The Sustainable Shift in Post-Pandemic Travel — Epoche C1
Four propositions about travelling better The claim to be examined here is that travelling in a lower-impact way — fewer flights, longer stays, locally owned accommodation, community-run activities — makes the journey better for the traveller as well as for the destination. Four specific benefits are usually named: deeper cultural immersion, slower and more mindful exploration, stronger personal connection with people and place, and relief from environmental guilt. An earlier version of this piece presented these four as remarks by a named specialist in sustainable tourism. That attribution could not be substantiated and has been removed; the propositions are set out below as claims and tested against published evidence, which is where they belonged in the first place. Two of the four survive with qualifications. One survives only after being restated. The fourth inverts: the best available research indicates that it describes a mechanism which makes high-impact travel easier rather than harder. Before any of that, the premise needs checking, because the whole argument is usually launched from a claim about what the pandemic revealed, and that claim is largely false. What the shutdown actually did to emissions The familiar version runs: travel stopped, the air cleared, the water in the canals ran clean, and people saw what their mobility had been costing. The visible part of this is true and the inference from it is not. Corinne Le Quéré and colleagues (2020) assembled daily estimates of global carbon dioxide emissions through the first months of 2020 by combining government confinement policies with activity indicators for each sector, and produced the most careful account available of what the shutdown removed. At the deepest point, in early April 2020, daily global emissions were about 17 per cent below the mean daily level of 2019. Their sectoral breakdown is the part that matters here. Surface transport — cars, buses, lorries — accounted for roughly 43 per cent of the decrease, the largest single contribution. Aviation, whose activity collapsed further and faster than any other sector's, contributed about 10 per cent. The clean air over cities was almost entirely a road-traffic effect, and the grounded aircraft had comparatively little to do with it. Two distinct things were conflated: local air quality, which is dominated by nitrogen oxides and particulates emitted at ground level near where people breathe, and greenhouse gas forcing, which is a global stock problem indifferent to where the emission occurred. The stock point is the decisive one. Atmospheric concentration responds to the cumulative total, not to the annual flow, so an emissions reduction of this size does not show up as an improvement — it shows up as a slightly smaller increase. The Global Carbon Budget assessment for 2021 (Friedlingstein and colleagues, 2022) put the fall in global fossil carbon dioxide emissions for 2020 at around 5 per cent for the year as a whole, and recorded a rebound in 2021 that returned emissions to close to their 2019 level. Concentration at the long-running monitoring stations rose throughout. A year in which the world's aircraft were parked, most offices were closed and a large fraction of the population stayed at home bought a reduction of about a twentieth, for one year, which was then given back. This is not an argument for fatalism, but it does relocate the argument. What the pandemic demonstrated was not that individual travel choices are the lever; it was closer to the opposite. Stefan Gössling, Daniel Scott and C. Michael Hall (2021), in an assessment of the pandemic's effect on tourism written while it was still under way, drew the corresponding conclusion for the industry: that the disruption exposed how thoroughly tourism systems are organised around volume growth, and that any durable change would have to come from how the sector is structured and priced rather than from an accumulation of better-informed holidaymakers. It is also worth recording that the policy framework the phrase "sustainable travel" comes from predates the pandemic rather than following it. The World Tourism Organization and the United Nations Development Programme published their mapping of tourism onto the Sustainable Development Goals in 2017. The pandemic did not create the agenda; it interrupted the activity the agenda was about. Why flying is worse than its carbon share suggests Aviation's share of global carbon dioxide emissions is often quoted at around 2.5 per cent, and is then used in both directions — as evidence that flying is a minor problem, or as evidence that it is a large one. Both uses misread it, and the reason is a piece of atmospheric physics that a traveller reasoning about trains and planes needs to have. David Lee and a large group of co-authors (2021) produced the standard accounting, covering the years 2000 to 2018. Their quantity is effective radiative forcing : the net change in the Earth's energy balance, in watts per square metre, caused by a given agent, after the fast adjustments of the atmosphere have taken place but before the surface has warmed in response. It is the measure that allows agents acting through different mechanisms to be added together. Their finding is that aviation's carbon dioxide amounted to about 2.4 per cent of anthropogenic carbon dioxide emissions in 2018, but that aviation's total effective radiative forcing was about 3.5 per cent of the total from all human activities — because roughly two-thirds of aviation's forcing comes from things that are not carbon dioxide at all. Those non-carbon terms are peculiar to flight and are the reason the sector cannot be assessed by fuel volume alone: Contrail cirrus , the largest single term. Water vapour and soot particles emitted into cold, ice-supersaturated air at cruise altitude nucleate ice crystals; the resulting line clouds spread into diffuse cirrus sheets that trap outgoing infrared radiation more than