Coordinated Ocean Wave Climate Project (COWCLiP)

Updated on 15 September 2026

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Introduction

Wind waves are ocean surface waves generated by the action of the wind blowing over the sea. Wave characteristics are controlled by wind speed (relative to surface currents), its duration, and the distance over which the wind acts on the water surface, known as ‘fetch’. The impact of a changing climate on wind wave conditions and its consequences has received increasing attention from both scientific and practitioner communities, particularly in the context of marine operations, ship routing, coastal management, and forecasting. Changes in extreme wind wave conditions are especially significant for coastal regions. Coastal erosion, flooding, and damage to infrastructure are linked to changes in wave height, period, and direction. Wind waves also play a critical role in the Earth’s system, influencing numerous processes that are essential for understanding, modelling, and predicting the coupled climate system. This includes ocean mixing, air-sea gas exchange, wave-ice interactions and wind/wave-driven surface currents.

The Coordinated Ocean Wave Climate Project (COWCLiP) is an international collaborative research project, originally a component of the work-plan for the JCOMM Expert Team on Waves and Storm Surge (ETWS), and now being part of the work plan for the WMO Expert Team on Coastal Hazards, Applications and Requirements (ET-CHAR).COWCLIP was established in 2012 (Hemer et al, 2012) to address a knowledge gap related to projected changes in wave conditions and to consolidate the growing wave climate modelling efforts that were tackling this gap, as wave conditions have typically not been included in general circulation models.

COWCLiP aims to aid comprehensive assessments of climate-driven changes in wave characteristics, both historically and in projected future scenarios, with an understanding of associated uncertainties. COWCLIP seeks to support these objectives by:

Providing a systematic, community-based framework and infrastructure to support validation, intercomparison, documentation and data access for historical wave climate datasets and future wave climate projections forced from Coupled Model Intercomparison Project (CMIP) datasets;
Connecting regional wave climate projections to coastal hazard modelling in support of climate risk assessment and coastal adaptation strategies;
Engaging the interests of the wave community into the wider climate community and ultimately developing coupled wind-wave Atmosphere-Ocean global climate models to support quantification of wind-wave driven feedback in the coupled climate system.

Objective

COWCLIP aims to raise the profile of wind-waves as a variable in the global climate system, both to foster and support the determination of:

The effects of climate variability and change on the wave climate, globally and regionally, and
The feedback influence of waves on the coupled ocean-atmosphere climate system.

Goals of COWCLiP are to:

Develop ensembles of wave climate projections that are freely accessible, including relevant information to support comprehensive climate impact studies
Establish a collaborative working group with an interest in global wave climate, historical and future variability and change
Translate wave climate projections science into useful information for climate impact assessments
Document wave climate projection methods being applied, and summarize existing wave climate projection studies
Define shared protocols for evaluating wave climate projections, such as variable selections, scenarios, and metrics to assess projected changes
Coordinate ensemble experiment design to obtain adequate coverage of sampling space and quantify the contribution of each uncertainty factor
To define the minimum set of analyses/validation required to foster inter-comparisons (projections and coupled models independently)
Develop the technical infrastructure to support the community working groups, such as data repositories, codes for reference statistical metrics, standardised output variables, and QC procedures.
Consolidate GCM-driven wave climate modelling efforts, understand the sources of variance between projections generated by different groups, and ultimately provide a robust picture of global and regional projected changes.

Results of COWCLIP have provided the foundation for the assessment of wind-wave climate variability and change within the Intergovernmental Panel for Climate Change (IPCC) Working Group 1 Fifth (AR5) and Sixth (AR6) Assessment Reports.

Tasks

COWCLIP objectives are organized around the following tasks:

Assessment of historical wave climate variability and change
Regional wave climate projections intercomparisons
Global wave climate projections intercomparisons
Coupled wave-GCM developments
Standardisation & guidance
Coastal extremes (including morphology & sea level contributions)

Tasks 5 and 6 were established in 2019, as the community recognized challenges related to suboptimal standardization and guidance, as well as the complexity of climate change impacts on the coastal and marine systems, in which waves are just one factor. Wave-driven impacts can be further exacerbated by rising sea levels or other coastal hazards, which reduce the return period of such compound events. Moreover, coastal artificialization reduces coastal resiliency, making coastal regions more and more vulnerable to marine hazards. Overall, understanding the interactions between waves, tides, storm surges, and sea-level rise is, therefore, essential for assessing future coastal risks and informing mitigation strategies. Along these lines, it was recognized that future work should be done in collaboration with SurgeMIP.

Peer-reviewed Publications

Community-driven peer-reviewed publications:

Casas-Prat, M., Hemer, M.A., Dodet, G. et al. Wind-wave climate changes and their impacts. Nat Rev Earth Environ 5, 23–42 (2024). https://doi.org/10.1038/s43017-023-00502-0

Erikson, L., Morim, J., Hemer, M. et al. Global ocean wave fields show consistent regional trends between 1980 and 2014 in a multi-product ensemble. Commun Earth Environ 3, 320 (2022). https://doi.org/10.1038/s43247-022-00654-9

Morim, J., Trenham, C., Hemer, M. et al. A global ensemble of ocean wave climate projections from CMIP5-driven models. Sci Data 7, 105 (2020). https://doi.org/10.1038/s41597-020-0446-2

Morim, J., Hemer, M., Wang, X.L. et al. Robustness and uncertainties in global multivariate wind-wave climate projections. Nat. Clim. Chang. 9, 711–718 (2019). https://doi.org/10.1038/s41558-019-0542-5

Hemer, M., Fan, Y., Mori, N. et al. Projected changes in wave climate from a multi-model ensemble. Nature Clim Change 3, 471–476 (2013). https://doi.org/10.1038/nclimate1791

Cavaleri, L., B. Fox-Kemper and M. Hemer, 2012. Wind-waves in the coupled climate system. Bulletin of the American Meteorological Society. 93 (11), 1651-1661. https://doi.org/10.1175/BAMS-D-11-00170.1

Hemer, M.A., X.L. Wang, R. Weisse, and V.R. Swail, 2012. Advancing wind-waves climate science: The COWCLIP project. Bulletin of the American Meteorological Society, 93 (6), 791-796. https://doi.org/10.1175/BAMS-D-11-00184.1

Hemer, M.A., X.L. Wang, J.A. Church and V.R. Swail, 2010. Coordinating global ocean wave projections. Bull. Amer. Meteor. Soc., 91 (4), 451-454. https://doi.org/10.1175/2009BAMS2951.1

Modelling activities, Datasets & Tools

Wave climate modelling activities: community maps

In 2015, COWCLIP started to compile wave climate modelling activities by participating centres with two interactive maps. These maps are meant to be updated periodically and are intended as a discovery tool: users can browse by scale and identify the global, regional, or local activities most relevant to their needs. This can potentially be used to find out about wave projections for a regional or local coastal study, or to use the underlying model output for research.

COWCLIP community ensemble statistics

COWCLIP coordinates the production of large community-driven, multi-method ensembles of global wind-wave climatology statistics, standardised across contributing centres to ease comparison among wave projections from different wave models, forcing datasets, and downscaling methods. These ensembles allow for better quantification of the uncertainty and are the basis for robust wave climate community activities, which have supported the IPCC assessments of wind-wave climate change (AR5 and AR6), and will support the upcoming AR7.

Statistics datasets are listed below:

COWCLIP2.0 (CMIP5-driven): coordinated ensemble of historical and 21st-century global wave climate statistics (significant wave height, mean period, mean direction; standard and extreme indices at monthly, seasonal and annual scales), archived in CF-compliant netCDF. Available via the AODN catalogue.
COWCLIP3.0 (CMIP6-driven): successor ensemble based on CMIP6 forcing; to be published soon.

Meetings & Reports

Organization

Co-Chairs:

Mercè Casas-Prat (Environment and Climate Change Canada, Canada)
Alberto Meucci (University of Melbourne & CSIRO, Australia)

Steering committee:

Lucy Bricheno (NOC, UK)
Guillaume Dodet (Ifremer, France)
Gil Lemos (IDL-FCUL, Portugal)
Andrea Lira Loarca (NATO-STO CMRE, Italy)
Héctor Lobeto Alonso (IH Cantabria, Spain)
Lorenzo Mentaschi (University of Bologna, Italy)
Paco Ocampo-Torres (CICESE, Mexico)
PG Remya (INCOIS, India)
Giovanni Besio (University of Genova, Italy)

Advisors:

Mark Hemer (CSIRO, Australia)
Nobuhito Mori (Kyoto University, Japan)

Former co-chairs:

Mark Hemer (CSIRO, Australia) - until 2025
Xiaolan Wang (Environment and Climate Change Canada, Canada) - until 2023

More information & Contact

We welcome your feedback and contributions!

If you would like to join our COWCLIP community mailing list, request more information and/or share any suggestions (always welcome!), please contact Mercè Casas-Prat (merce [dot] casaspratec [dot] gc [dot] ca (merce[dot]casasprat[at]ec[dot]gc[dot]ca)) and/or Alberto Meucci (alberto [dot] meucciunimelb [dot] edu [dot] au (alberto[dot]meucci[at]unimelb[dot]edu[dot]au))

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