A formidable space tourism industry could have a bigger climate impact than the aviation industry and reverse the recovery of the protective ozone layer if left unregulated, according to a new study led by UCL The future of the earth†
Thanks to UCL.
Published today in the magazine The future of the earthresearchers from UCL, the University of Cambridge and the Massachusetts Institute of Technology (MIT) used a 3D model to examine the impact of rocket launches and reentry in 2019, and the impact of projected space tourism scenarios based on the recent space race of billionaires.
The team found that black carbon (soot) particles emitted by rockets are nearly 500 times more efficient at trapping heat in the atmosphere than all other sources of soot combined (surface and aircraft) – resulting in an amplified climate effect.
In addition, while the study showed that current total ozone loss from rockets is small, current growth trends around space tourism point to a potential for future depletion of the Arctic’s upper stratospheric ozone layer in the spring. This is because pollutants from solid-fuel rockets and the warming of returning spacecraft and debris on return are particularly damaging to stratospheric ozone.
Research co-author Dr. Eloise Marais (UCL Geography) said: “Rocket launches are routinely compared to the emissions of greenhouse gases and air pollutants from the aircraft industry, what we show in our work is incorrect.
“Soot particles from rocket launches have a much greater climate impact than airplanes and other terrestrial sources, so there don’t have to be as many rocket launches as international flights to have a comparable impact. What we really need now is an expert discussion about the best strategy to regulate this fast-growing industry.”
To calculate the findings, the researchers collected information on the chemicals from all 103 rocket launches in 2019 from around the world, as well as data on reusable rockets and space debris. They also used the recent demonstrations of space tourism entrepreneurs Virgin Galactic, Blue Origin and SpaceX and suggested annual offers of at least daily launches by Virgin Galactic to construct a scenario of a formidable future space tourism industry.
This data was then processed into a 3D atmospheric chemistry model to investigate the impact on the climate and the ozone layer.
The team shows that the warming from soot is 3.9 mW m-2 from a decade of modern rockets, dominated by emissions from kerosene-fired rockets. However, this has more than doubled (7.9 mW m-2) after just three years of additional emissions from space tourism launches, thanks to the use of kerosene by SpaceX and hybrid synthetic rubber fuels by Virgin Galactic.
The researchers say this is of particular importance because when the soot particles are injected directly into the upper atmosphere, they have a much greater effect on the climate than other soot sources — with the particles being 500 times more efficient at trapping heat.
The team found that, in a scenario of daily or weekly rocket launches for space tourism, the impact on the stratospheric ozone layer threatens to undermine the recovery experienced after the successful implementation of the Montreal Protocol.
The Montreal Protocol, adopted in 1987, bans substances that deplete the ozone layer worldwide and is considered one of the most successful international environmental policies.
Research co-author Dr. Robert Ryan said: “The only part of the atmosphere that shows a strong recovery of the ozone layer after the Montreal Protocol is the upper stratosphere, which is exactly where the impact of rocket emissions will hit the hardest. We did not expect ozone changes of this magnitude would threaten the progress of ozone recovery.
“There is still much we need to know about the impact of rocket launch and reentry emissions on the atmosphere – particularly the future size of the industry and the types and by-products of new fuels such as liquid methane and bio-derived fuels.
“This study allows us to enter the new era of space tourism with our eyes wide open to the potential consequences. The conversation about regulating the environmental impact of the space industry must begin now so that we can minimize damage to the stratospheric ozone layer and the climate.”
Figure 1: Rocket launch locations and fuel types in 2019. The size of the marker on the map indicates the number of launches at each location. Pie charts show the proportion of the four major fuel types at each launch site. The numbers above each pie chart are the total mass of the propellant used in each country. Additional details are provided in Table S1 in Supporting Information S1.
Figure 6: Effect of rocket launch and re-entry emissions on global climate forcing. Bars show the GEOS-Chem-RRTMG top-of-the-atmosphere instantaneous radiative forcing of BC (orange), combined O3 and CH4 (blue) and polar stratospheric clouds (PSCs, red) after a decade of growth in 2019 emissions (left) and after 3 years of constant emissions from space tourism and growth in emissions in 2019 (right). The black solid line is the net effect of all forces. 3.3 Impact of proposed space tourism
The full paper in The future of the earth: “Impact of Rocket Launch and Space Debris Air Pollutant Emissions on Stratospheric Ozone and Global Climate.”
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