How Climate Change could have caused The Pandemic
Since the first reports of novel pneumonia in patients from China’s Wuhan district, the origins of SARS COV II have been heatedly debated and contested. However scientists and virologists agree on one thing: the virus most likely evolved in animals and through some mechanism passed to humans. Climate change probably also played a significant role. In other words humanity’s destructive relationship with earth’s ecosystems may have triggered the pandemic.
Habitat destruction and changing terrestrial biomes can force animals closer together and allow for the rapid spread of viruses through populations. In the case of our recent pandemic, the animal of origin was probably forced into unfamiliar biomes and spread across areas it wouldn’t naturally inhabit, causing the spread of new viruses and pathogens. This model for the spread of climate change is backed up with observed and computer simulated evidence.
For example the origins of the virus and subsequent spread of the pandemic follow predicted and observed patterns of bat density and migration. Consequently bats are the predicted animal of origin for the virus. Moreover extremely similar strains of covid viruses have been found in horseshoe bats and several other subspecies prevalent in regions where covid originated.
The shifts in global bat diversity echoed by shifts in viral spread suggest key roles of climate change in the origins of covid 19. The number of covid viruses present in an area is strongly correlated with local bat species richness. No mechanism for transport is suggested in this post however links between changing bat populations and the rapidly changing human virome are demonstrated and supported with computer analysis.
These changing bat populations are driven by climate change, which affects the spatial distribution of plant species necessary for bats survival forcing bats to migrate to new areas. These shifts not only impact the spatial distribution of bats and other zoonoses but also change the distribution and arrangement of species carefully arrayed through ecosystems to mitigate and prevent viral flow. This can result in novel host-pathogen interactions forcing viruses to evolve and change. Understanding these viral interactions between bats and other animal species native to regions they inhabit is the necessary first step in understanding and discovering the path SARS COV II followed to reach humans.
In a recent study Robert Beyer, Andrea Manica, and Camilo Mora investigated how climate change has affected bat populations over the course of the last century and discovered that bat hotspots coincided with areas of SARS CoV II origination. Their approach involved first examining and inferring the global distribution of vegetation using computer analysis then cross-examining their findings with observed bat population spatial distributions and known necessities for bat colonies. They derived data from the CRUTS v4.04 data set converting variables as necessary such as cloud cover which was converted to percent of sunlight available. They then imputed their data findings into the computer simulation BIOME4 which estimated and simulated vegetation over the last 50 years. BIOME4 then simulated incoming solar radiation, photosynthesis, the concurrent stomatal behavior, and ecosystem dynamics caused by changing plant populations. The global distribution of bats was then derived by combining this vegetation map with the extent of occurrence and habitat requirements for most regional bat species.
The data presented showed that tropical forests and savannahs were ideal habitats for most bat populations near the origin of covid 19. More alarmingly the data from BIOME4 also showed natural tropical shrublands across the southern Yunnan province being replaced by tropical savannahs and deciduous forests, a paradigm shift that pushed out many native species and made homes for bats. In other words climate change has been unnaturally reshaping ecosystems and environments, concentrating virus-carrying bats in select ecosystems near farmland and areas of high transmissibility.
However climate change not only risks increased concentrations of viral bats but also destroys complex buffers found in healthy ecosystems. A recent study by Mark Everard found that contemporary livelihoods and market patterns tend to degrade the mechanisms within ecosystems that help mitigate viruses. So climate change has not only been placing coronavirus carrying bats within close proximity of each other, but it has also been ruining their ecosystems and increasing the chances of viral mutation and transmission to humans.
Everard evaluated the effects of human-induced climate change on SARS COV II and ecosystems using the DPSIR framework. DPSIR is a policy-relevant organization tool for analyzing complex interrelationships between society and natural ecosystems. The primary constituting principles of DPSIR are Drivers such as socioeconomic activities, Pressures and human activities that stress the environment, State changes in ecosystems, Impact of those state changes on society, and Responses. This framework was used in understanding the complex human-environmental linkages entailed in facilitating and spreading zoonose viruses.
Everard cited growing populations, the resulting land use and domestication of animals, loss of biodiversity, urbanization and globalization, and changing geographies of human settlement as primary drivers. The growing human population has been increasing by some 8.1 million people each year and is currently estimated at 8.2 billion. This is strongly correlated with declines in global forest cover and the destruction of widespread natural habitats. Currently over 96 percent of all mammalian biomass is human or domestic and wild animals represent only 4 percent of all large organisms on earth. Industrial nitrogen fixation has increased as a result of globalization, with nitrogen fixed by human activities predicted to exceed nitrogen fixed through microbial processes by 2030. All these environmental consequences of climate change and aggressive human behavior are serious driving forces behind societal-environmental tensions.
Everard continued to point out that the changes described above change the natural environment and complex ecosystems both large and small within it. The UNEP recognized five principal pressures contributing to the increased virulence of zoonoses. These pressures are deforestation and other paradigm land shifts, antimicrobial resistance, aggressive and intensified agricultural practices, poorly regulated wildlife trade, and climate change. These pressures all bring wildlife and people closer together in situations, lending to the immediate spread of zoonoses.
The state change derived from the pressures and drivers explained above is a loss of biodiversity. Biodiversity plays a key role in diluting and preventing viruses from becoming enormously potent. However the pressures levied upon ecosystems by human actions have led to an unprecedented decline in biodiversity and the beginning of an extinction-level event. In other words the biodiversity necessary to mitigate the rapid flow of viruses has been eradicated. Now ecosystems consist almost entirely of compatible organisms and viruses can infect swaths of organisms. Drivers and pressures have eradicated our greatest protection against pandemics and zoonoses. This state change impacted environments clearly and viciously. Bats were forced into earth’s remaining tropical forests and covid viruses evolved rapidly in their populations. Farmland encroached slowly on these habitats and domestic animals began making contact with bats. At some point in 2019 the first instances of SARS COV II likely spread from bats to livestock living on farmland near bat habitats. The virus then easily spread from bats to humans and the rest is history.
In conclusion the long-standing belief that nature and bats are at fault for the covid outbreak is completely incorrect. If humans maintained better relationships with the ecosystems around us and worked harder to preserve the beautiful balance and diversity of earth we could have avoided the pandemic entirely. In fact we could have avoided a large list of zoonoses including dating back to the spanish flu. I think this research is a lesson to work with nature rather than against it. For preserving nature is not only in nature’s interest. It is in ours as well.
