What Is The Role Of Epidemics In Climate Change? A Focus on Anthrax
by Finlay Procter
In Northern Siberia
Vast swathes of land in the Northern Hemisphere are permanently frozen. Over 15% is covered in permafrost (Obu, 2021). Permafrost occupies nearly 65% of the territory of the Russian Federation; most of this phenomenon is found east of the Urals, in the sparsely populated Siberian region (Bykova, 2020).
Within this permafrost, historical and biological treasures have been found, locked in time for millennia. Well-preserved Pleistocene carcasses of mammoths, steppe bison, wild horses, and woolly rhinos have all been found in the frozen soil of Siberia (Flannery, 2018). In 2018, Russian scientists defrosted two nematode worms that had been buried nearly 100 feet below the frozen ground for roughly 40,000 years (Dapcevich, 2021). When they were first frozen, herds of rhino-sized wombats roamed the Australian continent, the Homo sapiens population numbered at most only 30,000 individuals, and the last of the Neanderthals eked out a dwindling existence in Gibraltar (Finlayson, 2006). When they were warmed up, the nematodes started moving, and even ate.
In the summer of 2016, in the Yamal peninsula of Russia, a reindeer carcass was exposed by melting permafrost, and with it were uncovered bacterial anthrax spores. The anthrax, preserved in the ice but not exterminated, spread to the local herd of reindeer. Over two thousand reindeer died, and the anthrax zoonotically leaped to people in the nearest village (Liskova et al., 2021). Dozens were hospitalised, and a 12-year-old boy died (BBC News, 2016). We wrote more about this event here.
The role of the climate crisis
Many observers were quick to link the 2016 Yamal anthrax event to the pernicious effects of anthropogenic climate change (Stella et al., 2020). With the poles warming at a rate three times faster than at the equator, the thawing permafrost and resultant methane ‘feedback loops’ have been a key focus for climate scientists for some time. Although the causal linkage between global warming and this specific epidemic may be simplistic at best, it serves as a palpable reminder of the high degree of epistemic uncertainty relating to our understanding of the future effects of a warming planet on disease.
In 2015, a seminal Lancet report suggested that “anthropogenic climate change threatens to undermine the past 50 years of gains in public health” (Watts et al., 2015). A warmer planet will almost certainly mean more people are at risk of more infectious diseases. For example, the number of months with environmentally suitable conditions for the transmission of malaria rose by 39% from 1950–59 to 2010–19 in densely populated highland areas in developing states (Romanello et al., 2021). The epidemic potential for dengue virus, Zika virus, and chikungunya virus has increased as well, as the geographic range in which they can survive has expanded (ibid). Similar findings have been observed in the environmental suitability for Vibrio cholerae, a pathogen estimated to cause almost 100,000 deaths annually (ibid).
Disease in a changing world
Rising temperatures is not the only way humans may have had an effect on the global state of disease. Studies have shown that deforestation and habitat fragmentation, which increases the likelihood that humans come into contact with disease reservoirs, can be quantitatively linked to Ebola outbreaks, as can bushmeat consumption and the capturing of wild animals (Rulli et al., 2017, Olivero et al., 2017). COVID-19 is also of zoonotic origin, most likely bat or perhaps pangolin coronaviruses. Many in the media and academia were quick to question whether humankind’s increasingly exploitative relationship with wild animals, in this case through the ‘wet markets’ of Wuhan, and our wanton wholescale destruction of the natural world, were to blame (Carleton, 2021).
The globalised food production systems of the 21st century also increase the risk of future diseases. A reliance on vast monocultures of crops and livestock has reduced the genetic diversity of domesticated species and ergo made them far more susceptible to epidemics, and thus far more likely to be centres of zoonotic transmission to human populations. Famously, the global banana trade is dominated by just one breed: the Cavendish (Saladino, 2021). Pork production has reached an unprecedented level of scale and homogeneity through one particularly fast-growing breed, the Large White, which is also heavily affected by diseases such as African Swine Fever (ibid). And most of the nearly 70 billion chickens that are slaughtered each year are of a select few broiler breeds from just two transnational corporations: Cobb and Aviagen (ibid).
Thus, the way humans are rapidly changing the planet is increasing levels of risk and uncertainty related to future disease. The climate crisis may have helped the spread of anthrax in the thawing permafrost, and is increasing the geographic range of a number of pathogens and disease vectors. Habitat destruction is increasingly putting human populations in contact with zoonotic disease reservoirs, and our homogenic food systems have been made more vulnerable to disease and more likely to be the source of future pandemics. How we prepare for this changing disease landscape will therefore be decided by how we manage these causes.
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