By Mark Watts, Executive Director of C40 Cities

Last week’s UN Summit on Biodiversity could not be more timely. Research published earlier this month found that animal populations are in rapid decline, having dropped an average of 68% since 1970 due to human activities, while evidence is accumulating that the increase in new diseases such as COVID-19 is linked to the destruction of natural ecosystems. We are, in the words of biologist Sir Ian Boyd, ‘on a collision course with the hard limits of nature.’

COVID-19 is only the latest in a series of novel disease outbreaks; recent decades have seen the emergence of Bird Flu, Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS). Experts are warning that animal-to-human diseases are increasing and will continue to do so without action to protect wildlife and the environment.  

This summer, the UN Environment Programme published a report titled ‘Preventing the Next Pandemic: Zoonotic diseases and how to break the chain of transmission’ showing how diseases are emerging more frequently from animals as the global population increases and humans encroach further and further into natural habitats. It is this increased contact between people and wildlife that allows pathogens to jump from their wildlife hosts to humans.

The report identifies the major human activities behind the increased risk: 

  • The high demand for animal protein accompanied by an increase in population drives the intensification and industrialisation of animal production, in which large numbers of genetically similar animals are kept in close proximity to each other, often in less than ideal conditions and resulting in populations that are more vulnerable to disease. Moreover, the expansion of croplands to produce animal feed drives deforestation, destroying natural habitats.
  • The trend towards lengthening food supply chains, which is driven by the increased demand for animal sourced food, new markets for wildlife food, and agricultural intensification, creates more opportunities for disease transmission.
  • Land use changes that occur to make way for the development of housing and other human activities, such as transport and resource extraction, increases interactions between people and wildlife. Rapid urbanisation can play a role, especially when poorly planned and with poor infrastructure.
  • As humans increasingly exploit wildlife for food, recreational hunting, trading in wild animals, and the use of animal parts for medicinal and other commercial products, the risk of disease transmission between wild animals and humans is increased. 
  • Diseases can now travel around the world faster than their incubation periods, and the increasing amount of human travel increases the risk of zoonotic diseases emerging and spreading.
  • Finally, climate breakdown is a major factor in the emergence and spread of diseases. Many diseases will thrive in a warmer, wetter, more disaster-prone world – that is, the one foreseen in future scenarios. Variation in climate tends to affect the many diseases transmitted by insects, ticks and other vectors; warmer temperatures could increase their numbers and the length of the season in which they are present in the environment. The changing climate also influences the numbers and the geographic distribution of species such as bats, monkeys and rodents – species in which emerging diseases often originate. 

It’s clear that there are considerable synergies to both preventing the next pandemic and acting on climate and ecological breakdown, such as diets that can support the growing global population without overshooting planetary boundaries. Overconsumption is most pronounced in the richest parts of the world, with trends in the Global South now steadily upwards, albeit from a much lower base. The Planetary Health Diet offers a solution; designed to feed 10 billion people with no further harm on the land system, biodiversity and wildlife, its widespread adoption would help to slash emissions. Last year, 14 global cities signed up to the C40 Good Food Cities Declaration, which commits mayors to aligning their food procurement policies to the diet, supporting an increase of healthy plant-based food consumption and reducing food waste and loss.

We also need to rethink our model of urban development, preserving buffer zones between human settlements and wildlife and reducing opportunities for the emergence of novel diseases. As cities grow and urbanization progresses worldwide, growth must be directed towards already settled areas, and where outward expansion is necessary it must be done in a way that promotes livable density levels while preserving wildlife. 

This year has sent a series of sharp reminders that we are not separate from the natural world. Events have made it so that we can longer ignore the destruction of our environment, but the solutions are within our reach.

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