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Trade is unprepared for the world’s waterways running dry.

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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Current conditions: A wave of summer heat is headed for the East Coast, with midweek temperatures surpassing 90 degrees Fahrenheit in Washington, D.C. • Guam and the Northern Mariana Islands are bracing for winds of up to 190 miles per hour as Super Typhoon Sinlaku bears down on the U.S. territories • At least 30 people have died in floods in Yemen, which just recorded its highest rainfall in five years.
The Trump administration is holding up some funding for grants at the National Oceanic and Atmospheric Administration, The Hill reported. On April 1, the University of Colorado put out a statement saying that a federal pause on funding had put scientists who collect data about the atmosphere “at risk for elimination” after the White House Office of Management and Budget had “not released these funds.” The university’s Cooperative Institute for Research in Environmental Sciences said that roughly 30 days before running out of funds to pay scientists, “we were informed that NOAA has put a pause on all grant actions.”
As I told you back in December, the Trump administration is also working to dismantle the National Center for Atmospheric Research in Colorado, an institution credited with many of the biggest scientific breakthroughs in our understanding of weather and climate over the past 66 years since its founding. In a post on X at the time, Russell Vought, the director of the White House’s Office of Management and Budget, called the institute “one of the largest sources of climate alarmism in the country,” and said the administration would be “breaking up” its operations.
Secretary of Energy Chris Wright is scheduled to testify Wednesday morning before the House Committee on Appropriations to defend the White House’s latest budget request for his agency. He’s not the only chieftain of a federal agency with relevance to Heatmap readers who’s coming before Congress this week.
U.S. Customs and Border Protection plans to launch the first phase of what’s called the Consolidated Administration and Processing of Entries tool in the agency’s automated commercial secure data portal to allow companies to request refunds of Trump administration tariffs the U.S. Supreme Court ruled unlawful earlier this year. Solar companies are among the thousands of American businesses that filed complaints with the U.S. Court of International Trade for refunds prior to the Supreme Court’s ruling. Those, according to Solar Power World, include American Wire Group, Canadian Solar, GameChange Solar, Fluke, Hellerman Tyton, Kinematics, JA Solar, Jinko Solar, Longi, Merlin Solar, Qcells, and Trina Solar.
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Established in early 2021, California Community Power is a quasi-governmental organization formed out of nine power providers across the Golden State. On Monday, the agency inked a series of deals with geothermal power developers to expand what’s widely considered one of the most promising clean-energy sources for California, which has some of the continent’s best hot-rock resources. XGS Energy, the Houston-based startup promising to build next-generation closed-loop geothermal systems, announced a deal to build 115 megawatts of power in the state. Zanskar, the geothermal company using AI to locate untapped conventional geothermal resources, also signed an agreement with the agency.
Zanskar in particular ranked among the most promising climate-tech startups on the U.S. market in Heatmap’s poll of experts earlier this year. The company last year announced its biggest find yet, Heatmap’s Katie Brigham reported last year. XGS, meanwhile, is drawing support from the nuclear industry, as I previously reported for Heatmap.
The developer behind a major Massachusetts offshore wind farm is suing its turbine manufacturer in a bid to keep the company from backing out of the project. By February, the Vineyard Wind project off Cape Cod had installed 60 of the project’s 62 turbines, as I reported at the time. Yet the parent company behind GE Renewables, the maker of the project’s turbines, said “it would be terminating its contracts for turbine services and maintenance at the end of April,” the Associated Press reported. GE Vernova, the parent company, says Vineyard Wind owes it $300 million already.
The war in Iran is taking a toll on Central African minerals. Miners in the Democratic Republic of the Congo are curbing output of copper and cobalt as the war cuts supplies of sulfuric acid needed for leaching minerals out of rock, Reuters reported. Mine managers are reducing cobalt production to conserve chemicals.
The deal represents one of the largest public-private partnerships in the history of the national labs.
I’ll admit, I thought I might be done covering fresh fusion startups for a while. In the U.S., at least, the number of new industry entrants has slowed, and most venture capital now flows towards more established players such as Commonwealth Fusion Systems and Helion. But in February, a startup called Inertia Enterprises made headlines with its $450 million Series A raise. It’s aiming to commercialize fusion using the physics pioneered at Lawrence Livermore National Laboratory, the only place yet to achieve scientific breakeven — the point at which a fusion reaction produces more energy than it took to initiate it.
That achievement first came in 2022 at the lab’s National Ignition Facility in Berkeley, California. On Tuesday, Inertia announced that it’s deepening its partnership with Lawrence Livermore, creating one of the largest private sector-led partnerships in the history of the national lab system. This collaboration involves three separate agreements that allow Inertia to work directly with the lab’s employees on research and development, while also giving the startup access to nearly 200 Lawrence Livermore patents covering fusion technology.
The startup’s team isn’t merely a group of enthusiasts galvanized by the national lab’s fusion milestone. Alongside Twilio’s former CEO Jeff Lawson and fusion power plant designer Mike Dunne, Inertia’s other co-founders is Annie Kritcher, a senior employee at Lawrence Livermore who has led the physics design for NIF’s fusion energy experiments since 2019.
“We’re not starting from zero,” Kritcher told me, putting it mildly. “And that was really, really important to me when I decided to co-found this company.” Or as Lawson told me after the company’s fundraise in February, “the government put 60 years and $30 billion into NIF trying to get that thing to work.”
The technical approach pursued by Lawrence Livermore — and now by Inertia — is called inertial confinement fusion. In this system, high-powered lasers are directed at a millimeter-scale pellet of fusion fuel, typically a mixture of the hydrogen isotopes deuterium and tritium. The laser energy rapidly compresses and heats the pellet to extreme temperatures and pressures, driving the nuclei to fuse and releasing enormous amounts of energy. But NIF didn’t build its system for commercial purposes. Rather, its primary mission is to support the domestic nuclear weapons stockpile by recreating the extreme conditions inside a nuclear detonation, allowing scientists to study how U.S. weapons perform without conducting explosive tests.
To translate the lab’s research into a commercially viable device, Kritcher explained, Inertia must significantly increase the lasers’ efficiency and power output, targeting a system roughly 50 times more powerful than existing lasers of its class. The startup is also working to scale production of its fusion targets to drive down costs and enable mass manufacturing.
Inertia is not the only company attempting to commercialize this general approach, however. Back in 2021, as Lawrence Livermore moved closer to its breakeven moment, the future founders of the startup Xcimer Energy were taking note. Convinced that the fundamental physics of inertial confinement had been proven, they thought, “if we’re going to do this, we have to do it now,” Xcimer's CTO, Alexander Valys, told me a few years ago. He and his co-founder quit their day jobs, and Xcimer went on to raise a $100 million Series A round in 2024. Others joined in on the hype, too — the Fusion Industry Association reports 13 fusion companies that were founded or emerged from stealth between summer 2022 and summer 2023, a record for the sector.
Kritcher told me that none are adhering as closely to NIF’s successful design as Inertia. “There are fundamental technical differences between us and the other laser approaches,” she told me, explaining that while Xcimer and others are using broadly similar methodologies to produce a hot, dense plasma, the underlying physics behind their plan diverges significantly. Xcimer, for instance, is developing a novel laser architecture that hasn’t yet been demonstrated at scale, along with a different fuel capsule design than the one validated by NIF.
Kritcher will be allowed to continue her work at the lab thanks to what the company describes as a “first-of-its-kind agreement” enabled by the 2022 CHIPS and Science Act, which allows scientists at the national labs to participate in commercialization efforts with the goal of accelerating the transfer of knowledge to the private sector.
For the fusion engineer, it’s the ultimate dream come true. She first arrived at Lawrence Livermore as a summer intern in 2004, just before her senior year at the University of Michigan, and “fell in love with the lab and the NIF project,” which was still under construction at the time. She opted to attend the University of California, Berkeley for her masters and PhD in nuclear engineering so that she could continue her work there.
“I was starstruck by the possibility of fusion energy and [it having] such a big impact on humanity, and that really kept me going for a long time,” she told me. But after the NIF facility was finally completed in 2009, it failed to achieve ignition by its initial 2012 target.
By then, Kritcher was a postdoctoral fellow, and attention at NIF began to shift toward supporting the nation’s nuclear stockpile. Fusion energy was “always in the back of my mind, driving me day to day,” she said, “but you sort of forget about it, and you lose a little bit of that excitement and spark.” Under her guidance, NIF ultimately reached that watershed moment, which has since been replicated numerous times. And when it did, "it just reopened all those old inspirational feelings and motivations and excitement and it was like a 180 turning point where we all just go, oh, fusion energy is possible again with this approach.”
Many of the lab’s employees feel similarly, she said, and this close collaboration will allow some of the nation’s foremost experts in inertial confinement to work with the startup across a range of technical capabilities, including “the laser side, the target fabrication side, the simulations team side, the code development side, our physics design side,” Kritcher enumerated.
Inertia is looking to bring its first pilot plant online in the “2030s to 2040s,” she told me. By contrast, Commonwealth Fusion Systems — the most well-capitalized company in the sector — plans to connect its first plant to the grid early next decade, while Xcimer is targeting 2035. Kritcher is unfazed, though. While she acknowledges that other companies might complete their facilities sooner, she argues that Inertia still has an upper hand given that NIF effectively serves as the startup’s demonstration plant, something no other company has built.
Not to mention that all of the sector’s projected timelines remain highly speculative. There are serious technical and economic challenges that would-be fusion energy companies will have to overcome — Inertia not excepted — and the industry’s status 10 years down the line remains anyone’s guess. What’s crystal clear, however, is that a serious new contender has entered the race.
Big questions about naval strategy and the oil economy with Cornell University’s Nicolas Mulder.
After negotiations between the United States and Iran broke down Sunday without a deal, the United States Central Command said it would “begin implementing a blockade of all maritime traffic entering and exiting Iranian ports” Monday morning.
It’s hardly like traffic through the Strait of Hormuz had been unencumbered before that. The strait has been largely closed to through traffic since the beginning of March thanks to the threat of Iranian strikes on ships going in and out of the Persian Gulf. That has remained the case even after the ceasefire deal was supposed to have opened up the waterway last week. Only a few countries have been able to get their tankers out, mostly those with close trade relationships with Iran, including China.
President Trump has been seeking to reverse that state of play and open the strait to non-Iranian traffic (e.g. oil, liquified natural gas, and fertilizer coming in and out of the Gulf states), whether by badgering European allies to help clear the strait and by having U.S. Navy ships traverse the channel to clear mines and demonstrate it’s safe to navigate. He appears to have ultimately settled on blockading the blockaders.
The president said Monday on Truth Social that 34 ships had sailed through the strait on Sunday, a number that has not been confirmed by third party sources. In the run-up to the U.S. blockade, about 10 to 12 ships were sailing through the strait per day, according to marine data service Kpler and The New York Times.
So, is the blockade an escalation of U.S. pressure on Iran? A violation of the ceasefire? A “pacific blockade” designed to pressure Iran without resorting to direct strikes? And how would it work, anyway?
I spoke with Nicolas Mulder, an assistant professor of history at Cornell University and the author of The Economic Weapon: The Rise of Sanctions as a Tool of Modern War, to try and get some of my questions answered. This interview has been condensed and edited for clarity.
Let’s start from the beginning. What is a naval blockade? And how does it different from typical naval warfare?
A naval blockade is actually interesting because it is a form of warfare that has been quite regulated for quite a long time already under international law. A lot of our modern understanding of the laws of belligerence and neutrality actually comes from blockades because they impose an important stricture on international maritime traffic. As a result, they raise all sorts of questions about who wars are fought between, and what wars mean for the civilian economies of the countries involved, and what they mean for the relationship of the belligerent states and third countries.
For most of U.S. history, the U.S. was not the blockader, but the neutral wanting to bypass blockades. The reason that the United States concretely intervened in the First World War and began to really involve itself with the power politics of Eurasia in 1917 is because it insisted on its neutral rights to trade with Britain when Germany had declared an unrestricted submarine warfare campaign that was effectively a blockade of the British Isles.
Even before that, the Union used it against the Confederacy.
In the 18th century, all the big great power wars — the Seven Years War, the various succession wars, the Napoleonic Wars — all of those involved blockades.
What I find interesting is that we have this ceasefire. We have these negotiations, which are apparently still going on. But then we also have the blockade. You seem to be arguing that blockades are a part of warfare. So, is this implying that the U.S. Navy is still potentially going to be shooting at stuff, even if there’s a so-called ceasefire?
That’s the big uncertain aspect of the current situation. We are not back into the same war that we were in last week before the ceasefire took effect. The way I would interpret this is that it’s a kind of fudge. From the perception of the Trump administration, it needs to do something to not look weak, but at the same time wants to avoid the risks of a full resumption of kinetic warfare and a massive air campaign, which they had pursued for six weeks to very mixed and disappointing effects.
The one historical parallel that I think can help us make sense of what they may be attempting to do now is the practice in the 19th century of “pacific blockade.” There were several conflicts, beginning in the 1820s with the Greek War of Independence and then through a whole bunch of Latin American wars and Asian conflicts, where European great powers would blockade small countries — not to declare war on them, but to prevent any of their ships from entering or leaving to put serious pressure on them.
What they were doing in that situation was to use wartime levels of pressure without initiating the full war because they knew that the target states were basically too weak to retaliate and did not have the naval power to contest that blockade.
How can we see this operation in Iran as part of a continuum of using these strangulation-type strategies against much weaker opponents?
One way to interpret what they’re trying to do now is to apply that Venezuela-Cuba template to Iran, and to wager that if they play this carefully, they might be able to bring real economic pressure to bear without provoking Iran into as full-scale a retaliation as it was undertaking before.
But that Venezuela-Cuba template is difficult to implement in the case of Iran for two simple reasons. One is just that Iran has, of course, shown that it has quite a lot of military capacity to retaliate with drones and missiles, and also mines and small ships and submarines. It also has the ability to widen its own maritime disruption in the region, for example by working with the Houthis to really stem the flow of traffic through the Bab-el-Mandeb Strait.
What works in the Western Hemisphere, where the United States has a really unrivaled military dominance, may not be reproducible in this strategic theater.
What does the geography tell you about the ability to impose or contest a blockade like this?
They may be doing it with multiple rings, or multiple screens — a light initial screen, and then bigger barriers of ships a bit further away, so as to not risk most of their force too close to the Iranian coastline. We saw in the early phase of the war that some carrier strike groups began to operate over time further and further away from the Iranian coast, presumably to avoid the risk of being hit with missiles and drones.
In this case, one of the questions is, what kind of resources are needed to keep that going? The U.S. did run a blockade against Iraq for most of the 1990s that was in the Persian Gulf itself, which is very narrow. Iraq’s ports are a tiny sliver of land that ends in the Persian Gulf. So that was a very small stretch of coastline.
Iran should still be manageable, but it will require a wider screen, and potentially one that really crosses the entire Arabian Sea somewhere from the southern coast of Oman, diagonally, northeastwards to Pakistan, or at least the Pakistan-Iranian border, and potentially a bit further out. And if there is also interference in the Red Sea, then the U.S. Navy is going to have to route most of disabled forces all the way around Cape of Good Hope to move that whole force into the Indian Ocean.
I think that the Red Sea contingency is quite important to how this shapes up.
CENTCOM said yesterday that this blockade is on ships going in and out of Iranian ports. I wonder if this is unique historically — both a blockade of Iran and trying to impose freedom of navigation elsewhere?
It’s interesting, right? Because indeed, there is the commitment to freedom of navigation. But then it also has been suggested that the U.S. Navy will stop all ships that have paid any toll or transit fee to the [Islamic Revolutionary Guard Corps], and that paying that toll ipso facto would make their passage illegal. For that I don’t know any good historical precedent.
The other historical precedent is probably actually the Ottoman Empire and Russia and World War I. The Ottoman Empire was bottling up Russia’s Black Sea Fleet in the Black Sea by its control over the Turkish straits, which actually imposed a really serious, long run cost on the Russian economy. It’s one of the things that really fed us in the Russian Revolution. But at the same time, the Ottoman Empire was itself being blockaded by British and French forces in the Mediterranean.
Iran is blockading [Gulf Cooperation Council] states selectively — though of course, it is allowing through some shipments. But those shipments are then going to be intercepted, presumably by the Americans. So the de facto result of it is that no one is really going to be able to leave the Gulf. And that’s kind of where I see this game theoretically ending up.
So it seems like the result of this won’t be hugely different than what things were a few weeks ago, just with fewer Iranian ships getting out.
Also ships of those countries that negotiated transit with Iran.
If you looked at the news coming out of Asia and the diplomatic communiques of a large number of Asian states that brokered bilateral arrangements with Iran — so Pakistan, India; Bangladesh had done so; China, of course — but also countries that have otherwise fairly good links with the United States — the Philippines, Malaysia, Vietnam — all of them had essentially accepted that some payment to the IRGC was now the new cost of doing business. They were so desperately in need of energy supplies for the population that they decided to enter negotiations, even if, in principle, they would prefer freedom of navigation.
The likely diplomatic contestation or diplomatic issues coming out of this blockade are also going to be related to Asia, and that’s where I would focus our attention.