Bringing a focus to the nearshore: A case for refining projections to aid coastal communities

While ocean acidification affects waters globally, its expression near coasts is often what stands to impact coastal communities directly. Research on down-scaling global models to the regional scale can help serve this need. However, in a recent regional vulnerability assessment on the Olympic Coast of Washington State, USA, we found the need to consider conditions in the very nearshore (<15 km), often farther inshore than model performance has been tested. To highlight this consideration, we show how a marine heat wave manifested differently across spatial scales through comparison of observations, how well output from a down-scaled regional forecast model matched observations, and describe how this information was used in a regional vulnerability assessment aimed at co-producing actionable information with Indigenous treaty tribes who have inhabited the Olympic Coast since time immemorial. Offshore gradients will vary geographically, but here we found temperature observations from moorings ~15 km offshore showed different dynamics than those even 25 km offshore, which were different still from observations ~500 km offshore. There is great potential for very nearshore model projections to be useful to coastal communities, but this requires evaluating and optimizing model performance at nearshore scales within the context of a given study. Key insights from our work are that our success depended on: tailoring outputs to the needs of the tribal co-participants via social science research; having observations within the nearshore and a gradient offshore; and evaluating the performance of models to the observations.