvement of the GPD+ WTC over the ERA WTC is maximal over the tropical oceans, particularly in the Pacific Ocean, showing that the model-derived WTC is not able to capture the full variability in the WPD field yet. The statistical assessment of GPD+ for the North American coast shows a reduction in SLA variance, when compared to the use of the ERA-derived WTC, of 1.2 cm2, on average, for the whole range of distances from the coast considered (0–200 km). Similar results are obtained for the European coasts. For the Indonesia region, the use of the GPD+ WTC instead of that from ERA leads to an improvement, on average, on the order of 2.2 cm2 for distances from the coast of up to 100 km. Similar results have been obtained for the remaining missions, particularly for those from ESA. Additionally, GPD+ recovers the WTC for a significant number of along-track altimeter points with missing or invalid MWR-derived WTCs, due to land, rain and ice contamination and instrument malfunctioning, which otherwise would be rejected. Consequently, the GPD+ database has been chosen as the reference WTC in the Sea Level Climate Change Initiative (CCI) products; GPD+ has also been adopted as the reference in CryoSat-2 Level-2 Geophysical Ocean Products (GOP). Strategies to further improve the methodology, therefore enhancing the quality of the database, are also discussed. The GPD+ dataset is archived on the home page of the Satellite Altimetry Group, University of Porto, publicly available at the repository https://doi.org/10.23831/FCUP_UPORTO_GPDPlus_v1.0 (Fernandes et al., 2019).

Briefly Noted

In January 2020, the UN Human Rights Committee ruled that states cannot deport people who face “climate change-induced conditions that violate the right to life.” According to a UN press release, the complaint in this case was filed by Ioane Teitiota who was denied asylum in New Zealand and deported with his family to his native Kiribati. Following his deportation, he filed a complaint with the Human Rights Committee, alleging that his deportation violated his right to life and that the rise of the sea level and other climate change impacts rendered Kiribati uninhabitable. Though the Committee determined that, on the facts, Mr. Teitiota's right to life was not violated, the Committee specifically indicated that “"this ruling sets forth new standards that could facilitate the success of future climate change-related asylum claims.” In particular, the Committee determined that asylum seekers need not demonstrate that they would face imminent harm if returned to their home states because the negative effects of climate change can occur suddenly and more slowly, over the longer-term.

Shelf sand supply determined by glacial-age sea-level modes, submerged coastlines and wave climate

Submerged paloeshorelines preserved on the continental shelf indicate the depths of the most frequent (modal) low sea-levels within the glacial stages of the Late Quaternary. Here we have determined the south-east Australian shelf configuration when sea level was 40 m and 60 m below present-day sea-level (depths of the most persistent paleoshorelines within the last 120 ka), and we resolve the wave climate variations influencing the sediment transport pathways over this period. We present evidence demonstrating that the combination of shelf morphological evolution, changes in sea-level and variations in wave climate is responsible for latitudinal changes in sediment transport and deposition during the interglacial states. The paleoshoreline and shelf evolution is key to understanding the distribution of present-day shelf sand deposits and the contemporary sand budget response to future wave climate changes.

On the uncertainty associated with validating the global mean sea level climate record

Satellite altimetry provides the ongoing sea level climate data record that provides evidence for one of the most significant manifestations of climate change on Earth. External and independent validation of satellite altimetry is a core component of mission design, providing confidence in such a seminal climate record. The global tide gauge network, corrected for the effects of vertical land motion, forms one of a suite of approaches used to validate satellite altimetry. Used as a tool to identify potential systematic error, the altimeter minus tide gauge approach ultimately leads to an improved geophysical data record through iterative diagnosis, correction and reprocessing of the mission record. A recent example includes the detection of a small but significant drift in the early part of the record associated with the TOPEX record. Here, we return to the approach that quantified the apparent drift in the TOPEX record and focus on further elucidating the uncertainty of that technique as a function of mission duration. We show that approximately 2.9 years is required to reach a validation uncertainty of ±1 mm/yr (1σ). This result appears optimistic by a factor of 1.5–2.2 in comparison to an error budget approach reported in the literature. Our results highlight the challenge of validating the altimeter record using a sparse and irregularly distributed network of tide gauges and points towards possible areas of future improvement in the validation approach.

Quality assessment of a satellite altimetry data product DT18 in the Norwegian Sea: A comparison to tide gauge records and drifters data

• The altimetric product DT18 reproduces the sea level variability in the Norwegian Sea with an average error 3–4 cm. • Statistical tests conducted for the DT18 reveal some problems. • Errors of the DT18 have a shape of “diamonds” in the open sea. • Ageostrophic factors influence strongly the real current velocities in the Norwegian Sea. The objective of this paper is to assess the quality of the gridded altimetric sea level product DT18 as well as altimetry data from the Sea Level Climate Change Initiative in the Norwegian Sea. We compare the satellite altimetry data with two types of instrumental data. We use tide gauge records to assess the quality in the coastal zone and data from surface drifting buoys to assess the quality in the open ocean. Thus, we aim to complement previous studies by providing the objective assessment of the quality and performance of satellite altimetry in this important region. We demonstrate that the product DT18 reproduces the sea level variability in the coastal zone at an acceptable level (an average error is 3–4 cm), and it reproduces the structure of the time series quite well (almost with a 96% correlation). We found out that altimetry substantially smoothes the pattern of the sea level. This pattern is revealed in the coastal zone as well as in the open sea, where, in addition, it also manifests errors in a shape of “diamonds”, which can be due to data interpolation from satellite tracks. We detected the influence of ageostrophic factors on the current velocities using altimetry in the open sea, and this is also true for the coastal zone. Statistical tests also showed some discrepancies between altimetry data and field (buoys and drifters) data in the open sea. This is manifested in the statistical inequality of variances and in differences of empirical distribution functions. Summing up, we assert that some errors or discrepancies in altimetric data are still observed in high latitudes, both in the coastal zone and in the open part of the Norwegian Sea.

Overtopping wave reduction capability of Rakuna IV armor block used for Rubblemound Breakwater

Run up, overtopping are the main reasons that damage and unstabilize the coastal and basin protective structures. So, overtopping wave is an inevitable load during coastal structures designing process, particularly at present very complicated real situation of global sea level rise and climate change. Based on the early researches, allowable mean overtopping wave discharges play an important roll in determining breakwaters' dimension such as top elevation, slope protective alternatives in the port side and so on. The more permissible average overtopping wave discharges, the lower breakwater top elevation needed. Moreover, the weight of armor blocks used on a seaside slope can be reduced. However, the port side slope needs to be properly protected against the impact of overtopping wave. Thus, researching the application of new armored unit blocks with high overtopping wave reduction capability that is corresponsive to typhoon-generated wave conditions is totally in need. Rakuna IV is one of the newly developed wave-dissipating blocks invented by Nikken Kogaku (Japan) in 2007, and the stability of this block for rubble mound breakwaters has been investigated under non-wave overtopping conditions by many researchers in Japan, Korea, China, and Vietnam. To be more exhaustive in the design of breakwaters with this kind of block, this study carried out experimental research on wave overtopping performance of RAKUNA-IV (overtopping reduction by roughness factor γr) in wave flume at Ha Noi Water Resources University. Based on the physical model tests' results, the author has determined the overtopping wave reduction coefficient γr of Rakuna IV block and its relationship with Irribaren number xm-1,0.

Geological field guides as educational tools: the Coorong, South Australia

The South Australian (SA) Division of the Geological Society of Australia (GSAust) has a working subcommittee responsible for preparation of geological field guides. The target audience for these guides comprises persons who have an interest in natural environments, but who do not necessarily have specialist education in the Earth sciences. Care is taken to avoid excessive and unnecessary use of jargon, but where required, technical terms are used with appropriate explanations; ‘dumbing down’ is avoided and suitable references are cited for those who seek further information. Field guides can be downloaded from the GSAust web site. Later editions may be updated for mobile devices. The over-arching aim of the subcommittee is to contribute to public education. The Coorong is a back-barrier coastal lagoon that, together with Lake Alexandrina and Lake Albert, constitute the modern estuary of the River Murray. The Younghusband Peninsula is a Holocene beach-dune barrier that was formed as the rising postglacial sea transported sandy sediment shoreward from the exposed Lacepede Shelf. The peninsula stabilised following culmination of the postglacial marine transgression, at the same time isolating a narrow back-barrier lagoon, the Coorong, from the direct impact of the Southern Ocean. The Coorong is a landscape icon rated highly as a tourist attraction. It has importance for ornithologists and other scientists (including geologists) and is the ancestral home of the Ngarrindjeri people. There is a diverse group of people who might be interested in a well-presented and authoritative field guide to this area. The Coorong and associated features thus provide a landscape that underpins consideration of two major concepts: Earth’s global climate has greatly varied during the Pleistocene; glacial and interglacial climatic events have been widely identified within a consistent chronologic framework; and the present global climate is interglacial. Sea-level is lower during cooler glacial times when increased amounts of water are stored as ice on land, particularly in the polar and highland (alpine) regions; sea-level rises during warmer interglacial times when meltwater from glaciers and ice sheets flows into the oceans; and in the present warm-interglacial climate sea-level is high.

The Tensile Root Strength of Spartina patens: Response to Atrazine Exposure and Nutrient Addition

Coastal wetlands are receiving basins for inland runoff that contains numerous compounds such as nutrients and herbicides, which may have negative effects on wetland plants. Spartina patens is a dominant emergent macrophyte in low salinity wetlands whose biomechanical properties contribute to wetland stability against erosive forces and herbivore grazing. We conducted two greenhouse experiments with six levels of nutrients and three levels of atrazine doses to test the hypothesis that exposure to nutrients and atrazine changes the tensile root strength of S. patens. The results revealed that the tensile root strength of S. patens was not affected by either atrazine exposure or nutrient addition after 60 days, whereas the plants treated with atrazine, nutrient addition, or an atrazine-nutrient combination had significantly less tensile root strength than the Control after 212 days. There were no significant differences in tensile root strength between the main effects and treatment combinations, and hence, no interactive effects of nutrient addition and atrazine exposure. These results suggest that the influx of poor quality water into coastal wetlands will decrease the tensile root strength of S. patens and make coastal wetlands even more vulnerable to sea level rise and climate change.

Government of India Policy of Fixing Minimum Support Price for Agriculture Products in relation to Water Resources of Peninsular India

85% of water resources is used in agriculture. Price of water is not taken into account while declaring the Minimum Support Price (MSP) for different crops by Government of India (GoI). Origin of water, depletion of groundwater table and its effect on sea level changes and climate are discussed with reference to geomorphology of Sahyadri hill range, where both east and west flowing rivers of peninsular India take their origin. New price based on incentive to be given to farmers who take up growing crops using less water compared to rice and sugarcane is suggested.

An assessment of areal and transect-based historic shoreline changes in the context of coastal planning

With increasing sea levels and anthropogenic coastal pressure, it is more important than ever to develop coastal zone management techniques that are based on sound scientific methodologies. In this paper shoreline change rates were calculated for Port Eynon Bay, Gower, Wales, UK, using a two-step approach (areal and transect-based), to predict future shoreline position and propose management strategies. A Geographical Information System (Qgis) was utilised to calculate shoreline position from historical aerial photographic evidence covering a 60-year period (1944–2014). Results highlighted an increase in the vegetation of 0.41 km2 and a seaward migration of the shoreline (0.3 m/yr.−1); temporal linear regression models constructed around the cumulative data confirmed a consistent trend of areal increase and shoreline migration. Wind components were qualitatively linked to shoreline changes. Models created to predict shoreline position at 10-year and 50-year epochs can be aligned with shoreline management plans and inform embayed beach shoreline assessments at all scales. A management process model was developed based upon the application of transect and areal assessments that can be utilised to inform CZM by identifying locations of vulnerability, enabling management strategy development, that improves resilience under scenarios of sea level rise and climate change.

Development of an ENVISAT Altimetry Processor Providing Sea Level Continuity Between Open Ocean and Arctic Leads

Over the Arctic regions, current conventional altimetry products suffer from a lack of coverage or from degraded performance due to the inadequacy of the standard processing applied in the ground segments. This paper presents a set of dedicated algorithms able to process consistently returns from open ocean and from sea-ice leads in the Arctic Ocean (detection of water surfaces and derivation of water levels using returns from these surfaces). This processing extends the area over which a precise sea level can be computed. In the frame of the European Space Agency Sea Level Climate Change Initiative ( http://cci.esa.int ), we have first developed a new surface identification method combining two complementary solutions, one using a multiple-criteria approach (in particular the backscattering coefficient and the peakiness coefficient of the waveforms) and one based on a supervised neural network approach. Then, a new physical model has been developed (modified from the Brown model to include anisotropy in the scattering from calm protected water surfaces) and has been implemented in a maximum likelihood estimation retracker. This allows us to process both sea-ice lead waveforms (characterized by their peaky shapes) and ocean waveforms (more diffuse returns), guaranteeing, by construction, continuity between open ocean and ice-covered regions. This new processing has been used to produce maps of Arctic sea level anomaly from 18-Hz ENVIronment SATellite/RA-2 data.

Paleoenvironmental implications of Holocene long-chain n-alkanes on the northern Bering Sea Slope

The records of high-resolution terrestrial biological markers (biomarkers) from Core B2-9 from the northern Bering Sea Slope over the last 9.6 ka BP were presented in the study. Variations in input of terrestrial long-chain nalkanes (referred to as n-alkanes) and vegetation structure in their source regions were investigated. The results show that the nC27 is the main carbon peak and has the greatest contribution rate of the total n-alkane content; this might be related to the abundance of woody plants and their spatial distribution in the source region. nC23 is another n-alkane having a relatively high content; this was mainly derived from submerged plants widespread along the coastal areas in the northern hemisphere. Total n-alkane content dropped quickly at ca. 7.8 ka BP, ca. 6.7 ka BP and ca. 5.4 ka BP, and was followed by four relatively stable stages mostly controlled by sea-level rise, climate change and vegetation distribution in the source region. Variation in carbon preference index (CPI) indicates that the n-alkanes primarily originated from higher land plants, and the average chain length (ACL) and nC31/nC27 ratio reveal the relatively stable presence of woody/herbaceous plants during the Holocene, and dominate woody plants in most of the time. Simultaneous variation in total n-alkane content, nC27 content and its contribution, CPI, ACL and nC31/nC27 ratio over several short periods suggest that the growth rate of the woody plant n-alkane contribution was lower than that of herbaceous plants and fossil n-alkanes under the particular climatic conditions of the source region.

Understanding Ebb Channel Dynamics through Locational Probability Analysis of Historical Maps: A Comparable Study

This study explores mesoscale estuarine dynamics and geomorphological evolution as digitised from historical maps. Estuarine ebb channel positions from the UK Ordnance Survey Old maps which covered 168, 125 and 132 years for Hayle, Gannel and Camel Estuaries, respectively, were analysed through time-weighted locational probability maps, and these were evaluated for channel behaviour over decades to centuries in the context of historical changes. These three estuarine systems, which are located in southwest England, have received considerable attention in terms of the impacts of mining on estuarine sedimentation but none on ebb channel dynamics. The results show that there are relatively marked differences in meandering pattern between the mid/inner sections of the estuaries in comparison with inlet and outer section of the systems. The most stable areas of the three systems are the inlets while there are limited shifts in length and width of the ebb channel within the systems. The examinations of the pixel data from the final probability maps from each of the systems indicate that high probability dominates the inlet region of Hayle and Camel, while the inner sections of the two estuaries show evidence of increased variability. Gannel, on the other hand, reported over two-thirds of its section in higher probability class. Sea-level rise, climate forcings and human intervention are observed to exert significant controls on the ebb channel dynamics in the study areas. This study has, therefore, shown the possibility of extracting important geomorphological features and dynamics from historical and archival survey maps.

Evaluating the Performance of Jason-2 Open-Loop and Closed-Loop Tracker Modes

AbstractThe Poseidon-3 altimeter on board Jason-2 includes a significant new capability with respect to its predecessors, an open-loop [Détermination Immédiate d’Orbite par Doris Embarqué (DIODE)/digital elevation model (DEM)] tracker mode. This innovative mode is capable of successfully tracking the backscatter signal over rapidly varying terrains, and thus it overcomes one of the limitations of the closed-loop Poseidon-2 tracker on board Jason-1. DIODE/DEM achieves this improvement thanks to a predetermined DEM on board that, when combined with DIODE orbit ephemeris, provides improved acquisition timing and reduced data loss in the coastal zone. As a further enhancement, Jason-3 and the Sentinel-3 programs will be capable of autonomously switching to this innovative mode in selected regions. To help recommend how these missions should utilize DIODE/DEM, the authors studied the impact of the tracker mode on the accuracy and precision of wave heights and wind speed, the continuity of the sea level climate data record, and the coverage in coastal regions. The results show close agreement between the open- and closed-loop tracker modes over the open ocean with the exception of some differences at high-tidal variability areas, the coastal zone, and sea ice regions. The DIODE/DEM tracker shows better performance than the closed-loop tracker mode at the coast and in the presence of sea ice. Jason-2, when operating in open-loop mode, allows for an approximately 5% increase of successful acquisitions at the ocean-to-land transition. However, open-loop tracking exhibits more variability in regions of high tides than closed-loop.

Sequestering seawater on land: a water-based solution to global issues

The ‘surplus’ of oceanic water generated by climate change offers an unprecedented opportunity to tackle a number of global issues through a very pragmatic process: shifting the excess water from the oceans onto the land. Here we propose that sea-level rise could be mitigated through the desalination of very large amounts of seawater in massive desalination plants. To efficiently mitigate sea-level rise, desalinized water could be stored on land in the form of crop, wetlands or new forests. Based on a US$ 500 million price to build an individual mega desalination plant with current technology, the cost of controlling current sea-level rise through water desalination approaches US$ 23 trillion. However, the economic, environmental and health benefits would also be immense and could contribute to addressing a number of global issues including sea-level rise, food security, biodiversity loss and climate change. Because these issues are intimately intertwined, responses should aim at addressing them all concurrently and at global scale.