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Airlines are committed to achieving net zero carbon emissions by 2050. The industry also recognizes that sustainability goes beyond carbon abatement. Aircraft produce other emissions in addition to CO2 which contribute to climate change. This is why, for the first time, experts discussed the non-CO2 impacts of aviation on climate change, to further explore the causes, impacts and potential solutions that the industry could look at.
Contrails are part of these non-CO2 emissions and were the focus of this session. As contrails vary by flight, there are many uncertainties around the magnitude of impacts. It’s likely that contrails are generated by as little as 10% of all flights. Although contrails are not always formed, their effect depends on whether they are persistent, the location and time of the day at which they are formed, the weather conditions, the combined effect of multiple contrails, and, importantly, whether they have a cooling or warming effect. This makes calculating their net climate effect on a per flight basis extremely complex.
Deviating flight paths appears to be the most promising solutions to mitigate contrails, but there is no one size fits all solution. “The science around contrails remains much more uncertain than for CO2. There is agreement around the warming effect of some contrails, but we do not know the scale of the warming,” said Florian Allroggen, Executive Director, Laboratory for Aviation and the Environment, MIT, who shared his insights on non-C02 emissions and the work he leads. This is based on the large-scale observation base studies -– using satellite data to understand where contrails form- – to find solutions to mitigate persistent contrails.
