Climate Change May Have Driven the Emergence of SARS-CoV-2

A new study published today in the journal Science of the Total Environment provides the first evidence of a mechanism by which climate change could have played a direct role in the emergence of SARS-CoV-2, the virus that caused the COVID-19 pandemic.

The study has revealed large-scale changes in the type of vegetation in the southern Chinese province of Yunnan, and adjacent regions in Myanmar and Laos, over the last century. Climatic changes including increases in temperature, sunlight, and atmospheric carbon dioxide – which affect the growth of plants and trees – have changed natural habitats from tropical shrubland to tropical savannah and deciduous woodland. This created a suitable environment for many bat species that predominantly live in forests.

The number of coronaviruses in an area is closely linked to the number of different bat species present. The study found that an additional 40 bat species have moved into the southern Chinese province of Yunnan in the past century, harbouring around 100 more types of bat-borne coronavirus. This ‘global hotspot’ is the region where genetic data suggests SARS-CoV-2 may have arisen.

“Climate change over the last century has made the habitat in the southern Chinese Yunnan province suitable for more bat species,” said Dr Robert Beyer, a researcher in the University of Cambridge’s Department of Zoology and first author of the study, who has recently taken up a European research fellowship at the Potsdam Institute for Climate Impact Research, Germany.

He added: “Understanding how the global distribution of bat species has shifted as a result of climate change may be an important step in reconstructing the origin of the COVID-19 outbreak.”

To get their results, the researchers created a map of the world’s vegetation as it was a century ago, using records of temperature, precipitation, and cloud cover. Then they used information on the vegetation requirements of the world’s bat species to work out the global distribution of each species in the early 1900s. Comparing this to current distributions allowed them to see how bat ‘species richness’, the number of different species, has changed across the globe over the last century due to climate change.

“As climate change altered habitats, species left some areas and moved into others – taking their viruses with them. This not only altered the regions where viruses are present, but most likely allowed for new interactions between animals and viruses, causing more harmful viruses to be transmitted or evolve,” said Beyer.

The world’s bat population carries around 3,000 different types of coronavirus, with each bat species harbouring an average of 2.7 coronaviruses – most without showing symptoms. An increase in the number of bat species in a particular region, driven by climate change, may increase the likelihood that a coronavirus harmful to humans is present, transmitted, or evolves there.

Most coronaviruses carried by bats cannot jump into humans. But several coronaviruses known to infect humans are very likely to have originated in bats, including three that can cause human fatalities: Middle East Respiratory Syndrome (MERS) CoV, and Severe Acute Respiratory Syndrome (SARS) CoV-1 and CoV-2.

The region identified by the study as a hotspot for a climate-driven increase in bat species richness is also home to pangolins, which are suggested to have acted as intermediate hosts to SARS-CoV-2. The virus is likely to have jumped from bats to these animals, which were then sold at a wildlife market in Wuhan – where the initial human outbreak occurred.

The researchers echo calls from previous studies that urge policy-makers to acknowledge the role of climate change in outbreaks of viral diseases, and to address climate change as part of COVID-19 economic recovery programmes.

“The COVID-19 pandemic has caused tremendous social and economic damage. Governments must seize the opportunity to reduce health risks from infectious diseases by taking decisive action to mitigate climate change,” said Professor Andrea Manica in the University of Cambridge’s Department of Zoology, who was involved in the study.

“The fact that climate change can accelerate the transmission of wildlife pathogens to humans should be an urgent wake-up call to reduce global emissions,” added Professor Camilo Mora at the University of Hawai‘i at Manoa, who initiated the project.

The researchers emphasised the need to limit the expansion of urban areas, farmland, and hunting grounds into natural habitat to reduce contact between humans and disease-carrying animals.

The study showed that over the last century, climate change has also driven increases in the number of bat species in regions around Central Africa, and scattered patches in Central and South America.

Source: University of Cambridge

UN Reveals 30% of the Entire Planet Supports Plant-Based Diet as a Climate Policy

With 1.2 million respondents in 50 countries covering 56% of the world population, the UN’s People’s Climate Vote is the largest ever survey of public opinion on climate change. The poll revealed that an overall average of 30 % of people in the surveyed 50 countries support the promotion of plant-based diet as a climate policy. The figure is as much as 42% in developing states and 33% in high-income countries.

The People’s Climate Vote was carried out by the UN along with the University of Oxford and various NGO’s, to educate people on the subject of climate change and the possible solutions thereof, as well as to survey the public around the world as to the actions they believe governments should take.

On the subject of plant-based diets, the report states, “Rearing livestock in a conventional way contributes to climate change mainly due to deforestation to expand pastures. Unless forest-friendly and regenerative and biodiversity conservation approaches are adopted in livestock and beef production, just like conventional agriculture it creates environmental and health impacts. Plant-based diets offer an alternative to provide nutritious food with lower methane emissions.”

The popularity of the concept of plant-based diet as a climate policy, compared to the overall average of 30% around the world, showed that 42% were in favour in small island developing states; 33% were in favour in high-income countries; 29% in least developed countries; and 29% in middle-income countries.

“The survey brings the voice of the people to the forefront of the climate debate. It signals ways in which countries can move forward with public support as we work together to tackle this enormous challenge.” Achim Steiner, Administrator, United Nations Development Programme.

Source: Vegonomist

Climate Change Threatens to Unlock New Microbes and Increase Heat-Related Illness and Death

The Journal of Clinical Investigation (JCI) recently published “Viewpoint” articles by Johns Hopkins University School of Medicine professors who warn that global climate change is likely to unlock dangerous new microbes, as well as threaten humans’ ability to regulate body temperature.

Johns Hopkins Bloomberg Distinguished Professors Rexford Ahima, M.D., Ph.D., and Arturo Casadevall, M.D., Ph.D., M.S., along with William Dietz, M.D., Ph.D., director of the George Washington University’s Sumner M. Redstone Global Center for Prevention and Wellness, and Susan Pacheco, M.D., associate professor in the Department of Pediatrics at the University of Texas Health Science Center at Houston, authored journal articles relevant to their fields that detail how rising temperatures around the world pose dangerous threats to humanity.

Ahima, director of Johns Hopkins’ Division of Endocrinology, Diabetes and Metabolism, wrote in the journal that “global warming threatens human thermoregulation and survival.”

Ahima explains that people generate body heat and have the capacity to regulate their temperature within a few degrees. But “as heat waves become more common, more severe, and longer, we expect to see more heat-related illnesses and deaths,” he writes.

Ahima cites a recent study that examined global heat-related mortality, pointing out that tropical and subtropical countries and regions will experience the sharpest surge in illness and death stemming from higher temperatures, while the United States and Europe can also expect increases.

Casadevall’s article explores “the specter of new infectious diseases” as a result of the changing climate.

“Given that microbes can adapt to higher temperatures,” writes the professor of molecular microbiology and immunology, and infectious diseases, at Johns Hopkins’ schools of medicine and public health, “there is concern that global warming will select for microbes with higher heat tolerance that can defeat our endothermy defenses and bring new infectious diseases.”

Endothermy allows humans and other warm-blooded mammals to maintain high temperatures that can protect against infectious diseases by inhibiting many types of microbes.

Casadevall cites a particular climate threat from the fungal kingdom.

“We have proposed that global warming will lead many fungal species to adapt to higher temperatures,” he writes, “and some with pathogenic potential for humans will break through the defensive barrier provided by endothermy.”

As an example, Casadevall points to the rise of Candida auris, a species of fungus identified in 2009 and called a “catastrophic threat” by the U.S. Centers for Disease Control and Prevention in 2017.

“The nearly simultaneous emergence of Candida auris on three continents, an event proposed to result from global warming, has raised the specter that increased warmth by itself will trigger adaptations on certain microbes to make them pathogenic for humans.”

Casadevall says that, while fungi present the most immediate threat, other microbes also adapt to evolving conditions such as temperature. He writes that “the conceptual threat originally identified with fungi, and exemplified by C. auris as the canary in the coal mine, applies across the microbial world.”

Dietz’s article addresses climate change and malnutrition, calling obesity, undernutrition and climate change a “syndemic,” or multiple epidemics that interact and share common underlying social or economic determinants and policy drivers. In her article, Pacheco discusses climate change’s adverse consequences regarding pregnancy and maternal, fetal and child health.

In all four JCI “Viewpoint” articles, long-term strategies are urged to reduce greenhouse gas emissions and slow the trend of rising temperatures.

Source : The Johns Hopkins University


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