ship emissions

Is transporting LNG bad for the climate? Shipping threatens the world – scientists

Scientists at Oxford University have revealed that ships emit aerosols that cool the atmosphere and mask the climate’s vulnerability to global warming. The results of the study are published in the journal Nature.

The team analyzed ship emissions data and developed a new method to quantify the impact of shipping on clouds. It is known that when a ship passes under a cloud, aerosol emissions become visible as a long line, similar to a contrail. This is due to the fact that aerosols affect the reflectivity of the cloud along the path of the ship. Although the vast majority of shipping emissions leave no visible traces, in this case the effect of aerosols can be determined by changing the properties of clouds, including the amount of droplets they contain and water in general.

The authors of the work analyzed a global database of routes of more than two million ships over six years and combined this data with historical weather records. They then modeled how aerosol emissions are carried by the wind and affect cloud cover. Satellite images have made it possible to measure the number of drops in the total amount of water (including in the form of water vapor) in polluted and unpolluted clouds.

It turned out that invisible aerosol trails contribute to a smaller increase in the number of droplets in clouds (50 percent less), but a greater increase in the amount of water compared to visible trails of emissions. This corresponds to the high cooling effect of the aerosols. Thus, clouds may be more responsive to air pollution than previously thought, and aerosols may have a strong cooling effect, masking the real vulnerability of the climate to global warming.

Aerosol emissions have a cooling effect on the planet as they create additional condensation nuclei on which cloud droplets form. Brighter clouds reflect more of the sunlight falling on them, preventing the earth’s surface from heating up.