• nsawaya

Emissions: Where to begin?

The largest source of my aggravation in the climate change fight, these days, is not climate denial. Factually, yea, climate denial is our biggest obstacle, for reasons that I won’t talk about here. But if we’re talking about non-rational aggravation factor, the main source is the well-meaning liberals who do all the useless things they can think up, hoping that they’re helping. People who, when climate change comes up in a conversation, mention that they’ve reduced their plastic consumption. Or those who righteously chastise anyone who leaves a lightbulb on for a few extra minutes.

(Plastics are unrelated to greenhouse gas emissions, except indirectly and in ways that probably place them low on the priority list. And energy use from light bulbs is not a major emissions concern when compared to the big challenges. These are topics for other days though.)

The first step, if you want to take your own actions seriously in reducing greenhouse gas emissions, is to know which activities are worst for climate across society as a whole. Many governments and nonprofits track these emissions by “sector.” These sectors are arbitrarily defined, but getting even a loose feel for them can be immensely useful in deciding how to prioritize.

For example, if you find out that you live in an area that gets most of its electricity from nuclear/hydro/solar/wind, and that the biggest emitter is the transportation sector, this gives you clues as to what you can do. You don’t have to worry about lightbulbs, except in regards to your wallet. But, your next car purchase should be electric. The purchase has a multiplier effect, because even just a few new electric cars in your area put pressure on relevant institutions---workplaces, public garages, apartment complexes, your utility---to rapidly build out more charging infrastructure. Then anyone else will have an easier time charging their cars, making it statistically more likely that more EVs are sold.

Similar rough conclusions can be drawn from other data, but the point is that looking at some data should always be the starting point. It seems obvious in hindsight, but, in my experience, the average person who claims to care about climate change does not go through this simple process.

So here I’ll be dumping the relevant numbers for four “communities.” I live in California at the moment, so I’m including a breakdown of California, the US, and the world. I’m throwing in Sweden as well, because I’m Swedish and travel there frequently, and I’ve been loosely following energy and climate politics there for a few years. These numbers are likely available for whatever country or state you live in.

As far as I understand, emissions categorized as coming from buildings or commercial/residential exclude electricity and district heat. Electricity and district heating (where for example hot water is centrally produced and then distributed across a city) are given their own category regardless of the end-user of the energy. So I think I’m correct in saying that the emissions of buildings/commercial/residential refers not to electricity use, but only to natural gas use (for cooking and water/space heating), leaking of chemicals for AC and refrigeration, and perhaps some smaller effects.

You might think the world’s emissions are the least relevant, but that isn’t necessarily true. I posit that global data is useful mainly because it helps us decide which technologies need to get cheaper. For example, even though only about 2% of California’s emissions come from cement production, they are 8% of global emissions. (Yes, cement production on its own is a huge global emitter.) But it still makes sense for California lawmakers to reduce cement emissions, for example by incentivizing the invention of alternative materials. If an inexpensive low-carbon building material is developed in California, this will presumably make the new option available for anyone in the world, leading to GHG reduction far outside our borders.

The four communities:


41% Transportation

( Passenger vehicles 28% )

( Heavy-duty / freight 9% )

( Ships/planes/rail 4% )

23% Industrial

16% Electricity Sector

( In-state 10%; Imports 6% )

12% Buildings

( Residential 7%; Commercial 5% )

8% Agriculture


29% Transportation

28% Electricity

23% Industry

12% Commercial & Residential

9% Agriculture


14% Agriculture, forestry and fishery

29% Manufacturing, mining, construction

14% Electricity / gas / heat / water / waste

22% Transportation

15% Households etc.

7% Other

I combined some categories from the given reference, to make it more easily comparable to the other data. Note that Sweden gets the vast majority of its electricity from nuclear and hydro (both carbon-free).


25% Electricity and heat

24% Agriculture / forestry / land use

21% Industry

(Industrial heating: ~10%)

(Cement: ~8%)

14% Transportation

(Air travel - 2-3%)

(Shipping - 2-3%)

6% Buildings

10% Fuel production

(“other energy […] such as fuel extraction, refining, processing, and transportation”)

Use this data to prioritize the content of your conversations with family, your calls to elected officials, and your letters to the editor. As Al Gore says in that old Southpark episode: Excelsior!


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