In 2023-24, the global temperature was more than 1.5℃ higher than in 1940, resulting in more than 10 record extreme weather events. The climate is now hotter than any time in the 3 million years human ancestors have existed.
We are on a trajectory for 4 degrees temperature rise by 2100; it has not been that hot since the Eocene epoch 35 million years ago.
To prevent a global temperature rise of more than 2℃ by 2040, carbon emissions will have to be reduced by 50% by 2035. The world’s 1.8 billion high to upper middle income people need to take responsibility for achieving 2/3 of this – more than 30% of global emissions – by changing their high emitting consumption habits.
Governments have been focused on emissions reduction targets and strategies for industrial production sectors, which have so far not reduced emissions globally. The crucial 50% emissions reduction is achievable, but only if strong consumer-side policies are enacted.
The reason emissions will have to be halved quickly is that the Earth’s oceans and biosphere can only assimilate about half of global carbon emissions, which were 53 billion tCO2e in 2023.
Atmospheric greenhouse gas concentrations are now increasing at such a rate that the climate will be at least 4℃ hotter than the 1950 – 80 temperature norm by 2100. Furthermore, the greenhouse gases already in the air won’t just disappear; 1/3 to 1/2 of every ton of fossil CO2 emitted will still be in the air in 1000 years.
Household emissions account for 55% (Australia, goods only) to 72% of global carbon. Here we assume an estimate of 64%, as we do not include commercial services.
Only 50% of current global emissions from all consumption sectors – household, government corporate and commercial – can be emitted if atmospheric concentrations of greenhouse gases are to stop rising. That means household emissions must fall from 64% to 32% of global emissions.
A simple computation – 0.32 * 53 billion / 8.1 billion people – equates to a Sustainable Personal Carbon Footprint (SPCF) of about 2 tCO2e person per year for everyone on the planet.
Five billion poor to low income people in the world already emit less than 2t CO2e per year. Therefore it is up to the 21% with incomes more than $7,300 per year. In particular the high income class earning more than $18,000 per year, which of course includes us.
Note: CO2e means “carbon dioxide equivalent”. CO2e is a measurement of the total greenhouse gases emitted, – CO2, methane, nitrous oxide and trace pollutants – expressed in terms of the equivalent warming potential of carbon dioxide. On the other hand, CO2 means carbon dioxide emissions only and is about 75% of CO2e.
Urban dwellers can achieve a carbon footprint of less than 3 tCO2e using existing technologies, while at the same time reducing living costs and having healthier lives.
Technology carbon may facilitate further embodied emissions reductions of up to 50% for non-meat foods, 20% for jet aircraft and 30% for other manufactured goods (author’s estimates) enabling the SPCF of 2 tCO2e by 2035.
By changing their consumption habits, average Australians can reduce their 12 tCO2e carbon footprints (Table 1) by 75%. That is 9 tCO2e (Table 2), over 6 tonnes of which are from the ‘mega-emitting’ items described below.
– Large personal vehicles – in particular those powered by fossil fuels.
– Red meats and bottled drinks.
– Flights and cruises.
– Excessive fossil fuelled home heating/ cooling and pool pumps.
Table 1. Average 12 tCO2e personal carbon footprint of people in Australia
Note: Table 1 reflects average personal emissions in one high income country – Australia. There are huge differences in the size and composition of individual carbon footprints globally. For example:
- Some frequent fliers are accountable for > 20t CO2e each year from jet aircraft alone. People in cold countries are likely to have much higher emissions from home heating.
Large personal vehicles
There are nearly 1.5 million cars on the planet in 2024; more than 98% are fossil fuelled. They are the fastest growing source of emissions, accounting for 11% of global CO2 emissions when embodied emissions are included.
The greatest footprint reduction – two to five tCO2e – can be achieved by changing personal transport habits. Large fuelled passenger vehicles such as 4WD wagons and pickups typically emit 6 tCO2 per year, three times the SPCF. They should not be used driver-only commuting or errands.
Small EVs together with e-bikes and electrified public transport – which is healthier as it is active transport – are the only passenger transport modes likely to enable a SPCF.
Red meats and bottled drinks
Red meats account for about 8% of global carbon emissions, mainly methane from ruminant digestion and CO2 from deforestation. Eating 1 kg of steak accounts for 25 kg of carbon emissions. Reducing consumption by 1 kg per week removes about 1.25 tCO2e per year. Red meats can be replaced by healthier protein rich foods such as plant proteins, chicken, fish, cheese, beans and eggs.
Bottled drinks are the other big dietary emitter. Substituting 1 litre per day with drinks in reusable cups, made at home or in cafés removes about 0.8 tCO2e from a carbon footprint, while saving up to 1000 bottles.
Food comprises over 50% of sustainable carbon footprints even when low carbon diets are adopted (Table 2). Future electrification of tractors and pumps together with improved agricultural nitrogen practices will likely enable substantial emissions reductions from non-meat foods.
Excessive fossil fuelled home heating/ cooling and pool pumps
Energy use in residential buildings accounts for 11% of global emissions. About 60% of it is from space heating and cooling. All space heating, water heating and cooking should be changed from gas and oil – which are linked to respiratory diseases – to clean electric appliances, in particular heat pumps.
Pool pumps and water heaters can be timed to operate only for a few hours in the middle of the day when solar energy is available. Despite using more electricity, typical carbon footprints can be reduced by more than 1 tCO2e when 90% renewable electricity (RE) is used, either by installing PV panels or purchasing renewable grid electricity.
In Australia, 82% renewable energy is part of a legislated 43% emission reduction by 2030 target. Ninety percent RE could be provided at less cost than the existing 60% fossil fuelled electricity. It will slash emissions from EVs, home appliances and water supply.
Flights and cruises
Air travel is very carbon intensive and inequitable, with 1% of the world population accountable for 50% of emissions from this source. Flying around the world economy class emits about 4 tCO2. This figure is at least doubled when contrails and nitrous oxides are taken into account and increased by three to nine times again when occupying business or first class seats.
Some frequent fliers fly hundreds of thousands of km per year, incurring more than 20 times the sustainable carbon footprint. Sustainable carbon footprints are unlikely to accommodate more than an average 1000 km flown per year.
Carbon fuels are the only foreseeable option to power medium and long haul commercial jet aircraft. Emissions reductions of up to 20% by 2035 will only be possible if all airlines adopt economy-only seating, maximum loading and use 10% sustainable aviation fuels.
Other
The other 30% of household reductions are mainly embodied emissions, summarised in Table 2, rows 5 to 11. In short, they are:
– Curtailing purchase of packaged products and newspapers.
– Re-using or recycling everything; buying fewer than 10 new clothing items per year.
– Reducing housing space to 40 sq m per person, similar to most Europeans (current Australian and US average is more than 80 sq m).
– Hire, rather than own, large leisure items such as boats and caravans.
Table 2: Example of a low carbon footprint of 3 tCO2e, achievable in 2024.
Will 1.8 billion people in the world embrace the SPCF of 2 tCO2e, when many exceed it 10-fold, there is no cost or stigma associated with climate pollution and much of the economy produces high-emitting items?
There is hope, as the inequity of carbon footprints is starting to be reported in the media and a many people have decided to make the shift to healthier low carbon lifestyles.
For example, I have already given up my high emitting habits and have maintained a carbon footprint of 3 tCO2e per year for the last five years.
I live with my wife in an outer suburban unit with a 5 kW PV system, commute 12,000 km a year in micro-EVs and public transport and travel 4,000 km a year for holidays in my home state of WA.
I do not consume red meats and minimize bottled drinks. Having not flown for four years, next year I will be due for one interstate flight. It helps to know one’s carbon footprint; a free calculator is downloadable here.
Many voters are realising that the status quo has not worked. The major political parties have failed to take effective action on global heating because they have been captured by the interests of fossil fuel corporations and marketers of high emitting goods.
Ongoing ‘grass roots’ actions need to continue, raising community awareness and convincing voters to elect governments that will prioritise climate action over corporate profits from fossil fuels.
Governments need to ban advertising of fossil fuels and high emitting goods, implement education campaigns and enact tiered sales taxes and incentives. Rationing of some mega emitting consumption items such as jet flights and cruises will probably be necessary.
Social Cost of Carbon Mortality of Items (SCCMI) is a policy tool that can be used by policy makers and in awareness campaigns. The monetised social cost of a tonne of CO2 emitted is estimated to be $400 – $700, which incidentally is close to the cost of ‘direct air capture’ of CO2.
If the world’s high and upper middle income nations succeed in attaining consumer carbon footprints of 3 tCO2e, the crucial 50% global reduction by 2035 can be achieved. Net zero emissions by 2050 may then not be a dream and today’s grandchildren may not be forced to live in a 4℃ hotter climate.
Appendix 1
Production Sector | Sectors – Percent of global emissions* | Estimated Emissions reduction by changing personal consumption (%) | Sectors -percent reduction of global emissions from changing to low carbon consumption |
| Cars – fuel plus 20% for embodied emissions | 11.0% | 80% | 8.8% |
| Red meats | 8.0% | 90% | 7.2% |
| Energy used in residential buildings | 11.0% | 30% | 3.3% |
| Flights (including NOx and contrails) | 5.0% | 80% | 4.0% |
| Other – upstream emissions of oil and gas used for cars and homes | 5.8% | 26% | 1.5% |
| Other – embodied – food, paper, landfills | 3.5% | 42% | 1.5% |
| Other – embodied – cement, chemicals in possessions and housing | 5.3% | 42% | 2.2% |
| Other – embodied – metals in housing and possessions | 7.9% | 13% | 1.0% |
| Other – Trucking, shipping, railing and piping of residential goods | 4.6% | 42% | 1.9% |
| TOTAL PERCENT of GLOBAL EMISSIONS | 62.1% | TOTAL REDUCTION IN GLOBAL EMISSIONS | 31.5% |
Table A1. Effect of adopting low carbon personal consumption on production sector emissions
