CALCULATIONS | Climate Call

HOW EMISSION VALUES WERE CALCULATED

The emissions values used in the card game Climate Call have been calculated by researchers at Chalmers University of Technology in Gothenburg, Sweden. Here, we give a general overview of how the values were calculated. Some example calculations (one for each category) are also presented. If you think something is unclear, or if you have a question about a specific card, please do not hesitate to contact us at hello@climatecallgame.com. We will try to get back to you as soon as we can!

The calculated emissions values are mostly based on information published in scientific articles, reports from official agencies and research institutes, and data from statistical databases. A selection of the most important data sources for each category are presented further down. In some cases, when no published information has been available, or when there is not one single “correct” value to use, the calculations are based on qualified estimates or assumptions (for example, how much food a dog eats per year). All calculations are based on as recent data as possible, and all emission values have been validated by comparing them with other published values.

There are a few different editions of Climate Call. The latest, from 2023 differs substantially in one aspect and that is that we have now included the increased climate impact that flying on high altitudes have. Praxis today is to include a factor of 70 % to the emissions from the fuel combustion. Else from this, we have just as in earlier editions only considered direct greenhouse gas emissions. The reason to why this wasn't included earlier is that these uncertain feedback mechanisms effects on the climate system, are hard to estimate. Aircrafts flying at high altitude cause both direct carbon dioxide (CO2) emissions from fuel combustion, as well as indirect effects, partly in the form of a heating effect due to high-level cloud formation, and partly in the form of a cooling effect due to emissions of particles that reflect incoming solar radiation back to space. These two effects somewhat counteract each other, and since there was no consensus among the world's climate scientists about the overall effect, we earlier chose to only consider the direct emissions from fuel combustions. Now that there is more of a consensus, we have also started applying a 70 % increase to the emissions from long flights. Changes in the surface area's reflectivity due to changes in land use (that is, how much of the sunlight is reflected back into space) are also excluded.

As the example with aircraft shows, there are many uncertainties in the calculations, partly because climate science is inherently complex, and partly because there is a wide variation in the emissions caused by different activities (for example, how much fuel a car consumes). If possible, we have used average values to make the numbers as representative as possible. The emission values on the cards have been rounded, and should not be regarded as exact and absolute, but rather approximative.

GREENHOUSE GASES

There are several different greenhouse gases that contribute to global warming. In ClimateCall, we consider the most important ones, namely carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Carbon dioxide comes mainly from the combustion of fossil fuels (coal, natural gas and oil), and from the cultivation of organic soils. Organic soils have high levels of organic matter that contains carbon. When the soil is cultivated, the organic material breaks down and the carbon is released to the atmosphere in the form of carbon dioxide.

Methane comes primarily from methane-forming microbes in the digestive system of ruminants and from animal manure. Methane-forming microbes thrive in these anaerobic (oxygen free) environments and they produce methane as they feed on organic material in the stomach of ruminants, and in manure.

Nitrous oxide comes mainly from the production of synthetic fertilizers, from the cultivation of organic soils, and from fertilizers and manure that have been spread on fields and pastures. In the soil, there are microbes that feed on nitrogen-containing compounds in fertilizers and manure, and in that process, nitrous oxide is formed.

Different greenhouse gases impact the climate to different degree. In order to compare and add up different greenhouse gases, their climate impact is converted to the corresponding amount of carbon dioxide, that is, the amount of carbon dioxide that has the same climate impact as methane. This is called the carbon dioxide equivalents.

There are different methods to calculate carbon dioxide equivalents, and the climate impacts can also be assessed over different time periods. For example, 1 kg of nitrous oxide has about 300 times larger climate impact than 1 kg of carbon dioxide, when the climate impact is assessed over a time period of 100 years using a calculation method called Global Warming Potential. The climate impact of 1 kg of nitrous oxide is therefore considered equivalent to 300 kg of carbon dioxide.

All greenhouse gases can be expressed as carbon dioxide equivalents, and by doing so, it is possible to produce a single value for the climate impact even when the emissions consist of several different greenhouse gases. The emission values in ClimateCall have been calculated using the Global Warming Potentials of different greenhouse gases over a time period of 100 years, in line with standard practice. More information about the greenhouse effect of various greenhouse gases can be found here.

Some cards have negative emission values. These refer to the avoided emissions that can be saved by doing an activity, for example, planting trees, recycling materials or installing solar panels. The saved emissions have been calculated as the difference between the emissions associated with the most likely alternative scenario, and the emissions associated with the particular activity. In the case with planting trees, the alternative scenario is simply not planting trees, and in the case of solar panels, the alternative scenario is using electricity from the grid. More detailed explanations are given further down.

GREENHOUSE GASES

FOOD/PROVISIONS

Within the category of food/provisions, greenhouse gas emissions from the following activities are included:

The cultivation of crops and rearing of animals, such as carbon dioxide emissions from tractors used on farms, and methane from ruminants.
Production of inputs used on farms, such as synthetic fertilizer, pesticides, electricity and fossil fuels.
Production of animal feed, such as hay and cereals.
Energy consumption associated with food processing, for example in dairies and mills.
Transport of synthetic fertilizers, fossil fuels and animal feed.
International and national transport of food, from the country of origin to the retail store.

However, greenhouse gas emissions from the following activities are not included:

Manufacture of packaging materials for food, since these emissions generally are small in comparison to the emissions from food production.
Transport of food from the retail store to the consumer. These emissions are not negligible, but are usually attributed to the transport sector, rather than to the food sector.
Energy consumption from cooking at home. These emissions are not negligible, but are usually attributed to the housing sector, rather than to the food sector.
Production of infrastructure (for example roads for transport), agricultural machinery and buildings (stores, farm buildings, storage buildings, etc).

What is included in the different diets?

The card game includes a number of cards with different diets: a mixed US average diet, a mixed EU average diet, and a vegan diet. The mixed diets (US and EU average) refers to the average consumption of food per person in the US and EU28 in 2013, respectively, and include emissions of food that goes to waste. The US and EU average diets are based on food intake data from the FAO database FAOSTAT.

The vegan diet is based on a research study from 2016. In the vegan diet, milk products have been replaced by soy and vegetable oils, and meat, eggs and fish have been replaced by vegetable protein sources, mainly legumes, nuts and seeds. Protein intake in the vegan diet is lower than in the other diets, but in line with recommended levels. All diets contain an equal intake of calories.

What is meant by a "meal"?

The term "meal" is used on the cards “beef”, “pork” and “chicken” (“a meal with 150 g chicken daily for a year”, for example). By “meal”, we mean that these meat products are all served with 300 g of potatoes. All hamburgers (beef burger, halloumi burger, and veggie burger) are served with 60 g of bread, and the weight of all burgers are 100 g. In all cases, the meat or meat substitute accounts for the larger part of the greenhouse gas emissions. 300 g of potatoes per day for a year, for example, only contribute with 40 kg CO2-equivalents.

What is halloumi?

Halloumi is a semi-hard cheese made from a mixture of milk from goats and sheep, and sometimes also cows. Halloumi originates from Cyprus and is widely eaten throughout the Middle East. Recently, it has also become popular in many Western countries. The cheese can be fried without melting and is therefore ideal as meat substitute in a burger.

Where does the food come from?

The food in all diets and meals refers to average consumption in the specified country/region. Import of food is considered as well, and we have considered the emissions from international as well as national transport (up to the store).

Why are the emissions from beef and dairy products so high?

Food products from cattle (beef, milk, cheese, butter, etc.) have larger greenhouse gas emissions compared to other food products, for three reasons: 1) cattle are ruminants that release methane (as opposed to pigs and chickens), 2) cattle have lower reproduction rates than pigs and chickens, and 3) cattle have lower feed conversion ratios than other animal species. A lower reproduction rate refers to the fact that a cow usually only gives birth to one calf per year, compared to a sow that gives birth to between 20 and 30 piglets per year, and a hen that lays several hundred eggs per year. The feed conversion ratio refers to the edible output in the form of milk or meat relative the input of feed.

Ruminants (such as cows, sheep and water buffalo) are characterized by their ability to digest grass. The grass is digested in the stomach with the help of special microbes that break down the cellulose in the grass. In this process, methane is formed, and emitted when the animal breathes. For dairy products, methane emissions from the digestive system of ruminants account for almost 50% of the total emissions.

Is energy use associated with transport from the store to the consumer included?

No, it is not included. Although these emissions are not negligible, they are usually attributed to the transport sector, rather than the food sector.

Is the food organic or conventional?

The emission values can be considered representative of conventional as well as organically produced food. Several major studies have compared the climate impacts between organic and conventionally food products and found that there are basically no differences (Meier et al., 2015; Tuomisto et al., 2012; Mondelaers et al., 2009). On one hand, synthetic fertilizers are not used in organic production systems, which is positive from a climate point of view since fertilizer production is very energy intensive. On the other hand, organic yield are lower, which means that the total climate impact from one hectare, or one farm, is distributed over less amount of food.

Note that Climate Call only deals with climate impacts and not other environmental impacts and health issues. Organic food products can have positive effects on other environmental issues (for example biodiversity), as well as health, but that is not considered here.

How has the food been transported before it reaches the consumer?

We have tried to make as realistic assumptions as possible about transport distances and means of transportation (truck / boat / train / airplane) in order to reflect reality as accurately as possible. For example, we have assumed that bananas are transported by boat from South America, and that all drinking milk is produced locally.

For most food products, transport only accounts for a small part of the total climate impact, since food transports are very energy efficient, in general. An exception is transportation by airplane, for example some exotic fruits, sugar snaps and asparagus. The climate impacts of air transported fruits and vegetables can be as high as for beef. This becomes clear when comparing the emissions of sugar snaps transported from the Netherlands by truck, and sugar snaps transported from Kenya by air. Sugar snaps transported from the Netherlands by truck have rather low emissions even though they are transported a relatively long distance (we assumed they are transported 1500 km, to a generic location in central Europe).

Is energy use associated with cooking at home included?

No, it is not included. These emissions are not negligible but usually attributed to the housing sector, rather than to the food sector.

Calculation example ”Food/provisions”

Halloumi burger once a day for a year

To calculate the greenhouse gas emissions from the daily consumption of a halloumi burger for a year, we used the following input data:

Amount of halloumi per burger: 100 g
Amount of bread per burger: 60 g
Emission factor of bread: 1.2 kg CO2 per kg of bread
Emission factor of halloumi: 9.9 kg CO2 per kg of halloumi

First, we calculated how much bread and halloumi is consumed in total per year. The calculation shows that 21.9 kg of bread and 36.5 kg of halloumi is consumed (60 g of bread×365; 100 g of halloumi×365).

Then, we calculated the greenhouse gas emissions by multiplying the total amount of bread and halloumi with their corresponding emission factors. The calculation shows that 388 kg of CO2 is emitted, which has been rounded to 400 kg on the card (21.9 kg of bread×1.2 kg of CO2 per kg of bread + 36.5 kg of halloumi×9.9 kg CO2 per kg of halloumi). The halloumi accounts for 93% of the total emissions.

The climate footprints of bread and halloumi include greenhouse gas emissions from the rearing of cows and the cultivation of cereals (including feed for the cows), the production of agricultural inputs, processing in the food industry (cheese making and break baking), as well as transports. We also considered food waste by an average of 37% for bread and 13% for cheese.

References "Food/provisions"

Food consumption in the average EU diets: FAOSTAT
Food consumption in the average US diets: FAOSTAT
Food consumption in the vegan diet: Chapter S1 in Bryngelsson et al. (2016) How can the EU's climate targets be met? An analysis of food and agriculture. SUPPLEMENTARY MATERIALS.
Greenhouse gas emissions from production of individual food items: Based on calculations using a model developed by researchers at Chalmers University of Technology, Gothenburg, Sweden. More information about the calculation model can be found in chapter S5 in Bryngelsson et al. (2016) How can the EU's climate targets be met? An analysis of food and agriculture. SUPPLEMENTARY MATERIALS.
Emission of methane from ruminant digestion: Moraes et al. (2014).
Emissions of nitrous oxide from cropland: Shcherbak et al. (2014) and Lesschen et al. (2011).
Transport distance: Google maps and ntmcalc.se

FOOD/PROVISIONS

TRAVEL & TRANSPORT

Within the category of travel & transport, greenhouse gas emissions from the following activities are included:

Combustion of fuels (petrol, diesel, jet fuel) in internal combustion engines in cars, buses and airplanes. The 2023 edition also account for the increased emissions airplanes cause flying at high altitudes, this with a 70 % increase to the fuel combusted.
Production of electricity that powers the train, electric car and electric bike.
Production of cars and buses. More precisely, we have considered the emissions from the production of the materials that cars and buses consist of. A car, for example, is considered to consist of carbon steel, stainless steel, aluminum, copper, glass, fiberglass, plastic and synthetic rubber.
Production of lithium batteries to the electric car and electric bike. Emissions from the production of the batteries account for a significant part of the emissions from the production of the electric car.

However, greenhouse gas emissions from the following activities are not included:

Production and maintenance of infrastructure, such as roads, railways and airports.
Production of aircraft and trains. Since the total mileage over the entire life span is very high for these vehicles, the emissions associated with production are very small when expressed per km. The material component is only included when it is considered significant.

What is meant by "average capacity utilization" and how large is it?

In the cases of air and rail transport, we have assumed an "average capacity utilization", which refers to how populated the flight or train is, on average. For the international flights (São Paolo – Chicago, Beijing – Los Angeles, Johannesburg – London, and Paris – New York), we assumed that the average capacity utilization is 80%, based on data from IFEU (2016). For the domestic flight in China from Beijing to Shanghai, we assumed that the average capacity utilization is 71%, which is the same as the average capacity utilization on flights within the EU (IFEU, 2016).

For the domestic flight in the US from Los Angeles to New York we assumed that the average capacity utilization is 85%, which is the average value for domestic flight in the US based on data from DOT (2016). Emissions were calculated for the entire flight or train ride and then distributed over all passengers.

For the train ride from Beijing to Shanghai, we assumed that the average capacity utilization is 70%, based on data from the International Rail Journal.

What has the greatest climate impact per km: car travel or air travel?

It depends on the distances travelled. Emissions per km are considerably higher for short flights (less than ca. 1000 km), as departure and landing are very fuel consuming and represent a larger share of the total fuel consumption for short flights. In addition, the air resistance is lower at higher altitudes, making long-haul flights more fuel efficient per km than short flights.

Long-haul flights emit on average ca. 0.1 kg CO2 per km (for average airplane capacity utilization), which can be compared to a medium-sized car which, on average, emits ca. 0.2 kg CO2 per km (excluding emissions from the production of the car). Car travel therefore emits more CO2 per km.

How are the emissions from the plane rides calculated?

For early editions: Only the direct emissions from fuel combustion are considered, although there are also some indirect effects associated with aviation. First of all, there is the so-called high-altitude effect which refers to the additional heating that emissions at around 10,000 meters cause. According to some estimates, the high-altitude effect doubles the climate impact compared with the combustion at ground level. The increased climate impact is due to the formation of oxides of nitrogen (NOx) and water vapor at a high altitude in the atmosphere, which contributes to the formation of clouds. Water vapor is a strong greenhouse gas, but cloud formation is one of the most uncertain parts in our understanding of the climate system.

In addition to this heating effect, recent studies have shown that airplanes also release particles (aerosols) that have a cooling effect, since they reflect incoming solar radiation back to space. These two indirect effects somewhat counteract each other, and since there was not yet any consensus among the world's climate scientists about the overall effect, we have chosen to only consider the direct emissions from combustion of jet fuel.

For Climate Call 2023: Yet more recent studies (with an increasing consensus among climate scientists) show that flying at high altitudes cause a 70 % increase to the fuel combusted.

Are packages shipped by air freight or airplanes that take both passengers and goods?

The packages are shipped by air freight, that is, planes that only carry goods.

How many passengers travel in the commuting car?

One passenger.

What assumptions were made about the train ride from Beijing to Shanghai?

We assumed the ride takes place with a China Railway high-speed train, operated by the China Railway, and powered by electricity. The average Chinese power mix was considered. The average capacity utilization was assumed to be 70%, based on data from the International Rail Journal.

Are the emissions from manufacturing aircrafts and trains included?

No, it is not included. Since the total mileage over the entire life span is very high for aircrafts and trains, the emissions associated with production are very small when expressed per km. The material component is only included when it is considered significant, that is, for cars and buses.

Calculation example ”travel & transport”

Train ride Beijing – Shanghai

To calculate the greenhouse gas emissions from this activity, we used the following input data:

Distance between Beijing and Shanghai, one way: 1320 km
Energy use per person and km for traveling with a Chinese high-speed train: 0.229 MJ (based on an average seat occupancy of 70%).
Emissions from the average Chinese power mix: 206 g CO2 per MJ

First, we calculated how much energy is used in total per person for the trip. The calculation shows that the round trip requires 605 MJ of energy per person (1320 km×2×0.229 MJ per person and km).

Then we calculated the greenhouse gas emissions for generating this amount of energy, by multiplying the amount of energy with the emission factor for the average Chinese power mix. The calculation shows that the trip emits 124 kg CO2, which has been rounded to 120 kg on the card (605 MJ×206 g CO2 per MJ).

References ”travel & transport”

Average capacity utilization on international flights: IFEU (2016)
Average capacity utilization on domestic flights in the US: DOT (2016)
Average capacity utilization on train ride in China: International Rail Journal (2015)
Typical commuting distances: Travel survey 2016 and USC (2015)
Fuel consumption of the commuting bus: The Swedish Association of Local Authorities and Regions (2015) Öppna jämförelser - Kollektivtrafik 2015. Average for bus services in the Stockholm region.
Fuel consumption SUV: EPA (2018)
Average yearly driving distance per person in the EU (year 2015): Odyssee database
Average yearly driving distance per person in the US: USDOT (2016)
Transport distance: Google maps and ntmcalc.se
Emissions from combustion of different fuels (g CO2 per MJ): JEC WTW (2014) and IFEU (2016)
Emissions from electricity generation (Nordic power mix): Martinsson et al. (2012)
Energy consumption flights (MJ per passenger and km): SAS CO2 calculator, ICCT and IFEU

Errata

In the first version of the game there was a typo on the card "COMMUTE BY BUS". The correct emissions number is 200 kg!

TRAVEL & TRANSPORT

HOUSING

Within the category of housing, greenhouse gas emissions from the following activities are included:

Production of electricity for heating and cooling.
Production of electricity for powering household appliances such as fridge, freezer and dishwasher.
Production of household appliances such as fridge, freezer and dishwasher.

However, greenhouse gas emissions from the construction and maintenance of houses and apartments are not included.

What is meant by "low-flow shower head” and “standard shower head”?

Different types of shower heads consume different amount of water. Modern shower heads generally consume significantly less water than old shower heads. We have assumed that the various shower heads use the following amounts of water:

Standard shower head: 12 liters per minute
Low-flow shower head: 6 liters per minute

In comparison, old shower heads consume on average 30 liters per minute. By “consume” we refer to the water that passes through the shower head.

Why is it written that the emissions are based on a "Nordic power mix" on the card with heating with a ground source heat pump?

The electricity consumption refers to the electricity used to power the ground source heat pump (also called a geothermal heat pump). The heat itself is extracted from the ground.

Why is the Nordic power mix used, and not the Swedish power mix (for cards that refer to housing in Sweden)?

Because there is a common electricity market in the Nordic countries (Sweden, Norway, Finland and Denmark), which means that there is significant trade of electricity between countries, and that electricity prices are decided on a common market place. It would be difficult, and not so relevant, to consider the Swedish electricity mix specifically.

What does the Nordic power mix consist of?

It consists of 40% electricity from hydro power, 35% from nuclear power, 12% from natural gas, 9% from wind power and 4% from coal power. The Nordic electricity mix releases on average 35 g CO2 per MJ, according to Martinsson et al. (2012), which can be compared with the global average of 172 g CO2 per MJ, according to Econometrica (2011). The Nordic power mix has a rather low emission value since a large share of the electricity comes from non-fossil sources.

What does the EU power mix consist of?

It consists of 44% electricity from natural gas, 26% from nuclear power, 11% from hydropower, 10% from wind power, 5% from coal power and 4% from solar power. The EU power mix releases on average 78 g CO2 per MJ, according to the EEA website.

What does the US power mix consist of?

It consists of 33% electricity from coal power, 32% from natural gas, 20% from nuclear power, 8% from wind power and 7% from hydro power. The US power mix releases on average 142 g CO2 per MJ, based on USDO (2016).

How hot is the water in the shower?

We have assumed that the water in the shower holds 39 °C. If the temperature would be reduced by 5 °C (to 34 °C) in the case of a 10 min shower with a standard shower head, the emissions would drop by 16%.

What indoor temperature have you considered?

We have not made any specific assumptions regarding indoor temperature, but used statistics from the Swedish Energy Agency on actual energy use for heating in Sweden.

How are the emissions affected if the indoor temperature is reduced?

Lowering the indoor temperature by 1 °C reduces energy consumption by about 5%, according to the Swedish Energy Agency.

How efficient are the fossil gas boiler and air conditioner?

The efficiency of the fossil gas boiler is measured as the ratio between the useful output (heat), and the input (fossil gas). We used the following average efficiencies:

Fossil gas boiler in the UK: 82.5% based on DECC (2014).
Fossil gas boiler in the US: 85% based on STRATEGO (2015).

The conversion efficiency of a boiler or furnace cannot be more than 100%. The air conditioner, however, functions in a different way. Instead of burning fuel to create heat (like the boiler), it uses electricity to move heat from one place to another (indoor to outdoor, in the case with cooling). Technically, an air conditioner works as a heat pump, and can have an efficiency above 100%. We assumed that the US air conditioner has a conversion efficiency of 310% based on STRATEGO (2015). This means that for every unit of electricity supplied, the air conditioner transfers more than three times as much heat from inside to outside the house, thereby cooling the house.

How are the saved emissions from using solar panels calculated?

The emission value is negative since it refers to the avoided emissions that are saved by using solar panels. The value on the card has been calculated as the difference between the emissions from using the average power mix in each country/region and the emissions from generating electricity using solar panels.

How efficient are the solar panels?

The nominal efficiency of the solar panels was assumed to be 16% and the performance ratio was assumed to be 75%, in all regions. The nominal efficiency is the share of the incoming energy that is converted to electricity, and the performance ratio is the relationship between the actual and theoretical energy outputs of the solar panels. The performance ratio mostly depends on the orientation of the solar panels and the incident solar irradiation.

Calculation example ”Housing”

Shower 5 minutes every day for a year with a low-flow shower head and hot water from an electric water heater in the US.

To calculate the greenhouse gas emissions from this activity, we used the following input data:

Water consumption, low-flow shower head: 6 liter per minute
Water temperature shower water: 39 °C
Water temperature incoming water (before heating): 13 °C
The energy requirement to heat one liter of water one degree: 0.004184 MJ
Emissions from electricity generation (average US power mix): 142 g CO2 per MJ

First, we calculated how much water is used in total per year by multiplying the water flow with the shower time and the number of days per year. The calculation shows that showering requires 10 950 liters of hot water per year (6 liters per minute×5 minutes×365 days per year).

Then we calculated the amount of energy required to heat 10 950 liters of water from 14 °C to 39° C by multiplying the energy requirement to heat one liter of water one degree by the number of degrees the water has to be heated (25 °C), and the total amount of water. The calculation shows that 1145 MJ is required per year to heat the water (25 degrees×0.004184 MJ per degree×10 950 liters of water).

Finally, we calculated the greenhouse gas emissions by multiplying the total energy requirement with the greenhouse gas emissions from electricity generation (average US power mix). The calculation shows that 163 kg of CO2 is emitted, which has been rounded to 160 kg on the card (1145 MJ per year×142 g CO2 per MJ).

References ”Housing”

Energy use for heating houses in Sweden: The Swedish Energy Agency's calculator
Average housing area for different housing types in Sweden: Statistics Sweden's Statistics Database
Efficiency of the fossil gas boiler for heating in the UK: DECC (2014)
Efficiency of the fossil gas boiler for heating in the US: STRATEGO (2015)
Efficiency of the air conditioner used for cooling in the US: STRATEGO (2015)
Emissions from electricity generation (Nordic power mix): Martinsson et al. (2012)
Emissions from electricity generation (US power mix): USDO (2016)
Emissions from electricity generation (EU power mix): EEA website
Average annual energy use for fridge/freezer in Germany: Odyssee National Report 2015
Average annual energy use for fridge/freezer in the US: EIA Energy Outlook 2017
Solar irradiation data in the EU: European Solar Irradiation Map
Solar irradiation data in the US: U.S. Solar Radiation Resource Maps

HOUSING

OTHER

What is considered a mid-sized dog?

We have assumed that the mid-sized dog weighs 15 kg. Information about how much mid-sized dogs eat were collected from the dosage table at Hundköket.se. Examples of mid-sized dogs are poodle, labrador, collie and samoyed.

What does the mid-sized dog eat?

We have not made any specific assumptions about what the dog eats, that is, what the feed contains, but assumed an average emission value of 1 kg CO2 per kg of dog food. This value is rather high considering that most dog food consists of by-products from slaughterhouses (products that would otherwise likely go to waste), yet low compared to other foods. For comparison, pork has an average emission value of about 6 kg CO2 per kg of pork.

How much energy does the TV consume?

The TV consumes 150 W when powered on, and 0.3 W in standby mode, which is normal for a new 65" TV with an OLED display, that is, the most energy efficient type of TV.

How were the emissions from the production of the laptop and smartphone calculated?

Emissions values for the new laptop and new smartphone were obtained from the electronics producer Apple and include the energy used in the factory, and energy use associated with mining and processing raw materials. Specifically, we assumed that the phone is an iPhone 7, and that the computer is a MacBook Pro 15", and obtained the corresponding emission values.

How were the emissions from the production of the TV calculated?

The emissions from the production of the TV were estimated by choosing a representative model, and estimating which materials it consists of. We considered an LG OLED65B7V from 2017 that weighs 23 kg. We assumed that the TV mostly consists of plastic and silicon, and small amounts of a wide variety of metals. The weight of each material was multiplied by the emission value for the corresponding material. Material-specific emission values indicate how much greenhouse gases are released due to extraction and enrichment of 1 kg material.

Electronics contain a large variety of different materials, and there is a large variety in emission values for different materials depending on how common they are in the Earth's crust, and how difficult they are to extract. As an example, it can be mentioned that the production of 1 kg of steel emits about 2 kg of CO2, while the corresponding emission figure for platinum is 34 000 kg of CO2.

We assumed that the TV has a life span of 7.5 years, and distributed the emissions from manufacturing over the entire life span.

What are the hot-spots in the manufacturing of electronic devices?

In the production of electronics, it is primarily the mining, processing and enrichment of raw materials (metals and silicon) that requires a lot of energy, and thus cause greenhouse gas emissions. In addition, energy is required for the manufacturing of electrical components. All of the above-mentioned production steps are included. Assembly of components to finished products is however not included since this production step requires negligible amounts of energy in comparison.

How were the saved emissions from recycling in Sweden calculated and what materials were considered?

The emission value is negative since it refers to the avoided emissions that are saved by performing this activity. The value on the card has been calculated as the difference between the emissions from production of recycled materials and the emissions from production of virgin materials.

The following packaging materials were considered: paper, plastic, glass, metal, PET bottles and aluminum cans. In total, most emissions are saved by recycling paper, cardboard and plastic, since these are the packaging materials that are used in largest quantities. On average, every Swede consumes 87 kg of paper packaging per year, 21 kg of plastic, 20 kg of glass, 4 kg of metal, 2.5 kg of PET bottles and 1.8 kg of aluminum cans.

Per kg of material, however, most emissions are saved by recycling aluminum. Recycled aluminum, emits 1 kg CO2 per kg aluminum, compared to virgin aluminum which emits 13 kg CO2 per kg aluminum. This can be compared with recycled paperboard which emits 0.6 kg CO2 per kg, and new paperboard which emits 3.2 kg CO2 per kg.

What is meant by “sequestration” on the card with planting trees in Uganda?

The emission value is negative, meaning that emissions are saved by performing this activity. The reason is that trees absorbs carbon dioxide from the atmosphere as they grow, through the process of photosynthesis. The absorbed carbon is stored in the tree biomass, both above and below ground. Some of the carbon is also transferred to the surrounding soil, for example as leaves fall off the tree fall and decompose on the ground. Planting and growing trees is therefore positive from a climate point-of-view.

The growing rate of 15 m3 per hectare per year as specified on the card corresponds roughly to three mature trees.

How were the emissions of cow leather calculated?

The emission factor for cow leather has been calculated using a so-called economic allocation principle. A cow causes a certain climate impact during its lifetime, due to the production of feed and methane emissions from ruminant digestion. At the same time, a cow produces many types of products such as milk, meat and leather. There are different ways of distributing the total emissions over the various products. Here, we used the economic value of the different products to distribute the emissions. According to the economic allocation principle, emissions are distributed in a way that reflects the economic value of different products. This method assigns a relatively low emission factor to leather since leather is mainly a by-product of milk and meat.

Calculation example ”Other”

Three pairs of leather shoes per year of cow leather

To calculate the greenhouse gas emissions from this activity, we used the following input data:

Production emissions for cow leather: 88 kg CO2 per kg of cow leather (the value applies to 2 mm thick leather).
The leather requirement for a pair of new leather shoes (including waste): 0.6 kg of leather.

First, we calculated the greenhouse gas emissions for one pair of shoes, by multiplying the leather requirement for a pair of new leather shoes, with the emission factor for leather. The calculation shows that a pair of new leather shoes emits 52.8 kg of CO2 (88 kg CO2 per kg of cow leather×0.6 kg of leather). Three pairs of leather shoes thus emit 158 kg CO2 (52.8×3), which has been rounded to 160 kg on the card.

The amount of leather that is needed to make a pair of new leather shoes includes waste due to cutting the leather. More specifically, almost 50% of the leather goes to waste.

References ”Other”

Production emissions for a new phone and computer: Apple Environmental Report
Feed consumption dog: Hundköket.se/hundfoder
Energy use in the production of TV: Stobbe (2007)
Energy use in the production of cow leather: Laurenti et al. (2016)
Use of leather in leather shoes: Gottfridsson et al. (2015)
Energy use associated with TV-watching in Germany: Odyssee National Report 2015
Average time spent on TV-watching in the US: EIA RECS (2009)
Emissions from open-air production of roses in Kenya: Bohm et al. (2013)
Emissions saved from planting trees in Uganda: Estimated from average growth in a Clean Development Mechanism project in Kachung, Uganda, and data on carbon content in trees from Forest statistic yearbook (Skogstatistisk årsbok), 2014. Total biomass estimated from Petersson (1999).
Emissions from greenhouse production of roses in the Netherlands: Calculations in a model developed by researchers at Chalmers University of Technology. More information about the model can be found in chapter S5 in Bryngelsson et al. (2016) How can the EU climate targets be met? An analysis of food and agriculture. SUPPLEMENTARY MATERIAL.

OTHER