Climate Change and the Rise of Zoonoses

In some parts of the world, Covid-19 has seemed to disappear. In other parts, people wonder if the pandemic will ever end. As a result of Covid-19, global economies have crashed, emission levels have sunk only to spike right back up, and ultimately, the state of the earth has been forever altered. This pandemic has cast a darkness humanity hopes to never face again. However, the unfortunate reality is, Covid-19 is just the start of the expansion and rise of all zoonotic diseases. As the earth continues to warm due to anthropogenic climate change, the dynamic interactions between humans and animals will inevitably change in myriad ways. This rapidly changing environment empowers zoonotic diseases to become increasingly transmissible. Humanity can either slow the warming of the earth and avoid future variations of Covid-19, or it can continue at the current rate of global warming and face severe repercussions in the future. 

Covid-19, which originated in Wuhan City, Hubei Province, China, came from animal-to-human transmission, classifying the virus as zoonotic. The World Health Organization (WHO) reported the most likely origin species to be bats, which then passed the disease to an intermediate animal before infecting humans. The immediate impact has been a dangerously infectious virus with over 504 million cases and 6.2 million deaths worldwide in the past few years, but this pandemic has proven to be more than just a global health crisis.

Covid-19 attacked societies at their core, increasing inequality, discrimination, and global unemployment. All segments of society have been affected, and thus the rise of zoonoses poses a vast threat to humanity. Beyond Covid-19, the world has also faced Ebola outbreaks for the first time in West Africa, Lyme disease in Europe and Asia, and the highest surge of Lassa fever in Nigeria ever recorded. An estimated 60% of emerging diseases are zoonotic in origin. 

Zoonotic diseases—diseases that spread from non-human animals to humans—are influenced by the core causes of climate change. Zoonotic infectious diseases are situated at the cross-section of environmental change, ecosystems, and health. Typically, these diseases are associated with the warmer latitudes of Earth’s hemisphere. However, the rising global temperature has caused more areas to be susceptible to disease outbreaks. For example, Nepal, a more mountainous and northern country, is generally too cold for dengue fever. Yet in 2006, the country faced its first outbreak. As our climate continues to warm, cases like Nepal will begin to become a pattern. To ensure this foreseeable future does not become a reality, humanity must understand and dismantle the linkage between climate change and zoonoses. 

Climate change influences the dynamic relationships between humans, animals, and land— leading to the rise of zoonotic diseases. A number of global warming and transmission patterns, such as deforestation, pollution, and mass migration, leave the future of diseases uncertain. Mass deforestation and forest fires strip animals of their habitats and cause them to migrate, often pushing them closer to other animals and humans. These atypical contacts increase the transmission of germs and disease. According to EcoHealthAlliance, deforestation is linked to 31% of disease outbreaks. Inevitably, anthropogenic assets that contribute to deforestation will disrupt the balance of the earth and incite impending disaster. 

Another factor of increased zoonotic diseases is worsening air quality. As pollution and particulate matter concentration in the atmosphere increases, carbon, sulfate, and nitrates penetrate humans’ lungs and bloodstreams. These particulates weaken the immune system, making the spread of diseases much more likely. By examining the number of cases and deaths in different cities, it becomes clear that cities with higher air pollution levels were more affected by Covid-19. Researchers, Xiao Wu and Rachel Nethery found that an increase of 1 microgram per cubic meter of fine particulate matter corresponded to a 15% increase in Covid-19 deaths. Humans must alter the way energy, industry, and natural capital are consumed to reduce pollution and improve air quality. 

An increasingly relevant cause for the linkage between climate change and zoonotic diseases is forced human displacement. As hundreds of millions of people are forced to find new homes, transmission patterns will shift drastically. This increased migration will spread diseases that emerge from nature’s shifts in stability. Climate change has already displaced millions of climate refugees and by 2050, the World Bank predicts there to be 140 million internally displaced people due to climate change. Clearly, this underlying human crisis within the climate crisis has hardly seen the worst of it. 

These diseases are also particularly detrimental to the public health, economies, and livelihoods in low and middle-income communities that are structurally disadvantaged to deal with and combat these outbreaks. It is therefore crucial that the global players most responsible for climate change as well as the poorer countries most affected, work together to avoid the dark future humanity is creating. 

The deplorable effects of zoonoses are likely to escalate in magnitude and intensity if humankind does not counter the root causes of climate change in the near future. The health of humans, animals, and society is at the center of the climate crisis, so to truly slow the spread of zoonoses, the root causes of climate change must be confronted. Protecting the future of humanity means putting our planet and people first. 


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