Climate Change Could Alter Waves Along Half the World’s Coast

file photo courtesy of Diamantino Rosa
file photo courtesy of Diamantino Rosa

By The Maritime Executive 08-22-2019 05:53:09

New research finds that warming associated with climate change will alter ocean waves along more than 50 percent of the world’s coastlines.

As part of the Coordinated Ocean Wave Climate Project, 10 research organizations, including the U.K.'s National Oceanography Centre and Australia's CSIRO, looked at a range of different global wave models in a variety of future climate scenarios, to determine how waves might change in the future.

While they identified some differences between different models, they found if the 2? Paris agreement target is kept, changes in wave patterns are likely to stay inside natural climate variability.

However, in a business-as-usual climate, where warming continues in line with current trends, the models agreed that significant changes in wave conditions will occur along 50 percent of the world’s coasts. About 40 percent of the world’s coastlines are likely to see changes in wave height, period and direction happening simultaneously.

Less than five percent of the global coastline is at risk of increasing wave heights. Such areas include the southern coasts of Australia and segments of the Pacific coast of South and Central America. Southern Australia is likely to see longer, more southerly waves that could alter the stability of the coastline. 

Decreases in wave heights are forecast for about 15 percent of the world’s coasts. In the U.K. coast, the mean wave height is projected to decrease by about 10 percent by the end of the century under the most extreme global warming scenario.

More generally, the study predicts increases in the mean average wave height for the Southern Ocean and the tropical eastern Pacific and decreases in the North Atlantic Ocean and portions of the northern Pacific Ocean. These changes are consistent with a relatively uniform decrease in projected surface wind speeds over the northern hemisphere extra-tropical storm belt.

Climate change is expected to change wind patterns around the globe which would alter global ocean wave conditions. Some areas will see the height of waves remain the same, but their wavelength or frequency will change. This can result in changes in the force exerted on the coast and any infrastructure there, and in some cases lead to increased wave-driven flooding. 

Similarly, climate change induced alterations to the direction of waves can change how much sand they move along the coast, potentially impacting coastal infrastructure. The study predicts that waves will travel from a slightly altered direction along over 20 percent of global coasts.

Earlier recent research analyzed 33 years of wind and wave records from satellite measurements and found average wind speeds have risen by 1.5 meters per second (eight percent). Wave heights are up by 30cm (12 inches) (five percent).