Hypermobility hits the wall

Also published on Resilience

Imagine a luxurious civilization in which every person has a motorized travel allowance of 4000 kilometers every year, with unused amounts one year carried forward to allow more distant journeys, perhaps every few years. Imagine also that non-motorized travel is not tallied in this quota, so that a person who makes their daily rounds on foot or bicycle can use all or most of their motorized travel quota for those occasional longer journeys.

It’s true that a motorized travel quota of 4000 km per year would seem a mite restrictive to most people in wealthy industrial countries. But such a travel allowance would have been beyond the dreams of all of humanity up until the past two centuries. And such a travel allowance would also mean a significant increase in mobility for a large share of the global population today.

Still, as long as we “electrify everything” why should we even think about reducing the amount of travel?

Australian scholar Patrick Moriarty floats the idea of a motorized travel allowance of 4000 km per year1, based on a recognition that the environmental harms of high-speed and motorized mobility go far beyond the climate-destabilizing emissions that come from internal combustion cars, trucks, trains, planes and ships.

In several articles and a recent book2 Moriarty and his frequent co-author Damon Honnery provide perspective on what Moriarty refers to as “hypermobility”. The number of passenger kilometers per person per year exploded by a factor of 240 between 1900 and 2018.3

“This overall 240-fold rise is extraordinary, considering the less than five-fold global population increase over the same period. It is even about 30 times the growth in real global GDP.”4

The global average for motorized travel is now about 6,300 km per person per year. At the extremes, however, US residents average over 30,000 km per person per year, while in some countries the average is only a few hundred km per person per year.5

Could the high degree of mobility now standard in the US be extended to the whole world’s population? Not likely. Moriarty calculates that if each person in the world were to travel 30,000 km per year in motorized transport, “world transport energy levels alone would be about 668 EJ, greater than global total commercial energy use of 576 EJ for 2018.”6

Increasing mobility services for the world’s poorest people, while decreasing motorized mobility for the wealthiest, is not only an environmental necessity, it is also a matter of equity. As part of examining those issues, we need to ask this simple question: what good is transportation?

We’re moving, but are we getting anywhere?

Moriarty calls attention to an issue that is so basic it is often overlooked: “What people really want is not mobility itself, but access—to workplaces, schools, shops, friends and family, entertainment etc.”7

Sometimes more mobility also means more access – for example, a person acquires a car, and that means many more workplaces, schools, and shopping opportunities are within a practical daily travel distance. But other times more mobility results in little or no gain in access. As two-car households became the norm in many rural areas, grocery stores and even schools consolidated in bigger towns, so that a car trip became necessary for access to things that used to be a walkable distance away in each small town.

Sometimes more mobility for some people means less accessibility for others. When expressways cut through urban neighbourhoods, lower-income residents of those areas may face long hikes across noisy and polluted overpasses just to get to school or a store.8

In the sprawling suburbs of North American cities, people typically drive much farther to get to work every day than their parents or grandparents did 25 or 50 years ago. But to what end? If you can now travel 50, or 70, or 100 km/hr on your commute, but the drive still takes an hour because you go so much farther, what have you gained?

Moriarty asks us to consider to what extent the explosion in mobility – hypermobility – has actually improved the quality of life even for those privileged enough to participate:

“Personal travel levels in wealthy OECD countries are several times higher than in 1950, yet people then did not regard themselves as ‘travel deprived’.”9

While the benefits of hypermobility are unclear, the costs are crushing and unsustainable.

Death rides along

Motorized transportation always comes with environmental costs. These costs are especially high when each individual travels in their own motorized carriage. Only a fraction of these environmental costs go away when a car or truck fueled by internal combustion is traded for an equivalent vehicle powered by electricity.

Many researchers have cited the high upfront carbon emissions involved in building a car or truck. Before the vehicle is delivered to a customer, a lot of carbon dioxide has been emitted in the mining and refining of the ores, the transportation of materials and parts, and the assembly. For currently produced electric cars and trucks, the upfront carbon emissions are typically even higher than the upfront emissions from an equivalent combustion vehicle. It will be a long time, if ever, before that manufacturing and transport chain runs on clean energy sources. In the meantime every new electric car signifies a big burst of carbon already emitted to the atmosphere.

If only the damage stopped there. But building and maintaining roads, bridges and parking lots is also a carbon-emissions intensive activity, with additional negative impacts on biodiversity and watershed drainage.  And though an electric vehicle has no tailpipe emissions, that doesn’t mean that electric driving is pollution-free:

“[N]on-exhaust emissions of fine particular matter from tire wear is actually greater than for equivalent conventional vehicles, because EVs are heavier than their conventionally fueled counterparts.”10

Finally, there is the direct toll from the inevitable, predictable “accidents” that occur when multi-tonne objects hurtle along roads at high speeds:

“In 2018, some 1.35 million people were killed on the world’s roads, with millions more injured, many seriously. Paradoxically, most of the casualties occur in low vehicle ownership countries, and are pedestrians and cyclists, not vehicle occupants.”11

Death reliably accompanies high-speed transportation – but the fatalities disproportionately accrue to those not privileged enough to travel.

Slowing the machine

To recap the argument: the mass production of high-speed vehicles has made possible an explosion in mobility for a privileged portion of the global population. But the energy costs of transportation increase exponentially, not linearly, with increases in speed.  Hypermobility was fueled overwhelmingly by fossil fuels, and even if we could recreate the infrastructure of hypermobility using renewable energies, the transition period would result in a burst of upfront carbon emissions which our ecosystem can ill afford. Finally, if we concentrate on ramping up renewable technologies to serve the rapacious energy demands of hypermobility, it will be more difficult and will take longer to convert all other essential energy services – for producing and distributing foods, for heating and cooling of buildings, and for distributing clean drinking water, to name a few examples – so that they can run off the same renewable electricity sources.

It is clearly possible for a society to prosper with a lot less motorized travel than our hypermobile society now regards as normal. Given the manifold environmental costs and manifest social inequality of a hypermobile society, we need to rapidly cut down not only on the use of fossil fuel in transportation, but also the total amount of motorized transportation as measured in passenger-kilometers (p-k) per person per year. This is the underpinning for Moriarty’s “tentative proposal for an average aspirational target of 4000 vehicular p-k per person per year.”12

But how to begin applying the brakes?

In an article titled “Reducing Personal Mobility for Climate Change Mitigation”, Moriarty and Honnery have examined the likely impacts of various factors on overall motorized mobility. Neither new information technology services, carpooling, or land-use planning changes are likely to result in significant reductions in travel, particularly not in the 10 – 25 year time frame that is so critical for staving off a truly catastrophic climate crisis. Large and rapid increases in the market price of fossil fuels, on the other hand, would dramatically hurt lower-income people while allowing high-income people – who consume by far the most energy per capita – to maintain their current personal habits. Thus Moriarty and Honnery conclude:

“The only equitable approach is to reduce the convenience of car travel, for example, by large travel speed reductions and by a reversal of the usual present ranking of travel modes: car, public transport, and active modes.” [emphasis mine]13

Expressed graphically, that reversal of priorities would look like this chart from Mikael Colville-Andersen’s book Copenhagenize:

From Copenhagenize, by Mikael Colville-Andersen, Island Press, 2018; reviewed here.

At the outset of the motor age, walking and cycling routes were as direct and convenient as possible. As streets were dedicated to fast, dangerous cars, walking and cycling routes started to zigzag through many detours, or they simply disappeared, while priority was given to auto routes.

To make our cities safer and healthier, while also reducing the voracious energy demands of motorized transport, we need to flip the hierarchy once more, putting active transportation first, public transit second, and cars third. That way we can improve access to essential services even as motorized mobility drops.

Within cities where most people live, I think Moriarty and Honnery are right that this change would result in a substantial reduction in overall motorized kilometers per capita, and would do so in a generally equitable manner.

Easier said than done, of course. While many European cities have made major strides in this regard, even timid moves to de-privilege cars are tough for city councils to enact in North America.

A personal travel allotment of 4,000 km per year will seem outrageously low to most North Americans, and it is hard to imagine any North American politician – at least anyone with a hope of ever being elected – saying a good word about the idea.

Yet the luxury of any high-speed travel at all is a recent phenomenon, and there is no reason to take for granted that this extravagance will last very long. We do know that we need drastic, rapid change in our energy consumption patterns if we are to avoid civilization-threatening environmental instability.

We might not find it within ourselves to voluntarily steer away from our high-speed, hypermobile way of life. But if, a few decades from now, our society is in free-fall due to rapid-fire environmental disasters, the complex infrastructure needed for widespread motorized transport may be but a faint memory.

* * *

Though I only came across Moriarty’s work a few years ago, for most of my adult life I unwittingly lived within a motorized travel allotment of 4,000 km/yr – with one major exception. More than 40 years ago, as a new resident of an urban metropolis, I realized it was a bizarre waste of horsepower to use a car simply to haul my (then) scrawny carcass along city streets. Besides, I found it healthier, cheaper, more interesting, and definitely more fun to ride a bike to work, to concerts, to stores, and nearly everywhere else I wanted to go. I was fortunate, too, to be able to choose a home close to my workplace, or change my workplace to be closer to my preferred home; throughout several decades I never needed to regularly commute by car.

But: I did get on a plane once or twice a year, and sometimes several times a year. For many years these air journeys accounted for most of my motorized transport kilometers. Later I learned that of all typical modern travel modes, air travel was the most environmentally damaging and the least sustainable.

In upcoming installments in this series I’ll look at the energy needs, both real and imagined, for personal transportation within cities; and at the impact of hyper-hypermobility as embodied in routine air travel.

Illustration at top of page courtesy of pxhere.com, free for personal and commercial use under CC0 public domain license.


See his brief article in Academia Letters, “A proposal for limits on vehicular passenger travel levels”, published in September 2021.

Patrick Moriarty and Damon Honnery, Switching Off: Meeting Our Energy Needs in a Constrained Future, Springer, 2022.

P. Moriarty, “Global Passenger Transport,” MDPI Encyclopedia, February 2021.

P. Moriarty, Academia Letters, “A proposal for limits on vehicular passenger travel levels”.

P. Moriarty, “Global Passenger Transport”.

P. Moriarty, “Global Passenger Transport”.

P. Moriarty, “A proposal for limits on vehicular passenger travel levels”.

For more on the trade-offs between mobility and accessibility see my article “The Mobility Maze”.

P. Moriarty, “A proposal for limits on vehicular passenger travel levels”.

10 P. Moriarty, “Global Passenger Transport”.

11 P. Moriarty, “A proposal for limits on vehicular passenger travel levels”.

12 P. Moriarty, “A proposal for limits on vehicular passenger travel levels”.

13 Patrick Moriarty and Damon Honnery, “Reducing Personal Mobility for Climate Change Mitigation”, in Handbook of Climate Change Mitigation and Adaptation, Springer, 2022, pages 2501 – 2534.