Addressing the Complex Trade-Offs in Reducing Aviation’s Climate Impact

New Research Highlights the Need for Concerted Efforts to Tackle Aviation’s Non-CO2 Emissions

Aviation’s impact on the climate extends beyond its well-known CO2 emissions. Non-CO2 emissions, including nitrogen oxides, soot, and water vapor, contribute to global warming through the formation of contrails and “contrail cirrus” clouds. To tackle these emissions effectively, a recent study emphasizes the need for collaborative efforts and a comprehensive approach. The research, conducted by Manchester Metropolitan University, the University of Oxford, the University of Reading, and Imperial College London, explores the potential solutions to limit aviation’s non-CO2 emissions and highlights the absence of a simple solution.

The Complex Effects of Non-CO2 Emissions

Aviation’s non-CO2 emissions have significant implications for both climate and air quality. Soot particles emitted by aircraft engines trigger the formation of contrails and “contrail cirrus” clouds, which contribute to warming the Earth’s atmosphere. The study underscores the uncertainties surrounding the complex climate effects of non-CO2 emissions. It also highlights the challenge of reducing emissions without inadvertently increasing CO2 emissions, as most conventional fuel alternatives involve trade-offs.

The Need for Collaboration and Trade-Off Analysis

The research emphasizes that addressing aviation’s climate impact requires a coordinated effort from various stakeholders. While short-lived, the non-CO2 climate impacts of individual flights must be balanced against the long-lasting effects of emitted CO2, which can persist for millennia. The study cautions against adopting strategies that decrease non-CO2 climate effects at the expense of increasing CO2 emissions. It also acknowledges the trade-offs between improving climate impact and local air quality, urging a careful consideration of measures that simultaneously benefit both.

Aviation’s Contribution to Climate Change

Although aviation accounts for approximately 2.5% of global CO2 emissions from human activity, its non-CO2 emissions contribute significantly to the energy balance of the atmosphere. These emissions are responsible for approximately 3.5% of radiative forcing and around 4% of the increase in global mean temperatures. Decarbonizing the aviation sector poses challenges due to its reliance on fossil kerosene (jet fuel) and the lengthy process of developing new aircraft and replacing older fleets.

The Urgency to Find Solutions

With the aviation sector poised for growth after the COVID-19 pandemic, its contribution to climate change is expected to rise. Recognizing the need to address this issue, the UK government, through the Natural Environment Research Council (NERC), has launched a £10 million research program to inform policy decisions. The study emphasizes the necessity of conducting further research to understand the complex trade-offs involved in reducing aviation’s non-CO2 emissions and to expedite the search for effective solutions.


Reducing aviation’s impact on the climate requires a multi-faceted and collaborative approach. The study highlights the challenges posed by aviation’s non-CO2 emissions and the trade-offs involved in mitigating them. As the aviation sector continues to grow, urgent action is needed to find solutions that balance climate impact and air quality. The research underscores the importance of ongoing research and collaboration to inform policy decisions and drive progress in this critical area.






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