The Impact of Ship Emission Controls Recorded by Cloud Properties

• Published in: Geophysical research letters Vol. 46; no. 21; pp. 12547 - 12555
• Main Authors: Gryspeerdt, Edward, Smith, Tristan W. P., O'Keeffe, Eoin, Christensen, Matthew W., Goldsworth, Fraser W.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16-11-2019
• Subjects: Aerosol effects; Aerosol-cloud interactions; Aerosols; Air pollution; Climate; Cloud observations; Cloud properties; Clouds; Connecting; Emission measurements; Emissions; Emissions control; emissions policy; Fuel oils; Identification methods; Masking; Meteorological satellites; Particulate emissions; Particulate matter; Particulate pollution; Particulates; Pollution; Pollution monitoring; Properties; Properties (attributes); Satellite data; Shipping; Ships; Sulfates; Sulfur; Sulfur content; Sulphur; Transponders
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2019GL084700

The impact of aerosols on cloud properties is one of the leading uncertainties in the human forcing of the climate. Ships are large, isolated sources of aerosol creating linear cloud formations known as shiptracks. These are an ideal opportunity to identify and measure aerosol‐cloud interactions. This work uses over 17,000 shiptracks during the implementation of fuel sulfur content regulations to demonstrate the central role of sulfate aerosol in ship exhaust for modifying clouds. By connecting individual shiptracks to transponder data, it is shown that almost half of shiptracks are likely undetected, masking a significant contribution to the climate impact of shipping. A pathway to retrieving ship sulfate emissions is demonstrated, showing how cloud observations could be used to monitor air pollution.
Plain Language Summary
Ships often burn heavy fuel oil, typically creating large amounts of particulate pollution, which is known to modify cloud properties. This creates linear cloud formations, known as shiptracks. In this work, we investigate how the occurrence and properties of shiptracks are related to the particulate emissions from individual ships. We show that the introduction of regulation on ship fuel has already produced a dramatic effect on cloud properties, with shiptracks almost disappearing completely in regions where fuel is regulated. With this new information about the particulates produced by specific ships, we also show that many shiptracks are likely undetected by current identification methods. This study also provides a pathway toward measuring ship emissions using satellite data.
Key Points
Ship fuel sulfate content controls have already had a significant impact on shiptracks
Almost half of shiptracks may be undetected by current methods
A potential method for retrieving ship emissions using cloud properties is demonstrated