Annex F: Scottish Trends in Greenhouse Gas Emissions, 1990-2003
Under the requirements of the UNFCC, the National Environmental Technology Centre (Netcen) compiles GHG inventories for the UK for submission to the UNFCCC. In addition to the national, separate disaggregated inventories 70 of greenhouse gas emissions are also presented for England, Scotland, Wales and Northern Ireland and are consistent with the UKGHG Inventory. The latest disaggregated inventory provides estimates of sectoral GHG emissions for 2003, and revises the estimates for emissions in the years 1990 to 2002. It was published in September 2005.
The Netcen report contains GHG emissions estimates for all the countries of the UK during the period 1990-2003. As well as providing estimates for each of the six greenhouse gases individually ( CO 2, CH4, N 2O, HFCs, PFCs, and SF6), the net impact of all six GHGs is combined to give an overall impact (measured in 'tonnes of carbon equivalent'). Netcen allocates emissions to over eighty types of activity, grouped into nine sectors. Some emissions are not estimated. In particular in accordance with IPCC guidance, emissions from international travel by air are not included in the inventories.
In addition to emissions, Netcen also estimates the amount of CO 2 removed through forestry growth (the carbon sink). The net emissions take account of these removals. The table summarises the changes in net emissions for the countries of the UK.
Net greenhouse gas emissions by country ( MtC)
( MtC = Millions of tonnes of carbon)
UK figures include an 'unallocated' component which is not factored into individual country's totals. The 'unallocated' component includes some emissions from energy industries and domestic aviation emissions among others. If a portion of these emissions is allocated to each country on a per capita basis, the reduction in net GHG emissions in Scotland between 1990 and 2003 becomes 13%.
Scottish greenhouse gas emissions by sector
The table overleaf summarises the breakdown of Scottish GHG emissions by major sectors. Unallocated emissions are not included in the Scottish figures. The sector categories used from the inventory are known as National Communication ( NC) format.
The sectoral breakdown provides information on the source of greenhouse gas emissions. Emissions from the energy supply sector relate to emissions resulting from generation of electricity and oil refining, which in turn supply power to end users such as the business and transport sectors. As a result, changes in these direct emissions for particular sectors may be the result of switches between type of fuel used by that sector rather than changes in energy consumption. For example if 1,000 households change from using electricity to gas, the direct emissions attributable to those households will rise - though overall emissions might fall if the energy supply sector were able to reduce their emissions by generating less electricity.
During 2003, the energy supply sector contributed 37% of Scottish emissions (excluding removals). With 17% of emissions the transport sector was the second biggest contributor. Agriculture, business and the residential sectors all contributed 11-12% of emissions each.
Between 1990 and 2003 the major areas of Scottish emissions growth were in the energy supply (+0.20 MtC) and the transport sectors (+0.18 MtC). The biggest fall in emissions was seen in the business sector, which contributed almost half of the net fall since 1990 (-1.15 MtC).
There were also significant percentage reductions in the industrial processes, public and waste management sectors (down 72%, 48% and 51% respectively). However, in absolute terms these impacts were more limited and direct emissions from each of these sectors now contributes less that 2% of total Scottish emissions.
Greenhouse gas emissions in Scotland and the UK by sector ( NC format)
% change 1990-2003
% of Scottish total emissions
Scotland as a % of UK
Land use change
Land use change
Across the UK, the biggest contributor to the fall in emissions was the energy supply sector (down by 11.4 MtC), a result of the increased commissioning and utilisation of combined cycle gas turbines over the period that exhibit higher generation efficiencies than conventional thermal plant, closely followed by the industrial processes sector (-10.6 MtC). Combined, these two sectors accounted for 80% of the decline in UK net emissions since 1990.
Scottish emissions by type of greenhouse gas
The table below shows changes in net emissions by type of greenhouse gas for Scotland and the UK, weighted by Global Warming Potential ( GWP). In 2003, 81% of net GHG emissions were as CO 2. As noted earlier Scottish forestry made a positive impact by acting as a 'carbon sink', reducing net CO 2 emissions. In total the growth of forestry bio-mass during 2003 reduced net CO 2 emissions by over 15%.
Greenhouse gas emissions in Scotland and the UK by type of greenhouse gas
% change 1990- 2003
% of Scottish total emisions
Scotland as a % of UK
change 1990- 2003
Removals ( CO 2)
Net CO 2 Emissions
Removals ( CO 2)
Net CO 2 Emissions
Nitrous oxide (N 2O) and methane ( CH4) also made a noticeable contribution to Scottish emissions, with respectively 8% and 7% of emissions (excluding removals) in 2003. The biggest cause of methane emissions was enteric fermentation amongst farm animals. Over 80% of nitrous oxide emissions were due to agriculture, predominately from manure and man made fertilisers. Combined, the remaining three greenhouse gases ( HFCs, PFCs and SF6) contributed less than 2% to net GHG emissions in Scotland.
CO 2 emissions accounted for the largest part of the fall in GHG emissions between 1990 and 2003 (-1.23 MtC equating to an 8% reduction). Taking account of removals, net CO 2 emissions in Scotland fell by 12% (compared with 6% in the UK). There were greater percentage reductions in emissions of methane (-35%) and nitrous oxide (-16%); accounting for falls of -0.64 MtC and -0.27 MtC respectively. 75% of the fall in methane emissions was due to reductions from waste management and underground mines. Most of the growth in emissions of HFCs and SF6 took place prior to 1998; between 2002 and 2003 HFCs increased by less than 5% while there was a small drop in emissions of SF6.
Methodological changes in Netcen estimates since the 2002 GHG inventory
Since last year's publication of the 2002 GHG inventory, there have been a number of methodological improvements in the way Netcen estimates GHG emissions. This has significantly altered our understanding of both the absolute level of GHG emissions and the rate of change in emissions over recent years.
In absolute terms the biggest change has been in the estimates of CO 2 emissions from Scottish soils, with the latest Netcen report more than halving their estimated impact (a reduction equivalent to almost 1 MtC per year). However, Netcen have also revised downwards their historic estimates, which has partially offset the impact relative to 1990. Industrial emissions (within the business sector) have also been revised down significantly since the publication of last year's 1990-2002 inventory.
The other key adjustment since last year is the inclusion of changes in forestry bio-mass. Forestry acts as a 'carbon sink', absorbing GHG emissions out of the atmosphere, and since 1990 the amount of carbon held within Scottish forests has grown considerable.
The 1990-2002 Netcen GHG inventory estimated that GHG emissions in Scotland had decreased by 5.5% since 1990. Due to the above changes in methodology and the inclusion of forest bio-mass, Netcen now estimates that net emissions have fallen by 14.0% between 1990 and 2003. In addition, to complement the various point-estimates reported and reflecting scientific uncertainty, Netcen also offers approximate 95% confidence intervals for its figures. Currently, these are given as around +/- 23% for total for Scottish GHG emissions. Further details on the methodology used and associated uncertainties are provided in the inventory and associated appendices.
It is also important to note that figures reported under the Kyoto Protocol follow specified estimation and reporting methodologies that comply with IPCC guidance but which may differ from other results due to variation in how sectors are defined and in geographical coverage. Hence, for example, aviation emissions are not assigned to Scotland. Equally, the use of road fuel sales, whilst giving consistent wide-area estimates, can misrepresent local emissions attributable to road transport if fuel is bought in one location but utilised elsewhere. As fuel costs have been lower in mainland Europe and Ireland than the UK, this methodology has resulted in some of the emissions from fuel consumed in the UK not being allocated to the UK and, conversely, being added to regions selling the fuel. Comparisons undertaken by Netcen in the latest disaggregated inventory indicate that this discrepancy has increased since 1990.