The Carbon Account for Transport (CAT) is published annually, and presents a detailed analysis of already published transport emissions data for Scotland. This is the eleventh edition of the CAT, and includes a detailed analysis of the latest emissions data (1990-2017), published by the National Atmospheric Emissions Inventory in June 2019.
1.1 Purpose of the Carbon Account for Transport
Reducing carbon emissions from transport has been a consistent strategic outcome of Scotland's National Transport Strategy, and the 2006 National Transport Strategy included a commitment to publish an annual carbon balance sheet for transport. This commitment is met by the CAT.
The CAT provides updates on the following information:
- Scotland's annual transport emissions from 1990 to 2017;
- emissions efficiency estimates across different modes of transport;
- emissions efficiency of road vehicles registered in Scotland;
- comparison of Scotland's emissions to those of the UK as a whole;
- key leading transport emissions indicators.
Each of the above monitors progress towards reducing transport emissions and supports the development of future policies to meet the statutory emissions reduction targets. However, the CAT is not a decision making tool. Its purpose is to present data and analysis for the consideration of future transport options.
1.2 Policy context
Earlier this year, the First Minister acknowledged that Scotland – like the rest of the world – faces a Climate Emergency and confirmed that the Scottish Government would accept the recommendations of the UK Committee on Climate Change to set a target of net zero greenhouse gas emissions by 2045 with interim reduction targets of 70% by 2030 and 90% by 2040. The Scottish Government has committed to updating the Climate Change Plan within six months of the Climate Change Bill receiving Royal Assent so that it reflects the more ambitious targets being established.
The factors affecting transport emissions are numerous and complex. Transport is a derived demand and there is a strong correlation to economic and population growth as well as land use decisions. The largest share of transport emissions comes from cars, which are the dominant mode of transport in Scotland. There is a particular challenge associated with reducing car emissions as a result of an increasing trend in single occupancy car trips.
The transition to zero emission vehicles will reduce carbon emissions significantly. We have already set out a bold ambition to phase out the need for new petrol and diesel cars and vans by 2032. This year's Programme for Government builds on this commitment to work with public bodies, the automotive sector and Scotland's innovation community to phase out the need for all new petrol and diesel vehicles in Scotland's public sector fleet by 2030.
In order to create successful places in the future means addressing more than just carbon emissions, it also means considering the combined effects of continued car dependency leading to more urban sprawl, inactive lifestyles and congestion. Our National Transport Strategy (NTS2), which is currently out for public consultation, recognises that we need to manage the demand for transport to help create great places for our future.
To do this we will embed the Sustainable Travel Hierarchy in decision making, promoting walking, wheeling, cycling, public transport and shared transport options in preference to single occupancy private car use. At the national level the Sustainable Investment Hierarchy will be used to inform budgetary decisions. This will consider investment aimed at reducing the need to travel unsustainably in the first instance.
This Government is strongly committed to investing in active travel and last year we doubled our annual investment in cycling and walking from £40 million to £80 million. That increased investment will continue, and is currently enabling 11 large-scale projects across Scotland.
Buses provide an essential service to millions of Scots, accounting for almost three quarters of all public transport journeys. In this year's Programme for Government we have committed to bringing forward transformational long term funding for bus of over half a billion pounds to reduce the impacts of congestion on bus services and encourage more people to make sustainable multi-modal journeys. The investment will take the form of a Bus Partnership Fund for local authorities and the roll out of infrastructure for the trunk road network to prioritise high occupancy vehicles, such as buses.
Emissions from aviation cannot be ignored and Scotland has shown global leadership by being the first country to include international aviation and shipping emissions in its statutory climate targets. Our ownership of Highlands and Islands Airports Ltd (HIAL) creates a unique opportunity for Scotland to create the world's first zero emission aviation region and to support the trialling and introduction of low or zero emission planes operating between airports across the Highlands and Islands, with the first such trials taking place in 2021. We will lead the charge to zero emission aviation with work to decarbonise all scheduled flights between airports within Scotland by 2040.
1.3 Background data and sources
All historical emissions data presented in this report were originally published in Greenhouse Gas Inventories for England, Wales, Scotland and Northern Ireland: 1990-2017 by the National Atmospheric Emissions Inventory. Data from other sources, such as Scottish Transport Statistics, are also presented in the report.
Each year, greenhouse gas inventories are updated to reflect improvements in the methodology used to estimate emissions, which often results in revisions to the entire time series. As such, the data in this report should not be compared to data published in previous editions of the CAT. A number of minor methodological changes have been made in this year's inventory, most notably the revision of several factors used in the calculation of maritime emissions. As a result, historical emissions estimates have generally seen a slight increase compared to previous estimates, with a more substantial revision to the 2016 figures.
Emissions from international aviation and shipping (IAS) were not originally reported in the inventory, but have been included since 2009 under a separate category called Exports. The Scottish Government has committed to including emissions from IAS in emissions targets, hence references to maritime and aviation emissions refer to the combined total of domestic and international emissions, unless otherwise stated.
In line with the methodology used to report against the Climate Change (Scotland) Act, emissions from transport only include those at the point of use, also known as tailpipe emissions. Lifestyle and displaced emissions, such as emissions from generating the electricity to power electric trains, are not included.
1.4 Measurement of greenhouse gas emissions
The emissions inventory reports emissions of carbon dioxide (CO2), methane, nitrous oxide, and the four F-gases (hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride, and nitrogen trifluoride). Overall emissions are given as a single figure, measured in megatonnes or kilotonnes of carbon dioxide equivalent (MtCO2e or KtCO2e), by weighting non-carbon dioxide gases by their global warming potential (GWP). The GWP of a greenhouse gas is defined as its warming influence relative to that of carbon dioxide over a 100 year period. For example, the global warming potential of methane over 100 years is 21, meaning that each tonne of methane emitted causes the same level of warming over 100 years as 21 tonnes of CO2. Approximately 99% of equivalent emissions in Scotland's transport sector are due to CO2, therefore a breakdown of emissions by greenhouse gas is not included in this report.
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