This graph was first compiled as the central illustration of Harrison’s 2019 book The Glasgow Effect: A Tale of Class, Capitalism & Carbon Footprint to illustrate the artist’s increasing amount of travel in the years running up to The Glasgow Effect in 2016 and the dramatic impact that the project had on reducing her carbon footprint for transport. It was updated in 2020 for display at Edinburgh Art Festival.

Carbon Graph (2019)

Harrison first compiled the ‘Carbon Graph’ over the course of a month (in April and May 2019) while she was writing her book by calculating the distance of all 3,628 journeys she made in motorised vehicles since registering as a self-employed ‘professional artist’ in 2004 (journeys on foot or by bike were excluded as they have zero carbon footprint).

The graph was then updated in July 2020 to show the impact of the coronavirus lockdown on her carbon footprint for transport, and exhibited on two billboard sites in Edinburgh for the Edinburgh Art Festival (30 July – 30 August 2020). As of 30 July 2020, she had made 3,988 journeys in motorised vehicles over the last 17 years.

To identify these journeys, Harrison reviewed all her records of ‘travel expenses’ in parallel with old diaries and photographs, and then used the websites below to calculate the distance in kilometres of each:

Harrison then multiplied the total annual distance for each transportation mode (Table 1) by the most up-to-date Conversion Factors (Table 2), issued by the UK Government’s Department for Business, Energy & Industrial Strategy in July 2018. The kg CO2e (kilograms of carbon dioxide equivalent) Conversion Factors take into account the impact of the seven main greenhouse gases that contribute to climate change, as defined by the Kyoto Protocol. The greenhouse gases are:

  • carbon dioxide (CO2)
  • methane (CH4)
  • nitrous oxide (N2O)
  • hydrofluorocarbons (HFCS)
  • perfluorocarbons (PFCS)
  • sulfur hexafluoride (SF6)
  • nitrogen trifluoride (NF3)

Table 1: Annual distances for each transportation mode (km)

  2004 2005 2006 2007 2008 2009 2010 2011
Taxi, Car & Van 1,261 174 916 420 481 1,045 313 921
Bus & Coach 743 669 668 2,811 1,099 596 602 143
Boat 0 67 446 13 0 4 8 46
Underground & Tram 1,167 1,542 835 1,142 992 1,174 1,368 1,312
Plane 1,441 2,478 664 0 0 3,290 36,877 0
Train 12,120 12,913 18,913 18,236 18,545 24,434 13,758 17,149
Total 16,731 17,843 22,441 22,622 21,117 30,543 52,926 19,570

  2012 2013 2014 2015 2016 2017 2018 2019
Taxi, Car & Van 388 940 405 50 0 2,122 924 242
Bus & Coach 553 936 161 201 0 258 439 165
Boat 107 102 0 120 0 0 0 15
Underground & Tram 1,124 1,102 1,175 1,272 0 684 661 656
Plane 1,528 22,692 3,435 4,715 0 4,090 2,453 0
Train 28,881 32,623 34,368 28,790 0 26,975 25,156 26,231
Total 32,581 58,395 39,544 35,147 00,000 34,129 29,633 27,309

Table 2: Conversion Factors

Transportation mode Conversion Factor kg CO2e with Radiative Forcing (RF)*
Ferry (average) 0.11287  
Coach 0.02801  
Local bus (average) 0.10097  
Domestic flight (average) 0.15780 0.29832
Short-haul flight (economy) 0.08440 0.15970
Long-haul flight (economy) 0.08610 0.16279
Black cab 0.21420  
Car (average) 0.17753  
National rail 0.04424  
London Underground 0.03760  
Light rail and tram 0.03967  

* Radiative Forcing (RF) is a measure of the additional environmental impact of aviation caused by emitting nitrous oxide and water vapour at high altitude. The Conversion Factors without RF were used for the Carbon Graph so it is still possible to see clear definition in the other modes of transport.

Carbon Graph (2019)