How climate change could bring humans and animals closer, and intensify the spread of zoonotic diseases

Climate change is changing the natural behaviour of many plants, animals and insects, and this actually has major implications on the human population as well. Studies are showing that due to climate change, the dry regions will become drier and the wet regions will become wetter. 

Overall, most of the places around Earth are steadily heating up and some places are at risk of running out of water. Based on new data inputs from the natural environment, climate models’ results are slowly converging to roughly about the same prediction outcomes as to where the liveable locations are on Earth. Even the birds have begun to change their migration patterns in response to climate change.

This is a serious concern because firstly, cities are going to be denser as more people start to move into urban areas. Secondly, new urban environments are going to sprout up in places where it is going to be more liveable and less affected by climate change. Thirdly, animals might also seek out the same liveable spaces to ensure their livelihoods. 

Animals will want to seek out places where they can find food, water and safe living spaces. When forest area reduces, there is a high possibility for the animals to forage beyond natural greenery. Inevitably, we could eventually find that we might have to live even closer to the animal kingdom than we previously thought.  

City people have poor animal husbandry practices, if any at all. Combined with high density living in urban areas, the social distance between humans and humans, also animals and humans, could only get less and less as the years go by. We are being led by our nose into a future whereby the spread of zoonotic diseases will only intensify. 

I was running through several climate models and showed particular interest in tying the results to the population density model. Just take a brief look at the following visualisations. 

The density of the blue spots is an indication of the population density of any country. If you look at the visualisations that are presented for Jarkarta, Indonesia, it looks like it could do well with some decentralisation. Indonesia has a lot of land spaces (white areas) but everyone chooses to congregate in Jakarta. 

The Indonesians made their choices which I am sure are certainly based on practical reasons but there is a serious need for decentralisation. The density of the red spot indicates hyper densification and West Jakarta is growing steadily to match the likes of Chennai, Bangalore, Delhi and Mumbai. 

These cities are real living proofs to how dense a living space can become. 

Just for information, a study found that at least 500,000 species of mammal virus are estimated to have the potential to spread in human populations, but the vast majority are currently circulating in wildlife, largely undescribed and undetected by disease outbreak surveillance (Carlson, Zipfel, Garnier, Bansal, 2019). Birds can also be carriers of diseases that could harm humans. Now, there is a growing body of evidence and research also showing that bird migratory patterns are changing due to climate change. It is subtle but surely happening. 

I zoomed into birds because countries are going to find it difficult to close its borders to this class of animals. This visualisation was produced by the UN Food and Agriculture Organization and helps us to better appreciate the migratory pathways of birds. From this, we can see that it is possible for avian disease outbreaks to spread from as far as Russia to Australia and vice versa. 

While governments are busy tackling the negative effects of the Covid-19 virus, certain parts of Europe and some East Asian countries are signalling red alerts for the appearance of Avian flu such as H5N5, H5N8 and H5N1. 

H5N1 is a type of influenza virus that causes a highly infectious, severe respiratory disease in birds called avian influenza (or “bird flu”). Human cases of H5N1 avian influenza occur occasionally, but it is difficult to transmit the infection from person to person (Taken from WHO). 

H5N8 is a subtype of the influenza A virus and is highly lethal to wild birds and poultry. H5N8 is typically not associated with humans; however, seven people in Russia were found to be infected in 2021 (Taken from Wikipedia). 

H5N5 virus is a type of highly pathogenic avian influenza that is supposedly replicating among domestic ducks and wild birds that share the same water. Such new subtypes of influenza viruses may pose pandemic threat (Li, Lv, Li, Peng, Zhou, Qin & Chai 2021).

There are already 6 avian influenza outbreaks in Europe this year. Now, health officials have stepped up to warn that large scale infections are possible if many variants appear during the same window period. 

While this is not an immediate danger at the moment, governments and planners around the world should keep tabs on such developments and find ways to grow sustainably and safely. 

 

References

Carlson, C. J., Zipfel, C. M., Garnier, R., & Bansal, S. (2019). Global estimates of mammalian viral diversity accounting for host sharing. Nature ecology & evolution, 3(7), 1070-1075.

Li, X., Lv, X., Li, Y., Peng, P., Zhou, R., Qin, S., … & Chai, H. (2021). Highly Pathogenic Avian Influenza A (H5N8) Virus in Swans, China, 2020. Emerging infectious diseases, 27(6), 1732.

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