Publication - Statistics

Scottish Greenhouse Gas Statistics 2021

Published: 20 June 2023
From: Chief Statistician
Directorate: Chief Economist Directorate, +1 more … Energy and Climate Change Directorate
Topic: Environment and climate change
ISBN: 9781835210260

Official statistics showing emissions of greenhouse gases in Scotland over the period 1990 to 2021.

Section B. Results – Net Sources of Scottish Greenhouse Gas Emissions

2021 results

Chart 2 presents the net sources and sinks of Scottish Greenhouse Gas Emissions in 2021, grouped by National Communication category.

Chart 2. Scottish Greenhouse Gas Emissions by National Communication category, 2021.

Column chart showing the emissions in MtCO2e, sorted from largest category to smallest. For more detail, see Table 2.

Main points

In 2021, Domestic transport (excluding International Aviation and Shipping) (10.9 MtCO2e) was the largest source of net emissions, followed by Agriculture (7.8 MtCO2e), Business (7.7 MtCO2e), Residential (6.3 MtCO2e) and Energy Supply (4.9 MtCO2e).

Table 2. Scottish Greenhouse Gas Emissions by Gas and by National Communications Category, 2021. Values in MtCO2e
NC category	Carbon Dioxide	Methane	Nitrous Oxide	Fluorinated gases	Total
Agriculture	1.2	4.6	2.0		7.8
Business	6.8	0.0	0.1	0.8	7.7
Energy Supply	4.4	0.4	0.0		4.9
Industrial processes	0.4	0.0	0.0	0.0	0.4
International Aviation & Shipping	0.7	0.0	0.0		0.7
Land use, land use change and forestry	-4.0	3.7	0.7		0.4
Public	0.9	0.0	0.0		0.9
Residential	6.1	0.1	0.0	0.1	6.3
Transport	10.8	0.0	0.1		10.9
Waste Management	0.0	1.4	0.1		1.5
Total net emissions	27.5	10.2	3.0	0.9	41.6

Main points

Carbon dioxide was the main greenhouse gas emitted or removed in most sectors, with the exceptions of the Agriculture and Waste Management sectors.

Methane was the main net gas emitted in the Agriculture (4.6 MtCO2e), followed by nitrous oxide (2.0 MtCO2e) and carbon dioxide (1.2 MtCO2e).
Almost all emissions in the Waste Management sector were emitted in the form of methane (1.2 MtCO2e).

Where F gases are emitted, they have been in relatively small amounts via the Business and Residential sectors.

Key Trends By national communications category.

Chart 3 presents the main sources of Scottish Greenhouse Gas Emissions from 1990 to 2021, broken down by National Communication categories.

Chart 3: Greenhouse Gas Emissions in Scotland, by National Communications category 1990 to 2021.

A series of line charts, one for each NC category. Each chart shows its category's time series in bold with the time series for the other categories also present but faded for comparison.

Main Points

All sectors exhibit a general downwards trend between 1990 and 2021:

Energy Supply emissions have seen the largest decrease in GHG emissions (-16.8 MtCO2e, a reduction of 77.6 per cent) followed by net LULUCF emissions (-5.7 MtCO2e, a reduction of 94.1 per cent), Waste Management (-5.0 MtCO2e, a reduction of 76.2 per cent), and Business (-4.2 MtCO2e, a reduction of 35.3 per cent).

Chart 4 shows how the generation of Scotland’s electricity has changed over time. Emissions from the electricity supply sector (such as power stations) are associated with these changes.

Chart 4. Generation of Electricity by Fuel, Scotland, 2004 to 2021. GWh of Electricity Generated by Year

Line chart with five time series. The time series are Fossil Fuels, Nuclear, Pumped Hydro, Renewables and Other. The largest downward change over the period was with Fossil Fuels, while the largest upward was with Renewables.

Data obtained from Scottish Energy Statistics Hub[5]

Main Points

Overall, the gigawatt-hours of electricity generated in Scotland decreased by 7.0 per cent between 2020 and 2021. Renewables were the single largest source of electricity generated in Scotland in 2021 at 57.0 per cent, followed by nuclear generation at 29.8 per cent with fossil fuel generation making up only 10.9 per cent of total electricity generation.

Long term (1990 to 2021) and short term (2020 to 2021) trends by category

Chart 5 shows how emissions have changed between 1990 and 2021 in all source categories. Chart 6 shows how emissions have changed between 2020 and 2021.

Chart 5. Change in net emissions by National Communication category between 1990 and 2021

Column chart ordered by the size of the change from smallest negative change to largest negative change. All changes are negative. Also shown beneath each bar is the size of the change in absolute and percentage terms. The largest negative change was in Energy.

Chart 6. Change in net emissions by National Communications category between 2020 and 2021.

Column chart ordered by the size of the change from largest positive change to largest negative change. Also shown either above or below each bar is the size of the change in absolute and percentage terms. The largest positive change was in Transport, the largest negative change was in Energy.

Total Emissions

Overall, there has been a 40.3 MtCO2e (49.2 per cent) decrease in net emissions between 1990 and 2021. Total emissions have increased by 1.0 MtCO2e (2.4 per cent) between 2020 and 2021.

Land Use, Land Use Change And Forestry (LULUCF)

LULUCF is a net source of GHG emissions in Scotland in 2021, emitting 0.4 MtCO2e of net emissions. In 1990 net emissions were 6.0 MtCO2e. In the periods 2011-2014, and 2016-2017, LULUCF exhibited net removals of greenhouse gases in Scotland.

Chart 7 below shows, for each sub-sector of the land use sector in 2021, that the net total includes some significant emissions sources, and equally significant ‘sinks’ which remove carbon dioxide from the atmosphere. Forestry and the related ‘harvested wood products’ categories are net sinks of GHG emissions in 2021, removing a net amount of GHG emissions of 7.3 MtCO2e and 1.7 MtCO2e respectively. All other land use types are net sources of greenhouse gas emissions, with croplands, grassland, settlements and wetland showing substantial net emissions to the atmosphere.

Chart 7. Sources and sinks of GHG emissions in Land Use, Land Use Change and Forestry, Scotland, 2021

Column chart, showing for each category the MtCO2e it is a sink and source for. The sink and source columns for each category are separate, with the sink columns being negative and the source columns being positive.

Domestic Transport

Domestic Transport has consistently been a large part of Scotland’s emissions. This sector showed dramatic reduction in emissions associated with the COVID-19 lockdown in 2020 (-2.6 MtCO2e) but have rebounded in the latest year by 1.1 MtCO2e.

Energy Supply

Energy Supply was historically the biggest contribution to emissions, but has seen large changes over the period covered by these statistics, reducing from 21.7 MtCO2e in 1990 to 4.9 MtCO2e in 2021 ( 77.6 per cent reduction). Overall emissions reductions in this sector are mainly due to reductions in emissions from power stations and the complete cessation of coal use for electricity generation in Scotland.

Between 2020 and 2021 Energy Supply emissions decreased by 0.5 MtCO2e (9.2 per cent decrease). This decrease was driven by an decrease in CO2 emissions from power stations. Chart 4 above shows the decrease in fossil fuel use for power generation in 2021.

Chart 8 below shows, for the first time, the contribution of energy from waste (EfW) emissions to total emissions from electricity generation in Scotland. EfW emissions have historically been very low and only reached a notable level from 2019 when these emissions equalled 0.3 MtCO2e. Emissions have stayed at this level since, but we expect future increases in these emissions as more plants, currently under construction, begin operation. In 2021, EfW plants contributed 19 per cent of total emissions from electricity generation.

Chart 8. Electricity generation emissions by fuel source, Scotland, 1990-2021.

Line chart showing two time series, energy from waste, and other electricity generation which represents all other fuel sources. Energy from waste remains smaller than other electricity generation for all years in the time series.

Business

This sector has seen a 4.2 MtCO2e (35.3 per cent) fall in emissions between 1990 and 2021. As shown in Chart 3, much of this decrease occurred between 1990 and 1995 – linked to a decline in emissions from manufacturing and the iron and steel industry over this time period. There was a further smaller reduction between 2008 and 2009 (-1.0 MtCO2e), coinciding with the recession. Between 2020 and 2021 there was a reduction of 0.2 MtCO2e in total emissions from business.

Agriculture

This sector has seen a 0.9 MtCO2e (10.8 per cent) fall in emissions between 1990 and 2021. Between 2020 and 2021 there was a increase of 0.1 MtCO2e (1.9 per cent).

Residential

The residential sector is dominated by direct fuel combustion for home heating in households. There has been a reduction of 21.0 per cent between 1990 and 2021. This long-term decrease is mainly due to a switch from less efficient solid and liquid fuels to natural gas for heating, and improvements in energy efficiency.

Residential emissions increased between 2020 and 2021 from 5.9 MtCO2e to 6.3 MtCO2e (+7.2 per cent). This change in emissions was caused by relatively colder temperatures in January, February and April 2021, resulting in more fuel being used for domestic heating (Chart 9).

Chart 9. Mean air temperature by month, Scotland. 2020 and 2021.

Line chart showing two time series of temperature in Celsius from January to December, one for 2020 and one for 2021. The time series for 2021 is notably lower in January, February, April and May. The two time series are more similar in November and December.

Data obtained from Met Office[6]

International Aviation and shipping (IA&S)

International aviation was affected dramatically during the early part of the COVID-19 restrictions with International shipping affected to a lesser degree. Between 1990 and 2021, international aviation and shipping decreased by 0.6 MtCO2e (47.3 per cent). Between 2020 and 2021 international aviation and shipping emissions decreased by a further 0.1 MtCO2e (15.2 per cent decrease).

Waste Management

Waste management emissions are dominated by methane emissions. Emissions from Waste Management have been relatively static over recent years, with a value of 1.5 MtCO2e for 2021, with no significant change from 2020. However, between 1990 and 2021 emissions reduced by 5.0 MtCO2e (76.2 per cent). This decrease is largely due to the progressive introduction of methane capture and oxidation systems within landfill management.

Public

The main source of emissions from this sector is the use of natural gas for heating public buildings. There was a 1.3 MtCO2e (59.5 per cent) fall in emissions from public sector buildings between 1990 and 2021. Emissions over the last few years have been relatively flat, with a value of 0.9-1.0 MtCO2e between 2014 and 2021.

Industrial Processes

This sector has seen a 1.4 MtCO2e (76.4 per cent) decrease from 1990 to 2021. Values have been relatively stable in recent years, with 2021 having a value of 0.4 MtCO2e. Most of the decrease in the sector happened between 1990 and 1995, and was associated with decreased emissions in the Nitric acid production industry and from a process known as sintering – a process associated with the iron and steel industry.

Emissions by type of gas

Chart 10 shows the trends in emissions, broken down by gas from 1990 to 2021.

Chart 10. Scottish Greenhouse Gas Emissions, by Gas, 1990-2021.

Line chart with 4 time series, for Carbon Dioxide, F-gases, Methane and Nitrous Oxide. Described in more detail below.

Main Points

Carbon dioxide is by far the largest contributor to Scottish greenhouse gas emissions in all years (66.0 per cent of all emissions in 2021) and is the most volatile series of all gases – largely driven by changes in energy supply emissions and to a lesser extent, emissions from the residential and business categories.
Methane is the second most common greenhouse gas in 2021 (24.5 per cent of all net emissions) followed by nitrous oxide (7.2 per cent) and F-gases making up the remainder (2.2 per cent).
Carbon dioxide has seen the largest reduction from 1990 to 2021 (32.1 MtCO2e reduction). There have also been reductions in both methane (7.8 MtCO2e reduction) and nitrous oxide (1.2 MtCO2e reduction). Emissions from fluorinated gases showed a large increase from 1990 to 2013 but have been declining since 2016. Although they still remain small in absolute terms, driven by the introduction of hydrofluourocarbons (HFCs) from 1995 onwards. These HFCs replace chlorofluorocarbons (CFCs) which were banned by the Montreal Protocol due to their impact on the ozone layer.

Charts 11 to 14 present results on individual gases broken down by main sectors over time. Chart 11 shows how carbon dioxide emissions have changed from 1990 to 2021.

Carbon Dioxide (CO2)

Chart 11. Carbon Dioxide ( CO2) Emissions by National Communications Category, 1990 to 2021.

Line chart showing six time series, for Business, Energy, LULUCF, Residential, Transport and Other. Described in more detail below.

Main Points

Chart 11 shows that Energy Supply is a key source of carbon dioxide emissions in all years between 1990 and 2015, after which the change in fuels used in electricity generation substantially reduces CO2 emissions from this source. Change in energy supply emissions is the main driver of changes in total carbon dioxide emissions. Emissions from this category have been volatile, with the highest emissions occurring between 1995 and 2003, and a spike in 2006, related to a greater use of coal in that year.
Transport (excluding international) is the next most common source of carbon dioxide emissions across the entire time-series. In 2015 Transport became the highest source of emissions for the first time in the time series.
Despite revisions to total greenhouse gases for the LULUCF sector, it has become a much greater net CO2 sink for Scotland over the period. In 1990 it emitted 1.4 MtCO2 of net CO2 emissions. From 1995, this sector became a net-CO2 sink, reaching a maximum in 2012 when it acted to sequestrate 4.8 MtCO2. Since that time, this net CO2 sink has been generally reducing to its current (2021) level where it reached net CO2 emissions of -4.0 MtCO2 These trends reflect forestry planting activities in the early 1990s reaching maturity and gradually reducing its potential to remove CO2.

Methane (CH4)

Chart 12. Methane ( CH4) Emissions by National Communications Category 1990 to 2021.

Line chart showing five time series, for Agriculture, Energy, LULUCF, Waste and Other. Described in more detail below.

Main Points

Methane emissions from Waste Management have fallen by 5.0 MtCO2e between 1990 and 2021 (a 77.9 per cent reduction). This is largely due to the progressive introduction of methane capture and oxidation systems within landfill management.
In the Energy Supply sector, methane emissions have fallen by 1.7 MtCO2e between 1990 and 2021 (a 82.1 per cent reduction), partly due to reductions in emissions from sources such as coal mining.
Methane emissions in the Agriculture sector have fallen by 0.8 MtCO2e between 1990 and 2021 (an 14.5 per cent reduction). This is mainly due to a decrease in livestock numbers (particularly cattle and sheep).
Land Use emissions of methane have risen very slightly over the entire time-series.

Nitrous Oxide (N2O)

Chart 13. Nitrous Oxide ( N2O) Emissions by National Communications Category, 1990 to 2021.

Line chart showing three time series, for Agriculture, LULUCF and Other. Described in more detail below.

Main Points

Agriculture is by far the main contributor to emissions of nitrous oxide. These are largely produced by agricultural practices on soils, and to a lesser extent by animal manures. Emissions of nitrous oxide in this sector have fallen by 0.4 MtCO2e between 1990 and 2021 – an 18.4 per cent reduction.
‘Land Use, Land Use Change And Forestry’ fell by 0.3 MtCO2e (31.6 per cent reduction) between 1990 and 2021.

Fluorinated gases (F-gases)

Chart 14. F-gas Emissions by National Communications Category, 1990 to 2021

Line chart showing three time series, for Business, Industrial and Residential. Described in more detail below.