Research News
Two US Navy vessels refuelling at sea. Photo: MC3 Juan Antoine King/Wikipedia
Shipping Traffic and Global Climate
Since 2004, ten young scientists from the Institute of Atmospheric Physics at the DLR in Oberpfaffenhofen and from the University of Bremen have researched the influence of ship emissions on the atmosphere and the climate. They have now presented their final report revealing some surprising results indeed: With around 800 million tonnes CO2 released into the atmosphere in the year 2000, the CO2 emissions of international shipping are approximately equal to aviation, but with 20 million tonnes it emits ten times more nitrogen oxides and with around 12 million tonnes even one-hundred times more sulphur dioxides. For their study, the young scientists used the data from the European Environmental Satellite Envisat and complex computer models. The effects on climate change are complex: By emitting the greenhouse gas CO2, shipping contributes to global warming. However, the high concentration of SO2 emissions initially counteracts this effect, for in the atmosphere, sulphurous compounds first react to create sulphuric acid, which together with water forms tiny droplets reflecting the sunlight back into space. SO2 thus effects a decline in temperature. Yet this effect occurs only regionally and is limited in time: The lifespan of these aerosols amounts to only a few days, whereas carbon dioxide stays in the atmosphere for over a hundred years. One also has to consider that SO2 emissions contribute to massive pollution of the air in coastal areas, in particular in ports.
Future Perspectives:
The five-year project funding of SeaKLIM amounting to 250,000 Euro per year was covered equally by the DLR and the Helmholtz Association. In the context of this funding, the group of young researchers could contribute towards climate protection. It is owed not least to their study that international shipping is facing stricter regulations to minimise SO2 emissions. The limit for sulphur content in marine fuels has already been reduced by a third to 1.0 percent in special shipping zones. As of 2015, the sulphur content must not exceed 0.1 percent in these protected areas. As an independent project, SeaKLIM contributed to the second greenhouse gas study by the International Maritime Organization (IMO) and will continue to work on shipping emission scenarios to safeguard the atmosphere and the climate also in the future.
