Rio de Janeiro is a leader among the Brazilian cities aggressively promoting low-carbon development. In 2011, the city passed a landmark climate change law  with a target to reduce greenhouse gas (GHG) emissions 8% below the business-as-usual (BAU) emissions scenario by 2012, 16% by 2016, and 20% by 2020.
Now Rio is conducting a GHG inventory for 2012, the first target year under its climate change law. The inventory will measure the city’s emissions against its 8% reduction target for 2012, and assess the effectiveness of GHG mitigation actions implemented so far. On July 2, the city government of Rio invited me and my colleagues from the Greater London Authority  and the Federal University of Rio de Janeiro  (COPPE) to a seminar  to share our experiences in conducting GHG inventories and to discuss Rio’s 2012 inventory. At the seminar, Nelson Moreira Franco, Director for Climate Change Management and Sustainable Development for the City of Rio, stressed that GHG inventories help identify emission sources and provide scientific evidence on GHG levels, so it is extremely important that the city gets it right. To me, the seminar covered four important items:
1. Use of the Global Protocol for Community-Scale Greenhouse Gas Emissions (GPC)
Rio’s last GHG inventory was completed in 2011 using 2005 data, before the 2012 release of the [GPC Pilot Version 1.0](C:\Users\WeeKean.Fong\Desktop\GPC Pilot Version 1.0). Therefore, the 2011 inventory was not fully consistent with the GPC framework. The GPC is a newly developed international standard to standardize the accounting and reporting of city-scale GHG inventories. Rio plans to conduct the 2012 inventory based on the GPC to ensure international compatibility. Rio recently joined the GPC pilot project , which provides a forum for over 30 cities around the world to share experiences and best practices on how to measure GHG emissions based on the GPC.
2. The Need for Methodological and Data Consistency
A consistent methodology to account and report GHG inventories ensures consistent tracking of emissions over time. Since Rio will report its 2012 inventory according to the GPC, it is essential to re-calculate the base-year inventory (2005 inventory) and BAU emission scenario to ensure consistency. Michael Doust from the Greater London Authority stressed that inventory reports must use transparent methodologies, data, and assumptions in order to meaningfully compare inventory results and allow possible future re-calculations.
3. Performance Tracking and Data Granularity
Besides presenting current emissions data, Rio’s inventory report should analyze the individual factors affecting the city’s emission profile, including the effects of each mitigation measure on its overall GHG emissions (such as the new sanitary landfill and bus-rapid-transit  project). In addition, the inventory should have detailed data breakdown to make it more actionable and help the city design more specific mitigation measures. For instance, road transport data could be divided into public and private vehicles, different modes (motorcycles, cars, vans, etc.), different fuel types, and even different routes in order to identify specific emissions sources and design measures to reduce them.
4. Trans-boundary Emissions
The city of Rio is interconnected with its surrounding regions. For instance, consumption of electricity from the regional electricity grid, car trips across metropolitan boundaries, and transfer of solid waste from the city to landfills in outlying areas all point to a close relationship between the urban core and its periphery. As specified in the GPC, Rio should take into account these trans-boundary GHG emissions.
Rio is committed to completing its 2012 GHG inventory before the end of 2013. This inventory will tell whether the city has achieved its 2012 target and is on track to achieve its 20% emissions reduction target by 2020. The city has taken an important first step in adopting the GPC. Going forward, besides the above points, the inventory team should pay attention to avoid double counting between in-boundary and trans-boundary emissions, conduct more detail analysis of transport sector emissions, and be transparent if there are any exclusions of emission sources. WRI’s GHG Protocol  team provided technical advice  for Rio’s 2005 base-year inventory, and looks forward to our continued partnership with Rio, now utilizing the GPC, in support of the city’s 2020 target.