MODELING PROPOSAL COORDINATING GLOBAL OCEAN WAVE CLIMATE PROJECTIONS

The IPCC AR4 recognized that insufficient projections of wave climate were available to assess the effects climate change will have on erosion of the world's coasts. At present, considerable research effort is placed into regional ocean wave projections, with forcing conditions derived from a select few emission scenarios from a select few GCMs. Such an approach limits the statistical confidence in the projections (limited ensembles), repeats a great deal of modeling effort, and leaves major gaps in the global coverage, particularly in those areas most at risk from changing wave conditions. In order to avoid these problems, we propose a shift to global (statistical and dynamical) projections that will come at substantial computational cost. This cost can be countered by interested parties participating in a coordinated approach (similar to the CMIP experiments), whereby individual research groups carry out global projections for selected scenarios. The aim should be to use different wave models and/or statistical downscaling approaches to produce ensembles of wave projections that correspond to climate projections from different climate models for different emission scenarios. When combined, a distribution of projections will be available that will allow an assessment of all three levels of uncertainty (associated with forcing, climate models, and downscaling methods, respectively), presenting projections with statistical confidence intervals. The proposed CMIP5 design will provide suitable data on a global scale for carrying out surface ocean wave projections, focusing on mid- and late-twenty-first-century time slices, to service the increasing demands of the coastal impacts community. Future studies could include dynamic coupling of wave processes into coupled ocean-atmosphere global climate models. © 2010 American Meteorological Society.