Global warming and future pandemics

A study published in the journal Nature says animal migration due to rising global temperatures and habitat destruction will lead to a “web of new viruses” that could affect human health. As a possible mitigation plan, they urge governments to improve zoonotic control and health system response capacity.

By Terre Vivante Agency

Global warming could trigger the next pandemic. This is revealed by a scientific study entitled “Climate change increases the risk of inter-species viral transmission”, published in the journal Nature. The research analyzes 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 due to rising global temperatures. The article suggests that the epicenter of this phenomenon will be tropical Africa, Southeast Asia and the areas where the human population will be the densest in 2070. The study considers it “inevitable” that the world is “hotter 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 are “silently” circulating among wild mammals, says the report published in Nature. This survey is one of the first to predict how global warming will alter wildlife habitats and increase encounters between species capable of exchanging pathogens.

Climate change will cause large numbers of animals to flee their ecosystems. As the species mix, they will transmit more viruses, which will promote the emergence of new diseases potentially transmissible to humans, anticipates the study. It also reveals that more and more wildlife are fleeing habitats damaged by rising temperatures, shrinking rainforests, urbanization and cultivated areas and wildlife trafficking.

The animals migrate to new, more favorable territories, but run the risk of encountering species that are unknown to them. Thus, ecosystems are geographically redistributed and more than 300,000 “first encounters” between species can take place. When mixing for the first time, these mammals will form new communities. This is fertile ground for new crosses of infections, especially viral ones.

For example, bats play a central role, according to the study, because they carry many viruses but do not develop disease. However, they can infect humans through another animal. This process is called zoonosis and is the cause of several epidemics such as Covid-19 or Ebola. “Bats have a high potential for virus spread and can infect a large number of species they encounter for the first time,” the study said. The team says that, in part because bats can fly, they are less likely to encounter obstacles to changing their habitat.

The authors of the research say that future increases in global temperature “are irreversible, even if global warming is limited to 2°C”. They say the Sahel region south of the Sahara Desert in Africa, the Ethiopian highlands and the Rift Valley in tropical East Africa, India, eastern China, Indonesia, the Philippines and certain populations in central Europe will be affected.

The research, which was conducted over five years, cross-referenced various climate models, 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 harbor a wide diversity of viruses transmissible to humans.

The team that did this work consists of Colin Carlson, Gregory Albery, Cory Merow, Christopher Trisos, Casey Zipfel, Evan Eskew, Kevin Olival, Noam Ross and Shweta Bansal.

A hotter and sicker planet: nothing to do?

During the Covid 19 pandemic, at least three academic studies postulated that the outbreak began when a previously unknown coronavirus jumped from a wild animal to a human, i.e. through zoonotic transmission . “We provide evidence that in the decades to come, 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 “an essential first step in understanding the future risk of climate change and land use during the next pandemic,” said Kate Jones, who models ecosystem and human health interactions at the 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 because these side effects occur in a complex human socioeconomic and ecological environment,” she said. Many factors could reduce the risk to human health, including increased investment in medical care or the fact that a virus cannot infect humans for whatever reason, he added.

Gregory Albery and Colin Carlson, authors of the Nature paper, say that while some increase in disease transmission is inevitable, it’s no excuse for inaction. The researchers therefore call on governments and the international community to improve monitoring and surveillance of wildlife diseases and zoonoses, especially in future hotspots like Southeast Asia. Improving sanitation 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 is associated with harmful components in the environment, according to the British scientific journal. The figure is exacerbated by poor air quality and the presence of chemical pollutants, noted the Lancet Commission on Pollution and Health.

In 2019, around 6.7 million premature deaths were attributable to air pollution, 1.4 million to water pollution and 900,000 to lead poisoning, reports research published on May 18.

The study’s lead author, Richard Fuller, added that “the impact of pollution on health 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 waste expelled into the air, water and soil usually do not kill directly, but they do cause serious heart disease, cancer, respiratory problems and acute diarrhea, the report says. “The health effects are enormous, and low- and middle-income countries are hit hardest,” he said.

The original article can be found here

Teresa H. Sadler