Everything is complicated. Scientists name the reasons for the mass death of animals worldwide
In China and Brazil, livestock is dying from drought or cold, fish are dying off the coasts of America and Europe, and large marine mammals are being stranded on the shores. Scientists blame global warming and predict catastrophes. But is everything so straightforward? This is what the RIA Novosti article explores.
Dying in the thousands
In Beijing, there is an atypical heatwave of 40 degrees Celsius for June. Huge areas of Inner Mongolia, Hubei, and Liaoning provinces are suffering from drought. Grazing animals are particularly affected. "Nearly 200,000 people and 760,000 head of cattle are experiencing water shortages," according to the media reports.
At the same time, in southwestern Brazil, where it is currently winter, nearly three thousand head of cattle have died from hypothermia, as reported by the region's veterinary department. Low temperatures are not a problem for local grazing animals. However, when combined with extremely dry weather, strong winds, and lack of shelter, it led to this tragedy.
Forest fires, which began in March, are gaining momentum in Canada. As of June 21, the area affected reached nearly six million hectares, with nearly three thousand fire outbreaks. Nothing like this has been observed in the country's entire history. Adult animals, sensing the smoke, flee to open spaces and enter populated areas in search of shelter and food. Residents encounter polar bears, owls, and injured animals colliding with window glass. Nests, chicks, and young offspring perish in the flames. "Many animals will leave their nesting sites or die, populations will shrink to a minimum or disappear," said Karen Hodges, a biology professor at the University of British Columbia, in an interview with local television.
Recently, in California, sea lions and dolphins were washed ashore with symptoms of intoxication: convulsions and frothing at the mouth. According to experts, the cause lies in neurotoxins produced by diatom microalgae. Hundreds of marine mammals have already died. This is the most massive poisoning witnessed in the region. Summer blooms of phytoplankton are a common occurrence, but pollution of the ocean and climate warming intensify the process, scientists believe.
Who is at Risk from Extreme Heat?
The blame for the mass deaths of animals is increasingly being attributed to global warming, which gives rise to abnormal weather phenomena. Scientists predict that natural disasters such as prolonged heatwaves, droughts, and floods will occur more frequently and with greater intensity. Human activities have likely exacerbated this trend, according to the report by the Intergovernmental Panel on Climate Change.
"The impact of climate warming is not very noticeable in the short term," explains Artem Kidov, head of the Department of Zoology at the K.A. Timiryazev Russian State Agrarian University. "A single hot summer will not lead to mass extinction. Yes, high-yielding breeds of domestic animals suffer from weather fluctuations, but indigenous breeds, such as those in Kalmykia and the Astrakhan region, graze and reproduce well even at high temperatures."
Research by Professor Ahmed Abilov from the L.K. Ernst Federal Scientific Center for Animal Husbandry confirms that during prolonged heatwaves, highly productive breeds of cows experience a catastrophic decline in their reproductive function. Along with his colleagues, the scientist observed herds in the Moscow region during the heat anomaly of 2010, which lasted for a month. At that time, the air temperature exceeded the norm by ten to twenty degrees.
Wild animals, on the other hand, have adapted to large temperature fluctuations over millions of years of evolution and have developed numerous survival mechanisms. "They seek shelter and spend a lot of time in water, like hoofed animals," says Artem Kidov.
In Australia, which suffered greatly from wildfires last year, it has been observed that possums can hide in deep hollows, while brown antechinus mice go into a state of torpor to survive hunger in scorched areas. According to estimates, only three percent of animals perish in fires, and seven percent in very severe fires.
The real danger of summer heat lies in the populations of newts, frogs, toads, and other amphibians that inhabit small temporary water bodies such as puddles, ponds, and streams. If these bodies of water dry up faster than the larvae and tadpoles undergo metamorphosis, the offspring die. "Several consecutive droughts can cause a population to fail to reproduce," notes Kidov. This occurs in southern regions of Russia, such as the North Caucasus. Subsequently, the number of predators that feed on amphibians, such as storks, waterfowl, minks, and badgers, sharply decreases. This is followed by a massive outbreak of pests in agriculture and forestry.
"In the long-term perspective, global warming will have a powerful effect on the animal world," the scientist asserts. However, he warns that the causes of mass animal deaths in different regions of the world may also be linked to infections that spread further northward, as well as the use of increasingly dangerous chemicals and zero-tillage methods that eradicate all life in and around fields.
Kidov cites the example of the crane deaths that occurred last autumn in the Stavropol Krai. "The past two years have been catastrophic for migratory birds such as pigeons, cranes, geese, owls, and falcons. They land in fields and consume rodents that have accumulated pesticide residues in their bodies. Then they fly for 30-40 kilometers and perish," explains the researcher.
No one can definitely claim that mass animal deaths or species extinction are directly related to global warming," says Alexey Surov, corresponding member of the Russian Academy of Sciences (RAS) and Deputy Director for Science at the Severtsov Institute of Ecology and Evolution of the RAS. The most well-known example is the polar bears that leave their habitats and approach humans due to hunger. However, according to scientists, there are currently a significant number of individuals.
There is no clarity regarding the deaths of Caspian seals this winter. "It is believed that climate indirectly plays a role, as the increased water temperature caused an infection," Surov continues.
He also recalls the mass die-off of saiga antelopes in Kazakhstan in 2015. Over half of the population perished during the spring and summer. Among the possible causes were exhaustion due to drought, poisoning from unfamiliar plant food, and infection. However, there is no definitive answer.
Another example is the mortality of reindeer in recent years in Yamal. "During migration, animals get trapped on ice and break their limbs, rendering them unable to move, leading to the death of several thousand reindeer," explains Maxim Maksimchik from the Tyumen Scientific Center of the Siberian Branch of the RAS. Scientists encountered these facts while studying the genetics of reindeer to improve breeding work (a program supported by the Ministry of Science and Higher Education). For the 700,000-strong population in the Russian Arctic, this is not critical, but for indigenous peoples who rely on reindeer herding, losing a third of their herd is a serious threat. Moreover, such cases have become more frequent in recent years. "The exact cause is unknown. It is being investigated," adds the specialist.
According to Alexey Surov, such events occur from time to time, for example, in Mongolia, where sudden temperature changes without snow lead to the mass death of livestock. "Whether this is related to climate warming is unclear," adds the expert.
Global warming is progressing slowly. Over the past century and a half, the average annual temperature has increased by half to one degree. It will take decades or even centuries of observation to determine how successfully animals adapt to these changes. "Currently, it is known only that heat-loving species are expanding their ranges northward," states the biologist.
According to scientists, many cases of mass animal mortality and the disappearance of certain species occur with human involvement. After all, Homo sapiens is the most populous mammal species. It all began 12,000 years ago with the extermination of megafauna by our ancestors and continues on a large scale worldwide. That is why this process is called the sixth, or anthropogenic, mass extinction.