How the current coronavirus pandemic links to questions of ecological sustainability in the anthropocene
Any global crisis prompts environmental scientists to consider linkages to ecological disruptions. In our rush to gain "panic policy dividends" we need to be cautious about what ecological insights and policy prescriptions we derive from current crisis.
Nobel laureate Joshua Lederberg famously said that "the single biggest threat to man's continued dominance on the planet is the virus." The biological entities called viruses exist in the twilight zone between life and non-life and remain an elusive subject of evolutionary study. While the invisible biotic world of microbiology is often synonymous with dread, only around 1% of all microbes can actually cause disease in humans. Within the realm of microbes, bacteria, unlike viruses, have found redemption in our contemporary worldview through their positive role in digestive processes. Viruses have received less attention for their constructive role in ecological sustainability but their virtue should not be completely eclipsed by their vice. Nevertheless, Lederberg's words appear prophetic in our current pandemic crisis, even though humanity has endured numerous prior pandemics in history. What makes the situation different now is the speed of contagion spread due to globalization, as well as the economic and social impacts which are consequent as a result.
The origin of the novel coronavirus that causes COVID19 disease is widely believed to be a wild mammal that likely carried the virus and transmitted the virus to humans in the wet market of Wuhan, China in the autumn of 2019. The virus has strong similarity with coronaviruses found in bats, and research undertaken by the Ecohealth Alliance suggest that bats have the largest virus reservoir of potential spillover to humans. The next question pertains to how transmission occurs. No doubt any human interaction with wildlife raises risk but this rise is particularly higher when wild animals with dormant virus reservoirs are activated through contact with humans. This can happen through bushmeat consumption (as with Ebola), contact of wild fauna like ducks and geese with domestic chickens (avian flu) or captive pet and meat sale markets (as may be the case with SARS or COVID19). Stress factors which can activate viruses definitely include captivity and close proximity with other animals, as is often the case in markets and during pet transport. However, this could conceivably happen with zoos and domestic pet populations as well.
The role of climate change and habitat loss with regard to zoonotic disease prevalence is more complex and deserves greater care in policy formulation. Vector-borne diseases such as malaria are dependent on climatic ranges. Natural and human-made habitats can be conducive to their prevalence. A warming climate will on the one hand increase the altitudinal and latitudinal range of certain mosquito species, while it may also lead to dryer soil conditions which are less conducive to mosquito larvae. The situation with regard to the impact of climate change on influenza and corona viruses continues to perplex researchers. The viruses tend to be seasonal in temperate climates but they are still active in warmer tropics and overall infection rates are comparable. Understanding virus vitality under different temperature and moisture must be an urgent priority for pandemic prevention.
Overall far greater research is needed before any definitive claims can be made about the linkages between global environmental change and the wide and complex range of zoonotic pathogens. What is clear is that wildlife management in the anthropocene must go beyond simply ascribing blame on habitat loss as there are contemporary pathogens such as Lyme disease which have a far more complex zoonotic transfer ecology. We also need to be more alert to the consequences of our interaction with other animals as global environmental change and population densities continue to exacerbate stress on organisms. In areas such as remote unpopulated forests, it may be easier to follow a preservationist path and have much less human-wildlife interaction to mitigate zoonosis. At the same time human engagement with wildlife for research is also important, since many organisms in biodiverse ecosystems offer great hope for both chemical and biological pharmaceuticals. Furthermore, there are cultural and subsistence aspects of some forms of animal consumption which need to be reconciled with modern standards of health, hygiene and sustainable consumption metrics, but we must do so consistently and without prejudice and xenophobia. A key element of epidemic and pandemic prevention will be limiting the scale and extent of such interactions through protected areas management that considers pathogen exposure potential. Some measured level of zoonotic exposure can also build immunity to potential pathogens as was observed with some of the market vendors in Guangdong during the SARS epidemic. Key to balancing exposure immunity and disease spread potential is monitoring the serology of such populations regularly to identify any antibody anomalies as well as the virus reservoirs in animal populations.
Nevertheless, reducing animal-based diets as well as far greater care with pet health and their exposure to wildlife are likely to reduce chances of zoonotic disease transfer. However, there are also a range of disease microbes which can find their reservoir in soil, plants and fungi as well and the phenomenon of sapronoses (disease transmission from abiotic or non-living substrates) should not be discounted either in its pathogenic potency. Diseases such as tetanus have historically spread through such mechanisms widely before vaccines were found. In such cases environmental impact mitigation itself may not be adequate. We simply need to be vigilant and monitor the risks and the evolutionary processes which will always spring surprises on us through mutations and horizontal gene transfer (a phenomenon which has also led to the emergence of antibiotic resistance bacteria).
Human disease development in the face of environmental change will require constant research, global coordination and data exchange to keep up with the speed with which ecology and pathogenic agents are changing. There are still immense unknowns in this field which continue to confound us. Consider the case of the infectious facial cancer which is destroying the Tasmanian devil population in Australia which is under threat of extinction from the disease. So far there is no linking of this disease to human activity nor has animal to human transmission occurred but the potential for such transfer deserves study. Viruses in plants are thus far not able to transmit to humans but they do seem to find their way into insects and there are potential pathways for pathogenic entry into human systems. Research under ice sheets has also discovered viruses and bacteria which could potentially be pathogenic when they are released to the environment due to climate change melting the planet's polar regions.
The advent of the anthropocene has made it even more incumbent upon us as a species to consider the feedback loops of impact on biological systems from our activities while recognizing that nature has its own agency too. Pathogens have impacted humans even when we had a relatively benign impact on natural systems in our earlier history. Sustainable coexistence with biological agents does, however, require much greater investment in knowledge transfer. If we are simply to consider viruses (excluding other pathogenic agents like bacteria), there are around 220 known types of viruses that are known to cause disease in humans. However, there are an estimated 320,000 virus types just in mammals (based on statistical extrapolations). An estimate published in 2013 suggested that it would cost ~$6.3 billion to discover these viruses (or ~$1.4 billion for 85% of the total diversity). If we even doubled or tripled that cost now to discover other major virus types in a range of invertebrates that have contact with humans, it would still be a minor fraction of the $2 trillion bailout package being considered now by congress due to the impact of the novel coronavirus. Furthermore, we might even discover some virtuous viruses in the process which help us with nanotechnology.
Our aim should be to ensure, as best possible, that no virus or pathogenic entity is "novel" in an age when we have so many analytical tools at our disposal. Developing such a knowledge base would be an essential step in then charting out our sustainable coexistence path with the biotic diversity on our planet. Greater coordination between major environmental research projects and public health research entities deserves immediate attention. Organizations such as the Ecohealth Alliance which focus on pandemic prevention already have a broad partnership base with international environmental organizations. The next step may be more specific project coordination and data collection with organizations such as the Global Environment Facility and its implementing agencies that particularly service the Convention on Biological Diversity, the UN Convention to Combat Desertification and the UN Framework Convention on Climate Change. There is good evidence for the systemic linkages between biodiversity, land degradation and climate change which in turn can be threat multipliers for pandemic vulnerability.
Finally, while current environmental indicators may seem to be improving in some areas as result of low human activity patterns in the pandemic, there is no room to be sanguine. Recovery from such disruptions in the anthropocene means finding an optimal path between caution and paranoia. We will need to find win-win opportunities for lifestyles with lower ecological impacts while still mitigating health risks that can spark survivalist selfishness. For example a return to using low carbon public transport with greater hygiene care while not impacting risks of future contagions. Ultimately, in the post-COVID19 anthropocene, global environmental governance mechanisms will need to be more tightly coupled with individual responsibility if we are to have an ecologically and economically efficient path forward towards sustainable development.