A study published in the journal Nature says that animal migration due to rising global temperatures and habitat destruction will lead to a “network of new viruses” that could affect human health. As a possible mitigation plan, they urge governments to improve the zoonotic control and response capacity of the health system.
By Living Earth Agency
Global warming could trigger the next pandemic. This is revealed in a scientific study entitled “Climate change increases the risk of cross-species viral transmission”, published in the journal Nature. The research analyses a future “network of new viruses” that will jump from species to species and increase as the planet warms, due to the migration of wild animals because of rising global temperatures. The paper suggests that the epicentre of this phenomenon will be tropical Africa, Southeast Asia and areas where the human population is densest in 2070. The study considers it “inevitable” that the world will be “warmer and sicker”, but points out that there are other variables that do not directly impact human health.
The study argues that over the next 50 years, climate change could lead to more than 15,000 new cases of mammals transmitting viruses to other mammals. Currently, at least 10,000 viruses capable of “jumping” to humans circulate “silently” among wild mammals, says the report published in Nature. This survey is one of the first to predict how global warming will change wildlife habitats and increase encounters between species capable of exchanging pathogens.
Climate change will drive large numbers of animals to flee their ecosystems. As species mix with each other, they will transmit more viruses, which will favour the emergence of new diseases potentially transmissible to humans, the study anticipates. It also reveals that more and more wild animals are fleeing from habitats that have been damaged by rising temperatures, shrinking tropical forests, urbanisation and cultivated areas, and wildlife trafficking.
Animals migrate to new, more favourable territories, but run the risk of encountering species unknown to them. In this way, ecosystems are redistributed geographically and more than 300,000 “first encounters” between species may occur. By mixing for the first time, these mammals will form new communities. This is fertile ground for new crossovers of infections, especially viral ones.
For example, bats play a central role, says the study, as they carry numerous viruses but do not develop disease. However, they can infect humans through another animal. This process is called zoonosis and is the origin of several epidemics such as Covid-19 or Ebola. “Bats have a high potential to spread the virus and can infect a large number of species they encounter for the first time,” the study says. The team says that, partly because bats can fly, they are less likely to experience barriers to changing their habitats.
The research authors argue that future global temperature increases “are irreversible, even if global warming is limited to 2°C”. They say the Sahel area south of the Sahara Desert in Africa, the highlands of Ethiopia and the Rift Valley in tropical East Africa, India, eastern China, Indonesia, the Philippines and some populations in central Europe will be affected.
The research, which was conducted over five years, cross-checked various climate modelling, data on natural habitat destruction and how viruses are transmitted between species. The study took into account a total of 3139 species of mammals, which are home to a large diversity of viruses that can be transmitted to humans.
The team that carried out this work is made up of Colin Carlson, Gregory Albery, Cory Merow, Christopher Trisos, Casey Zipfel, Evan Eskew, Kevin Olival, Noam Ross and Shweta Bansal.
A hotter, sicker planet: nothing to do?
During the Covid 19 pandemic, at least three academic studies postulated that the epidemic began when a previously unknown coronavirus passed from a wild animal to a human, i.e., zoonotic transmission. “We provide evidence that in the coming decades the world will not only be warmer, but also sicker,” Gregory Albery, a biologist at Georgetown University in Washington and co-author of the study, told DW.
The study is “a critical first step in understanding the future risk of climate change and land use in the next pandemic,” said Kate Jones, who models interactions between ecosystems and human health at University College London.
Jones praised the study but urged caution in discussing its implications for human health. “Predicting the risk of mammalian-to-human viral jumps is more complicated, as these secondary effects take place in a complex human socio-economic and ecological environment,” she said. Many factors could reduce the risk to human health, including greater investment in medical care or that a virus cannot infect humans for some reason, he added.
Gregory Albery and Colin Carlson, authors of the paper published in Nature, say that while some increase in disease transmission is inevitable, that is no excuse for inaction. The researchers therefore call on governments and the international community to improve monitoring and surveillance of wildlife and zoonotic diseases, particularly in future hotspots such as Southeast Asia. Improving health infrastructure is also essential, they warn.
Deaths from air and water pollution
On the other hand, the Lancet published a report stating that air pollution caused nine million deaths in one year. One in six premature deaths are associated with harmful components in the environment, says the British scientific journal. The figure is exacerbated by poor air quality and the presence of chemical pollutants, the Lancet Commission on Pollution and Health noted.
In 2019, about 6.7 million premature deaths are attributable to air pollution, 1.4 million to water pollution and 900,000 to lead poisoning, reports the research published on 18 May.
The study’s lead author, Richard Fuller, added that “the health impact of pollution remains far greater than that of war, terrorism, malaria, HIV, tuberculosis, drugs and alcohol. The number of deaths caused by pollution rivals those caused by tobacco.
Pollution and wastes expelled into the air, water and soil do not usually kill directly, but they cause serious heart disease, cancer, respiratory problems and acute diarrhoea, the report says. “The health effects are enormous, and low- and middle-income countries are the hardest hit,” he said.