## 1. Which fuels or activities produce more CO_{2}?

__QUESTIONS__

Which of these activities produces more CO_{2} emissions? (calculate them in kg of CO_{2})

*(Using 13 litres of petrol or 10 litres of diesel) *

Petrol = 2.3 x 13, Diesel = 2.7 x 10 = __29.9 kg__ CO_{2} for petrol and __27 kg__ for diesel

- Using your
**LED TV** for 5 hours a day during a week?

*(A 50” LED TV uses 100 watts, to convert to kWh, multiply kW by number of hours)*

5 x 7 hours at 100 watts = 3.5 kWh = __3.5 kg__ CO_{2}

**Boiling water** in the electric kettle for a family for a week?

*(A kettle uses 1200 W and it takes 3 minutes to boil water and this is done 10 times a day – or does your family drink more tea?)*

1200 x 10 x 3 x 7 = 210 minutes (3.5 hours) or 4.2 kWh x 0.283 = __1.19 kg__ CO_{2}

- Heating the water with natural gas for a week of daily 5 minute
**showers**?

*(Heating 30 litre of water to 40°C uses 1.1 kWh in the form of gas, where emissions from natural gas are 0.2 kg CO*_{2}/ kWh burned)

Heating the water for a week uses 7.7 kWh so 0.2 x 7.7 is 1__.54 kg__ CO_{2}

- Mobile phone usage for the family in a week. Assume the family does an average of two full charges a day.

(Typical phone charges at 0.015 kWh and takes 2 hours to charge fully)

4 x 7 x 0.005 = 0.014 kWh x 0.283 = __0.396 ____kg__ CO_{2}

- Play station for 20 hours a week

(A Playstation 4 Pro uses 139 W)

139 x 20 = 2.4 kWh = __7.87 kg__ CO_{2}

## 2. How to quantify CO_{2} emissions in terms of volume and mass?

__QUESTIONS__

*How many cubic metres of CO*_{2} would 5000 kg CO_{2} occupy? *2500 m*^{3}*A factory states that it releases 10 tons C per year (for its greenhouse gas emissions). How many m*^{3} of CO_{2}e is this? *10,000 kg x 44/12 = 36,667 kg CO*_{2}, so ½ x this is 18,333 m^{3}*If UK car emissions released 3 GtC in a year and all the CO*_{2} remained in the atmosphere, by how much would the CO_{2} concentration increase?

*0.47 x 3 = 1.41 ppmv*

*Go to **see last year´s UK Carbon emissions **published by the government (*Provisional GHG emissions*). In **2019 i**t was 351.5 Mt CO*_{2} Considering the UK population is 63 million and world population is 8.3 billion, are our carbon emissions representative of global average emissions? ((World emissions in 2017* were 36 Bt)*

*63m/8.3b =0.81 % of population and CO*_{2} emissions are 351.5Mt/36000Mt = 0.98 %, so the population of the UK creates more CO_{2 }*than their population dictates, we produce 0.98/0.81 =1.21 times more CO*_{2} than the average world population

*(figures for 2020) 500 ppm; increase of 100 ppm between 1950 and 2020 (in 70 years), that is a 0.7 ppm average increase; it has increased 4 ppm since 2018 (in 2 years), 2 ppm increase per year. The rate of increase of CO*_{2} concentration has increased since the 1950s.

*Why has CO*_{2} concentration not decreased in 2020 if CO_{2} emissions have dropped?

*The lifetime of CO*_{2} means that it stays around in the atmosphere for many years and you will not see a decrease in the CO_{2} from the year that you stop releasing it, it will gradually level off, that is why we need to reach our CO_{2} emission peak as early as possible, to see the results a few years later.

## 3. Steps towards reaching carbon neutrality

QUESTIONS to discuss as a class

- Do you think the UK is on its way to becoming a low carbon economy? Why do you think some countries like Estonia are way behind the UK and countries like Sweden are way ahead? (http://www.globalcarbonatlas.org/en/CO2-emissions is a useful information source)

Estonia still burns a lot of coal, hence its high CO_{2} emissions. Sweden has 80 % of its electricity from nuclear and renewables

- The UK has a goal of reaching Carbon neutrality by 2050- do you think we are on our way to reaching that?
- What percentage of our anthropogenic (human) CO
_{2} emissions are absorbed by the oceans?

31 %

- If a fully grown tree absorbs 22 kg of CO
_{2} per year and an acre of forest, 2.5 tons of Carbon, if we wanted to neutralize our country-wide annual emissions of 351.5Mt* CO_{2}, how many more trees or acres of forest would we need?**

351500/2.5 = 140600 acres. There are 60 million acres in the UK, so actually, only adding 0.234 % of the land as forests would do this!

*The latest government statistics on UK annual CO2 emissions (for 2019) was 351.5 Mt CO2 equivalent

**UK forests absorbed 21 million tonnes **CO**_{2} in total in 2020, so they are working away continuously at helping to neutralise our emissions!