Here’s an image that feels too heavy-handed to be true, like a film student’s blundering attempt at metaphor. In the height of last summer, Europe shimmering under 104 degree heat, a coal barge carried fuel down the arid Rhine river, but it was only a quarter full. That was the most it could haul without scraping the bottom of the barely-flowing trickle the river had become. The coal was headed for recently fired-up, old power stations.

If you’re able to think past the thickly suffocating heat-haze of late last summer you might remember there was a string of articles about fantastic things emerging from river beds. Amazing old statues and carved rocks, all of them dire warnings that “if you see me, then weep” because they indicated deadly levels of drought.

In China huge areas of Sichuan were shut down, factories forcibly closed to conserve power. The Yangtze ran dry, revealing its own ancient statues and calling a halt to cargo shipments. The Mississippi took until February 2023 to recover its water level from the 2022 summer drought.

This wasn't happening in any specific part of the world, unless you count “the northern hemisphere” as very specific. And it wasn’t just a hot summer or a dry spell. It was a vision of what’s likely to get even worse over the next 10 years. Economies, much less ecosystems, are unprepared for the world’s rivers drying up.

Let’s start with the science. What keeps freshwater rivers flowing are mostly mountain glaciers. They can basically be considered natural water towers, storing ice and snow in the winter that melt and feed rivers in the summer. As climate change makes winters milder and summers hotter, glacier shrinkage has been increasing, with repercussions for Earth’s waterways that are quickly felt by humans.

Rapid glacier melt first poses a higher risk of flooding, but then there’s the more extended threat of not enough water flowing down from the mountains. The Alps, Hindu Kush, Pamir, and Himalayas are particularly badly affected, according to the most extensive study that’s been done into the situation, put together by ETH Zurich and the University of Toulouse. The Himalayas are particularly worrying, per the research, because without glacier meltwater, it’s possible the entire region will run arid (at temperatures MIT researchers warn will be unlivable for humans in the near future). In the Alps, there’s a less immediate threat of reaching a heat level that will cook your organs, but the problem is still going to bludgeon Europe with its bluntly obvious warning that we should have done something sooner.

This is where Earth’s near-groan-worthy metaphors come back into play. In 2022, the Alpine-meltwater-fed Rhine reached water levels measured as low as 2.4 inches in parts of Germany. That’s not navigable by ships, even only laden at a quarter of their normal load, which meant that Germany’s recently fired-up coal power stations (responding to a lack of natural gas after Russia’s invasion of Ukraine) were starved of the fuel that would otherwise be shipped up the then-dehydrated river.

That might sound like a way for nature to strike back. We cook the planet, she takes our fuel for doing it away. But an unpredicted and pretty immediate consequence of our complacency in the face of climate change might not be the dramatic wildfires and extreme climate events as much as everything just slowly, sweatily stopping. For months on end.

River transport isn’t talked about all that much unless you’re particularly interested in logistics and you’d be forgiven for thinking it’s something out of industrial history. Coal barges don’t really fit with the image of modern Germany but that’s how fuel, including oil, gets moved around, massively more efficiently than by road. In Germany, the Rhine accounts for 86 percent of inland shipping and is a vital route for coal and oil, as long as they’re still used. (Except when the river is dry, of course.)Twelve million tonnes shipped along it in the first five months of 2022,

To put it into perspective, it’s not dissimilar to how the U.S. nearly hit disaster last year with a planned railway strike that would have completely throttled goods movement, from crops to cars, across the country. But while you can argue with industrial action (and god knows the railroads tried), there’s no negotiating with a dry riverbed.

But back to Europe. At the same time as Germany was puzzling out the movement of coal, France was throttling its electricity network, running on low power after its system of relatively clean nuclear power stations had to be partially shut down.

Squabbling over the same dry Rhine, plants didn’t have enough water to cool reactors running at full pelt. The plant in Fessenheim, France’s oldest, had to be shut down in August over fears the river water it used to cool itself would be so super-heated it would result in mass die-offs of fish when it had been cycled through the reactor. By September the energy shortage was so severe France simply changed the law to let that happen. Nature takes away our rivers? We’ll screw them even harder.

Over in China, 8.2 billion tons of goods are moved around each year by river. Even during the lockdown-struck 2020, the Yangtze moved 2.9 billion tons alone. But in 2022, authorities in Sichuan had to resort to using gigantic drones and rockets to seed clouds and force rainfall, in order to get the power back on to factories dependent on hydroelectric dams. The economic impacts of extended shutdown in China’s sixth biggest economic region forced the desperate move, but it’s not one that can be pulled off regularly or as a long-term solution to a problem that’s going to keep happening.

In the U.S., parts of the Mississippi hit record lows in the summer and fall of 2022 due to extreme drought. Barges got stuck in the mud, freight traffic got backed up for days along the vital waterway, and cargo prices spiked. The river that 92% of American agricultural exports travel down was responsible for a $64 billion cost to on trade. It took $20 billion just to close marinas up and down the river. A bill to try to protect waterways, amongst other natural infrastructure, has been passed around Congress but is yet to pass.

The world runs on energy, as a physical process as much as a phone battery percentage, and the situation with rivers is going to keep cutting the world off from it. And it’s happening quickly. Back in 2019 the IPCC released a report into the effects of climate change on the Earth’s water systems that reassured us that despite falling river levels there was, as yet, only "limited evidence" that hydropower production would be affected. You can scratch that one out and put in a dead certainty, just three years later. No one writing the report would have suspected that coal would be the other energy casualty of droughts with the world supposed to be transitioning rapidly away from dirty energy production.

Switching from trucking to river freight is an environmental priority, too. Due to CO₂ emissions and the catastrophe that is tire particulate pollution, the waterways are a much better way to carry heavy loads. The EU’s green plan is to switch a "substantial amount" of the 75 percent of freight currently carried on roads to waterways by 2027, which is unfortunately going to be literally scuppered by boats being unable to navigate waterways. And the more we don’t switch, the worse we make the problem that's causing this dry-up in the first place.

There isn’t going to be a quick answer. The impacts of glacial retreat are, according to the latest (and last, until 2030) IPCC report, "approaching irreversibility" for some ecosystems and even clever drones and cloud seeding can't actually control the weather in the long term. Rivers have been systems of security since ancient civilizations but we might not be able to rely on them going forwards.

It’s been another warm winter, with not much to thaw for this summer. The dire warning the dry rivers are giving us is very much from this century, with record lows set to be seen again.

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