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Greenhouse Gas Emissions: Why hasn’t UK Transport done its share?

There are 25 years of data between the Royal Commission on Environmental Pollution (1994) and the most recent non-Covid year (2019). Sounds like a good time for a review? Well, here’s one anyway.

Unlike most other major sectors (especially energy generation), UK Greenhouse Gas (GHG) emissions barely fell at all over this period. It’s now the single largest category of GHG emissions (see chart below, sourced from the Department for Transport)

In fact, the position is significantly worse if one includes international aviation (UK aviation emissions are estimated to be 13-15% of the UK’s total GHG emissions).

So, ignoring international aviation emissions for the moment (as most UK stats do), what stopped transport from doing its share of the lifting?

There were some improvements in average car GHG emissions per mile over this time. However, these were more than offset by the growth in traffic (see chart below from Department for Business, Energy and Industrial Strategy)

 

 

Some groups recognised the need to also reduce traffic back in the 90’s and eventually The Road Traffic Reduction Act was passed in 1997 but national targets don’t appear to have ever been taken on.

Further factors arguably acted as a drag on the reduction in GHG per mile:

  • In this time period, average car engine size barely changed at all. In fact, it grew from 1.6L in 1994 to 1.8L in 2009 before falling to 1.7L in 2019. Some of this is due to the rise in SUV’s.
  • People kept their cars longer. The average in 1994 was 6.7 years but this had risen to 8.3 years by 2019.

A lot has been made about technical fixes coming to the rescue for the Climate Emergency. Certainly, the banning of new diesel and petrol vehicles from 2030 will have a significant impact. However, the experience of the last 25 years is that the speed that both technical innovation and GHG savings spread through the national fleet will vary with things such as average car size and age.

Given the increasing prices of cars (both new and second hand), will drivers delaying the purchase of electric cars further delay the GHG savings? On the other hand, given the embodied energy in a car, would delaying replacing your car be better for GHG emissions overall?

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