Scottish consumer-based emissions (1998 to 2009):
Methodology
Kate Scott and John Barrett, University of Leeds
21.03.2012
Contents
1
Introduction ................................................................................................................................... 2
2
Changes to previous methodology ................................................................................................ 2
3
Methodology and data (1998 to 2009) .......................................................................................... 3
3.1
Scottish consumption expenditure ....................................................................................... 4
3.2
Greenhouse gas emission intensities by product .................................................................. 4
3.3
Scottish consumer-based emissions...................................................................................... 5
4
Method standardisation................................................................................................................. 5
5
2013 revisions ................................................................................................................................ 6
References .............................................................................................................................................. 7
2
1
Introduction
Greenhouse gas (GHG) emissions can be allocated to a country in different ways: territorial-based,
production-based and consumption-based emission reporting. Territorial-based emissions, as
reported by the UK to the UNFCCC, sums emissions released within the UK territory and shows
progress made by individual countries in reducing greenhouse gas emissions. However, emissions
from international aviation and shipping are excluded due to issues of allocation. A productionbased account, as reported by the UK to Eurostat, sums emissions released from UK economic
activities reported in the System of National Accounts. Aviation and shipping are included and
typically allocated to countries based on the operator of the vessel. Consumption-based emissions
allocate emissions to the consumers in each country, usually based on final consumption
expenditure reported in National Accounts. Emissions embodied in imports are included in the
account, and emissions embodied in exports are excluded (these are assigned to the country that
purchases the final products). Consumption-based emissions are currently not reported officially by
any country, but they are increasingly estimated by researchers (for example see reviews by
Wiedmann et al., 2007; Wiedmann, 2009).
There is a marked difference in end results depending on the chosen system. Evidence at the UK
level demonstrates that emissions growth from consumption is outpacing emission reductions from
production efficiency gains (Wiedmann et al, 2008). Therefore from a territorial or production
perspective gains in efficiency by UK industry show a reduction in UK emissions, in contrast to a
consumer perspective where increasing levels of consumption result in increased emissions (Barrett
et al., 2011).
The provision of goods and services to meet Scottish demand is a driving force for greenhouse gas
emissions not only within its boundary but elsewhere in the world. Every good and service
purchased has a supply-chain impact associated with it (i.e. the sum of emissions released at every
stage in the production supply chain). Products may have been produced within the UK or produced
abroad and imported to Scotland; or parts of the supply chain may have occurred both in the UK and
elsewhere.
This report accompanies the Scottish consumer-based emissions account for 1998 - 2009 provided
by the University of Leeds. It documents (1) the change in methodology from the previous Scottish
consumer-based emissions account for 1990 to 2006 (2) the updated methodology and data
employed, (3) a standardised method for future annual updates to Scotland’s consumer-based
emissions accounts and (4) anticipated revisions to the next (2013) update.
2
Changes to previous methodology
A time series (1992 to 2006) of Scotland’s greenhouse gas consumer emissions account was carried
out by the Stockholm Environment Institute in October 2009. The methodology and results are
available from http://www.scotland.gov.uk/Publications/2009/10/28101012/0. The method has
been revised due to the recent availability of Scottish supply and use tables for 1998 to 2007. Trial
3
data from the Scottish National Accounts Project (SNAP)1 are used for 2008 and 2009. Supply and
use tables show the expenditure patterns of all consumers in Scotland within one consistent data
set. Previously household consumption was estimated from a combination of data sources: the UK
Expenditure and Food Survey from the Office of National Statistics, the Regional Travel Survey from
the Department for Transport and regional energy consumption data from the Department for
Energy and Climate Change. Other final demand categories, largely government and capital
investment, were proportioned from UK input-output tables by Scottish population.
The results for 1998 to 2006 from both time series are shown in Figure 1. Whilst the results are
compatible for most years, emissions from capital investment are now estimated to be
approximately three to six times higher. Some differences exist within household emissions;
however, the change in data sources and the aggregation of results by different product categories
mean it is difficult to make a direct comparison. Emissions from government remain similar.
Figure 1: Comparison of results
There is a break in the updated series from 2003 to 2004 that is explained primarily by the
application of a more sophisticated methodology from 2004 (shown by the dotted line). Before 2004
only bilateral trade links with the UK/Scotland are considered and imported products are assumed to
be made with the technology of the country from which they are imported. From 2004 trade is fully
incorporated into a global model which means that product efficiencies reflect the technology of
every country along the supply chain (i.e., the emissions embedded in third-country imports of our
trade partners are considered fully).
3
Methodology and data (1998 to 2009)
Two data sets are combined to calculate emissions from Scottish consumers: Scottish consumption
expenditure from Scottish National Accounts and product emission intensities from the UK
environmentally-extended multi-region input-output model (UK-MRIO).
1
Described in the next section
4
3.1 Scottish consumption expenditure
Expenditure by eight categories of final consumers on 126 products is available from the Combined
Use section of Scottish Supply and Use Tables2 in purchasers’ prices (in £million)3. The categories of
final consumers are:








Households
Non-profit institutions serving households (NPISHs)
Non-resident household expenditure in Scotland
Central government
Local government
Gross fixed capital formation (GFCF)
Valuables
Change in Inventories
126 products are classified according to Standard Industrial Classification (SIC). However, the
product intensities described in the next section are available only at 123 sectors; therefore 3
sectors have been aggregated4. Expenditure includes consumption of products imported to Scotland.
Supply and use tables are available for Scotland for 1998 to 2007. Therefore, additional data sources
were examined to estimate consumer expenditure for 2008 and 2009. The Scottish National
Accounts Project (SNAP)5 provides more recent economic statistics in Scotland (up to and including
2010), building on supply and use data estimates of income, expenditure and other relevant
economic indicators. This is in its trial stage; however, they are constructed in a completely
comparable manner to that used in constructing the supply and use tables6 and are unlikely to be
revised substantially going forward. As with any other economic statistic, estimates are always liable
to revisions. SNAP publishes consumer expenditure by consumer category7 for 2008 and 20098,
disaggregated by 12 high-level consumption products. As a check, total expenditures from 2007
SNAP data were compared to 2007 combined use data and are the same. However, products are
classified according to COICOP (Classification of Individual Consumption According to Purpose), not
SIC. Therefore, for 2008 and 2009 the total level of consumer expenditure by category was used, and
it was assumed the composition of spend (i.e. expenditure on 123 product groups) was the same as
2007. It is anticipated this will be improved and revised with the release of updated supply and use
tables in the next annual update (refer to section 5).
3.2 Greenhouse gas emission intensities by product
Product intensities (kt CO2eq. per £million) representing the full supply chain impact of products
purchased in the UK are calculated using a UK-MRIO model, as compiled for Defra. The method is
documented in Wiedmann et al. (2008). Products are classified by SIC which represent aggregated
groups of goods and services final consumers purchase. The model has been updated and now
2
http://www.scotland.gov.uk/Topics/Statistics/Browse/Economy/Input-Output
Retail and wholesale trade are the only sectors presented in basic prices
4
Sectors 2, 3 and 18
5
http://www.scotland.gov.uk/Topics/Statistics/Browse/Economy/SNAP
6
http://www.scotland.gov.uk/Topics/Statistics/Browse/Economy/SNAP/SNAPQNA1
7
GFCF, Valuables and Changes in Inventories are aggregated into one category, therefore results are shown by
6 final consumers
8
The totals for 2007 are the same as the totals in the 2007 Combined Use table
3
5
includes years 2007 – 2009 (this is used in Wiedmann and Barrett, 2011). The product intensity sums
the intensity (or efficiency) of the production process in the country of origin for each part of the
supply chain to produce the final product. These are expressed using purchasers’ prices to align with
the consumer expenditure data.
3.3 Scottish consumer-based emissions
Consumer expenditure is multiplied by product intensities to provide emissions from consumption at
the product, consumer and national level. Additional to the energy embodied in the goods and
services people consume is the emissions released directly from energy used by households to heat
homes and run private transport (e.g. gas boilers and petrol). Direct greenhouse gas emission
estimates for the domestic sector from Scottish Environmental Accounts (available for 1998 to
2006)9 and UK regional environmental statistics (available for 2007 to 2009)10 are added to the
consumer account to calculate the full consumer-based emission account for Scotland.
4
Method standardisation
Four further future annual updates have been confirmed. To ensure a consistent time series, data
sources and methods will remain the same. If revisions are made to the data or method, the time
series of results will be revised and the source of changes documented. The structure of updates is
as follows:
1. Final consumption expenditure by category and product group is extracted from the
Combined Use table from Scottish Supply and Use tables (in £ million, purchasers prices).
This includes expenditure on imported products.
2. 123 product intensities are extracted from the UK-MRIO model produced at the University
of Leeds (in purchasers’ prices). These represent the average supply chain intensity of
products consumed in the UK.
3. Consumer expenditure is multiplied by product intensities to provide emissions from
consumption at the product, consumer and national level.
4. Direct emissions from the domestic sector are added to the emissions account.
5. Where data is unavailable, additional data sources should be examined and used as
appropriate.
6. A summary of the data and methods used, and any revisions made will be documented. This
may simply state the same method used previously was employed and the updated year(s)
data sources.
9
http://www.scotland.gov.uk/Topics/Statistics/Browse/Economy/SNAP/expstats/EnvironmentalAccounts
http://www.decc.gov.uk/en/content/cms/statistics/local_auth/co2_las/co2_las.aspx
10
6
5
2013 revisions
2008 and 2009 Scottish Supply and Use tables are due to be released in October 2012. This will
provide more accurate expenditure data and will overcome the assumption that the composition of
consumer spending was the same in 2008 and 2009 as 2007. Expenditure patterns for these years
will be revised.
SIC (2003) used in the 2007 tables has been updated to SIC (2007) which has re-defined the
classification of sectors to reflect the changing nature of the economy to an increasingly servicebased one. The forthcoming release of Supply and Use tables will be in the new allocation system.
The number of manufacturing sectors represented is fewer (they have been aggregated) and the
number of service sectors has increased (they have been disaggregated). Additionally, the allocation
of spend between sectors has been revised. One classification system will be chosen for all years.
7
References
Barrett, J., Le Quéré, C., Lenzen, M., Peters, G., Roelich, K., and Wiedmann, T. (2011) Response to the
Energy and Climate Change Committee Consultation on Consumption-based Emission Reporting,
UKERC, London, UK.
Wiedmann, T. and Barrett, J. (2010) A Greenhouse Gas Footprint Analysis of UK Central Government,
1990-2008; Report to the UK Department for Environment, Food and Rural Affairs by the Centre for
Sustainability Accounting. Defra, London, UK.
Wiedmann, T., Wood, R., Minx, J.C., Lenzen, M., Guan, D. and Harris, R. (2010): A carbon footprint
time series of the uk – results from a multi region input–output model, Economic Systems Research,
22:1, 19-42.
Wiedmann, T., 2009. A review of recent multi-region input-output models used for consumptionbased emissions and resource accounting. Ecological Economics 69, 211-222.
Wiedmann, T., Wood, R., Lenzen, M., Minx, J., Guan, D. and Barrett, J. (2008) Development of an
Embedded Carbon Emissions Indicator - Producing a Time Series of Input-Output Tables and
Embedded Carbon Dioxide Emissions for the UK by Using a MRIO Data Optimisation System. Final
Report to the Department for Environment, Food and Rural Affairs by Stockholm Environment
Institute at the University of York and Centre for Integrated Sustainability Analysis at the University
of Sydney. EV02033, June 2008. Defra, London, UK. http://randd.defra.gov.uk.
Wiedmann, T., Lenzen, M., Turner, K., Barrett, J., 2007. Examining the Global Environmental Impact
of Regional Consumption Activities - Part 2: Review of input-output models for the assessment of
environmental impacts embodied in trade. Ecological Economics 61, 15-26.