Ship emission variations during the COVID-19 from global and continental perspectives.

The COVID-19 pandemic and the International Maritime Organization's (IMO) 2020 fuel-switching policy have profoundly impacted global maritime activities, leading to unprecedented changes in shipping emissions. This study aimed to examine the effects from different scales and investigate the underlying drivers. The big data model Ship Emission Inventory Model (SEIM) was updated and applied to analyze the spatiotemporal pattern of global ship emissions as well as the main contributors in 2019 and 2020. Overall, ships emitted NOx, CO, HC, CO2, and N2O declined by 7.4 %-13.8 %, while SO2, PM2.5, and BC declined by 40.9 %-81.9 % in 2020 compared with 2019. The decline in CO2 emissions indicated a comparable reduction across vessel tonnages. Ship emissions occurring at cruising status accounted for over 90 % of the ship's CO2 emission reduction. Container ships, chemical tankers, and Ro-Ro vessels were the primary contributors to the emission reductions, with container ships alone responsible for 39.4 % of the CO2 decrease. The ship's CO2 emissions variations revealed the decline-rebound patterns in response to the pandemic. Asian-related routes saw emissions drop in February 2020, followed by a rebound in May, while European and American routes experienced declines starting in May, with a recovery in August. Further analysis of CO2 emission in Exclusive Economic Zones (EEZs) showed high temporal consistency between vessel CO2 emissions, sailing speeds, and international trade volumes across continents, and exhibited heterogeneity in main contributing ship type of emission reduction on continental scale. Our study reveals the short-term fluctuation characteristics of global ship emissions during the pandemic, particularly focusing on their spatiotemporal evolution and the inherent disparities. The results highlight the correlation between global ship emissions and trade, as well as the operational status of ships, and their rigidity.

Assessment of global shipping risk caused by maritime piracy.

Due to the frequent occurrence of piracy incidents, normal trade, and transportation activities have been hindered. This paper uses the Piracy and Armed Robbery dataset in the Global Integrated Shipping Information System to analyze the types and evolutionary characteristics of shipping risk caused by piracy and the piracy behavior patterns in different seas. This study found that there are three regions with high incidence of piracy in the world, and their gathering centers change dynamically over time. Piracy incidents can be divided into four categories based on the quantitative assessment of shipping risk caused by piracy. Shipping risk caused by piracy shows different evolution characteristics in different seas, affected by factors such as the evolution of national political situations and anti-piracy measures. Based on the qualitative assessment of the shipping risk caused by piracy, the piracy corpus reflects the diverse patterns of piracy in different seas. In the process of pirate attacks, the diversity is mainly manifested in violence and selectivity. In the consequences of pirate attacks, the targets that pirates pay attention to vary significantly in different seas. This research will help to strengthen the dynamic monitoring of shipping risk caused by piracy, and further contribute to the research on maritime transport safety.