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Comment by mikeash | Hacker News Reader

That’s not true. They produce more sulphur dioxide, a pollutant that cars don’t emit much of in general, and which the heavy fuel used by ships generates in abundance. Somehow the story morphed from “a few ships emit more of this specific pollutant than all cars” to “more pollution” to “more CO2.”

The entire worldwide shipping industry accounts for about 3% of humanity’s CO2 emissions.

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And how does that 3% compare to the total CO2 from personal vehicles?

"Road transport" was 16.5% of global emissions in 2008: https://www.who.int/sustainable-development/transport/health...

Road transport includes all transportation on roads, which isn't passenger vehicles. Passenger vehicles are less than half of that and growth of the CO2 emissions from passenger vehicles is nearly flat year over year. The maritime shipping sector, on the other hand, is growing emissions output as much as 75% every 15 years.

> The entire worldwide shipping industry accounts for about 3% of humanity’s CO2 emissions.

To my knowledge personally owned vehicles account for a similar percentage of total CO2 output, so that number while small is a red herring. People tend to generate more CO2 per capita as a result of air conditioning than from the vehicles they drive.

It's quite believable that passenger cars also account for something the neighborhood of 3% of total CO2 emissions. My point was not to say that shipping is completely irrelevant, it's to point out that it is not so grossly overpowering as your original comment suggested. The idea that a handful of ships match the CO2 emissions of all cars is completely divorced from reality.

If you want to find the exact number that cars account for, I'm sure you can find it. Just don't use whatever source you got that initial CO2 claim from.

Do you have sources for all of these claims?

You are very incorrect on most of what you've posted here, but this is embarrassing since you could verify this with basic math.

An air conditioner typically consumes in the neighborhood of 4kW, less than half the day, less than half the year.

So, being generous, 6000kWh annually for air conditioning.

Gasoline has the equivalent of 34kWh/gallon, which implies air conditioning uses the equivalent of 176 gallons of gas per year.

The average person in the US drives over 13,000 miles per year. The average car gets 25 mpg. That is 520 gallons.

> which implies air conditioning uses the equivalent of 176 gallons of gas per year.

Yes, cars do produce more CO2 than air conditioning, but in the context of CO2 emissions, you can't just compare "equivalent of gas gallons".

First, not all electricity is generated from fossil fuels (63% in the US, much less e.g. in many parts of Europe).

Second, to produce 6000 kWh of electricity from fossil fuels, you have to burn much more than the theoritical amount, because the efficiency of conversion is much lower than 100% (although in cold climates you may use combined heat & electricity production).

In the end these are irrelevant details, as we must stop burning fossil fuels anyway. Every part of the chain is important, and the argument "but x produces even more CO2 than y, so I keep using y" is of course stupid.

> An air conditioner typically consumes in the neighborhood of 4kW

That is not true globally. I live in Kuwait, which can get up to 140F during the day in the summer.

At any rate if you want numbers (since people are crying about research without doing any of their own) here are some: https://news.ycombinator.com/item?id=19438999

How many days was Kuwait over 130F last year?

Most days May through September experience an average high of actual temperature of around 120F each day with 100% sunshine. Its the heat index that brings it up to about 140F. You have to understand that during the summer here there is relatively lower humidity during peak sunlight which refracts less light before hitting the ground. The ground here is also highly reflective of heat, which is felt at least 5 to 6 feet off the ground (the height of most people).

Another way to look at (and there is a lot of data on this) is which nations produce the most CO2 per capita and then work backwards asking why that is.

Developed countries with high car ownership and countries with very small populations and very large hydrocarbon extraction industries.

That isn't accurate either. The country that outputs the highest CO2 per capita is Qatar. Qatar left OPEC within the last year because their oil extraction is so low. Qatar's primary hydrocarbon extraction is LNG (liquefied natural gas) which is a low CO2 emitter relative to oil refinement.

Also, most the countries here have a higher than average population density compared to the global average due to a small geographic footprint.

Trinidad & Tobago, Australia, and Turkmenistan are high in addition to Qatar. What they all have in common is they are high LNG exporters, which involves liquifaction trains. LNG liquifaction trains are extremely CO2 intensive, along with heavy oil refining (see Curacao, Aruba, et al per capita CO2)

In reality difference is probably 4x - household has two cars and AC is shared over 2 people.

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