Robustness and uncertainties in global multivariate wind-wave climate projections

• Published in: Nature climate change 2019-09, Vol.9 (9), p.711-718
• Main Authors: Morim, Joao, Hemer, Mark, Wang, Xiaolan L., Cartwright, Nick, Trenham, Claire, Semedo, Alvaro, Young, Ian, Bricheno, Lucy, Camus, Paula, Casas-Prat, Mercè, Erikson, Li, Mentaschi, Lorenzo, Mori, Nobuhito, Shimura, Tomoya, Timmermans, Ben, Aarnes, Ole, Breivik, Øyvind, Behrens, Arno, Dobrynin, Mikhail, Menendez, Melisa, Staneva, Joanna, Wehner, Michael, Wolf, Judith, Kamranzad, Bahareh, Webb, Adrean, Stopa, Justin, Andutta, Fernando
• Format: Article
• Language: English
• Subjects: 704/106/694; 704/106/694/2739; 704/106/694/2786; 704/829; 704/829/2737; Adaptation; Climate adaptation; Climate Change; Climate Change/Climate Change Impacts; Climate effects; Climate models; climate-change impacts; Coastal climates; Coastal effects; Earth and Environmental Science; Environment; Environmental Law/Policy/Ecojustice; ENVIRONMENTAL SCIENCES; Global winds; Multivariate analysis; ocean sciences; Ocean wave heights; Offshore; physical oceanography; projection and prediction; Significant wave height; Significant waves; Uncertainty; Wave climate; Wave direction; Wave height; Wave period; Wind; Wind waves
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/s41558-019-0542-5

Understanding climate-driven impacts on the multivariate global wind-wave climate is paramount to effective offshore/coastal climate adaptation planning. However, the use of single-method ensembles and variations arising from different methodologies has resulted in unquantified uncertainty amongst existing global wave climate projections. Here, assessing the first coherent, community-driven, multi-method ensemble of global wave climate projections, we demonstrate widespread ocean regions with robust changes in annual mean significant wave height and mean wave period of 5–15% and shifts in mean wave direction of 5–15°, under a high-emission scenario. Approximately 50% of the world’s coastline is at risk from wave climate change, with ~40% revealing robust changes in at least two variables. Furthermore, we find that uncertainty in current projections is dominated by climate model-driven uncertainty, and that single-method modelling studies are unable to capture up to ~50% of the total associated uncertainty. There are large uncertainties in wind-wave climate projections that need to be resolved to allow adaptation planning. A multi-method ensemble of global wave climate projections shows robust changes in wave height, period and direction that put 50% of the global coast at risk.