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Comment by epistasis | Hacker News Reader

I'm mainly focused on California, with a bit of a look at the US. Transportation is the biggest single sector source of emissions, and completely dwarfs agriculture:

CA (41% of emissions): https://ww2.arb.ca.gov/ghg-inventory-data

US (29% of emissions, PDF page 3): https://www.epa.gov/sites/production/files/2021-04/documents...

Industry is a big emitter as wel, but it also dwarfs agriculture. And since California is such a major agricultural exporter, it's not like it's offloading their agriculture emissions.

When I see people talking about meat as a big contributor to emissions, I assume that they are trying to drive a political wedge to stop any climate action. Not eating meat has a small effect for the climate, but causes absolutely massive political and cultural backlash. And it's quite likely that we will become carbon negative by 205-2060 without decreasing meat consumption.

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Not trying to poke holes in your theory because it's been enlightening to me, but wouldn't it make more sense to look at the global statistics? I think since it's a global problem, it might be a mistake to take an overly US-centric (or worse yet, CA-centric) perspective.

In that context of global use, industry (29.4%, if you add industrial and cement/chemical processes) does exceed road transport (11.9%) and total transport (16.2%). For that matter, agriculture (18.4%) is still higher than transport. I think the GP claim that transport "doesn't hold a candle" to ag/industrial emissions is a bit aggressive, but it's not as lopsided worldwide as the data you shared either. To be fair, the data is 5 years old so maybe the proportions have changed.

https://ourworldindata.org/emissions-by-sector

Good questions!

I think policy at a particular level of government should be devoted to the domain that it controls.

So at the local government level, I advocate for the most influential policy, based on the numbers of what's being emitted there. In my small coastal community, replacing natural gas with heat pumps has a huuuuge impact on emissions. In most of the SF Bay, land use and allowing housing near jobs is by far the most impactful change.

If we are setting policy globally, sure, focus on global numbers, but we don't really set policy globally. Individual governments make broad promises for reductions, but it would be a mistake for a government to base their actions on global numbers rather than their own numbers.

I don't think that decarbonization is solvable through personal actions, but when I'm looking to change my personal impact, I look at what my actions are doing, not what the average person's actions are doing.

This seems like a bit of contradictory logic to me regarding focusing on local policy and then stating that hyper-local decisions aren't enough to solve the problem. It's hard for me to ascertain from your response where the effective policy threshold is set. From your perspective is it at the personal, local, state, nation-state, or global level where it's sufficient to solve the problem?

Policy can be (and is) created globally. I think we can impart global climate policy, but only to the level the individual state actors are willing to hold others accountable. If your local community bans natural gas fired heating, but also doesn't hold people accountable for breaking that standard it's not going to be an effective policy. Global policy is very much the same.

In the US, local policy is the best we have for changing land use at the moment. I'd love nothing more than for states or the feds to wrest control away from municipalities and counties, since local levels do not have a good understanding of land use. However, acting on the local level does not preclude acting at higher levels. It's just that both changing policy and changing who controls the policy might be a bigger challenge than working within the current separation of powers.

And even though local communities only change small parts of a system it's still changing the system, and demonstrating to other cities what is possible. My planning commissioners think that apartments "destroy" neighborhoods. When they see nearby communities adopting apartments without neighborhoods getting destroyed, it makes change more likely.

One thing about setting policy at a higher level is that it would still have the same effect that lower levels should enact to optimize their decarbonization path. Even if global policy is the same, different regions have different decarbonization paths.

That’s because those statistics are ignoring CO2 from economic activity. A Californian buys a computer manufacturered in Asia and these statistic only count the CO2 created to move it from the harbor to their house. All the CO2 from manufacturing, mining, and transporting it across the ocean are ignored.

So I take it that you agree that transportation dwarfs agriculture?

As far as Foreign imports of consumer goods accounting for a huge chunk of our carbon, that claim has never held up when I investigated it. In particular, Our World in Data had some fantastic plots showing that, though I don't have time to locate them at the moment.

Could I turn the tables on you and ask for some substantiation of the claim that import of consumer goods is a major source of emissions attributable in the US? Because the amount of carbon that goes into making a computer seems pretty trivial compared to that of making a car, and from burning a gallon+ a day.

Also, for evidence of the inherent sustainability of urban areas over suburban areas, check out these maps:

https://coolclimate.berkeley.edu/maps

I forget if they account for carbon from imported goods or not, but it's a consumption based inventory, rather than the typical production based inventory.

I found a bit of time to do some digging. My conclusion: US transportation is about 7x the emissions of the products we import from China.

The embodied carbon in Chinese exports peaked in 2008, and has been decreasing, the most recent estimate I found was 1.4Gt in 2015 [1]. This is already less than the US transportation emissions of 1.7Gt in 2015 (from the EPA PDF I linked above).

And the US share of that 1.4Gt is only about 18% (409/2273B$ [2]), for about 0.25Gt of CO2 equivalents.

[1] Fig 1C https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/201...

[2] https://wits.worldbank.org/CountryProfile/en/Country/CHN/Yea...

By your analysis Hong Kong’s share of that 1.4 Gt would be 14.5%, which hardly seems reasonable.

Cold you say more about that? You seem to be saying that you don't believe that HK is the second largest export market, but that's not my analysis, that's the numbers available from pretty much any source you can find.

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