By Csilla Vámos
Carbon dioxide (CO2) emissions from anthropological sources raise atmospheric and oceanic CO2 levels and contribute to ocean acidification. The GasDrive project hopes to contribute to efforts to curb CO2 emissions by a novel ship design. However, it is possible that this new ship design may still contribute to local CO2 emissions in the water, which may lead to ocean acidification. The goal of this thesis is to estimate where marine areas sensitive to an increase of CO2 are located.
Sensitivity to CO2 was measured taking two variables into account: Dissolved Inorganic Carbon (DIC) and cargo shipping routes. The study area was the North Pacific Ocean and parts of the Indian, Atlantic, and Arctic oceans. DIC datasets from different months were used to estimate DIC in the study area using cokriging. These DIC estimations were compared to another researcher’s DIC estimations in an overlapping region to assess accuracy. CO2 sensitivity in the study area was assessed two ways. The first way was by making a present day CO2 sensitivity map based on present day DIC levels estimations and shipping routes. The second way was by making a map that showed the change in CO2 sensitivity in the study area between present day and preindustrial eras. The map showing current CO2 sensitivity was compared to a global map of aragonite saturation, which measured the study area’s vulnerability to CO2 increase and to ocean acidification. Shipping routes, their location and the impact that they may have to the sensitivity of a marine area were also explored.
Results showed that the DIC estimates found in this research did not differ much from the DIC estimates from other research, indicating that the cokriging method used is reliable. The CO2 sensitivity map revealed that sensitivity for added CO2 in the waters is high in the waters south of the Bering Strait and low in the waters in Southeast Asia. The change in CO2 sensitivity map showed that CO2 sensitivity varies spatially and in magnitude throughout the study area. Comparing the CO2 sensitivity map to the aragonite saturation map revealed that the sensitivity map generally agreed on sensitive areas in the southern half of the study areas, but larger disagreements were found in the northern half.
The results of this study are valuable for determining where sensitive areas in the ocean are located so that steps can be taken to avoid additional CO2 emissions in these areas to prevent the increase of ocean acidification. Recommendations for future research include using more DIC datasets for analysis, updated data (less than five years old), use of more variables to better calculate DIC estimations and CO2 sensitivity, and more research on how the characteristics of different marine environments influence the response to CO2 sensitivity.
Keywords: ocean; GasDrive; ocean acidification; dissolved inorganic carbon; shipping routes; cokriging