Saturday, February 7, 2015

Pacific winds and waves to change significantly in coming century: new report

A complex projection of wave and wind trends in the Pacific over the next century suggests a lot of change in our future.

The just-published study looks at models of wind speed and direction, wave height and period and other features. Perhaps surprisingly, not everything goes in the same direction, nor even keeps going in the direction it started in over the coming century.

If that sounds strangely complicated, well, yes, it is. But also important for planning mitigation measures for coastal communities that will be threatened by changing wind and wave regimes.

“Waves…impact coastal infrastructure, natural and cultural resources, and coastal-related economic activities of the islands,” the paper’s authors write.

The study for the U.S. Geological Survey is entitled “Future Wave and Wind Projections for United States and United States-Affiliated Pacific Islands" and was prepared by Curt D. Storlazzi, James B. Shope, Li H. Erikson, Christie A. Hegermiller  and Patrick L. Barnard.

It starts with the warning that “Changes in future wave climates in the tropical Pacific Ocean from global climate change are not well understood.”

It ran multiple models for multiple locations for multiple time periods. 

The study suggests that during the winter months, December to February, in general, we can expect wave heights to increase through the first half of the century, and then to decrease for the second half.

In summer, June to August, wave heights are expected to increase throughout the century. 

And during the fall, September to November, they are expected to decrease throughout the century.

But those are general statements. There are significant regional differences.

Depending on the statistical model used, not only wave height and wind speed, but wave directions and wind directions also change seasonally with location and season.

The specifics of the study are dense, and beyond the capacity of this report, but for those interested in coastal mitigation, the wave and wind projections are an important resource.

“The data generated by this effort are expected to be crucial in projecting future transient sea level extremes on coasts and small islands, because winds and waves are the key processes driving extreme water levels and inundation,” the authors write.

Here is a USGS press release on the study. It includes this line from Jeff Burgett, Science Coordinator for the Pacific Islands Climate Change Cooperative: “Natural resource managers, communities, and engineers will all benefit by being able to prepare for the shifts in inundation risk shown by this study.  This work shows that the degree of change we see will depend on how greenhouse-gas emissions change."

Citation: Storlazzi, C.D., Shope, J.B., Erikson, L.H., Hegermiller, C.A., and Barnard, P.L., 2015, Future wave and wind projections for United States and United States-affiliated Pacific Islands: U.S. Geological Survey Open-File Report 2015–1001, 426p.,

© Jan TenBruggencate 2015

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