DarrellJun 5, 2023
Charlie Stross

Panama Canal’s Continuing Draft Reductions Pose Threat to Trade

Buried lede: it's due to a drought reducing water availability for the locks. Cause is climate change. https://maritime-executive.com/article/panama-canal-s-continuing-draft-reductions-pose-threat-to-trade

Panama Canal’s Continuing Draft Reductions Pose Threat to Trade

Concern is growing that a significant climate event is unfolding at the Panama Canal, with the potential of impacting one of the world’s most importan...

The Maritime Executive
Jun 4, 2023 at 5:49pmWeb
Show threadDNAvinciJun 4, 2023
@cstross
Pure ignorance about how the panama canal and locks work:
Wait... Do they use FRESH water for the canal? The furthest it can be from ocean is 40km. Is there some (bigger than digging the panama canal) engineering challenge to pumping salt water 40 km?
I'm sure the ocean level is higher than ever...
Show threadCharlie StrossJun 4, 2023
@dnavinci The Panama Canal crosses a mountain range—there's a huge drop-off. And it takes tens to hundreds of thousands of tons of water to flood just one of the locks. Pumping water in such volumes to such altitude would be horrifically energy-intensive, so it's designed to run from rainfall trapped in reservoirs.
Show threadTormod HalvorsenJun 5, 2023

@cstross @dnavinci

Thanks, I can't believe I never knew this. I also always assumed salt water from either ocean was used. Remembering learing about the existence of the canal in school, but never a word about the design of it. Live and learn, I guess... 🤯

Show threadAubrey PowellJun 5, 2023

@cstross @dnavinci I too hadn't realized it crossed fresh water until now! But from what I'm reading, "crossing a mountain" seems a bit misleading. The inland waterways are 85' above sea level.

That said, I think these are natural waterways and pumping salt water into them would probably be ecologically horrific.

Show threadAubrey PowellJun 5, 2023

@cstross @dnavinci Wait, sorry! Reading further (https://en.wikipedia.org/wiki/Gatun_Lake), it appears these waterways were created as part of the panama canal project. They aren't natural.

If I had to guess, they don't fill it with seawater because, while the height isn't that extreme, the VOLUME of water is so large that it would still be intensely expensive.

Gatun Lake - Wikipedia

Show threadCharlie StrossJun 5, 2023

@cifram @dnavinci A quick back of the envelope calculation shows that pumping the volume of water displaced by the ships using the canal to the height of Gatun Lake would, at 100% efficiency, use roughly 100% of Panama's electricity production (which is mostly from hydropower). Meanwhile it takes *more* water than that to move the ships through the locks, and pumps aren't 100% energy efficient, so that's a minimum.

Also the ecological damage of flooding a tropical rain forest with seawater ...

Show threadEd DaviesJun 5, 2023
@cstross @cifram @dnavinci Not to mention the ecological damage of cross-contamination between the two tropical oceans. Creatures stuck to the bottom of boats and in ship's ballast tanks and making their way through the Suez canal are enough of a problem without directly moving large quantities of water directly between oceans which have been effectively isolated for 3 million years.
Show threadGraydonJun 4, 2023

@dnavinci @cstross There were two competing canal plans; the one we have, using fresh water and going over the mountains in Panama, and a sea level canal through Nicaragua.

There is a Chinese businessman with forty-plus years left of fifty year rights to built and operate such a canal from the Nicaraguan government; the project is considered defunct but could wake up.

Lake Nicaragua is part of that route; "ecological disaster" is a mild term for salting it up.

Show threadGraydonJun 4, 2023

@dnavinci @cstross Probably the least awful option is massively upgrading the Isthmus of Tehuantepec railway connection, but that still involves loading and unloading ships.

The deeply crazed option would be various PANAMAX+ bathtubs and the world's largest funicular railway. (On the plus side, presumably you could use the braking energy from descending bathtubs to provide most of the energy requirements to lift ascending bathtubs.)

Show threadCharlie StrossJun 4, 2023
@graydon @dnavinci Or come up with a giant-sized versio of the Falkirk Wheel: https://en.wikipedia.org/wiki/Falkirk_Wheel
Falkirk Wheel - Wikipedia

Show threadDNAvinciJun 4, 2023
@cstross
Ah, for some reason I glased over the mountain part when doing my book report 25 years ago.
In retrospect it was a ridiculous decision, and that certainly fits with the rest of the shit-show that my 6th-grade comprehension had already identified
@graydon
Show threadGraydonJun 4, 2023

@cstross @dnavinci Would that use less water? I suppose you could build elevated canals and fill them with sea water, so it's "up, across, down", probably by stages.

A CVN will fit in the New PANAMAX locks, at least at the waterline. It'd be something to see photos off the flight deck edge at the top of either the funicular or the wheel. ("we can fly!")

Show threadVery Human RobotJun 4, 2023
@cstross
The climate crisis doesn't look like Mad Max, it looks like this!
Show threadTormod HalvorsenJun 5, 2023

@StompyRobot @cstross

It doesn't look like Mad Max YET, but damned if I dare to rule it out.

Show threadVery Human RobotJun 5, 2023

@airwhale @cstross
Well, TBF, some places DO look like that...

But crop failure and floods are much closer in time.

Show threadSimon WaldmanJun 4, 2023
@cstross A direct parallel there with the European waterway systems last summer, which saw coal barges 1/3 full to keep their draught down.
Show threadBruceJun 4, 2023

@cstross

Nicaragua may like it. There are the occasional rumblings about making a larger canal anyway.

Show threadDave Wilburn Jun 4, 2023
@cstross sure, but it's somewhat unfair that big boats only get stuck in the Suez.
Show threadex or current IDF unwelcomeJun 5, 2023
@cstross Back to old idea of using nuclear explosives to build a sea level canal
Show threadRegularSizePJun 13, 2023
@cstross they could easily fix this by installing desalination plants on both coast and returning salt to the oceans to make denser water and shore up freshwater security. Not enough profit unless they require Pepsi and Coke to bottle water from the sea for use in Central and South America.
Show threadCharlie StrossJun 13, 2023
@RegularSizeP Two problems. (a) Desalination is extremely energy-intensive, and (b) if you simply pump concentrated saline back into the ocean you kill the local ecosystem, which is adapted to a narrow range of salinity: you'd need to diffuse it over a huge area (more expense and energy-intensivity).
Show threadRegularSizePJun 13, 2023
@cstross (Thanks for Halting State.) The alternative is going to destroy those ecosystems anyways. We know the currents are slowing and the oceans are warming. Diffusion could be carried with unmanned spreaders. Energy wise, we are talking about pushing skyscrapers through a canal to avoid going around a continent. We have come a long ways in less than 200 years.