This is part V of a blog series - A Primer on 2006 IPCC Guidelines for Emission Inventories. 

Introduction

GHG emissions from agriculture, forestry and other land use(AFOLU) activities are poorly known, notably so for recent years. This is a fundamental gap, including the lack of an international reporting on AFOLU emissions figures at regular intervals. This poses a problem identifying the necessary interventions needed today and in coming decades for reducing the threat of climate change on the planet and the role that could be played by appropriate climate change actions. Climate action in agriculture, forestry and other land use are of significant interest to many countries, where AFOLU(Agriculture, Forestry and Other Land Use) activities represent a large portion of national economies and are particularly at risk under climate change. Hence regular updates of AFOLU emission estimates matter greatly for both scientific research and policy reasons. GHG emissions are estimated from official national activity data and geospatial analyses, applying international standard methodologies of the Intergovernmental Panel on Climate Change (IPCC) to ensure consistency with GHG Inventory processes established under the climate convention. The IPCC guidelines provide a methodological guidance for preparing annual greenhouse gas inventories for the AFOLU sector. With four main sub-sectors in consideration, the key greenhouse gases of interest are carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4).

Livestock

Livestock includes animals such as cattle, pigs, mules, asses, camels, swine, sheep, goats etc raised by humans for food and agricultural purposes. Livestock is one of the predominant sources of anthropogenic CH4 emissions from the AFOLU sector as animals produce methane (CH4) as a part of their normal digestive process. Hence livestock can be a significant source of greenhouse gas emissions and as greenhouse gas emissions from human activities increase. The 2006 IPCC guidelines provides methodological guidance for determining emissions from livestock which includes CH4 emissions from enteric fermentation and manure management system, direct and indirect N2O emissions from manure management system. 

CH4 emissions from enteric fermentation are estimated for major ruminant animal types, e.g., dairy cows, other cattle, poultry, sheep, swine and other livestock (buffalo, goats, llamas, alpacas, camels, etc). Enteric fermentation occurs as a direct result of a ruminant digestive process in which the food passes through the digestive tracts and ferments, which is then broken down into simple molecules to be absorbed by the animals. CH4 is produced as a by-product of enteric fermentation where ruminant animals are the major sources but non-ruminant animals also emit CH4.

Manure Management System (MMS) mainly involves practices in collection, treatment, storage, and application of manure to soils that can not only improve yields, but can also have other co-benefits, such as reducing nitrate and phosphorus (P) leaching, as well as reducing ammonia (NH3) volatilization, nitrous oxide  (N2O) and methane(CH4) emissions. Methane (CH4) is produced from the decomposition of manure under aerobic conditions and N2O is produced under aerobic or mixed(aerobic/anaerobic) conditions. In MMS, CH4 emissions can be affected by the amount of manure produced from livestock and manure that decomposes anaerobically. The temperature and the time required for the decomposition of manure in various MMS also affects the amount of CH4 produced. When manure is handled as a solid or when it is deposited on pastures and rangelands, it tends to decompose under more aerobic conditions and less CH4 is produced. The manure management system includes the following types: 

1. Anaerobic lagoons
2. Liquid systems
3. Daily spread
4. Solid storage
5. Dry-lot
6. Pasture/range/paddock
7. Other miscellaneous systems.

CH4 is produced from the decomposition of manure under aerobic conditions and N2O is produced under aerobic or mixed(aerobic/anaerobic) conditions.

Land

Trees absorb CO2 from the atmosphere and they store some of this carbon as perennial aboveground and belowground biomass throughout their lifetime. Depending on how the soil is managed and other environmental factors, dead organic matter in the soil acts as carbon pools storing some of the carbon from trees. This process where carbon is stored in dead organic matter and soils is called biological carbon sequestration. Since biological sequestration absorbs CO2 from the atmosphere and stores CO2 in these carbon pools,  it is also known as carbon sinks.

Emissions or sequestration of CO2, as well as emissions of CH4 and N2O, can occur from management of lands in their current use or as lands are converted to other land uses. Carbon dioxide is exchanged between the atmosphere and the trees and soils on land, for example, as cropland is converted into grassland, as lands are cultivated for crops, or as forests grow.

The revised 2006 IPCC guidelines is intended to improve consistency and completeness in the estimation and reporting of greenhouse gas emissions and removals. The six land-use categories in the 2006 IPCC Guidelines are: 

1. Forest Land
2. Cropland
3. Grassland
4. Wetlands
5. Settlements
6. Other Land

Each land category is further subdivided into land remaining in that category (e.g. Forest land remaining Forest Land) and land converted to another land between all land types (e.g. Forest Land converted to Cropland). The 2006 IPCC Guidelines for National Greenhouse Gas Inventories recommends reporting fluxes as per changes within each land category and conversions between all land types. The term “flux” is used to describe the exchange of CO2 to and from the atmosphere, with net flux of CO2 being either positive or negative depending on the overall balance.

Aggregate sources and non CO2 emission sources on land

This final category provides a description of the generic methodologies to be adopted for the inventory of nitrous oxide(N2O) emissions from managed soils, C stock change associated with harvested wood products and CH4 emissions from rice cultivation.

The inventory of nitrous oxide(N2O) emissions from managed soils, includes direct and indirect N2O emissions from additions of Nitrogen to land due to deposition and leaching, and emissions of carbon dioxide(CO2) following additions of liming materials and urea-containing fertiliser. Methods are provided to estimate total anthropogenic emissions of N2O(direct and indirect) from managed soils. N2O is produced naturally in soils through the processes of nitrification and denitrification. Nitrification is the process of aerobic oxidation of ammonium(NH4+) to nitrate(NO3-), and denitrification is the anaerobic reduction of nitrate(NO3-) to nitrogen gas(N2). N2O is a gaseous intermediate that is produced during the denitrification process and a by-product of the nitrification process that leaks from microbial cells into the soil and ultimately into the atmosphere.

Furthermore 2006 IPCC guidelines outlines the method to estimate carbon stock change associated with harvested wood products The section provides guidance on how to estimate and report the contribution of these harvested wood products(HWP) to annual AFOLU CO2 emissions/ removals. HWP include fuelwood, sawn timber for housing, particle board, furniture, etc. HWP constitutes a carbon reservoir since carbon is stored in HWP for extended periods of time, this storage time needs to be taken into account. The time carbon is held in products will vary depending on the product and its uses. For example, fuelwood may be burned in the year of harvest; many types of paper are likely to have a use life of less than 5 years and sawnwood used in buildings may be held for decades to over 100 years. Estimates of carbon release from HWP are presented in order to indicate clearly the role annual carbon release from HWP plays in the overall AFOLU system of carbon removals and release.

The goal is to compile national-level statistics for each category and develop a national level classification system applicable to all the three categories in the AFOLU sector according to 2006 IPCC guidelines. The objective is to estimate total greenhouse gas emissions and removals at the appropriate tier level in support of key category analysis. Our aim is to compile data into reporting tables, document and archive all information needed to create an inventory, including activity data, emission factors, documentation of the data sources, descriptions of the procedures, as well as the outcomes for each source category.

Cover Photo by B Udaykiran on Unsplash