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Learning about GHG Inventories and How to Drive Practices

When it comes to climate change, there is plenty of blame to go around. Finger pointing happens on every level. Politicians blame oil and gas companies. Residents blame politicians and everyone has an opinion on recycling. In reality, the web of complicity is complex and often completely separate from individual choice. Meanwhile, conferences like the UN Climate Change Conference of the Parties – more commonly known as COP26 try to coordinate actions and policies on a global scale.

Since human impact on climate is largely attributed to greenhouse gas (GHG) emissions, it is of utmost importance to understand how to account for these: identifying how, by whom, and where these emissions are produced.

A recent study by the Climate Accountability Institute in the United States found that 20 fossil fuel companies could be linked to one-third of all GHG emissions. To better determine where the other two-thirds of emissions are concentrated, there is an increased focus on the measurement, reporting, and verification of GHGs. In order to explore this topic and learn how to account for emissions, we invited Clarla Mariño Viteri, who works in Germany for the International Council for Local Environmental Initiatives (ICLEI) in the Climate Data Team, to teach us about the development, maintenance, and implementation of GHG inventories. We will share our learnings from her session here.

What is a Greenhouse Gas Inventory?

A GHG inventory considers emissions from five main sectors: stationary, transportation, waste, industrial processes, and agriculture/forestry activities. There are a few miscellaneous activities within cities that fall outside these main categories as well. Each of these sectors are sorted into three scopes of emission:

  • Scope 1 emissions come from inside a city, including agriculture, stationary fuel combustion, industrial processes, waste and wastewater within the city, and transportation within the city.
  • Scope 2 includes all emissions that come from grid-supplied energy.

Scope 3 includes all emissions that occur outside the city but are caused because of the city (for example, waste and wastewater that are exported outside the city boundaries for treatment.)

Class presentation 26/10/21 of Carla Mariño Viteri, recreated by authors

Source: Class presentation 26/10/21 of Carla Mariño Viteri, recreated by authors


In order to complete an inventory, cities must take these steps: first, define the inventory boundaries; second, identify data requirements by asking, ‘What data should be gathered?’; third, identify involved departments; fourth, define processes depending on the data available; and fifth, identify any data gaps and how to solve these, estimating if necessary. Identifying the proper boundaries and data sources are key to ensuring that GHG emissions can be compared year after year.

Class presentation 26/10/21 of Carla Mariño Viteri, recreated by authors

Source: Class presentation 26/10/21 of Carla Mariño Viteri, recreated by authors

There are a variety of reasons these inventories are important – primarily the ability to set targets, create action plans, track performance, and allow data to be aggregated among communities. The Global Protocol for Community-Scale Greenhouse Gas Emissions Inventories is a globally accepted framework that supports urban climate mitigation and establishes emissions baselines. These inventories grew partially out of the Paris Agreement of 2015, leading communities and leaders to account for the emissions they produced. After setting targets, communities around the world needed to be able to translate their respective emissions data to a common framework. Compiling a GHG inventory considers the whole city’s metabolism: giving an overview of the impact of every aspect, from the creation of energy and goods to the end of their lifecycle as they pass through the environment. The complexity of a city becomes apparent when you begin to categorize the emissions and understand the true magnitude of equivalent CO2 emissions.

When GHGs Meet Geopolitics

During the first two weeks of November 2021 at COP26, world leaders established new GHG emissions targets that will shape how urban systems adjust to and measure CO2 emissions moving forward. Some say that the outcome of this important meeting was positive, but it has also been criticized for not going far enough – especially for the countries responsible for most of the emissions. For example, the US and China pledged to boost climate cooperation over the next decade, but have yet to give any concrete plans on how this will be accomplished. Most countries’ pledges that have been made are not specific both in target emissions or goals. It is not clear how each country is going to stop deforestation by 2030, a key promise of COP26. Overall, there is a lack of enforcement and sanctioning of countries that do not meet their self-proclaimed goals. However, this can be positive because countries are encouraged to remain part of such international agreements.

All GHGs (CO2eq) per capita. Source

All GHGs (CO2eq) per capita. Source

It is interesting to examine the politics behind the agreed-upon targets among different nations at COP26.

GHG emissions inventories can help us with this and could lead us to understand how some of the goals were negotiated and why they were targeted first. For example, more than 100 countries agreed to stop deforestation by 2030. Keeping GHG emissions in mind, the decision to halt deforestation is illuminated in a new way. By examining the type of targets set by the GHG inventory, we already have insight into which direction the negotiations might go.


Incremental ‘fixes’  or radical change?

Setting a deadline or limit year (like 2030) can have different climate change implications. For example, an earlier deadline could actually result in higher CO2 emissions, rather than a date further out that gradually reduces emissions. The image below shows these two possibilities. The red line, though a sooner target date, results in higher total CO2 emissions, while the light blue line is a later target but a gradual reduction that could result in significantly less CO2 emissions in total.

Class presentation 26/10/21 of Carla Mariño Viteri, recreated by authors

Source: Class presentation 26/10/21 of Carla Mariño Viteri, recreated by authors

According to new targets set, m the 2020 goals. However, major emitters like China, Russia, and India have not yet signed onto this goal. At the local level, it is crucial for cities aiming at achieving such a national target to be well aware of their direct and indirect emissions. GHG inventories are the key to this process. They help decision-makers determine areas of focus and hold industries accountable for their impact.

When meetings like COP26 happen, national leaders agree to turn their pledges into actions. However, in reality these actions often occur at a city-level, rather than national. This can have significant impacts for cities who are the actors responsible for reducing their emissions and impact. Overall, cities produce more than 60% of the world’s emissions while occupying less than 2% of the land. Based on this fact alone, cities’ GHG emissions have a huge impact on climate change. However, learning about the GHG inventories makes it clear that there are trade-offs when it comes to accuracy and resources spent on measurement. Cities are typically able to measure Scope 1 and Scope 2 emissions easily, but they struggle to find data for Scope 3 which is all emissions that occur outside the city but are caused by the city. For these emissions, estimations are required. To conduct a more accurate accounting would require investing both time and money. However, the data presented at COP26 makes it clear that the world is running out of time. So, the question becomes, is it worth it? Do we need to be so precise when such drastic changes are required?



Activists around the world are demanding more radical change:

‘To stay below the target set in the Paris agreements and thereby minimizing the risk of setting off irreversible chain reactions beyond human control we need immediate drastic annual emissions cuts, unlike anything the world has ever seen.’ – Greta Thunberg

Will cities actually reduce emissions through incremental ‘fixes’ to the existing form of cities? Or do they need to drastically change the way they operate in totality? Does the entire metabolism of a city need to shift to a ‘new normal’ to achieve the goals necessary to reduce GHG emissions? Accounting by way of GHG inventories makes the problem transparent, guiding city leaders and decision-makers. By specifying where emissions are coming from, leaders can identify strategies that address each problem and allow for local solutions. However, this leaves us with more questions than answers. How are we going to operate on our cities to implement reduction measures? And when we do, will this be enough?


Authors: Elena Luongo & Steph O’Connor