Perspective on aircraft in the stratosphere: 50 years from COMESA through the ozone hole to climate

Abstract

A perspective is given on the emissions of aircraft in the stratosphere, on the occasion of the 50th anniversary of the article that initiated concerns about the ability of nitrogen oxides from supersonic airliners to carry chain reactions that would destroy stratospheric ozone, and so subject the biosphere to damaging ultraviolet reaction. The response of the American, British and French governments engaged meteorology, photochemistry and radiative transfer as never before. The UK programme, COMESA (Committee on the Effects of Stratospheric Aircraft), is reviewed, and its influence on subsequent developments through concerns about chlorofluoromethanes, the ozone hole and on to climate change is traced briefly. Perspective is given on the current situation, particularly as regards the effects of aerosol particulate matter, which can include emissions from aircraft, forest fires, volcanoes, sea spray, dust, the biosphere and gas‐to‐particle conversion.

Review: The Effects of Supersonic Aviation on Ozone and Climate

“…2 estimates based on mean of E39/C CCM, SLIMCAT CTM, OsloCTM2, ULAQ-CCM. 3 estimate based on a climate response model, AirClim. 4 estimates based on CESM/WACCM4.…”

“…The development of civil supersonic transport (SST) aircraft has been pursued since the late 1960s and 1970s and can be traced back to the late 1950s. At the same period, concerns were expressed that aircraft emissions of nitrogen oxides (NO x , where NO x = NO + NO 2 ) might impact the stratospheric ozone layer [1][2][3]. The emissions from aviation trigger changes in atmospheric processes and chemistry that lead to a radiative imbalance, a radiative forcing (RF) change, e.g., [4][5][6][7][8].…”

“…A large body of scientific literature exists, but a systematic review of more recent results, comprising an evaluation of concepts for emission inventory generation, major assumptions on engine technology, route network and fleet developments as well as concepts applied in order to estimate climate impact of future SST air transport is currently lacking. Hence, the objective of this review paper is (1) to describe the historic context of supersonic aviation, (2) to present and review scientific understanding on physical and chemical processes determining the overall climate effect of supersonic aviation, (3) to present concepts of physical climate metrics in order to assess the climate effect of supersonic aviation while reviewing underlying assumptions and (4) to provide an overview on regulatory aspects applying to supersonic aviation, as well as (5) summarise key findings and recommendations which should be considered in future climate impact assessment studies.…”

The stratosphere: dynamics and variability

“…Finally, for over fifty years it has been recognized that the stratosphere is extremely vulnerable to the effects of human activity (Tuck, 2021), with the well-being of the ozone-layer of particular concern. The Montreal Protocol was agreed to safeguard the ozone-layer but a range of human activities such as those causing wild fires (Stocker et al, 2021), speculative geoengineering proposals for mitigating climate change (Tilmes et al, 2018;Smith et al, 2022), space tourism and high altitude leisure flights by dangerously polluting rocket powered hobby aeroplanes (Larson et al, 2017;Ryan et al, 2022), are all likely to affect the variability in the stratosphere and hence surface weather and climate.…”

The climate impact of hydrogen-powered hypersonic transport

“…The impact of supersonic aircraft at stratospheric altitudes is often discussed in terms of ozone concentration changes and ultraviolet radiation, and extensive overviews on these topics have recently been published (Zhang et al, 2021;Tuck, 2021;Matthes et al, 2022). The first notes indicating that NO x from supersonics might significantly affect the ozone layer were published in the 1970s (Crutzen, 1970(Crutzen, , 1972Johnston, 1971).…”