Earth System Modelling

We coupled the outputs from the MariTeam model with NorESM, the Norwegian Earth System Model, to investigate the climate impact of shipping beyond simple climate metrics. Traditional climate assessments of shipping often focus on direct emissions and their immediate effects, but by integrating MariTeam’s detailed shipping emissions data with NorESM’s advanced climate modeling capabilities, we gain a more comprehensive understanding of how these emissions interact with atmospheric processes, cloud formation, and radiative forcing. This approach allows us to capture long-term feedback mechanisms and regional climate effects that are often overlooked in simpler assessments. By doing so, we provide a more nuanced perspective on the role of shipping in climate change, supporting the development of more effective mitigation strategies and policies that consider both near-term and long-term environmental consequences.

Concentration

To further explore the effects of shipping emissions on the climate system, we conducted an experiment by running NorESM for 12 years with shipping emissions fixed at 2018 levels. This approach allows us to analyze how constant shipping-related emissions influence atmospheric SO₂ concentrations over time. Below, we present the simulated values for SO₂ concentration in the atmosphere, illustrating how these emissions are transported and dispersed. Our results highlight that a significant fraction of SO₂ emitted from ships does not remain over the ocean but is instead carried onto land, where it can contribute to air pollution and regional climate effects. This finding underscores the need to consider the broader environmental and health impacts of shipping emissions beyond their immediate sources.

Short Wave Climate Forcing

Shortwave Cloud Forcing (SWCF) refers to the influence of aerosols and clouds on the amount of solar radiation that reaches the Earth’s surface. Sulfur dioxide (SO₂) emissions from shipping contribute to the formation of sulfate aerosols, which increase cloud reflectivity and enhance cooling effects by scattering incoming sunlight. Our simulation results demonstrate that SO₂ emissions from shipping have a noticeable cooling effect in the atmosphere, reducing the amount of solar radiation reaching the surface. This finding emphasizes the complex role of shipping emissions in climate dynamics, as they can lead to both warming effects from greenhouse gases and cooling effects from aerosol interactions. Understanding these competing mechanisms is crucial for accurately assessing the net climate impact of shipping and formulating effective climate policies.