Pictured above: Green shipping has become a priority for policy-makers, especially at the behest of the Green Deal, with its emissions under the spotlight
A scientific paper co-authored by several members of the Department of Geosciences within the Faculty of Science (Prof. Ray Ellul, Prof. Alan Deidun, Dr Adam Gauci, Mr Martin Saliba, Dr Ing. Francelle Azzopardi, Ms Rebecca Muscat, Mr Marvic Grima, Mr Tonio Caruana), as well as by Prof. Charles Galdies from the Institute for Earth Systems and by representatives from the Finnish Meteorological Institute, has drawn light on the putative impact of the COVID-19 pandemic on shipping traffic within Maltese waters and on associated atmospheric emissions.
The study availed itself of multi-annual atmospheric data collected at the Tal-Gurdan monitoring station, with such a monitoring station being recognised as a Global Atmosphere Watch (GAW) station in 2001, for a marine area measuring 200km by 200km. By virtue of its strategic location, such a monitoring station is well placed to monitor atmospheric emissions linked with Mt. Etna volcanic activity but also those emissions linked with shipping traffic, given than an estimated 90% of all East-West shipping traffic in the Mediterranean traverses the Malta-Sicily Channel north of Gozo. It is estimated that Greenhouse Gas Emissions (GHG) from shipping within the Mediterranean comprises 7% of the global shipping-derived GHG emissions and that roughly 85,000 vessels traverse this region on average each year.
Variation of ozone, nitrogen oxides, and sulfur dioxide with wind direction
The emissions monitored through this station include those for ozone, sulfur dioxide, nitrogen oxides, methane, carbon monoxide, carbon dioxide and water vapour. Atmospheric emission data was also gleaned from the SENTINEL-5 precursor satellite, which is part of the Copernicus Atmospheric Monitoring Services (CAMS) and is thus equipped with a TROPOspheric Monitoring Instrument (TROPOMI) spectrometer that provides seven bands between the ultraviolet (UV) and shortwave infrared (SWIR).
CO2 (a), CO (b), NOx (c), SOx (d), and PM2.5 (e) emissions for all vessel types
The study also availed itself of shipping traffic data gleaned through the AIS (Automatic Identification System) operated by the Department of Geosciences, implemented through two AIS antennae located at the Tal-Qroqq campus and also at Tal-Gurdan and through which vessel positions and a number of vessel attributes/metrics (e.g. destination, IMO registration number, speed, etc) can be inferred. The STEAM model, developed by the Finnish Meteorological Institute, was applied in order to predict the atmospheric emissions arising from the shipping traffic volumes within Maltese waters as observed through the AIS antennae.
During the first COVID partial lockdown in 2020, a strong activity from sailing, pleasure, and high-speed craft was still recorded within Maltese waters. However, the number of passenger ships declined around the end of March 2020. This remained low throughout the month of April 2020. Due to the closure of international ports, the number of hours spent by cargo and tanker ships in Maltese waters was considerably lower than in previous years. However, despite the partial lockdown measures, the total number of vessels, as well as the total time spent by vessels across all categories in the Malta Channel, remained more or less the same throughout 2020. This means that international seaborne trade persisted during the pandemic.
Vessel tracks for different categories recorded on 6 March 2020 (left) and on 19th April 2020 (right)
Carbon dioxide comprised 96% of all shipping-related emissions, followed by nitrogen dioxide (2.34%) and sulfur dioxide (1.40%). In addition, from the actual trace gas measurements, it was concluded that SOx and NOx emissions are slowly decreasing over time. Moreover, through the global agreement capping the sulfur content of fuel used in shipping for non-ECA (Emission-Control Area) regions such as the Mediterranean, which came into force on the 1January 2020, sulfur emissions from ships are expected to start decreasing in the coming years.
The study has been published within the peer-reviewed Journal of Marine Science and Engineering and is available for download online.