Scottish greenhouse gas emissions 2017

Section A. Introduction to Greenhouse Gases

Purpose of this Publication

The "Scottish Greenhouse Gas Emissions 2017" Official Statistics publication contains the results of the Scottish Greenhouse Gas Inventory for 1990-2017. The Scottish Greenhouse Gas Inventory is the key data source for understanding the origins and magnitudes of the emissions. The inventory is compiled in line with international guidance from the Intergovernmental Panel on Climate Change (IPCC). Data are reported by source sector (such as energy supply) and by greenhouse gas (such as carbon dioxide). The inventory is also used to report data against targets as required under the Climate Change (Scotland) Act 2009.

Using the Statistics. Which measure to use and when?

The official statistics publication "Scottish Greenhouse Gas Emissions 2017" includes data on two categorisations of greenhouse gas emissions.

• Estimated net source emissions. These are sometimes referred to as "territorial" emissions, as they are produced within a country's territory or economic sphere. Section B contains results using this categorisation.
• Estimated net source emissions which have been adjusted to take account of trading in the EU Emissions Trading System (EU ETS). Section C contains results using this categorisation.

The publication does not contain information on consumption-based emission estimates. This refers to greenhouse gas emissions which are associated with the spending of Scottish residents on goods and services, wherever in the world these emissions arise together with emissions directly generated by Scottish households, through private heating and motoring. This information was most recently published in December 2018 for the years 1998 to 2015 as part as part of the Official Statistics publication: "Scotland's Carbon Footprint 1998-2015". Section E contains information on what territorial emissions are excluded from the greenhouse gas inventory.

The table below shows how to use the different categorisations of statistics on greenhouse gas emissions.

	Estimated Source Emissions (Section B)	Estimated Source Emissions Adjusted to take into account of EU Emissions Trading System (Section C)
Adjusted for EU Emissions Trading System	x	√
Used for reporting progress against Scotland's Climate Change Targets 1	x	√
Can be compared with EU countries – note that comparable data for 1990-2017 will not be available for the time of this release	√	x
Can be compared with UK 2	√	x
Includes International Aviation and Shipping	√	√
Includes North Sea Oil & Gas	x	x
Data on individual greenhouse gases	√	x
Data on Scottish Government source sectors	√	√
Base Year	1990	Baseline Period (Variable)

¹ Further information on Scotland's Climate Change Targets can be found in Section C.

² Direct comparisons between Scotland and the UK can be made by adding up the results for the four Devolved Administrations separately. The UK figure in this case would exclude offshore emissions.

Which greenhouse gases are reported on and how do they contribute to global warming?

The basket of greenhouse gases consists of carbon dioxide, methane, nitrous oxide, and the four F-gases (hydrofluorocarbons- HFCs, perfluorocarbons – PFCs, sulphur hexafluoride- SF₆ and nitrogen trifluoride- NF₃). These gases are weighted by Global Warming Potential (GWP), so that total greenhouse gas emissions can be reported on a consistent basis. The GWP for each gas is defined as its warming influence relative to that of carbon dioxide over a 100 year period. Greenhouse gas emissions are then presented in carbon dioxide equivalent (CO₂e) units. In the case of some of the F-gases, the global warming potential is listed as being within a range of values, due to the gases existing as a variety of isotopes with differing GWPs.

Table A1. List of Greenhouse Gases and their contribution to Scotland's net greenhouse gas emissions, 2017

Name of Greenhouse Gas	Chemical Formula	Global Warming Potential (GWP) (Conversion factor to carbon dioxide equivalent) 1	Contribution to Scotland's Net Greenhouse Gas Emissions in 2017 (in MtCO2e)	Percentage of Scotland's Net Greenhouse Gas Emissions in 2017 (in MtCO2e)	Examples sources of gas
Carbon dioxide	CO2	1	29.6	73.0%	All other sources of greenhouse gases, including removals (carbon sinks)
Methane	CH4	25	6.4	15.8%	Waste management, enteric fermentation and animal waste
Nitrous oxide	N2O	298	3.2	7.9%	Agricultural soils
F-gases 2			1.3	3.3%	Industrial air conditioning, refridgeration, use as tracer gases, semiconductors
Hydrofluorocarbons	HFC	12 - 14,800	1.1	2.8%
Perfluorocarbons	PFC	7,390 - 17,340	0.1	0.4%
Sulphur hexafluoride	SF6	22,800	0.0	0.1%
Nitrogen trifluoride	NF3	17,200	0.0	0.0%
Total Net Greenhouse Gases			40.5	100.0%

The Global Warming Potentials (GWPs) are based on international reporting standards, as set by the Intergovernmental Panel on Climate Change (IPCC)^[2].

Section B contains further data on the individual greenhouse gases. Section D contains a more detailed discussion of the causes and impacts of revisions between the 1990-2016 and 1990-2017 inventories.

Reporting of the Baseline Period and 1990

In this publication, a single 1990 Base Year is used for all estimated source emissions (Section B). This year is referred to as "1990" in charts, tables and text.

A different baseline is used for the reporting progress against Scotland's Climate Change Targets, using the emissions adjusted for trading in the EU Emissions Trading System (EU ETS). This is referred to as "Baseline Period" when referring to changes over time in the charts, tables and text.

The Baseline Period for reporting against Climate Change Targets is:

• 1990 for carbon dioxide carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O)
• 1995 for Fluorinated gases (F gases)^[3]: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF₆), nitrogen trifluoride (NF₃)

Within this publication, data are estimated for the Baseline Period; and the years 1990, 1995 and 1998 to 2017.

What are net emissions and carbon sinks?

The emissions reported are the combination of emissions minus removals from the atmosphere by carbon sinks. Carbon sinks are incorporated within the three sectors of agriculture and related land use, development, and forestry, which include both emissions and removals resulting from afforestation, reforestation, deforestation and forest management together with changes in land use. These are known as "removals" as they offset emissions.

Sectors

This publication provides the latest estimates of Scotland's greenhouse gas emissions by source from 1990-2017. For the purposes of reporting, greenhouse gas emissions are allocated into sectors as follows:

Energy supply - Emissions from fuel combustion for electricity and other energy production sources, and fugitive emissions from fuels (such as from mining or onshore oil and gas extraction activities). North Sea oil & gas emissions are not allocated to Scotland^[4].

Business and industrial processes - Emissions from industry and from those in combustion in industrial/commercial sectors, industrial off-road machinery, process sources from decarbonisation of raw materials (such as from limestone use in cement plants) and refrigeration and air conditioning.

Transport (including International Aviation and Shipping) - Emissions from domestic aviation, road transport, railways, domestic navigation, fishing and aircraft support vehicles. It also includes international aviation and shipping emissions attributed to Scotland.

Public Sector Buildings - Emissions from combustion of fuel in public sector buildings.

Residential - Emissions from fuel combustion for heating/cooling and garden machinery and fluorinated gases released from aerosols/metered dose inhalers.

Agriculture and Related Land Use - Net emissions from cropland, grassland along with net emissions from land converted to cropland and grassland. It also covers emissions from livestock, agricultural soils, stationary combustion sources and off-road machinery.

Development - Net emissions from settlements and from land converted to settlements. This should not be confused with, for example, residential emissions; these relate to conversion of different land types to developed land, and changes in N₂O and CO₂ stocks from soils, urban trees.

Forestry - Changes in net emissions relating mainly to stock changes, resulting from afforestation, deforestation and harvested wood products.

Waste management - Emissions from waste disposed of to landfill sites, waste incineration, and the treatment of waste water.

When emissions are reported by source, emissions are attributed to the sector that emits them directly. These high-level sectors are made up of a number of more detailed sectors, which follow the definitions set out by the Intergovernmental Panel on Climate Change (IPCC), and which are used in international reporting tables which are submitted to the United Nations Framework Convention on Climate Change (UNFCCC) every year. Section E contains a more detailed mapping of what is included in each source. It also contains information on which greenhouse gas emissions are excluded from the greenhouse gas inventory and why they are excluded.

The sector breakdowns in this report are primarily based on the National Communication (NC) sectors, which are used in the UK Greenhouse Gas Inventory.

However, in order to associate emissions from conversion of grassland to and from cropland, and liming of agricultural land with other agricultural activities, we have made the following changes to the grouping of the Land Use, Land Use Change and Forestry (LULUCF) and Agriculture sectors in the NC classifications.

Firstly, we have created an Agriculture and Related Land Use sector, which includes all emissions in the NC sector Agriculture together with those LULUCF emissions associated with agricultural practices, such as croplands and grasslands. The remaining LULUCF emissions are grouped into a Forestry sector (changes in emissions relating mainly to stock changes resulting from afforestation, deforestation and harvested wood products) and a Development sector (changes in emissions resulting from land use change to settlements).

These sector definitions were aligned with those that were reported in the Scottish Government publication "Low Carbon Scotland - Meeting the Emissions Reductions Targets 2013-2027". The sector definitions used in the Scottish Government's Climate Change Plan publication published last year differ slightly and consideration will be given to the reporting structure of future Scottish Greenhouse Gas Emissions publications to correspond with legislative and user needs.

The Scottish Government also reports on International Aviation and Shipping emissions attributed to Scotland, along with other Transport emissions. International Aviation and Shipping emissions are categorised as an IPCC international "Memo" item. A detailed mapping between the sectors used in this report and the NC sectors and Intergovernmental Panel on Climate Change (IPCC) sectors is given in Section E.