Comment by netsharc

https://climate.mit.edu/explainers/freight-transportation

> While nearly three-quarters of the world’s cargo is carried by ocean-going ships, road vehicles like trucks and vans make up the majority, 65%, of freight’s emissions. Most ships burn fossil fuels and emit carbon, but they carry large amounts of freight at the same time, making them the most efficient way to move cargo. Road freight, however, can emit more than 100 times as much CO2 as ships to carry the same amount of freight the same distance. Road transport is also a fast-growing sector—80% of the global increase in diesel consumption can be attributed to trucks. E-commerce and home delivery are two reasons for this growth.

The distance from Shenzhen to Long Beach is some 300 times the distance from Long Beach to Pasadena, depending on where exactly in Pasadena and which route you take. The CO2 emissions factor for a truck is some 10-100x that of a container ship. The exact ratio depends on what kind of truck, and what scope of emissions are being included. The more one accounts for, the more it will favor the boat. But overall, the emissions from the oceanic leg of the trip are probably anywhere from 1-3x those of the truck.

The distance the boat has to cover is 11800 kilometers, and the truck covers only 54 kilometers. Taking that average of 12 times more usage from the table of sibling comment means the ship is still 20x worse.

Unfortunately a video but this covers it: https://www.youtube.com/watch?v=0aH3ZTTkGAs It talks about the meme about "pears grown in Argentina, packed in Thailand, sold in the US"

Gemini's summary about the shipping CO2 sections:

Shipping accounts for 80% of all international transport but only 37% of transport's carbon emissions (9:13 - 9:18).

Road transport is highlighted as the "King of pollution," making up less than 10% of international transport but over half of emissions (9:26 - 9:32).

Ferrying pears across the Earth is actually less carbon intensive than driving them in a truck to a packing plant across one's own country (9:48 - 9:52).

All international shipping combined is responsible for only 2.5% of global emissions (9:58 - 10:15).

I did some napkin math on this as I recently picked up a 3D Printer and wondered the environmental comparison to print-at-home vs pick something up at the store and I was surprised. Had some help from Claude but "last mile delivery" is absolutely where the majority of the kWh is burned in the supply chain.

Container ships use ~0.015 kWh per ton-km[1] and a car is ~1.35 kWh/km.

If you go to the store and end up getting >10 things it becomes "worth it" from an energy standpoint. Anything less printing at home seemed to be more economical... Not an expert though just saying it opened my eyes to how inefficient "last mile delivery" energy consumption is.

[1] https://www.withouthotair.com/c15/page_95.shtml (old reference)

If the goal is reducing carbon emissions, making shipping emit half as much (650 Megatonne to 325 Mt) would be less of a gain than making trucking emit only 80% of its carbon (2,230 Mt to 1,830 Mt).

The question is which is easier to do (ROI)... to cut the shipping fuel carbon footprint by half, or over the road trucking (that's about 1/4th of all the shipping) by 20%? For that matter, moving 25% of the over the road trucking to rail would accomplish that too.