Managing the Invisible: Which Greenhouse Gases Should be Measured and Reported in the GPC Inventory?

Greenhouse Gases Measured at GPC

The first step towards achieving "Net Zero" for a city or taking concrete steps in the fight against climate change is to recognize the enemy. Our enemy in this fight is greenhouse gases that heat the atmosphere. But when we say "greenhouse gases", we are not talking about a single gas. The GPC Standard provides a clear chemical framework for cities to manage their emissions in a consistent and transparent way.

But which gases are cities required to measure in a GPC inventory and why are these measurements vital?

Seven of the Kyoto Protocol: Mandatory Gases

The GPC Standard sets the Kyoto Protocol as the reference point for GHG inventories to have global validity. Within this framework, there are seven main greenhouse gases that cities should include in their emission calculations. However, in terms of reporting requirements, these gases are divided into two categories.

1. The Minimum Mandatory "Big Three"

There are three key gases that every city must measure and report on for its inventory to be considered valid:

• Carbon dioxide (_CO2): The most common greenhouse gas. It comes from fossil fuel use (transportation, heating), electricity consumption and waste processes in cities.
• Methane (_CH4): This gas, which has a much higher potential to warm the atmosphere than carbon dioxide, originates mainly from landfills and wastewater treatment plants.
• Nitrous Oxide (_N2O): It is a gas with a high impact on global warming, usually originating from transportation and industrial processes.

2. Industrial Gases (F-Gases)

In addition, if there is significant industrial activity or product use in the city, the following four gas groups need to be accounted for

• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)
• Sulfur Hexafluoride (_SF6)
• Nitrogen Trifluoride (_NF3)

These gases are often produced in cooling systems, electronics manufacturing and heavy industrial processes.

A Common Language:_CO2e(Carbon Dioxide Equivalent)

Different gases (e.g. Methane and Carbon Dioxide) do not cause the same damage to the atmosphere. The GPC therefore requires all these different gases to be reported in a single unit: _CO2e(Carbon Dioxide Equivalent).

This way, the impact of methane is expressed in terms of carbon dioxide and the total "carbon footprint" of the city can be summarized in a single figure. This calculation methodology ensures that the data is consistent and comparable on a global scale.

Why do we measure in such detail?

It is not enough to simply "measure carbon"; knowing which gas is coming from where is key to creating solutions. Here are the main reasons why GPC requires this detailed gas breakdown:

1. Accurate Action Planning: Knowing the source of the emission (e.g. is it landfills from methane or traffic from_CO2?) allows cities to identify mitigation actions that will have the greatest impact.
2. Global Compliance and Financing: Reporting in this internationally recognized framework makes it easier for cities to comply with platforms such as the GCoM and access climate finance.
3. Transparency: By providing a consistent standard of measurement across cities, it allows for transparent tracking of progress.

Ultimately, creating a GPC inventory is a record of a city's chemical relationship with the atmosphere. The more detailed and accurate this record is, the more feasible it is to manage the city's climate future.