Scottish Greenhouse Gas Statistics 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.

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.

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.

Data obtained from Scottish Energy Statistics Hub^[4]

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.

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.

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.

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).

Data obtained from Met Office^[5]

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.

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)

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 MtCO_2. 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)

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)

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)

Main Points

• F gases are the most potent greenhouse gases with high global warming potentials but they are emitted in very small quantities. As a result, they contribute less to global warming than the other greenhouse gases in Scotland. (For targets these gases use 1995 as a baseline year rather than 1990)
• There is a sharp increase in HFC gases of 0.9 MtCO₂e between 1990 and 2014 (from 0.2 MtCO₂e in 1995 to 1.2 MtCO₂e in 2014), but have since decreased every year from that peak. This change is almost entirely in the Business sector. This increase is because F gases were introduced to replace chlorofluorocarbons (CFCs), which were used in appliances such as industrial air conditioning units. CFCs were banned under the Montreal Protocol, as they were contributing to the depletion of the ozone layer.
• F gas emissions in the residential sector result from the use of aerosols and asthma inhalers, and represent around 0.1 MtCO₂e in 2021.

Table 3. Greenhouse Gas Emissions in Scotland by National Communications Category: 1990 to 2021. Values in MtCO₂e

	1990	2020	2021	1990 - 2021		2020-2021
				Change	% change	Change	% change
Agriculture	8.8	7.7	7.8	-0.9	-10.8%	0.1	1.9%
Business	11.9	8.0	7.7	-4.2	-35.3%	-0.2	-2.8%
Energy Supply	21.7	5.3	4.9	-16.8	-77.6%	-0.5	-9.2%
Industrial processes	1.9	0.4	0.4	-1.4	-76.4%	0.0	6.2%
International Aviation & Shipping	1.3	0.8	0.7	-0.6	-47.3%	-0.1	-15.2%
Land use, land use change and forestry	6.0	0.3	0.4	-5.7	-94.1%	0.0	12.3%
Public	2.3	0.9	0.9	-1.3	-59.5%	0.0	4.7%
Residential	8.0	5.9	6.3	-1.7	-21.0%	0.4	7.2%
Transport	13.6	9.9	10.9	-2.6	-19.3%	1.1	10.7%
Waste Management	6.5	1.5	1.5	-5.0	-76.2%	0.1	5.1%
Net Emissions	81.9	40.6	41.6	-40.3	-49.2%	1.0	2.4%

(some early years omitted to fit table on page, full table available in the accompanying excel tables file)

Table 4. Scottish Greenhouse Gases, by gas, 1990 to 2021. Values in MtCO₂e

Pollutant	1990	2020	2021	1990 - 2021		2020-2021
				Change	% change	Change	% change
CO2	59.6	26.5	27.5	-32.1	-53.9%	1.0	3.7%
CH4	18.0	10.1	10.2	-7.8	-43.2%	0.1	0.6%
N2O	4.2	3.0	3.0	-1.2	-28.3%	0.0	-0.3%
F-gases	0.2	1.0	0.9	0.8	456.5%	-0.1	-6.4%
HFC	0.0	0.9	0.8	0.8	27086.8%	-0.1	-6.6%
NF3	0.0	0.0	0.0	0.0	339.0%	0.0	0.0%
PFC	0.1	0.1	0.1	-0.1	-57.8%	0.0	-4.9%
SF6	0.0	0.0	0.0	0.0	2.6%	0.0	-3.7%
Net emissions	81.9	40.6	41.6	-40.3	-49.2%	1.0	2.4%

(some early years omitted to fit table on page, full table available in the accompanying excel tables file)

Table 5. Detailed breakdown of transport emissions (domestic and international) 2019 to 2021: Values in MtCO₂e.

Transport mode	2019	2020	2021
Cars	5.7	4.2	4.7
Light_duty_trucks	1.7	1.5	1.8
Heavy_duty_trucks_and_buses	2.2	1.9	2.2
Railways	0.2	0.1	0.1
Domestic_aviation	0.4	0.2	0.2
Aviation_Bunkers	1.5	0.5	0.4
Domestic Shipping & Fishing	2.0	1.8	1.7
International shipping	0.4	0.3	0.3
Other	0.3	0.2	0.2
Total emissions	14.4	10.7	11.6

(some early years omitted to fit table on page, full table available in the accompanying excel tables file)

Table 6. Breakdown of Land Use, Land Use Change and Forestry ( LULUCF) Emissions. Values in MtCO₂e.

LULUCF category	1990	2020	2021
Cropland	6.3	4.8	4.7
Sink	0.0	0.0	0.0
Source	6.3	4.8	4.8
Forestry	-5.2	-7.4	-7.3
Sink	-5.6	-7.8	-7.6
Source	0.4	0.4	0.4
Grassland	3.0	1.9	1.9
Sink	-1.8	-1.2	-1.2
Source	4.9	3.1	3.1
Harvested Wood Products	-0.7	-1.6	-1.7
Sink	-0.7	-1.6	-1.7
Indirect N2O emissions	0.1	0.1	0.1
Source	0.1	0.1	0.1
Settlement	1.5	1.4	1.4
Source	1.5	1.4	1.4
Wetland	1.0	1.2	1.2
Sink	-1.4	-1.4	-1.4
Source	2.4	2.6	2.6
Net LULUCF Emissions	6.0	0.3	0.4

(some early years omitted to fit table on page, full table available in the accompanying excel tables file)

Table 7. Electricity generation emissions. Values in MtCO₂e.

Generation type	1990	2019	2020	2021
Energy from waste (EfW)	0.0	0.3	0.3	0.3
Other electricity generation	14.7	1.7	1.4	1.3
Total emissions	14.7	2.0	1.7	1.6

(some early years omitted to fit table on page, full table available in the accompanying excel tables file)