Charlie StrossJun 4, 2023

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
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 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 Powell

@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

Jun 5, 2023 at 7:19amWeb
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.