The UN greenhouse gas inventory follows the principles of the Greenhouse Gas Protocol developed by the World Resources Institute and the World Business Council for Sustainable Development and is compatible with ISO 14064. The Greenhouse Gas Protocol has been modified to suit the specific needs of participating UN entities. The results of the latest greenhouse gas inventory can be seen here.
The October 2007 decision of the Chief Executives Board (CEB) limits the boundary of the UN greenhouse gas inventory to emissions from facility operations and travel that can be influenced by management-level decisions. These include emission categories associated with the purchase or generation of electricity and heat (such as steam), use of refrigerants (for air-conditioning and refrigeration) and air, sea and ground transportation.
The inventory includes the six greenhouse gases (GHG) originally covered by the Kyoto Protocol: CO2, CH4, N2O, HFCs, PFCs and SF6. Additionally, the UN also logs the emissions of other GHGs not covered by the Kyoto Protocol, namely hydrochlorofluorocarbons (HCFCs) that are governed by the Montreal Protocol and are reported under the ‘Optional Emissions’ category. GHG emissions are reported separately for each greenhouse gas both in terms of their mass, and as an aggregate using the common comparable unit of carbon dioxide equivalents (CO2eq), using the global warming potential (GWP) of each substance.
The common minimum boundary excludes several sources of greenhouse gas emissions that could result from UN activities. Recommended best practice is to voluntarily document all sources of emissions not included in the minimum boundary under an additional category called Optional Emissions. These include:
Estimation and reporting of the emissions is done through the following tools:
The substantive inputs for developing the system were provided by the Sustainable United Nations (SUN) team, and software development was led by DFS. The air travel emissions calculator is a proprietary product of ICAO.
Over the past years improvements have been made to the data collection systems, for example:
The changes made to data collection and reporting tools as well as the development and updating of proxy methodologies have made data reporting easier. It is expected that this will facilitate a larger coverage of offices and facilities in the future. The number of participating entities has grown over time and new organisations and Focal Points have joined the project. Future efforts will focus on replacing or upgrading the existing reporting system wiht a more versatile system and improving the reporting depth (i.e. inclusion of additional offices) among participating organisations and data quality.
Responding to the magnitude and significance of emissions from air travel and transportation used for official travel, a decision was taken by the EMG to make reporting mandatory, despite this being optional under the Greenhouse Gas Protocol. In accordance with international guidance of the protocol, emissions from the combustion of biomass or bio-fuels in equipment and vehicles are reported as an information item only. Similar guidance exists for Ozone Depleting Substances controlled by the Montreal Protocol such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), which are mostly used as refrigerants. However, due to their significant presence in UN facilities they have been included under the Optional Emissions category. It has also been decided to make the reporting of CFCs and HCFCs mandatory in the future. While recognising the significance of non-CO2 effects of aviation no provision was made for their estimation or incorporation - pending more clarity and internationally accepted guidance on this issue.
Aspects of the methodologies used initially have been simplified over time in recognition of internal capacity and resource limitations. It is accepted that in some circumstances this affects the accuracy of the inventory. Such changes were made in Refrigerants, Purchased Steam and Vehicles (mobile sources). Where data was not readily available, estimates were based on clearly defined assumptions and proxies. A review of the methodologies, data and process is undertaken annually and the IMG is actively involved in this process. More rigorous methods and procedures will be introduced, based on feedback, as resources allow.
A few agencies have prepared Inventory Management Plans (IMPs) and others are expected to follow suit. An IMP is an internal document that records the details of each inventory and helps to institutionalize the process for preparing a high quality inventory. Efforts will also be made to develop a quality assurance and control (QA&QC) programme for the inventory, including external verification.
The use of a common methodology and the development of proxy methodologies for issues identified as major data gaps have helped to improve the comparability of the inventory across agencies and between years. However, detailed analysis is needed to interpret the trends. The difference in the size, nature and operations of agencies, changes in coverage of offices across years, changes in methodologies, scope and underlying databases of the emissions calculator means that comparisons cannot be accurately made unless detailed analysis is done.
From reporting year 2009 the process and methodology have not changed much and are therefore comparable up to a point. It is more difficult to compare this data with that of 2008. After 2008, changes were made to the methodologies for Purchased Steam, Purchased Electricity and Refrigerants. In addition, there have been rearrangements and changes in the contents of the emission categories. In 2008, total reported emissions included Optional Emissions (inclusive of Biomass-related emissions). From 2009 total emissions no longer include Optional Emissions, which are reported separately. Biomass-related emissions are excluded from the Optional Emissions and are being reported as an information item only. Another important difference is that in 2008, the emissions from Refrigerants included CFC’s and HCFC’s, whereas since 2009 these are reported under Optional Emissions.
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