Why did the virus SARS-CoV-2, which caused the COVID-19 pandemic, start infecting people? There is evidence that our interactions with the natural environment are creating perfect conditions for pathogens to move from wild animals to people, as population growth, urbanization and climate change bring us into closer contact with wildlife. Medical News Today looks at the connections between health, sustainability, and the environment, and the lessons we must learn from the pandemic.
The Paris agreement, signed in 2015, was a global commitment to work toward net-zero emissions and the United Nations’ (U.N.) sustainable development goals.
As many as 192 countries, plus the European Union — a further 27 countries — joined the agreement, which came into force in November 2016. Details for its implementation were finalized in 2018 at the U.N. Climate Change Conference in Katowice, Poland, and in 2021 at the U.N. Climate Conference in Glasgow, UK.
Climate change and sustainability were constantly in the news. Despite a few dissenting voices, most experts recognized that people are largely responsible for climate change and that measures must be implemented rapidly to combat climate change.
Then, in December 2019, COVID-19 struck. Suddenly, there was a more urgent concern for governments to deal with. Climate change rapidly became a problem for the future. People were dying now from this new disease.
But what many began to realize was that the two issues were inextricably linked. The population growth that drives climate change also increases the likelihood of disease transfer from animals to humans.
COVID-19 is not the first zoonotic diseaseTrusted Source — a disease that is naturally transmissible from some animals to humans. The World Health Organization (WHO) records more than 200 such diseases, and unless we react to it in the right way, COVID-19 will not be the last.
Health and environment
“The major determinants of global health and sustainable development are poverty, population, and pollution — all of these are linked to both COVID-19 and the climate crisis.”
– Dr. Jagdish Khubchandani, professor of public health, New Mexico State University
The WHO estimates that more than 13 millionTrusted Source deaths each year are due to avoidable environmental causes, and it names the climate crisis as “the single biggest health threat facing humanity.” So climate and health must be addressed in parallel.
But how is climate linked to COVID-19? The prevalent theory is that COVID-19 moved to humans from bats via an unknown animal vector that was sold in, or had an association with, a wet market in Wuhan, China. And it is not the first disease to move in this way.
According to Amanda McClelland, senior vice president of Prevent Epidemics at Resolve to Save Lives, a global health organization that aims to prevent cardiovascular disease and epidemics:
“There is a strong link between climate change and infectious disease outbreaks. With greater global connectivity and urbanization, habitat loss, and changing environmental conditions, the potential for novel pathogens to become pandemic threats has significantly increased.”
Interactions with wildlife
People are accelerating climate change in many ways — population growth, burning fossil fuels, deforestation, urbanization, and environmental degradation are all adding to the problem. And as populations increase, people need more land, so they move into and use new areas.
They, or their domesticated animals, come into contact with wild animals. Many wild animals carry pathogensTrusted Source: Bats, for example, as well as being prime suspects for COVID-19, harbor several other viruses that cause disease in humans, such as rabies, Ebola, and SARS.
Dr. Kunjana Mavunda, board-certified pediatric pulmonologist and expert in travel medicine and global pandemics, told Medical News Today that “[t]he bat can hold several viruses that can be deadly to humans at the same time and not have a problem.”
However, passed to domestic animals and then to people, pathogens that are harmless to their original host often result in disease. The Centers for Disease Control and Prevention (CDC) estimate that three in every fourTrusted Source emerging diseases spread to humans from animals.
Dr. Mavunda added: “Societies that have markets where different species of wild animals are kept together in crowded conditions with poor hygiene — there is a high risk of the pathogens these animals having being transmitted, mutating and then transmitting to humans.”
And it is in developing countries that these conditions are most likely, as Dr. Khubchandani explained to MNT:
“The demand for resources like food cause greater animal husbandry, higher dependence on animals, and interactions with pests and pets without safety and sanitation. […] In such scenarios, we always notice that emerging infectious diseases originate from developing countries.”
Poverty, inequality, and climate change
In 2015, all U.N. member states adopted the 17 sustainable development goals. In summary, the goals are that ending poverty, reducing inequality, and driving economic growth must go hand in hand with tackling climate change and working to preserve the natural environment.
But what has been the impact of COVID-19 on these goals?
At the start of the pandemic, widespread lockdowns and a huge reduction in travel led to reductions in emissions of carbon dioxide (CO2), the main contributor to climate change. One study reported that in April 2020, global CO2 emissions were 17% lowerTrusted Source than the mean levels for 2019.
However, emissions climbed rapidly once the early lockdowns ended and economic activity revived. Overall, in 2020, emissions were down by only 6.4%Trusted Source for the year, and they are continuing to increase.
And in March 2022, the International Energy Agency reported that, in 2021, global CO2 emissions had rebounded to their highest ever level. The report stated that these emissions, driven by an upsurge in coal use, were “more than offsetting the previous year’s pandemic-induced decline.”
“National and regional lockdowns showed improvements to air quality, water quality, and the return of wild animals into towns and cities, with the reduced traffic and noise. But, and this is a big ‘but,’ all the effort put into working from home and social distancing only had a small impact on the input of CO2 into the atmosphere.”
– Dr. Keiron Roberts, lecturer in sustainability and the built environment, School of Civil Engineering and Surveying, University of Portsmouth, United Kingdom
So COVID-19 may have, briefly, helped the fight against climate change, but that effect was short-lived.
As Dr. Roberts explained to MNT: “COVID-19 showed us the scale of change we would need to do to reach net-zero under all the current policies and initiatives, which is massive. COP26 in Glasgow last year, and UNEA 5.2 recently, are keeping the climate agenda alive, but we need to keep working harder to help meet the Paris Climate Agreement.”
No time for complacency
The impact of the pandemic has been uneven. In high-income countries, comprehensive vaccination programs have ensured that almost everyone has had access to vaccines. Some high-income countries have vaccinated the vast majority of their population.
However, low- and middle-income countries tell a different story. Many have vaccinated less than 10% of their population. If vaccination does not increase in these countries, they will once again be left behind, delaying global recovery and, almost certainly, leading to the evolution of more variants.
Once again, poverty has impacted health. Combating poverty is one of the U.N. Sustainability Goals, and COVID-19 shows us how vital it is that this goal is achieved.
We should not forget the words of Dr. Tedros Adhanom GhebreyesusTrusted Source, director general of the WHO:
“No one is safe until everyone is safe.”
What can COVID-19 teach us?
As other global concerns, such as the war in Ukraine and the cost of living crisis, come to the forefront, many governments are winding down their efforts to combat and control COVID-19.
But COVID-19 has not gone away — the United Kingdom is still recording around 1,000 deaths each week from COVID-19, and the U.S. more than 500 per day, despite widespread vaccination.
To minimize the chance of future pandemics, we must learn lessons from COVID-19.
“We must think about work, life, society, education in novel ways that help the maximum number of people live a quality life. […] Essentially, we cannot think of just today, but decades in advance about SDGs.”
– Dr. Jagdish Khubchandani
Amanda McLelland echoed these sentiments, noting that “[w]e have an imperative to invest more in critical public health infrastructure that is vital to an effective, coordinated, equitable public health response to emerging outbreak and future zoonotic pandemics.”
“While global public health officials have long been sounding the alarm on the link between climate change and an increase in pandemic threats, it is my hope that our work as a society to improve environmental sustainability will also help us minimize the risk of future pandemics as we better understand and acknowledge the delicate relationship between humans, animals, and our shared ecosystem.”
COVID-19 may have distracted attention from sustainability and climate change, but it has highlighted the need to achieve the U.N. sustainable development goals. As attention moves from the pandemic, we must ensure it lands on the global environmental threats that are so inextricably linked to our health.
One lesson from COVID-19 is that countries must work together if goals are to be achieved, and now is the time to apply this lesson to a sustainable future.