Measuring our impacts

Establishing a base-line of greenhouse gas emissions is the first step in manaing and reducing these emissions. Greenhouse gas emission inventories allow institutions to identify the main sources of emission and to take action to reduce them whilst achieving efficiency gains.

Many UN agencies collected data on their greenhouse gas emissions for the first time in 2008, though some have been preparing inventories since 2004.

In 2009 the first coordinated approach to a UN-wide greenhouse gas emission inventory with a common methodology was implemented. The use of a common boundary and methodology ensured that data was aggregated and allows comparisons across all UN system organizations.

This exercise was difficult but successful, and resulted in baseline greenhouse gas inventories that are crucial for moving towards climate neutrality. As this was the first time most organizations had prepared a greenhouse gas inventory, data gaps, estimates and the use of proxies could not be avoided. However, the exercise was a useful learning experience, which will improve practices and make data collection more efficient and easier in the future.

UN system methodology and tools

The calculation of greenhouse gas emissions is based on the Greenhouse Gas Protocol of the World Resources Institute (WRI) and World Business Council on Sustainable Development (WBCSD), which is compatible with the ISO 14’064 standard for greenhouse gas accounting. It is the most widely used international accounting tool for government and business leaders to understand, quantify, and manage greenhouse gas emissions and draws upon internationally recognized methodologies for calculating greenhouse gas emissions from buildings and transport. The goal is to provide a credible and transparent approach to quantifying and reporting greenhouse gas emissions reductions.

UN Greenhouse Gas Calculator

The 2009 UN Greenhouse Gas Calculator estimated greenhouse gas emissions resulting from building-related emissions and travel by road and rail. It provided the methodology and suggested emission factors for calculating greenhouse gas emissions from official vehicles, buses, trains, taxis, self-generated power, refrigerants, purchased heat and steam, and electricity. The calculator was developed, programmed and designed by the United Nations Department of Field Support/Information and Communications Technology Division (DFS/ICTD) with input from the WRI, which provided emission factors and internationally recognized methodologies. Staff from over a dozen organizations across the UN system also made contributions and have pooled their expertise, skills and knowhow in the service of the organization as a whole.

The tool was specially designed for UN agencies, funds and programmes to facilitate the preparation of their baseline greenhouse gas emission inventories. It aimed to ensure that the inventories of the UN organizations were consistent, comparable with one another, transparent and based on the best available information sources.

The UN Greenhouse Gas Calculator methodology was explained in detail in its user manual. The calculator and the user guide provided step-by-step instructions on how to prepare an inventory according to the common boundary agreed by the UN system for its greenhouse gas emission accounting. After the required activity data were entered into the tool, the greenhouse gas footprint was automatically estimated by applying a set of default emission factors, allowing flexibility to enter more specific data where available.

International Civil Aviation Organization (ICAO) Aviation Carbon Emissions Calculator

The International Civil Aviation Organization (ICAO), one of the UN system organizations, developed a methodology for calculating the carbon dioxide emissions from official air travel. A tool for calculating emissions is available on the ICAO website together with a description of the methodology underpinning the Calculator. The UN system organizations chose to use this tool for estimating emissions from air travel, as there can be significant differences in emissions for the same trip travelled via different routings. A special interface to the ICAO tool was developed by the ICAO secretariat for specific use by the UN system organizations, to facilitate the aggregation of travel data. This tool complemented the UN Greenhouse Gas Calculator. The methodology applied the best publicly available industry data to account for various factors such as aircraft types, route specific data, passenger load factors and cargo carried. The methodology makes a distinction between cabin class factors “economy” and “premium”, and weights these with a ratio of 1:2.

Non-CO2 emissions from air travel

The full climate impact of air travel goes beyond the effect of CO2 emissions alone. For example, aircraft emit nitrogen oxides (NOx), which tend to increase the level of ozone and reduce the level of methane, both of which are greenhouse gases. Aircraft also contribute to water condensation in the atmosphere, which has a warming effect. There is still considerable scientific uncertainty about the scale and dynamics of these effects.

The Special Report on Aviation and the Global Atmosphere, prepared by the Intergovernmental Panel on Climate Change (IPCC) in 1999, estimated the overall climate impact of aviation to be between two to four times larger than that of the CO2 emissions alone. It used a Radiative Forcing Index (RFI) in these estimates. The RFI for aircraft in 1992 was estimated to be 2.7 with aviation’s total contribution to radiative forcing being approximately 3.5 %.

More recent data in the 2007 IPCC Fourth Assessment Report suggests an RFI of 1.9 for aircraft in 2005 and aviation’s contribution being at 3 %. Although reference to the RFI is made, the report states that the RFI should not be used as an emission metric since it does not account for the different residence times of different forcing agents. Other metrics such as Global Warming Potential (GWP) and Global Temperature Potential (GTP) could be considered as alternatives. However, to date, the IPCC has not provided further guidance on these issues, but work is underway in the Fifth Assessment Report.

In its decision on how to consider the effect of non-CO2 gases, in the EMG, the UN system organizations weighed up various factors, including scientific uncertainty, risk to reputation, the need to follow the precautionary approach, the need to maintain high environmental standards, and legal and budgetary considerations. A collective decision was taken, on a provisional basis and until further guidance is provided by the IPCC, in keeping with the current WRI/WBCSD methodology, only to take into account the effects of CO2 from air travel.

The ICAO and UNEP secretariats were also requested to convene a meeting of experts who will be identified based on, inter alia, recommendations of the IPCC. The meeting will aim to provide further guidance as a matter of priority on the question of an appropriate metric to account for all greenhouse gas effects from aviation, while waiting for additional guidance from the IPCC. Preparations are underway to convene this meeting in 2010.

The decision to account provisionally only for CO2 emissions has resulted in some UN organizations describing their current approach as carbon neutral (as opposed to climate neutral), but the goal of reaching climate neutrality remains in place.

Alternative reporting format

An alternative reporting format was made available to UN agencies that had already concluded their greenhouse gas emission inventory for 2008 before the inventory tools were available or where other means of compiling the inventory had been used. If methods other than that agreed by the WRI/WBCSD were used, the assumptions had to be explained in the individual organization’s inventory management plan. Information on emissions for each of the Kyoto Protocol gases, kilometers travelled, number of trips and kWh electricity used etc. was to be entered in this pre-formatted Excel spreadsheet. Data submitted in this alternative format was treated in the same way as data submitted in the UN greenhouse gas Calculator inventory tool.

Results

You can see the results of the 2008 inventory process here and for the 2009 process here.

Next steps

In 2011 UN organizations are compiling the latest generation of greenhouse gas inventories.