Coordinated Ocean Wave Climate Project (COWCLiP)

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Surface wind waves were identified in the Intergovernmental Panel for Climate Change (IPCC) Fourth Assessment Report (AR4) as one of the key drivers in the coastal zone, but little information was available on projected changes under future climate scenarios. The main focus was on the influence of sea-level rise and inundation effects. The IPCC Working Group II recognized that risks to coastal population and ecosystems required inclusion of a broader range of coastal drivers of change. One of the key drivers, which had not received sufficient prior attention , was wind-waves. 

The Coordinated Ocean Wave Climate Project (COWCLiP) is an international collaborative research project, originally being 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 and Emergency Response (ET-CER).

COWCLiP ( aims to aid comprehensive assessments of climate driven changes in wave characteristics (ultimately of global extent), both historically and in projected future scenarios , with 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 CMIP datasets;
  • Describing best practice for regional wave climate projections, and;
  • Engaging 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.

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The aims of COWCLiP are to raise the profile of wind-waves as a variable in the global climate system – both to foster and support determination of:

  • the effects of climate variability and change on the wave climate, and
  • the feedback influences of waves on the coupled ocean-atmosphere climate system.

Goals of COWCLiP are:

  • Establish a collaborative working group with interest in global wave climate historical and future variability and change
  • Resolve priority questions to aid climate impacts community
  • Document wave climate projections methods being applied, and summarize existing wave climate projection studies
  • Define a working protocol for wave climate projections:
  • Agreed standard inter-comparison experiments to obtain adequate coverage of sampling space, to establish variance associated with several layers of uncertainty
  • Minimum set of analyses/validation requires to foster inter-comparisons (projections and coupled models independently)
  • Develop a technical framework to support the working group
  • Project data server, QC, standard variables, etc.

Future 21st Century changes in wind-wave climate have broad planning implications for coastal and offshore ecosystems and infrastructure. Atmosphere-ocean general circulation models (GCM) are now routinely used for assessing and providing future projections of climatological parameters such as temperature and precipitation, but generally these provide no information on ocean wind-waves. To fill this information gap a growing number of studies are using GCM outputs and independently producing global and regional scale wind-wave climate projections. To consolidate these efforts, understand the sources of variance between projections generated by different groups, and ultimately provide a robust picture of projected changes, we present strategies from the community derived multi-model ensemble of wave climate projections (COWCLiP) and an overview of regional contributions. The objective of COWCLiP is to make community based ensembles of wave climate projections freely accessible to the scientific community, to provide the necessary information to support comprehensive coastal impacts of climate change studies.

Results of COWCLiP 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.

More detailed information is available at the COWCLiP web page

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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.

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.  

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.

Hemer, M.A., Y. Fan, N. Mori, A. Semedo and X.L. Wang, 2013.  Projected  Changes in wave climate from a multi-model ensemble, Nature Climate Change 3, 471–476.

Morim, J. et al., 2019. Robustness and uncertainties in global multivariate wind-wave climate projections. Nature Climate Change 9, 711–718.

Morim, J. et al., 2020. A global ensemble of ocean wave climate projections from CMIP5-driven models. Scientific Data. 7, 105.

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