Date of Award

Fall 12-2021

Document Type


Degree Name

Master of Science (MS)


Ocean & Earth Sciences


Ocean and Earth Sciences

Committee Director

Hans-Peter Plag

Committee Member

C. Ariel Pinto

Committee Member

Hannah Torres

Committee Member

John Klinck


The growing urban built environment in the coastal zone poses an unknown risk to the marine biosphere as a source of marine debris. Plastic, since its introduction in the mid- 1900s, is now used in nearly all aspects of human life. Growth in human population and urbanization in coastal zones has resulted in the accumulation of large stocks of plastic in the coastal built environment, and these stocks are still growing exponentially. The coastal zone is exposed to a number of hazards including storms, tsunamis, and sea level rise, and most of these hazards are expected to change in the future due to climate change. The accumulation of plastic and other potential marine debris in the coastal zone creates a growing risk of plastic marine debris originating from the coastal zone, which will impact future generations for a long time. Risk is the possibility of consequences where the outcome is uncertain, and here the consequence is additional plastic marine debris entering the ocean. To quantify this risk, the product of hazard probability, fragility of the urban coast, and the exposed assets, measured in the amount of plastic, is used. The hazard probability is determined by the changing hazard spectrum as a result of climate change. The fragility of the urban coast is identified for three case studies through analysis of the damage caused in these locations by specific hazardous events. Unfortunately, the production and use of plastic in society is not well documented and the available data cannot be used to calibrate and validate a comprehensive stock and flow model for plastic in the urban coast. Therefore, the amount of plastic exposed in the case study locations and globally is estimated by population and amount of plastic per person. Using the estimated hazard probabilities, the fragilities, and the exposed amounts, the quantification of risk resulted in understanding that, for example, by 2050, one or more tsunamis with a wave height less than 2 meters in Japan could result in, on average, 74,000 tons of plastic marine debris. One or more cyclones making landfall in the Bahamas could result in, on average, 9,796 tons of plastic marine debris. For Jakarta, the city is likely to be abandoned and a scenario where leaving 20% of the plastic in urban built environment behind could result in 272,800 tons of plastic marine debris. These examples, along with other compiled in the study, indicate the scale of the risk for future generations.


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