Scottish Greenhouse Gas Statistics 2022

Why are some greenhouse gas emissions not considered in this statistics release?

The methods used to compile the Scottish Greenhouse Gas Inventory are consistent with international reporting and are therefore comparable to the greenhouse gas emission estimates reported by all other EU Member States and other Annex 1 parties[1] to the UNFCCC. All countries estimate and submit their greenhouse gas inventory estimates to be consistent with methods set out in international guidance for national inventory methods from the Intergovernmental Panel on Climate Change (IPCC), known as the IPCC (2006) guidelines.  The IPCC (2006) guidelines state that national inventories should report on all anthropogenic (human) emissions and removals of greenhouse gas emissions, as a result of human activities within a country’s territorial sphere.

However, there are some emissions and removals of carbon dioxide that occur as a result of short-cycle biogenic processes.  This biocarbon has only recently been abstracted from the atmosphere before it is then re-released as carbon dioxide. In accordance with the IPCC (2006) guidelines, these emissions and sinks are therefore excluded from the greenhouse gas inventory, as they could lead to double counting. If countries do choose to estimate these biocarbon emissions, they are reported outside of the national inventory total, as a memo item to that country’s submission to the UNFCCC.  This means that some sources and sinks of greenhouse gases are not included in the Scottish and UK inventory totals.

Examples of reasons for why some sources and sinks of greenhouse gases are not included in the greenhouse gas inventory

1. Due to short-cycle biocarbon (carbon only been recently abstracted from the atmosphere)

• Carbon dioxide (CO2) emissions from biomass combustion.   For example, this includes CO2 emissions from biomass power stations
• Process emissions in food and drink production.  These include CO2 emissions from brewing, fermenting and malting and in the production of food.
• CO2 emissions from biodegradable waste to landfill.   Emissions are not estimated where they arise from biogenic sources of waste such as food.  Fossil-derived organic matter (such as plastic) is assumed to be non-biodegradable and there are no emissions associated with its decomposition.

However, methane (CH4) emissions from biodegradable waste sent to landfill are considered in these greenhouse gas statistics as they are formed by the anaerobic (oxygen-free) decay of organic matter in solid waste disposal sites.

2. Where there has been no anthropogenic influence

• Natural accumulation and storage of carbon in peatland.  For emissions or removals of peatland to be considered for IPCC reporting, they require humans to alter the peatland – either through wetland drainage, rewetting, peatland extraction or through another land use change.  The UK and Scotland has elected to include the IPCC (2006) Wetlands Supplement as part of their inventory reporting from the 1990-2019 vintage of the inventory:  http://www.ipcc-nggip.iges.or.jp/home/wetlands.html

3.  Beyond the territorial definitions as prescribed by the IPCC (2006) reporting requirements

• “Blue carbon”.  Blue carbon refers to the carbon captured by the world's oceans and coastal ecosystems. The carbon captured by living organisms in oceans is stored in the form of biomass and sediments from mangroves, salt marshes and seagrasses.  However, it should be noted that research in underway to being to develop estimates of the environmental changes resulting from changes to coastal wetlands environments.

 

Glossary

Adjusted emissions

See GHG Account

Afforestation

The act or process of establishing a forest on land that has not been forested in recent history.

Baseline Period

Emissions reduction is based on a Baseline Period.  For the greenhouse gases CO2, CH4 and N2O, 1990 was specified as the baseline.  1995 is the baseline for emissions of the F-gases.

Carbon dioxide (CO2)

Carbon dioxide is one of the main gases responsible for climate change.  It is mostly emitted through the oxidation of carbon in fossil fuels, e.g.  burning coal.

Carbon sink

A carbon sink is a natural or artificial reservoir that accumulates and stores CO2 for an indefinite period.

Climate change

Climate change is a long-term change in the earth’s climate. This can be accelerated by human activity, e.g. by releasing CO2 into the atmosphere.

Deforestation

The removal of forest stands by cutting and burning to provide land for agricultural purposes, residential or industrial building sites, roads, etc., or the harvesting of trees for building materials or fuel.

Fluorinated gases (F-gases)

F-gases are the generic name given to HFCs, PFCs, SF6 and NF3.  These have been used as replacements for CFCs, which are ozone depleting substances that have been banned under the Montreal Protocol.  They have very high global warming potentials.

Greenhouse effect

The greenhouse effect is the process by which heat from the sun is trapped within the Earth’s atmosphere by greenhouse gases.  This process is also known as radiative forcing.

GHG Account

The Climate Change Committee (CCC) recommended a new method of adjusting emissions for the purposes of reporting against targets in this, and future, publications. This adjustment acts to remove the impact of revisions to the historical time-series.  This is known as the GHG Account and the calculation in detailed in section C.

Greenhouse gas

A greenhouse gas is a gas which absorbs infrared radiation emitted from the surface of the Earth, helping to retain a portion of that energy in the atmosphere as heat. 

Global warming potential (GWP)

GWP is a measure of how much a greenhouse gas is estimated to contribute to global warming.  It is a relative scale which compares the potency of each gas to CO2.  

Hydrofluorocarbons (HFCs)

HFCs are produced commercially as a substitute for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs).  HFCs are largely used in refrigeration and insulating foam.  Their Global Warming Potentials range from 4 to 12,400 times that of CO2, depending on the gas type.

Inventory

The inventory contains greenhouse gas emissions estimates for Scotland and the UK.  The Inventory is a disaggregation of the UK Inventory, which is based on five major sectors: energy, industrial processes, agriculture, land-use, land-use change and forestry, and waste.

IPCC

The Intergovernmental Panel on Climate Change (IPCC) assesses the scientific, technical and socio-economic information relevant for the understanding of the risk of human-induced climate change.  They provide advice to the UNFCCC on the scientific evidence and developments which are used to inform National Inventories.

LULUCF

Estimates of emissions and removals from land use, land use change and forestry (LULUCF) depend critically on assumptions made on the rate of loss or gain of carbon in Scotland’s carbon rich soils.  In Scotland, LULUCF activities, taken as a whole, acts as a slight source in recent years although acted as a net sink between 2009-2017, absorbing more greenhouse gas emissions than it releases.

Methane (CH4)

Methane is a greenhouse gas that is around 28 times more potent in the atmosphere than CO2 over a 100-year time horizon.  Main sources include agriculture and landfill.

National Communication (NC) Sectors

The UK NC sectors are agreed groupings of the more detailed sectors reported to the United Nations Framework Convention on Climate Change by the UK.  This report no longer uses NC sectors.

Nitrogen trifluoride (NF3)

Nitrogen trifluoride is a greenhouse gas that is around 16,100 times more potent in the atmosphere than CO2 over a 100-year time horizon.  The main source of nitrogen trifluoride is in the making of semiconductors.

Nitrous oxide (N2O)

Nitrous oxide is a greenhouse gas that is around 265 times more potent in the atmosphere than CO2 over a 100-year time horizon.  The main source is agricultural soil.

Other Petroleum Gas (OPG)

This consists mainly of ethane plus some other hydrocarbons, excluding butane and propane.

Perfluorocarbons (PFCs)

PFCs are a by-product of aluminium smelting.  They are also the replacement for CFCs in manufacturing semiconductors.  The Global Warming Potentials of PFCs ranges from 6,630 – 11,100 times that of CO2 over a 100-year time horizon.

Radiative forcing

An externally imposed perturbation in the radiative energy budget of the Earth's atmosphere. Such a perturbation can be brought about by changes in the concentrations of radiatively active species (e.g.  greenhouse gases), changes in the solar irradiance incident upon the planet, or other changes that affect the radiative energy absorbed by the surface (e.g.  changes in surface reflection properties). 

Sequestration

The process by which carbon sinks remove carbon dioxide (CO2) from the atmosphere.

Source (UNFCCC definition)

Any process or activity which releases a greenhouse gas or a precursor greenhouse gas to the atmosphere.

Sulphur hexafluoride (SF6)

It is largely used in heavy industry to insulate high-voltage equipment and to assist in the manufacturing of cable-cooling systems.  Its global warming potential is 23,500 times that of CO2 over a 100-year time horizon.

UNFCCC

In 1992, the UNFCCC was adopted as the basis for a global response to climate change.  The ultimate objective of the Convention is to stabilise greenhouse gas concentrations in the atmosphere at a level that will prevent dangerous human interference with the climate system.

 

Acknowledgements

We would like to thank our contractors, Ricardo, in consortium with Aether, Rothamsted Research and the Centre for Ecology & Hydrology for their invaluable support in compiling and improving the Scottish greenhouse gas inventory every year. Links to the Devolved Administrations inventories for each year can be found here: Devolved Administrations - Greenhouse Gas Reports - NAEI, UK (beis.gov.uk)