A Trend is a Trend until it Bends

Thank you for your comments on my previous post on ‘Personal mobility – A sustainability journey’. A key driver of sustainability (or unsustainability) will be the number of cars worldwide. As mentioned in the previous post, the International Energy Agency and OECD estimate that at the end of 2010 the number of cars on the planet surpassed 1 billion, and that by 2035 this number could double. Daniel Sperling and Deborah Gordon in their book Two Billion Cars: Driving Toward Sustainability make the same claim.

How can they be so certain? As a strategic foresight ‘pracademic’ my motto is ‘A Trend is a Trend until it Bends’ or, in other words, I am always on the outlook for discontinuities – social, technological, economic, environmental, and political.

In its 2001 Global Energy Scenarios, Shell introduced the ‘energy ladder’ concept and demonstrated, based on observations over 30 years in dozens of both emerging and developed economies, that a non-linear relationship (an S-curve type of relationship) exists between primary energy demand and disposable income per person (in constant purchasing power parity terms):

  • At $3,000 energy demand increases rapidly driven by industrialisation and urbanisation and the shift from biomass to commercial fuels.
  • At $10,000 energy demand continues to rise but at a slower pace as industrialisation and urbanisation matures.
  • At $15,000 energy demand growth slows dramatically driven by economic growth from services.
  • At $25,000 energy demand does not change much anymore because of efficiency and the fact that the energy needs of industry and households have been met.

Can we not make a similar S-curve observation in terms of demand for cars? In the emerging markets of India and China, demand growth for cars continues to rise, while in OECD countries demand growth for cars has stalled — in fact in some developed economies it is declining.

There may be another set of phenomena, such as ‘leap-frogging technologies’ and ‘change in behaviour’, which could imply that even historically S-curves are not a good predictor of the future, making linear predictions even less reliable. The Internet and changing human resources policies allow people to work from home part of the weak, requiring less use of cars. In crowed cities with good public transportation systems, people tend to shy away from cars or have only one car per household instead of two.

While it is likely that the number of cars will increase, I doubt that we will see 2 billion cars by 2035.

In the next post we will explore the unsustainability of personal mobility.