Updated: Jan 2, 2021
Since the Chernobyl disaster nearly 35 years ago nature has been recovering and has reclaimed the irradiated territory now referred to as the ‘exclusion zone’ once occupied by man. The speed and magnitude to which this natural recovery has taken place not only demonstrates the negative impact humans had on the surrounding environment, but also illustrates the potential for rapid recovery should nature be left to its own devices.
On Saturday 26th of April 1986, in the North of Ukraine near Pripyat, a steam explosion and fires at the number four reactor in the Chernobyl power plant released around 5% of the core into the wider environment (1). Many consider this event to be the most severe nuclear disaster in recorded history. As a point of comparison, the amount of radiation released was 400 times higher than that released by the atomic bomb dropped on Hiroshima back in 1945 (2).
Immediately after the explosion, two Chernobyl plant operators were killed, weeks after the event a further 28 emergency workers and plant operators died from acute radiation syndrome. Where these figures are largely agreed upon, long-term estimates regarding the total loss of life have not proven as unanimous and a host of experts, researchers and committees have reported varying degrees of estimated severity (Figure 1).
The human-impact extended beyond fatalities: a handful of international studies found that those exposed to radiation were more likely to report higher rates of anxiety, unexplained physical symptoms and general poor health (8). Additionally, the resettlement of 350,000 people (1) from the areas affected was an operation of significant magnitude and one which altered the lives for all that were involved.
Following the explosion, flora and fauna in the surrounding environment were also adversely impacted in varying degrees depending on their proximity to the power plant. According to a report by the UN Chernobyl Forum Expert Group in 2005, the three major kinds of environmental damage caused were (9):
· Increased mortality of coniferous plants, soil invertebrates and mammals
· Reproductive losses in plants and animals
· Chronic radiation syndrome of animals (mammals, birds, etc.).
Perhaps the most visually blatant manifestation of environmental radiation damage was the formation of the “Red Forest” after the explosion. 20-30 square Kilometres from Chernobyl (an area later labelled as the ‘First zone’), a vast 400-hectare expanse of scotch pine forest ‘burned down’ from the significant accumulation of radioactive emissions, converting the landscape from a vibrant green into a Brownish-Red (10).
Figure 2 – Brown/Red colouration of pine forests as a result of radiation uptake after the Chernobyl explosion (10).
In August and September of 1986 (4-5 months after initial fallout), the examination of wild and domestic animals shot alluded to underlying reproductive dysfunction and chronic radiation syndrome the event had caused. The examination of farmed chickens showed no eggs within nests or in their ovaries (9) pointing towards radiation-induced sterility within the immediate blast zone. In addition to this, several animals examined demonstrated signs of chronic radiation syndrome, characterised by reduced body mass, lower fat reserves, bloated lymph nodes, liver and spleen as well as haematomas within the liver and spleen (9).
Over a vaster timescale, the influence of prolonged radiation exposure on wildlife genetics has been a topic researched by a handful of scientists. A study conducted in 2001 suggested that unnatural mutation rates in plants and animals of up to 20 times had been caused by radiation (11). Studies conducted on a range of taxa in more heavily irradiated locations have reported a range of physical anomalies including the stunting/propelling of growth, development of facial deformities, appendage growth, partial albinism, reduced brain size and cataracts (12,13,14,15).
This said, physical malformations as a result of radiation is generally accepted to be low when considering the degree of exposure taxa in the exclusion zone have been subject to. Though more rapid mutation has been occurring at the DNA level, many of these mutations are thought to be neutral or ‘silent’, meaning they do not alter the phenotype (observable characteristics) of the respective organisms affected. Essentially, most animals and plants, though mutants, look the same as those found beyond the exclusion zone.
Figures 2, 3 + 4 – Radiation exposure in the years following the disaster caused some pine trees to show physical mutations. Pine trees have been observed to exhibit stunted growth/dwarfism (top), gigantism (middle) and enhanced vegetative growth (bottom) (10).
Figure 5 – A barn swallow with radiation-induced partial albinism (left) and without (right) (15). (Feathers with a darker, melanin-based colour are paler in Chernobyl barn swallows, showing a more colourful, bluer plumage compared to the duller, darker colouration in swallows in areas unaffected by radiation.)
Despite the acute levels of radiation local wildlife was initially subject to, by the next growing season, due to a combination of reproductive recovery and new organism immigration, population viability of a number of plants and animals recovered substantially (9). Quite paradoxically the exclusion zone became (and continues to be) a nature refuge for many taxa that have flourished in the absence of humans.
Though invertebrates (including spiders, bees, butterflies and grasshoppers) have suffered and reduced in abundance since the event (11,16), populations of a handful of larger, more charismatic taxa have grown. Amongst these include a handful of birds (white-tailed eagle, crane, stork, eagle owl, grouse, duck, etc.) and mammals (including elk, deer, lynx, boar, bear, beavers and wolves) (9,11,17). A study conducted in 2015 particularly estimated that wolf populations within the exclusion zone compared to those in nearby human-occupied territory were seven times higher (18), not only demonstrating population recovery but expansion also.
Not only is there evidence of recovery in endemic fauna, but a successful introduction initiative was also carried out in the exclusion zone. Around 20 years ago, 36 endangered Przewalski wild horses were released into the area. Nowadays their numbers are thought to be five times higher than this founding population (19). Presently the species is established in the area surrounding Chernobyl, the exclusion zone is now considered part of the species’ increasingly diminishing native range (along with Mongolia, China and Kazakhstan) that used to span vast areas across Asia and Europe (19,20).
What can we learn from Chernobyl?
One conclusion that can be drawn from environmental recovery after Chernobyl is the constricting impact humans had on the area previous to evacuation. If nature has been able to proliferate after the disaster despite the radiation, what does this demonstrate about the vast damage our activity has on nature? The case study of Chernobyl illustrates that anthropogenic influence (agricultural/Industrial pollution, hunting (etc.)) is more restrictive to wildlife than the effects of the most severe nuclear disaster in recorded history. As a result, we must reflect upon the environmental sustainability of said practices causing environmental damage and adapt to lessen this impact moving forward.
A more enthusiastic perspective might be that the recovery observed serves as an example of how quickly nature can reclaim its territory and flourish in the absence of humans. Though nature worldwide is currently experiencing catastrophic declines (The recent Living planet report (2020) detailed a 68% population decline in 21,000 mammal, bird, amphibian, reptile and fish populations from 1970-2016)(21), wildlife recovery at Chernobyl might act as a beacon of hope, representing the potential for change should nature be left to its own devices.
After only 35 years, under less than ideal circumstances, and with quite limited conservation support, the Chernobyl exclusion zone has demonstrated the potential nature possesses for growth and recovery. If global, top-down rewilding initiatives were able to provide conditions resembling the scope and level of human influence reduction seen in Chernobyl then the road to recovery, though long, may yet be attainable.