DIFFERENT EDITIONS OF THE GAME

Since the start in 2018, we have released several editions of the Climate Call card game. These editions include partially different sets of cards. Detailed explanations for calculations are available only for a selection of cards, and they refer to the edition published in 2024. Most cards in the latest edition, from 2026, have the same emission values as the 2024 edition, so the calculations are still useful if you have the newer edition.

How do you know which edition you have? Check the card box! The edition year is printed on the side of the box.

If you compare cards from different editions, or compare your cards with the calculations on this website, you’ll notice that the numbers on some cards differ. There are several reasons for this, described below. We update the game continuously so that the emission values are as current and accurate as possible. We do not recommend mixing cards from different editions, as they are not entirely comparable. 

Changes introduced in the edition published in 2026

This edition is mostly the same as the previous edition from 2024. However, some cards have updated emission values compared with the 2024 edition. This applies, for example, to some of the heating cards, since we have updated the electricity emission values and heating standards for some countries. The set of cards is otherwise the same.

Changes introduced in the edition published in 2024

Compared with earlier editions, the 2024 edition includes the following changes:

• We have included the so-called high-altitude effect for flights, which has increased emissions for all flights over 500 km (see below).
• We have rounded all figures to two significant digits and the nearest multiple of five, instead of a less precise rounding we used previously.
• We have introduced an updated food model, which forms the basis for the food cards (more info below).
• We have updated the value used to convert methane to CO2 equivalents, so that it better reflects current research (it’s now lower than it was before).
• We have updated the carbon dioxide equivalents emitted per kilowatt-hour of electricity for all relevant countries.
• We have corrected some errors that were discovered.

New food model (2024)

A new, research-based food model was introduced in 2024, developed by Stefan Wirsenius at Chalmers University of Technology. In this model, the emission values for different foods are based on updated data and represent average emissions per kilogram of food consumed in the EU. The average diets were also reviewed and adjusted to better represent consumption in the EU (the previously used diets represented food consumed in Sweden). The model also includes the latest value for converting methane to CO2 equivalents (the so-called GWP value), which is lower than the value used previously.

Enhanced climate impact due to high-altitude emissions (2024)

Airplanes flying at high altitudes cause both a direct impact on the climate in the form of carbon dioxide emissions from fuel combustion and indirect effects linked to emissions at high altitudes. The indirect effects include a warming effect due to high-altitude cloud formation (water vapor being a potent greenhouse gas) and a cooling effect due to emissions of particles that reflect incoming solar radiation back into space.

Because these effects are challenging to estimate and counteract each other, previous editions of the game considered only the direct climate impact from fuel combustion. However, thanks to new climate research published in 2021 (Lee et al., 2021), and greater consensus among researchers regarding the net effect, we have included the so-called high-altitude effect (also called non-CO2 effects) in the 2024 edition of Climate Call.  

How much the climate impact is amplified depends on the altitude at which the emissions occur, which in turn depends on the distance flown (the longer the distance, the higher up in the atmosphere the aircraft flies). We have considered an enhancement factor of 0% for flights under 500 km, 70% for all flights over 1000 km, and a linear increase of the enhancement factor from 0% to 70% for all flights between 500 and 1000 km.

The inclusion of the high-altitude effect means that all longer flights have higher emissions in the 2024 edition of Climate Call, compared with earlier editions. This also affects the cards related to air freight.