What life-style decision can I make to reduce my carbon footprint most efficiently?

Question

I'm interested in the sustainability, especially the carbon footprint, of life-style decisions regarding:

• transportation (i.e. get an electric car, use bike and public transport)
• dietary: going vegan or vegetarian
• home efficiency (i.e. using led lights, etc.)
• proactive investing in carbon sink (i.e. fund no profits against deforestation, planting trees).

My major goal is to fight carbon emissions, so I'd like to know the order of magnitude of these different actions. What I already do: I currently don't eat meat, but rarely fish, eggs. More often diary. I live in a small apartment with my girlfriend in the city center (northern Italy), I'm able to walk and ride a bike for many of my movements. We share a methane car. I donated last year to treesforthefuture.org, and other ngos related with afforestation, and compensated a year of carbon emissions. I try to buy local veggies from a friend.

Answer 1

The simplest rule to follow is this:

Buy Less Stuff

Some people replace large articles of furniture (couch, fridge, bed) every 3-5 years, often for reasons of style or fashion. That stuff has to be made and shipped to where you buy it. If you keep those things for 30 years (which is by no means impossible or even particularly difficult) you have a big impact.

Some people buy food half made for them in boxes, bags, and cans. That requires shipping raw ingredients to a factory, building and running a factory, and shipping the finished goods to the store. Buying meat from the farm yourself (especially if you didn't drive to it) has a lower carbon footprint than buying Tofurky or Hamburger Helper and not eating meat. The "stuff" that is the box, bag, can and the time-and-effort of the factory people is stuff you don't need. Buy raw ingredients and cook them. Buy them from the farm if you can.

Some people own many pairs of shoes, dozens of shirts and pants, a cupboard full of candlesticks and placemats and gadgets and knickknacks. Every one of these items has to be made (from cloth, petroleum products, metal, whatever) in a factory that had to be made, and so on. If you don't buy these things, you save all that footprint. How many candlesticks does one home need?

Sure, walk or bike when you can. Take public transport. Eat less meat. Use LED bulbs and don't waste electricity. But the biggest impact you will ever have - on the planet, on CO2, on your health, and on your retirement savings - is to Buy Less Stuff.

Answer 2

I already provided an answer to this question here, which was written based on personal experience and knowledge, but in this second answer I wanted to address some interesting details and specific measures I found online.

Paper 1

A recent survey paper from the University of Lund says that the best lifestyle choices to reduce your footprint are:

 1. Having 1 less child              saves about 58.6 tons CO2e/year*
 2. Living car free                  saves about  2.4 tons CO2e/year
 3. Avoiding air travel              saves about  1.6 tons CO2e/year
 4. Eating a plant-based diet        saves about  0.8 tons CO2e/year

*Assuming you live in a developed country.
This number will be lower if a developed country reduces its footprint

Paper 2

Similar measures but with different numbers were presented in this Dutch news article from 2015. The article was based on scientific research by a Dutch NGO called 'Milieucentraal', who's goal it is to inform the public about energy and the environment. According to Milieucentraal the average Dutch household (2.2 persons) emits 23 tons of CO2 per year. The 3 largest areas are:

Transportation      5.6 tons CO2/year per family, 
                        4.0 for car use
                        1.4 for flying
                        0.2 for public transport

Food                5.6 tons CO2/year per family, 
                        2.3 for plant-based food
                        1.9 for animal products
                        1.3 for other (including bars and restaurants)

Energy use at home  4.1 tons CO2/year per family
                        3.0 ton natural gas
                        1.1 for electricity

Source (in Dutch): NOS news article. Note that the latest version of the Milieucentraal website has slightly different numbers for the totals but doesn't list subcategories.

Milieucentraal also investigated the best measures you can take to reduce this footprint:

 1. Take the train to work instead of the car (about 180km return trip) 7500kg CO2/year
 2. Don't fly to your holiday destination (24000 km return trip)        5400kg CO2
 3. Place 15 solar panels on your roof                                  1800kg CO2/year
 4. Insulate your walls                                                 1600kg CO2/year
 5. Insulate your roof                                                  1400kg CO2/year
 6. Insulate your floor                                                  600kg CO2/year
 7. Buy a smaller car (and rent a bigger car when you really need one)   500kg CO2/year
 8. Use an energy monitor and check which appliances consume most        400kg CO2/year
 9. Efficient/reduced heating (close doors, turn down heat at night)     360kg CO2/year
 10. Reduce food waste by a half                                         350kg CO2/year
 11. Don't eat meat 2 days a week                                        320kg CO2/year
 12. For short distances take a bike instead of a car                    310kg CO2/year
 13. Drive your car efficiently                                          290kg CO2/year 
    (shift to high gear quickly, use cruise control, check tyre pressure)
 14. Don't buy food that's flown in or is grown in heated green houses   200kg CO2/year
 15. Evict high-consuming energy appliance                               190kg CO2/year 
    (e.g. aquarium, 2nd fridge, waterbed, sauna)                         
 16. Install a more efficient shower head                                120kg CO2/year
 17. Dry your clothes outside instead of in the dryer                     90kg CO2/year
 18. Shower one minute shorter                                            60kg CO2/year
 19. Wash clothes at low temperatures                                     25kg CO2/year

Source (in Dutch): http://www.klimaatklappers.nl

Answer 3

My answers are from general browsing on reputable American environmental news and urban planning websites so forgive me for not citing scientific and exact research.

transportation (i.e. get an electric car, use bike and public transport)

In Italy the gas tax for gas and diesel is enough to discourage excessive driving or large SUVs. Buying electric or hybrid car will not offset carbon that much because you still have to charge the car. Can't be certain your electricity company uses a renewable energy source and not coal.

dietary: going vegan or vegetarian

Those ideas are nice and healthier but the transport of goods uses gas. Unless you're buying from a local farmer can't be certain they're not importing it from across the continent or country.

home efficiency (i.e. using led lights, etc.)

One LED bulb lasts 7-22 years and uses less power than CFL and incandescent so this is a effective way to reduce carbon footprint.

proactive investing in carbon sink (i.e. fund no profits against deforestation, planting trees).

Donating money to plant trees and maintain forests is noble but unless you buy lots of acres of rain forests it's hard for the common person, non-billionaire, to make an impact.

Answer 4

Living in a dense (vertical) city with public transport. I explained it in details all over the place

https://sustainability.stackexchange.com/a/2417/476 - you cannot use trees to capture CO2 https://sustainability.stackexchange.com/a/2398/476 - using neighbours for heat isolation https://sustainability.stackexchange.com/a/2402/476 - composting in NY city

This way, you can reduce energy and all other wastes tenfolds compared to average "middle class" lifestyle and achieve sustainability. Bill Rees, the author of "ecofootprint concept", has finally came to the same conclusion.

https://youtu.be/ugv0OY6LyuE

Afterwards you can look at lightening electronics, garbage separation/recycling and more vegetarian diet. But these are ridiculously tiny savings compared to what you save migrating from your suburb into a dense city. In dense city you have 10-100 closer distances to everything and share almost every piece of infrastructure, whereas suburbs enable/demand evrything privately, and you consume immense reousrces starting from the precious lands. You consume tens times more lands if you own a beatiful house with grass than living in a flat in 10-floor building. You heat not only your flat but living rooms of your neigbours, so heating is shared, whereas in private house you have a large surface area leaking the heat. Furthermore, heat power plants produce hot water and heating, which can be used only in a dense city because you cannot distribute hot water over large distances. You get heat for free in dense cities! The pipes, electiricty channels all are tens or thouthands times shorter in dense city. One street lamp in a vertical illuminates thouthands of people whereas ten lamps are needed to illuminate a single person in suburbs (see these sick astronomers look at the form of the lamps and do not notice that they can have 1000x less of them if collapse all this 1-floor infrastructure into one big building). Guess what savings and light pollution is in both cases. Public transport is more effective than car (energy waste per person/distance) and travels considerably shorter distances, giving 10-100 time energy savings over private car in a "human friendly suburb". See, we have 10-100 overconsumption of everything, thanks to horizontal infrastructure of private cottages. Capitalists need to increase consumption, regardless of the Earth consequences. Sustainability is a communist thing. That is why ruling class will tell you distract you looking for "new sources" and "sequestration" instead of saving that your dream, to have a nice house in beatiful place, is what causes all the environment collapse.

Answer 5

General recommendations

In many households in the developed world the largest sources of CO2 emissions are transportation (car fuel), electricity, heating and food. This means that the average household can reduce its carbon footprint most effectively by taking measures such as:

• installing PV panels to generate electricity
• buying an electric vehicle (assuming you can charge it with renewable energy)
• take public transport more often
• switching to a meatless diet
• insulate your home

Indirect CO2 emisisons from stuff you buy may also have a big impact, so it's always a good idea to reduce your consumption where possible, and reuse things as much as possible.

Personalised recommendations

Personalised recommendations are rather difficult. There can be very big differences in the CO2 emissions of the average household per country (see for example this list), but it could also be that you've already taken measures and that you are far from being an 'average household'. Consequently it's best to carefully investigate your own lifestyle yourself to see where improvements can be made.

A good way to start is to check a few online carbon footprint calculators to find out how much CO2 emissions you are currently responsible for. Carbon footprint calculators are far from perfect (see also this article), but it's probably the best we have for personalized recommendations. There is a short list of calculators in this site's carbon footprint tag information, but there are also many others. Some calculators, like the Cool California calculator for example, show intermediate results for different categories. This way you can see what currently is your biggest contribution to CO2 emissions, and by tweaking with the parameters you can try to find out what reductions may be possible for you.

To get the most accurate result I recommend selecting calculators that were developed in your country of residence, or that at least allow you to select the country where you live (and hope they use recent and accurate data to make the calculations). I also recommend checking the results of more than 1 calculator, unless you are quite positive the calculator is founded on scientifically sound principles and uses recent and relevant data. Note that not all calculators include indirect CO2 emissions (that were emitted to manufacture a product or service before you started using it), so be careful when comparing results between several calculators.

Alternatively if you really want to make an effort and love spreadsheets and tweaking parameters, I recommend using the GHG emissions spreadsheet created by the EPA.

Tree planting

AFAIK there are no carbon footprint calculators that also show how much you can reduce your CO2 footprint by participating in a tree planting scheme. The efficiency of such a scheme would depend on many things such as; the type of tree planted, the geographical location where they are planted, the amount of space a tree has to grow, and the lifespan of the tree.

A figure you encounter often is that a tree can absorp up to 48 lbs of CO2 per year, but note that this figure is a maximum so the average CO2 absorption during it's lifespan will be lower. To give a rough estimate: a tree will generally absorb around 1 tonne (about 2200 lbs) of CO2 during it's life-time. However, the actual reduction of CO2 will be lower than this calculated amount because the CO2 will be released again once the tree dies. Tree planting alone will never be enough to compensate for all the CO2 that is emitted, so ultimately other solutions are needed. If you do decide to participate in a tree planting scheme, be careful that the particular scheme is legit and doesn't introduce monocultures because this may reduce biodiversity.

Answer 6

Becoming a vegan is the fastest way to do this. Check out this film for clear evidence:http://www.cowspiracy.com/facts/