But in February, the work came to a sudden halt when Russia invaded and immediately occupied the region around Chornobyl, which lies about 100 kilometres north of Kyiv. Hundreds of researchers and other workers were forced to leave. By the time Prots finally returned this April, he found armed soldiers guarding the route to his study site, which was studded with Ukrainian landmines. Prots says he never expected to find himself doing conservation work in a war zone, but “you need to work in any condition that’s possible”, he says.
The war has devastated Ukraine and hobbled research nationwide, but the impacts on science in the Chornobyl region are particularly stark. For decades, the Chornobyl exclusion zone, a region that has been largely empty of people since the 1986 nuclear disaster, had been intensely studied by researchers keen to understand the long-term effects of radiation and how ecosystems change when unperturbed. The zone had developed a reputation as a unique natural laboratory and Soviet, Ukrainian and international researchers had accrued radiation and ecological data sets over more than 30 years.
The invasion shattered that research, as scientists fled, data collection was interrupted and labs were looted by Russian soldiers. Ukraine retook the region after just five weeks but, because the exclusion zone lies on a strategically important route from Belarus to Kyiv, it has endured months of environmental damage and military fortification. “Most of the scientific activity has come to a screeching halt,” says Timothy Mousseau, an ecologist at University of South Carolina, Columbia, who has studied Chornobyl since 2000. “The area has absolutely been decimated.”
Now, as the war heads towards its third year, some researchers are finding creative ways to restart their studies — but the work is difficult and the environment has changed. Scientists at the Frankfurt Zoological Society in Germany, for example, are analysing footage from camera traps located in the Chornobyl Biosphere Reserve, a protected area for wildlife research that covers two-thirds of the exclusion zone. They hope to use the data to assess the war’s impact on animal behaviour. “It was an unexpected experiment,” says Denys Vyshnevskyi, head of the reserve’s science department.
Accidental science zone
When Chornobyl’s reactor 4 exploded on 26 April 1986 in what was then part of the Soviet Union, the resulting fire ejected radioactive isotopes that contaminated 155,000 square kilometres of Ukraine, Belarus and Russia, and caused spikes in radioactivity as far away as Canada and Japan (see ‘Chornobyl in a conflict’). Authorities eventually evacuated an area of 4,760 square kilometres: around 2,600 square kilometres of northern Ukraine became the Chornobyl exclusion zone, with the rest in Belarus. Access to the reactor and to badly contaminated areas remained tightly controlled, but a changing cast of more than 3,000 workers came in. Some built a protective sarcophagus around the reactor’s ruins; others worked as guards, firefighters or tour guides for a growing stream of international tourists curious to visit the region.
The Chornobyl accident created a rare opportunity to study the effects of radiation. The exclusion zone became home to a cluster of research institutes that have been supported by Ukrainian authorities and partnerships with overseas universities since Ukraine became independent in 1991. Air, water and soil monitoring sites are scattered across the zone. From these, scientists have built up decades-long data sets on the decay, dispersal and impact of radionuclides.
The data have shown that concentrations now vary from hazardous to low levels across the zone, and the pattern still reflects the wind direction immediately after the explosion — with a narrow smear of high radiation west of the exploded reactor, following the path of the radioactive plume. Researchers have also examined the long-term effects of radiation exposure on wildlife — with conflicting results. A 2009 study, for example, found that the abundance of insects and spiders in the Chornobyl zone declined with increasing radiation1; other studies found only subtle effects on ecosystems2.
The long-running data sets are the bedrock of Chornobyl’s status as an internationally important laboratory, says Jim Smith, an environmental scientist at the University of Portsmouth, UK, who has studied Chornobyl since 1990. In 2022, Smith’s team used data from 35 years of groundwater monitoring to show that radionuclides are no longer at dangerous levels across much of the zone, but that a few hotspots remain close to the reactor3. Research from the exclusion zone has also informed the development of nuclear power plants and nuclear emergency planning around the world, as well as the response to the Fukushima nuclear accident in 2011. “So it is a resource that is of benefit globally, not just locally,” says Mike Wood, an ecologist at the University of Salford, UK, who worked at Chornobyl.
Early indicators
Researchers at Chornobyl detected signs of Russia’s impending invasion four months before hostilities even began, says Mousseau. He and others were monitoring the movement of wolves and other wildlife using about 100 motion-activated cameras. Some in the Ukrainian exclusion zone picked up Russian troops making incursions across the border, prompting the team to alert the authorities — a fact that Mousseau was allowed to reveal publicly only in May.
When the Russian army stormed the border on 24 February 2022, it immediately captured the exclusion zone. Sergii Paskevych, deputy director of research at the Kyiv-based Institute for Safety Problems of Nuclear Power Plants (ISP NPP) of the National Academy of Sciences of Ukraine, was in the Chornobyl area with his colleagues that night. Amid fear and confusion, “all the main stations of the institute decided to evacuate everyone. We left everything in Chornobyl that night,” Paskevych says. As they drove away at 6 a.m., they saw Ukrainian troops arriving and placing explosives under bridges that, hours later, would be destroyed. “After that, I realized that it’s serious,” says Paskevych. “It’s not a simulation. It’s real war.”
During Russia’s short occupation of the exclusion zone, the country’s forces looted and damaged many research labs and facilities. In Chornobyl town, for example, they destroyed servers and stole hard drives from Ecocentre, a laboratory that led radiation monitoring across the zone, says Gennady Laptev, a radiological monitoring expert at the Ukrainian Hydrometeorological Institute in Kyiv.
This interrupted the long-term data collection in the region, and some researchers fear that historical data could be permanently lost. “Computers were stolen, records were destroyed,” says Smith. Wildlife studies were also disrupted, because researchers were unable to access field sites or retrieve many of the camera traps — some of which stopped working when their batteries ran out.
Slow return
On 31 March 2022, Ukraine announced that it had regained control of the exclusion zone, and from June that year, some researchers started making efforts to restart their work. But the return has been slow and halting. Work is punctuated by the sound of explosions and gunfire. “It is difficult to live under rocket attacks,” says Valery Kashparov, director of the Ukrainian Institute of Agricultural Radiology in Kyiv.
The biggest issue now, say many scientists, is a lack of staff. Although scientists do not have to serve in the military, Paskevych and many others have volunteered to fight. At the ISP NPP, a skeleton crew of essential workers is now on site evaluating the safety risks, says ISP NPP radiobiologist Olena Pareniuk. And collaborators abroad are unable to return. “For most of us, our institutions aren’t overly keen on us saying ‘Right, we’d like to go and do fieldwork in an area where there remains active conflict’,” says Wood.
Access to research sites around Chornobyl is another huge problem. Scientists can enter around half of the exclusion zone, estimates Vyshnevskyi. About one-third is currently under strict military control, says Prots, including areas close to the Belarusian border. But in reality, many research sites are inaccessible because much of the land is now dotted with mines or tightly controlled by the army, which fears a Russian invasion through Belarus.
Sharing the exclusion zone with the military comes with risks. Twice in the three months after Russia’s withdrawal, researchers from the Chornobyl Reserve were apprehended by Ukrainian soldiers, says Vyshnevskyi. The second time they were blindfolded and detained for a few hours before being returned to a local police checkpoint. Since then, scientists have learnt to give advanced warning of their movements, he says.
A handful of Ukrainian researchers have made initial forays back into the forests to try to get ecological monitoring systems back online. Prots says the soldiers have been good-natured — if a little surprised — to find scientists out looking for bats and beavers in the middle of a war zone. Mousseau, whose wildlife cameras happened to pick up early signs of Russian troops, says that he and his team are now trying to install more. “That might be useful for Ukrainian security services as well as our wildlife studies,” he says.
Vyshnevskyi says that his main focus now “is to assess the damage to the natural environment from the occupation”. Chornobyl researchers have joined with other scientists in an effort launched by Ukraine’s environment ministry in July 2022 to track military actions that cause environmental harm, from groundwater contamination to forest fires. By early December, a network of thousands of citizen reporters had submitted at least 2,600 reports of environmental harm, causing an estimated €52.4 billion (US$56.6 billion) worth of damage. Wood says that when international researchers are able to return to the zone, one obvious action will be to repeat work such as wildlife tracking, to quantify the changes. They will want to know “what was the zone like when we last did this? What’s it like now?”, he says.
Wetland defences
Prots is one of those trying to restart their work. The nuclear power plant is located in Polesia, Europe’s largest inland wetland wilderness. But long before it was built, and starting in earnest in the 1920s, the Soviet Union drained vast areas for farming.
In the past few years, thanks to the drier land and climate change, wildfires have torn through forests around Chornobyl. Research conducted after fires swept through in 2020 suggests that the radionuclides released by the blazes pose little threat to people outside the exclusion zone4, but some local scientists want to see further research. They’re concerned that future fires could damage ecosystems, release carbon from peatlands and, by moving radionuclides around, complicate efforts to study — and eventually reopen — the zone.
Prots wants to study whether reintroducing wetlands to the area would cut those potential risks. This would follow on from work done since 2007 on a wetland conservation and restoration project in the Carpathian mountain forests in western Ukraine5. Since 2021, Prots has been funded by the Whitley Fund for Nature, a UK conservation charity, to study whether rewilding could safely and affordably prevent wildfires, as part of an international coalition including Smith and Laptev.
Before the invasion, Prots had finalized plans for a pilot project, due to start in 2022, that involved clearing silt and debris from the ageing network of canals and sluice gates and using the waters to flood an 8-square-kilometre patch of former swampland near the Pripyat River. He had hoped this would create conditions that would lure back the Eurasian beaver (Castor fiber), a rodent whose dam-building can support wetland ecosystems in the long term. “If we start this restoration, beavers will come,” he says. During the pilot, the team planned to observe the effects of restored wetland on wildlife and carefully monitor radionuclides to ensure that flooding did not cause dangerous levels to run off into surrounding areas. Then, if successful, the approach could be scaled up to restore wetlands across the exclusion zone.
o Prots’ surprise, as the war drags on, his proposal has drawn fresh interest from firefighters keen to avert increasingly frequent wildfires, and from Ukraine’s military, which hopes that swamps will provide effective defences against Russian troops. “Many people are recognizing now that in this border area, the best war defence would be having natural habitats,” says Prots. “This could be a big win of this war: to have restored moist wetlands.”
In theory, Prots’ project could begin as soon as Ukraine’s military can spare the services of a ‘sapper’ to clear the tracks of explosives, which were placed to prevent Russian troop advances. But the team’s hope of starting this summer were dashed. The sappers were needed elsewhere, especially following Ukraine’s counteroffensive, which encountered heavily mined Russian lines.
Uncertain future
With no end to the war in sight, some researchers fear that science at Chornobyl will never recover to pre-war levels and that many of the scientists who left the country will not return. Sergey Gashchak, deputy director of science at the Chornobyl Center’s International Radioecology Laboratory, says that research was already struggling with insufficient funding from the Ukrainian government and a long-term decline in science education, resulting in fewer qualified scientists and little funding for PhDs. The war has finally “killed” science here, Gashchak wrote in an e-mail. “No projects, no money, no people.”
Others are more optimistic that their data collection and studies can be resumed — if the break is not too long. “If it’s another year, let’s say, it wouldn’t be that big a problem, because many of the ecological dynamics are not that fast,” says Germán Orizaola, a zoologist at the University of Oviedo, Spain, who studies amphibians in Chornobyl. But Orizaola worries that the interruption of international collaborations by the war and the COVID-19 pandemic will result in a lasting reduction in foreign funding, which was a key source of support. “All that money is not reaching Ukraine now,” says Orizaola.
Whenever the conflict ends, scars around Chornobyl are likely to persist for some time. Along the Ukraine–Belarusian border, a 100-metre-wide strip of vegetation has been razed and now divides the forest. Prots says these zones are laid with explosives, which animals triggered routinely during his visit, and he and other researchers fear the strip could become entrenched. Prots compares the zone of deforestation to the barbed-wire-topped barriers of the old Iron Curtain. “We are facing, now, this completely new reality.”
Nature 624, 244-246 (2023)
doi: https://doi.org/10.1038/d41586-023-03861-2
