The rise in infectious disease pandemics: What role does climate change have to play?

By Dr Neeraj Nishchal

Climatic changes have been associated with an increase in infectious disease pandemics, especially by previously unknown pathogens. The changing climate has been proposed as a basis for the COVID-19 pandemic. A recent paper in the journal Science of the Total Environment has unfolded the link between climate change and the ongoing COVID-19 crisis.

It has been postulated from the beginning of the pandemic that this novel coronavirus has jumped to humans from bats. This link is a near-sighted view obscuring the big picture. Human greed has resulted in deforestation, urbanization, overcrowding all of which have resulted in the greenhouse effect causing global temperature to rise and changing rainfall patterns. The change from a tropical shrub-land to a deciduous woodland has made the environment more conducive to bats. This has led to bats harboring numerous viruses migrating to the area, increasing the probability of viral transmission to humans.

This is just one of many plausible theories. The rising global temperatures have led to many animals migrating away from the tropics towards the cooler poles. Such an erratic migration pattern leads animals to come in contact with other animals that they normally wouldn’t creating an opportunity for pathogens to get into a new host. 

Deforestation for industrial and agricultural purposes has led to major habitat loss as well. These dynamics increase contact between animals and humans which has not been observed before. The increased contact raises the probability of transmission of zoonotic diseases with increasing frequency.

Urbanization and overcrowding provide an easy opportunity for the respiratory spread of infection, so does poor sanitation leading to many water-borne disease outbreaks. With easy accessibility for people around the world to move from one place to another across the globe due to widespread air travel, diseases are no more confined by geographical boundaries. Hence causing global pandemics.

While the beginning of the COVID-19 pandemic might have roots in climate change, the transmission of COVID-19 rests on human shoulders. Rising pollution levels across the globe lead to the increasing transmission of airborne and droplet viruses. Areas with elevated pollution levels are also shown to have increased severity of respiratory illnesses and may contribute to severity of COVID-19 with higher mortality rates.

This pandemic has been a warning. Climate change has taken a back seat now that all resources are directed to the management of COVID-19 cases. However, we would do well to realize that we are focusing only on the tip of the iceberg. The worst is yet to come if we do not take emergent stringent action to reverse the damage our species has already caused to this planet. It is prudent to take health aspects into considerations while making environmental policies to come up with global health policies to prevent future pandemics.

The writer is Dr.Neeraj Nishchal Associate Professor Department of Medicine , AIIMS.