If you’ve reached this far and are left wondering “What does 'Scope’ mean?” and “What is t-CO2eq?” we’ve selected a few FAQs for your reference per below.

Q1. What does the unit “t-CO2eq” measure？

A.It is a standard unit used to express the impact of different greenhouse gases other than CO2 and convert them into CO2’s equivalent amount. 
Each gas has different global warming potential, but by using one standardized unit (t-CO2eq), it allows for a simplified comparison.

Q2. What is “Scope”？（Scope 1・2・3）

A.GHG emissions are classified into 3 categories, or scopes, depending on the source of the emissions.
・Scope1：direct emissions by the organizer（fuel use, etc.）
・Scope2：indirect emissions from purchased energy, such as electricity, by the organizer
・Scope3：indirect emissions from miscellaneous activities, such as travel, accommodation, procurement of goods, that go beyond the organizer

Q3. What is “calculation range（boundary conditions)”?

A.It determines what to include and exclude from the calculation.  For example, the results would vary for ”travel” depending on the subjects (just the runners or also staff?) and estimation methods.
So, it is essential to specify and explain the calculation range in the disclosure report, as it greatly affects the results.

Q4. Why does the Tokyo Marathon use the 2-axis approach？

Scope is an internationally recognized concept with high reliability, but to the untrained eyes, it can be quite difficult to understand.
Therefore, the Tokyo Marathon organizes data not only by scope but also by activities (travel, lodging, etc.) to clearly show “where (scope) × what (activity)” generate the most emissions.

Q5. Why did you conduct preliminary measurements before the marathon?

By predicting the major contributors of GHG emissions before the event takes place, we can map out effective countermeasures beforehand.
The Tokyo Marathon Foundation and its sustainability partner, ASUENE Inc, will work hand-in-hand for the next 3 years to build an eco-friendly event.
As the first step in this journey, we focused on collecting data and analyzing which contributing factor can be reduced and by how much.
※The preliminary measurements are based on data from Tokyo Marathon 2025.

Q6. Which specific calculation method is used to measure the emissions？

For the Tokyo Marathon 2026, we are quantifying event-related activities based on globally accepted standards (such as the GHG Protocol).
This includes not only electricity and fuel used at the venue, but also transportation, water/food supply, procurement of goods, and waste disposal.  We are organizing emissions that are difficult to identify by multiplying activity rate by emission factor.

Q7. What is the margin of error? How accurate are the measurements？

The actual figures may be different from the preliminary measurements.
This is because preliminary measurements are estimates predicting “what is likely to happen.” Factors such as weather, participant movements, operational conditions and transportation volumes will greatly affect the actual outcome. 
But these estimates can help identify which activities (travel, lodging, goods, etc.) are most significant.  This provides valuable insight in determining where to focus our efforts.  After the marathon, we will conduct a “post-event measurements” based on actual data.  We will continuously improve our data collection methods to deliver more accurate and reliable information.

Q8. What is estimated to be the total emissions of Tokyo Marathon 2026？

Based on the preliminary measurements, we predict around 26,029 t-CO2eq. 
Most of the emissions will come from Scope 3 (travel, accommodation, etc.).

Q9. What was the biggest cause of the carbon footprint？

Emissions generated from staff’s travel account for 88.4% of the total. In other words, travel (distance and mode of transport) required to participate in or be involved with the event has greater impact than any other factor, including electricity used at the venue.

Q10. Why is “travel” such a big contributing factor?

The Tokyo Marathon is an event involving not only runners, but also a large number of staff, volunteers, stakeholders and supporters. 
As most people travel individually, the total volume of transportation accumulates, resulting in a significant amount of emissions.

Q11. Is there anything we can do?

Yes, every little bit helps.  Here are some examples:
・use public transportation
・reduce the number of trips/distance traveled
・cut down on disposable waste（e.g. use reusable water bottle）
The key is to start with something small and continue to build from there.