High levels of aviation are causing global warming, not only through greenhouse gas emissions, but also through additional clouds. This is the conclusion reached by scientists from the University of Leipzig, Imperial College London and the Pierre-Simon Laplace Institute in Paris. They studied the extent to which aircraft-caused cirrus clouds occurred during the hard global lockdown between March and May 2020, and compared the values with those for the same period in previous years. The study was led by Johannes Quaas, professor of theoretical meteorology at the University of Leipzig, and has now been published in Environmental research letters.
Cirrus clouds, known for their tall, wispy strands, contribute to global warming. When cirrus clouds form naturally, large ice crystals form at an altitude of about 36 kilometers, in turn reflecting sunlight back into space, albeit to a small extent. However, they also prevent the radiated heat from escaping from the atmosphere and therefore have a net heating effect. This is the dominant effect in cirrus clouds.
When the weather conditions are favorable, contrails form behind the planes. These can persist and spread to form larger cirrus clouds. In this case, their effect on the climate is much greater than that of narrow trails alone.
The researchers led by Professor Quaas analyzed satellite images of clouds in the northern hemisphere, between 27 ° and 68 ° North, in the period from March to May 2020. They then compared them with images of the same period in previous years. “Above all, our studies reveal a clear causal relationship. Since clouds vary greatly depending on the weather, we would not have been able to detect the effects of air traffic in this way under normal circumstances. The lockdown period due to the COVID-19 pandemic provided a unique opportunity to compare clouds in air traffic corridors at very different traffic levels.
Analysis of the data collected showed that nine percent less cirrus clouds formed during the global lockdown, and that clouds were also two percent less dense, “Professor Quaas said.” The study clearly shows. that airplane contrails lead to additional cirrus clouds and have an impact on global warming. “According to Professor Quaas, the data collected confirmed previous estimates based solely on climate models:” Our study may improve the ability to simulate these effects in climate models. “
Despite the team’s findings, there still hasn’t been enough research into the impact of aviation on global warming. A European research collaboration involving Prof. Quaas’s research group is currently studying the precise mechanisms in detail. “Strict global containment has been helpful for our research. In order to mitigate or even avoid the effect of global warming, flight routes could be adapted in the future to avoid the formation of cirrus clouds, for example by separating flight lanes. Said the professor of theoretical meteorology at the University of Leipzig.
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Material provided by University of Leipzig. Note: Content can be changed for style and length.