Comparing Carbon Footprints

This problem offers an opportunity to discuss issues relevant to all of us, as well as talking about orders of magnitude and conversions between grams, kilograms, and tonnes.

There is also the opportunity to talk about estimation, and why a range of values may be the most appropriate answer.  There is a lot of uncertainty in the values, and lots of aspects which can affect the degree of uncertainty.  Students can discuss how useful having an "uncertain" set of values could be and why it is important to keep updating our understanding of environmental impacts.

You can hear Tamsin Edwards talking about uncertainty in climate change modelling in this "The Life Scientific" Podcast.

This problem is one of a collection designed to develop students' carbon numeracy; we hope it will encourage students to think about the issues surrounding climate change.  You can find the complete collection here.

This problem also featured in an NRICH Secondary webinar in November 2021.

In the interactivity, the pairing of the items is based on the following data from the book How Bad Are Bananas? by Mike Berners-Lee:
 

An email:  

0.03g CO2e spam email picked up by your filters
0.2g CO2e short email going from phone to phone
0.3g CO2e short email sent from laptop to laptop
17g CO2e long email that takes 10 minutes to write and 3 minutes to read, sent from laptop to laptop
26g CO2e an email that takes you 10 minutes to write, sent to 100 people, 99 of whom take 3 seconds to realise they should ignore it and one of whom reads it

A plastic carrier bag: 

3g CO2e very lightweight variety
10g CO2e heavier supermarket bag
50g CO2e heavyweight 'bag for life'

Drying your hands:

0g CO2e letting them drip
2g CO2e Dyson Airblade
10g CO2e one paper towel
11g CO2e standard electric dryer

A Zoom call: 

2g CO2e per hour on a 13-inch MacBook Pro
10g CO2e per hour on an averagely efficient laptop
50g CO2e per hour desktop computer with screen +embodied emissions in the computer
-20 tonnes CO2e potential saving on a meeting in Hong Kong with two people flying from Europe

A paper carrier bag: 

12g CO2e recycled and lightweight
80g CO2e a fashion bag from mainly virgin paper

An apple: 

0g CO2e plucked from the garden
32g CO2e local and seasonal
80g CO2e shipped, seasonal
290g CO2e shipped, out-of-season, frozen

Boiling a litre of water: 

40g CO2e using an electric kettle
50g CO2e using a gas kettle on fairly low heat
115g CO2e using a saucepan on the gas without a lid

A banana: 

110g CO2e each

An orange: 

150g CO2e each

An hour watching TV: 

132g CO2e BBC iPlayer streamed on 13-inch MacBook Pro
170g CO2e terrestrial TV viewed on 55-inch LED TV
206g CO2e BBC iPlayer viewed on 55-inch LED TV
237g CO2e Terrestrial TV viewed on 42-inch plasma TV

A shower: 

55g CO2e 3 mins, efficient gas boiler, aerated showerhead
160g CO2e 5 mins in a 5kW economy electric shower
250g CO2e 5 mins in a typical 8kW electric shower
1kg CO2e 15 mins in an 11kW electric power shower

A loaf of bread: 

630g CO2e an 800g loaf produced and sold locally
1kg CO2e same 800g loaf transported extensively by road

1kg of rubbish to landfill: 

590g CO2e average bin contents
9.1kg CO2e aluminium and copper

Taking a bath: 

200g CO2e modest bath heated by solar energy
500kg CO2e modest bath heated by efficient gas boiler
1kg CO2e generous bath heated by efficient gas boiler
1.6kg CO2e generous bath heated by electricity

A pint of milk: 

0.51kg CO2e pint of oat milk
0.55kg CO2e pint of soya milk
1.1kg CO2e pint of UK cow's milk
1.8kg CO2e global average milk

A bottle of wine: 

1.3kg CO2e from Britain or France
1.4kg CO2e shipped from Australia, with 200 road miles
1.65kg CO2e transported 1500 miles by road from Italy

A bunch of flowers: 

0 CO2e picked from your garden, no inorganic fertiliser
110g CO2e snapdragon, grown and sold locally
1.7kg CO2e bouquet of 15 mixed stems grown outdoors in the UK and sold separately
2.4kg CO2e rose grown in a hothouse in The Netherlands or an outdoor-grown Kenyan rose airfreighted to Europe
32.3kg CO2e bouquet of five Kenyan or Dutch roses, five Dutch lilies and three Kenyan gypsophilia

1kg of rice:

3kg CO2e efficiently produced
4kg CO2e average production
7.1kg CO2e poor production with excessive fertiliser

A pair of shoes: 

1.5kg CO2e rubber crocs
8.5kg CO2e synthetic
11.5kg CO2e average mix
15kg CO2e all leather

A night in a hotel: 

3kg CO2e bed and breakfast in a nice hotel that takes its footprint seriously
30kg CO2e dinner, drinks, bed and breakfast in a hotel with average eco credentials
75kg CO2e night in a lavish hotel with no eco credentials

A leg of lamb: 

42kg CO2e 2kg joint at the checkout

A necklace: 

0 CO2e handed down, or made from driftwood and shells
230kg CO2e £500 worth of new Welsh gold
710kg CO2e £500 worth of gold and diamonds from Africa

A new carpet: 

76kg CO2e thin polyurethane carpet with thin underlay, 4m x 4m
290kg CO2e the same area covered in thick wool, polypropylene or nylon with generous underlay

Keeping a pet for a year: 

25kg CO2e per year for a goldfish
310kg CO2e per year for an average-sized cat
770kg CO2e per year for an average-sized dog
2500kg CO2e per year for a Great Dane

A mortgage: 

1000kg CO2e per year £200,000 on 2.5 per cent interest

An operation: 

1 tonne CO2 hip replacement or knee surgery
2.3 tonnes CO2e heart bypass operation
31m tonnes CO2e UK healthcare total

A tonne of steel: 

400kg CO2e general steel - 100 per cent recycled
1.1 tonne CO2e virgin steel - using hydrogen instead of coal in the manufacturing process
1.8 tonnes CO2e global average - 25 per cent recycled
2.3 tonnes CO2e virgin steel - blast furnace with coal
2.9 billion tonnes CO2e annual global production

Photovoltaic panels: 

5 tonnes CO2e for a 4kW domestic array
1.2 tonnes CO2e annual carbon saving from a 4kW domestic array

Return flight London to Hong Kong: 

3.5 tonnes CO2e economy class
4.5 tonnes CO2e premium economy
10 tonnes CO2e business class
13.9 tonnes CO2e first class

A new car: 

4 tonnes CO2 Citroën C1, Peugeot 107, basic specs
8 tonnes CO2e Ford Focus Titanium
11 tonnes CO2e Renault Zoe (electric)
12 tonnes CO2e Toyota Prius plug-in hybrid
25 tonnes CO2e Range Rover Sport HSE

A wind turbine: 

30 tonnes CO2e 15-kW turbine, installed
500 tonnes CO2e 15-kW turbine, 20-year payback
134 tonnes CO2e a 100-kW turbine, installed
2619 tonnes CO2e net savings over a 20-year lifetime
1046 tonnes CO2e a 3MW turbine, installed
81538 tonnes CO2e net savings over a 20-year lifetime

Space tourism and travel: 

330 tonnes CO2e Blue Origin New Shepard tourism flight
600 tonnes CO2e SpaceX Falcon 9 flight to the International Space Station
7060 tonnes CO2e Space Shuttle flight
10,300 tonnes CO2e first flight to the moon, 1969

Having a child:

210 tonnes CO2e baby born in 2020 into a family with a UK-typical footprint who then respects climate science
775 tonnes CO2e same baby with the UK's current carbon footprint
5000+ tonnes CO2e baby who grows up to be both wealthy and carbon-careless

A volcano:

1 million tonnes CO2e Mount Etna in a quiet year
5 million tonnes CO2e Holuhraun eruption, Iceland, 2014
42 million tonnes CO2e Mt Pinatubo, Philippines, 1991

The Football World Cup: 

2.8 million tonnes CO2e 2010 South Africa World Cup
2.7 million tonnes CO2e 2014 Brazil World Cup
2.2 million tonnes CO2e 2018 Russia World Cup

A new coal mine:

8.4 million tonnes CO2e Woodhouse Colliery, Cumbria

Cryptocurrencies: 

46 million tonnes CO2e Bitcoin in 2019
68 million tonnes CO2e all cryptocurrencies in 2019

Wildfires: 

923 million tonnes CO2e Australian bushfires in 2019
8.6 billion tonnes CO2e global wildfires in 2019

A war:

9 million tonnes CO2e UK military bootprint in 2019
200 million tonnes CO2e US military operations in 2019
400 million tonnes CO2e Iraq War, 2003-19
690 million tonnes CO2e 'limited' nuclear exchange of 50 15-kilotonne warheads
3.3 billion tonnes CO2e annual global military bootprint

Black carbon: 

9 billion tonnes CO2e globally per year

Burning the world's fossil-fuel reserves: 

5.3 trillion tonnes CO2e burning the 'proven reserves' of conventional coal, oil and gas
9.3 trillion tonnes CO2e add tar sands and shale oil
45 trillion tonnes CO2e burn all recoverable resources