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The Situation at Chernobyl Is Deteriorating

The Situation at Chernobyl Is Deteriorating

Two weeks ago, Russian forces seized control of the defunct Chernobyl, once the site of the world’s worst nuclear meltdown, and Zaporizhzhia, Europe’s biggest active nuclear power plant, raising concerns of nuclear risks in the middle of a war zone. 

Although Chernobyl’s last reactor went offline in 2000, the site now serves as a nuclear waste storage facility—and a highly contaminated one. The situation there is deteriorating; the facility lost power on Wednesday, and backup diesel generators have only enough fuel for two days. The 210 technical personnel and guards have not been allowed to rotate out to rest. The UN’s International Atomic Energy Agency, which promotes the peaceful use of nuclear energy and prevents nuclear weapon proliferation, says they lost contact with Chernobyl’s radiation monitoring systems on Tuesday. Unless officials can restore power, experts fear Chernobyl could once again become the site of a nuclear calamity.

“To have a long-term loss of power is certainly a concern,” says Ed Lyman, a senior global security scientist at the Union of Concerned Scientists and coauthor of the book Fukushima: The Story of a Nuclear Disaster. Some of Chernobyl’s waste has been transferred into dry casks, but considerable quantities of fuel rods remain in a pool that requires cooling. That’s where the biggest risks currently are. “Without electrical power to the cooling pumps, the spent fuel pool will start heating up,” Lyman says. Water will gradually evaporate or boil away, exposing the fuel rods and releasing radioactive gasses. 

Chernobyl’s New Safe Confinement structure also needs electricity. This is the facility built around the concrete “sarcophagus” that surrounds what’s left of the damaged reactor Number Four, which melted down in the 1986 disaster. The confinement structure’s ventilation system must run to prevent the exposed nuclear fuel within it from becoming more hazardous. Without power, the site’s 1.5 billion-euro decommissioning program could be imperiled, Claire Corkhill, an expert on nuclear material degradation at the University of Sheffield in the United Kingdom, wrote on Twitter and in an email to WIRED.

Some experts worry more about the personnel, who haven’t been able to leave after their shifts, which normally would have ended two weeks ago. “I’m concerned about the poor and heroic staff workers, and whether they’re in a good mental state to run all the equipment,” says Ferenc Dalnoki-Veress, a scientist-in-residence and nuclear physicist at the Middlebury Institute of International Studies at Monterey. He likened them to stressed and sleep-deprived passenger jet pilots flying in a combat zone. “You wouldn’t want to be flying in that airplane,” he says.

Not everyone agrees about how dangerous Chernobyl’s situation might be. Lyman estimates that if the cooling system isn’t running the way it’s supposed to, there’s a window of at least a couple of weeks before the threat of meltdown arises. Dalnoki-Veress thinks it might be months until the risk becomes high. On Wednesday, Rafael Mariano Grossi, director-general of the IAEA, tweeted that so far there is “no critical impact on safety,” although in a press statement the agency said that “the lack of power is likely to lead to a further deterioration of operational radiation safety at the site.” But on the same day, Ukraine’s foreign minister Dmitro Kuleba wrote on Twitter that the limited power to cooling systems makes “radiation leaks imminent.” 

The Amazon Rainforest May Be Nearing a Point of No Return

The Amazon Rainforest May Be Nearing a Point of No Return

The Amazon is also taking longer to recover from perturbations like weather events, which unfold over weeks or months, as well as the longer time frames of drought. “That suggests that the system is slowing down,” says climate scientist Chris Boulton of the University of Exeter, lead author of the new paper. “It’s taking longer to recover from the short-term fluctuations that are perturbing it away from its happy place.” 

You wouldn’t know that from a more simplistic measurement of the Amazon, like satellite images that show only the rainforest’s land cover—where the forest is and isn’t. VOD allowed Boulton and his colleagues to parse the biomass in much finer detail, giving them a more complete picture of how the Amazon responded to extreme droughts. Not well, as it happens: Loss of resilience spikes when the landscape dries out. “There’s been three 1-in-100-year droughts in the Amazon fairly recently,” says Boulton. The team saw a spike in their signal during the droughts of 2005, 2010, and 2015, he continues, “which suggests that it’s picking up that kind of change in resilience. But that’s alongside a general increase in the approach toward a tipping point, regardless of those individual events.”

Another major threat is logging, including a kind that’s done by thinning selected trees but leaving others. But even if loggers don’t completely raze an area, they can still destabilize the forest. “What is concerning is in addition to deforestation, which is relatively easy to monitor and keep track of, we’re seeing a big increase in what is called forest degradation, where biomass is extracted from the forest,” says environmental scientist Pontus Olofsson, who studies the Amazon but wasn’t involved in the new work. “So they’re cutting down trees, but not to the point that the land cover is changing. So that land cover remains forest, but with fewer trees.” 

Ranchers, too, contribute to a more subtle weakening of the landscape. They may fell trees but leave a patch of forest standing. Because the animals left inside that little patch are now surrounded by barren land, they don’t dare leave their island. Even birds won’t risk trying to make the journey out of the patch. At the same time, the edges of that rainforest are now exposed to open air, and they rapidly degrade. A rainforest is supposed to be wet, but now its edges are baking in the sun. Over time, rainforest vegetation dies off, and savanna-style grasses creep inward. 

This can even happen on a smaller scale when people slice through the Amazonian biomass to build a road or electric lines—the edges of that slice will dry out, initiating that creep. “What happens in the deforested area doesn’t stay in a deforested area,” says tropical ecologist Paulo Brando of UC Irvine, who studies the Amazon but wasn’t involved in this new research.

This new study found that the Amazon loses resilience when it’s butted up against human activity. Brando’s own research has found that about 17 percent of the southeast Amazon, where deforestation is particularly acute, is within 100 meters of one of these dried-out edges. That’s a huge problem, because the Amazon is an extremely sensitive hydrological machine: Trees soak up rain and release water vapor as they photosynthesize—so much water, in fact, that the Amazon generates its own rain. “Evapotranspiration is very important in the water cycle to produce precipitation,” says Gatti. ”The Amazon can put in the air a comparable amount that the Amazon River discharges to the ocean—it’s a very big amount of water vapor in the atmosphere.” 

Iceland Bets on Herd Immunity

Iceland Bets on Herd Immunity

Thordis Björg, who lives in Reykjavík, the capital where more than 60 percent of the population lives, has an autoimmune disorder that puts her at risk from Covid. She calls Willum Thór Thórsson, the Minister of Health who enacted the decision to drop the restrictions, “the Minister of No-Health.” “He does not really talk about the trade-off of infecting everyone. He’s just looking at the hopeful side of it,” Björg says. 

Iceland has had a relatively mild pandemic experience, recording just 62 deaths and around 133,000 cases in total. In the first few months of 2020, its strategy of quashing any outbreaks using painstaking genomic surveillance, testing, and contact tracing was declared a success and a scientific marvel: The country had “beat the coronavirus,” “hammered COVID with science,” or—put more elegantly—“Scienced the Crap Outta COVID.” At the end of June 2021, the government triumphantly announced it was lifting all restrictions. But the supposed return to normal didn’t last long. By the end of the month, numbers began to shoot up. Restrictions were reintroduced in late July, just a month later. They were dropped again at the end of August and stayed that way until, on December 1, Iceland declared its first case of Omicron. By December 21, tighter restrictions were introduced, and those only began to loosen at the beginning of 2022.  

Iceland is one of a growing list of European countries rapidly abandoning almost all their Covid restrictions. At the beginning of February, Denmark became the first country in the European Union to drop all restrictions, with officials saying they no longer considered Covid “a socially critical disease.” On February 9, Sweden followed suit, though symptomatic people are still advised to stay at home. In Switzerland and Austria, almost all Covid restrictions have been scrapped (apart from mask mandates in certain situations and, in Switzerland, the requirement to self-isolate for five days after a positive test). Europe might be nearing a “plausible endgame for the pandemic,” Hans Kluge, the World Health Organization’s director in Europe, said at a news conference in early February.  

In other parts of the world, nations that enjoyed low case counts throughout the first two years of the pandemic took the opposite approach as Omicron surged regionally. The fragile health care systems of Pacific Island nations like Kiribati, Palau, and Tonga meant that the virus’s arrival necessitated a rush to vaccinate their populations, introduce mask mandates, close schools, or institute lockdowns. China, which remains vulnerable to Omicron due to the use of less-effective inactivated-virus vaccines, is still pursuing a “dynamic zero-Covid” policy that aims to contain outbreaks through strict lockdowns and tracing apps.

Most bizarrely, for the lion’s share of these European countries, including Iceland, the decision to roll back restrictions came amid soaring Omicron waves. Denmark had the second-highest infection rate in the world at the time. But, as Jens Lundgren, a professor of infectious diseases at the University of Copenhagen, says, the virus was no longer considered “a socially critical disease” by the government, meaning it wasn’t threatening critical infrastructure—hospitals, in particular. That being the case, he says, “it would be impossible to continue to argue that it was still necessary to maintain restrictions.” 

Africa’s Oldest DNA Is Helping Address Science’s Racial Bias

Africa’s Oldest DNA Is Helping Address Science’s Racial Bias

Human history is written in DNA. Where our ancestors lived and who they loved—the story is right there if we can see into their genes. The trouble is that the ravages of climate and time degrade DNA, making its secrets harder and harder to detect. Gradually, however, scientists have begun to peer back through time by sequencing ancient DNA. In 2016, researchers at the Max Planck Institute for Evolutionary Anthropology pieced together DNA from a skeleton found in a cave in northern Spain. The human ancestor it was from lived more than 430,000 years ago.

Other ancient DNA discoveries have filled in our knowledge of humanity’s distant past. A Siberian cave yielded up a bone that DNA analysis revealed belonged to a woman from 90,000 years ago who was half Neanderthal and half Denisovan. Another skeleton from the same cave gave us Neanderthal DNA from 120,000 years ago. But all of this DNA has something in common: Almost all of it comes from Europe and Asia. The oldest DNA from sub-Saharan Africa—the place where the whole human story began—dates back to less than 10,000 years ago.

Now a new discovery of the oldest African DNA is pushing back against this bias, and in the process revealing how our ancestors lived and moved around the continent tens of thousands of years ago. The findings add further evidence to the idea that, at some point around 20,000 years ago, some people in Africa started to come together in larger, more settled populations. Evidence of beads and pigments from burial sites suggests that something changed in Africa 20,000 years ago that made these societies more closely resemble those of today. Now DNA evidence suggests that it may have had to do with these ancient movement patterns. “We’ve never had any actual genetic evidence for that until this time because we’ve never had any skeletons,” says Jessica Thompson, an anthropologist at Yale University and coauthor on this new study.

The big problem facing archaeologists is that ancient DNA does not survive for long in tropical environments. Heat and humidity break it down, making it extremely difficult to extract from bones. That’s one reason the best-preserved ancient genomes that scientists have been able to access tend to come from cold, dry environments—often in caves that are shielded from the weather. For this study, Thompson and her colleagues had to work with extremely small fragments of bone—in one case the DNA came from a single finger bone from an infant. The oldest DNA they managed to recover from African bones dated to between 17,000 and 20,000 years ago, although in this case there was so little bone available that the researchers had to estimate the date from ostrich egg artifacts found in the burial site.

Thompson and her colleagues analyzed the DNA of 34 individuals—six of them for the first time—who lived in Africa between 500 and 20,000 years ago. By analyzing specific regions in these genomes, they were able to model how ancient populations may have moved around between 50,000 and 20,000 years ago. These findings will help tell the history of people in south-central Africa, says Maggie Katongo, an assistant keeper of archaeology at Livingstone Museum in Zambia, graduate student at Rice University, and one of the study’s coauthors. “This kind of research gives us information that can be used to tell the story of these past communities that might have lived around different parts of Zambia,” she says.

The researchers compared the ancient African DNA with samples from people living in present-day Africa to get an idea of how much genetic variation there is between people living in different places and times. The ancient DNA from south-central and eastern Africa revealed that these people had ancestors who came from three different parts of the continent: Central Africa, southern Africa, and eastern Africa. “It shows that there was a lot of long-distance movement and mixture and that eastern Africa, in particular, is a really important hub,” says Thompson.

DeepMind Has Trained an AI to Control Nuclear Fusion

DeepMind Has Trained an AI to Control Nuclear Fusion

The inside of a tokamak—the donut-shaped vessel designed to contain a nuclear fusion reaction—presents a special kind of chaos. Hydrogen atoms are smashed together at unfathomably high temperatures, creating a whirling, roiling plasma that’s hotter than the surface of the sun. Finding smart ways to control and confine that plasma will be key to unlocking the potential of nuclear fusion, which has been mooted as the clean energy source of the future for decades. At this point, the science underlying fusion seems sound, so what remains is an engineering challenge. “We need to be able to heat this matter up and hold it together for long enough for us to take energy out of it,” says Ambrogio Fasoli, director of the Swiss Plasma Center at École Polytechnique Fédérale de Lausanne.

That’s where DeepMind comes in. The artificial intelligence firm, backed by Google parent company Alphabet, has previously turned its hand to video games and protein folding, and has been working on a joint research project with the Swiss Plasma Center to develop an AI for controlling a nuclear fusion reaction.

In stars, which are also powered by fusion, the sheer gravitational mass is enough to pull hydrogen atoms together and overcome their opposing charges. On Earth, scientists instead use powerful magnetic coils to confine the nuclear fusion reaction, nudging it into the desired position and shaping it like a potter manipulating clay on a wheel. The coils have to be carefully controlled to prevent the plasma from touching the sides of the vessel: this can damage the walls and slow down the fusion reaction. (There’s little risk of an explosion as the fusion reaction cannot survive without magnetic confinement).

But every time researchers want to change the configuration of the plasma and try out different shapes that may yield more power or a cleaner plasma, it necessitates a huge amount of engineering and design work. Conventional systems are computer-controlled and based on models and careful simulations, but they are, Fasoli says, “complex and not always necessarily optimized.”

DeepMind has developed an AI that can control the plasma autonomously. A paper published in the journal Nature describes how researchers from the two groups taught a deep reinforcement learning system to control the 19 magnetic coils inside TCV, the variable-configuration tokamak at the Swiss Plasma Center, which is used to carry out research that will inform the design of bigger fusion reactors in future. “AI, and specifically reinforcement learning, is particularly well suited to the complex problems presented by controlling plasma in a tokamak,” says Martin Riedmiller, control team lead at DeepMind.

The neural network—a type of AI setup designed to mimic the architecture of the human brain—was initially trained in a simulation. It started by observing how changing the settings on each of the 19 coils affected the shape of the plasma inside the vessel. Then it was given different shapes to try to recreate in the plasma. These included a D-shaped cross-section close to what will be used inside ITER (formerly the International Thermonuclear Experimental Reactor), the large-scale experimental tokamak under construction in France, and a snowflake configuration that could help dissipate the intense heat of the reaction more evenly around the vessel.

DeepMind’s neural network was able to manipulate the plasma inside a fusion reactor into a number of different shapes that fusion researchers have been exploring.Illustration: DeepMind & SPC/EPFL 

DeepMind’s AI was able to autonomously figure out how to create these shapes by manipulating the magnetic coils in the right way—both in the simulation, and when the scientists ran the same experiments for real inside the TCV tokamak to validate the simulation. It represents a “significant step,” says Fasoli, one that could influence the design of future tokamaks or even speed up the path to viable fusion reactors. “It’s a very positive result,” says Yasmin Andrew, a fusion specialist at Imperial College London, who was not involved in the research. “It will be interesting to see if they can transfer the technology to a larger tokamak.”

Fusion offered a particular challenge to DeepMind’s scientists because the process is both complex and continuous. Unlike a turn-based game like Go, which the company has famously conquered with its AlphaGo AI, the state of a plasma constantly changes. And to make things even harder, it can’t be continuously measured. It is what AI researchers call an “under–observed system.”

“Sometimes algorithms which are good at these discrete problems struggle with such continuous problems,” says Jonas Buchli, a research scientist at DeepMind. “This was a really big step forward for our algorithm because we could show that this is doable. And we think this is definitely a very, very complex problem to be solved. It is a different kind of complexity than what you have in games.”