Climate change: evidence review of mitigation options in the Transport sector

2 Approach to the evidence review

The study involved a detailed evidence search to better understand the current knowledge base. The evidence search used a three-way approach.

• Systematic literature search,
• Call for evidence,
• Review of current research grant programmes.

Certain areas of interest have already been covered by two recent studies. First, the Department of Energy and Climate Change ( DECC) ^[1] funded co-benefits project (Smith et al., 2017) identified key research areas and relevant literature for a UK (and international) context. This work provided particularly good coverage on health-related co-benefits in the transport sector. Secondly, the Department for Environment, Food and Rural Affairs ( Defra) funded SPLiCE project (2015) summarised evidence on the positive and negative impacts of energy technologies, by conducting a 'review of reviews'. This study, for the Scottish Government, provides an opportunity to consider the role of quantitative models and the implications of co-impacts for social equality in particular detail.

2.1 Literature search and key outcomes

The literature search for the Scottish context study took place from July to August 2016 and covered four sources:

• Scopus (research articles, including articles in press, and books)
• Repec (economics articles and working papers)
• ResearchGate (articles, working papers and conference papers)
• Google Scholar (all of the above)

Relevant grey literature was searched for on the websites of key organisations including the European Environment Agency ( EEA), the International Energy Agency ( IEA), the World Health Organisation ( WHO) and the World Bank. Some further references were added by 'snowballing', i.e. adding important papers referred to by some of the papers reviewed. A particular point of relevance is that there is a large transport research evidence base that is not necessarily framed as co-benefits. For example, there is historic literature on congestion reduction that does not use a co-benefits terminology. Where appropriate, therefore, more focused searches were undertaken to cover these areas.

In total over 300 relevant papers were identified, with over 100 of relevance to the Scottish context. Their bibliographic details were entered into a database. Most papers in the transport literature as it relates to co-benefits were framed in terms of active travel, but a number also considered energy efficiency including electric vehicles.

2.2 Call for evidence and research grant analysis

A call for evidence was directed at key research organisations, identified by: the Scottish Government; from the literature search and other networks from Scotland and the rest of the UK. This resulted in over fifteen submissions with responses from a broad range of organisations. These were added to the evidence database.

A research grant analysis was undertaken to understand current and planned research relevant to the co-benefits agenda within the UK and internationally. Research funding sites reviewed included the Engineering and Physical Sciences Research Council ( EPSRC), the Natural Environment Research Council ( NERC), the Economic and Social Research Council ( ESRC), the Department for Transport ( DfT) and Scottish Government websites. Relevant examples include work funded by the National Institute for Health Research to evaluate the health and wellbeing impacts of major change in the urban environment - the introduction of the M74 motorway in Glasgow and associated urban improvements. The final outputs from the work will be published in July 2017.

2.3 Framework for the report

Climate change mitigation in the transport sector can be framed around a shift / reduce / improve framework ( e.g. Dalkmann and Brannigan, 2007). This approach is used in this study to reflect the broad range of mitigation options available to the Scottish Government.

This captures:

• Shift to lower carbon modes [ Chapter 4]
  • Increased levels of walking and cycling ( i.e. shifting from motorised to non-motorised transport)
  • Increased use of public transport and car clubs ( i.e. shifting from private to public transport)
• Reduction in the need to travel [ Chapter 5]
  • Land use planning
  • ICT - teleworking
  • Demand management
• Improvements in efficiencies [ Chapter 6]
  • Lower carbon transport modes
  • Increased network efficiencies

The above framework is used to set out the literature review findings in Chapters 4 to 6 with an overview of results presented in Chapter 3. Chapter 7 summarises the main co-benefits and adverse side-effects as they relate to air quality, noise and congestion reduction reflecting the relevance of these outcomes across shift / reduce / improve mitigation actions. Chapter 8 presents conclusions and recommendations.