A new study reassures that rerouting planes to avoid generating climate-warming contrails is less likely to inadvertently worsen climate change than previously believed. The researchers from Sorbonne Universite and the University of Reading are behind this study. That finds for most aircraft creating contrails over the North Atlantic, the climatic benefit of avoiding these contrails outweighs the additional carbon dioxide released from alternative flight paths.
The new research, published in Atmospheric Chemistry and Physics, demonstrates so-called CO2 equivalence. The idea of comparing the climate impacts of carbon dioxide and contrails. Various methods of calculating CO2 equivalence were developed. And the choice of which one to use has often been politically driven. Scientists used to be concerned too that some methods would mislead. For example, by giving the impression that not causing contrails would save the climate. When flying in a way that would avoid them could be counterproductive.
Yet, this new study suggests that, on the majority of flights over the North Atlantic. The environmental benefit of contrail avoidance consistently outstrips the negative impact of extra CO2 emissions. Contrails are white streaks left behind by airplanes that can trap heat in the atmosphere and contribute to global warming. Thus, the study expands on previous research that suggested a possible mitigation of climate impact by rerouting flights to avoid contrails.
Co-author Professor Nicolas Bellouin of the University of Reading said. “In theory, rerouting flights to avoid contrails could cut aviation’s climate impact and make flying greener. Our results overcome one of the key obstacles to contrail avoidance. But we still need finer predictions and in-field testing to bring this into practice.”
They had studied almost half a million flights across the North Atlantic in 2019. And estimated how much heating those flights would have caused due to CO2 emissions and contrails. In the first step, they evaluated exactly how the presently used flight routes would contribute to global warming as time progresses. They estimated that the CO2 emissions and contrails of such flights would warm the climate by about 17 mK for flights in the year 2039 and by 14 mK for flights in 2119. A microKelvin is an extremely small unit of temperature rise.
Finally, the researchers simulated how aircraft could avoid all contrails by using only 1% more fuel. Under those conditions, rerouting would significantly reduce total warming. By 2039, it would cut warming by about 5 mK, or 29% less compared to scenarios without rerouting. By 2119, it would decrease warming by around 2 mK, or 14% less.
The team used nine different approaches to quantify the climate impact. For the most part, those approaches concurred that flight rerouting would indeed help cool the climate, given that planes can avoid contrails as predicted. The researchers say that substantial uncertainty about predicting exactly where contrails will form. And exactly how much warming they cause continues to exist. They suggest focusing early efforts at flight rerouting on those flights that produce the most warming contrails when the climate benefits of rerouting are clearer.
ANI
