An epidemic is an outbreak of disease that spreads quickly and affects many individuals at the same time. A pandemic is a kind of epidemic:

  • One which has spread across a wider geographic range than an epidemic, and which has affected a significant portion of the population.

Coronavirus (COVID-19) is a pandemic and it has now been reported on every continent except Antarctica.

The COVID-19 pandemic has created an unparalleled global and social crisis in the world in such short period of time which impacted significantly all aspects of life. Consequently, the world has been transformed. Thousands of people have already died, and hundreds of thousands more have fallen ill, from this pandemic that was previously unknown before appearing in the city of Wuhan in December 2019. For millions of others who have not caught the disease, their entire way of life has been changed as a result of this pamdemic.


According to the World Health Organization (WHO):

  • COVID-19 is disrupting life-saving immunization services around the world, putting millions of children at risk of diseases like diphtheria, measles and polio;
  • Immunization services is substantially hindered in at least 68 countries and is likely to affect approximately 80 million children under the age of 1 living in these countries; and
  • Routine childhood immunization services have been disrupted on a global scale since March 2020 that may be unprecedented since the inception of expanded programs on immunization (EPI) in the 1970s.
The Shared Visual Language of the 1918-2020 Pandemics

COVID-19 marks the return of a very old – and familiar – enemy. Throughout history, nothing has killed more human beings than the viruses, bacteria and parasites that cause disease. Not natural disasters like earthquakes or volcanoes. Not war – not even close. Over the millennia, epidemics, in particular, have been mass killers on a scale we can’t begin to imagine today – even in the time of the COVID-19:

  • Take the mosquito-borne disease malaria. It has stalked humanity for thousands of years, and while death tolls have dropped significantly over the past 20 years, it still snuffs out nearly half a million people every year;
  • The plague of Justinian struck in the 6th Century and killed as many as 50 million people, perhaps half the global population at the time;
  • The Black Death of the 14th Century – likely caused by the same pathogen – may have killed up to 200 million people;
  • Smallpox may have killed as many as 300 million people in the 20th Century alone, even though an effective vaccine – the world’s first – had been available since 1796;
  • Some 50 to 100 million people died in the 1918 influenza pandemic – numbers that surpass the death toll of World War One, which was being fought at the same time;
  • The 1918 flu virus infected one in every three people on the planet. (Read more about how the 1918 flu changed the world); and
  • HIV, a pandemic that is still with us and still lacks a vaccine, has killed an estimated 32 million people and infected 75 million, with more added every day.

Given the tremendous impact of pandemics on people’s lives combined with the fact that many experts believe that global heating and other environmental disturbances could facilitate the development of more novel viruses such as COVID-19. Here is a graph which illustrates the impact of climate change on human health:

Centers for Disease Control and Prevention

The dangerous health effects of climate change begin with the emissions that cause it. Black carbon, methane, and nitrogen oxides are powerful drivers of global warming, and, along with other air pollutants such as carbon monoxide and ozone. The problem extends beyond cities with famously poor air quality, such as New Delhi, Beijing, and São Paulo. Ninety percent of the world’s urban dwellers breathe air containing unsafe pollution levels, according to the World Health Organization (WHO).

Deadliest Contagious Diseases

The fact of the matter is that climate change exacerbates chronic and contagious disease, worsens food and water shortages, increases the risk of pandemics, and aggravates mass displacement. The broad environmental effects of climate change have long been discussed as long-term risks; what’s clear now is that the health effects are worse than anticipated—and that they’re already being felt.


From smog hanging over cities to smoke inside the home, air pollution poses a major threat to health and climate. The combined effects of ambient (outdoor) and household air pollution cause about seven million premature deaths every year, largely as a result of increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections:

  • 4.2 Million deaths every year as a result of exposure to ambient (outdoor) air pollution;
  • 3.8 million deaths every year as a result of household exposure to smoke from dirty cook stoves and fuels; and
  • 91 percent of the world’s population lives in places where air quality exceeds WHO guideline limits.

The dangers start at the beginning of life. Toxic pollutants cross the placenta, increasing the risk of preterm birth and low birth weight, which can cause lifelong damage to multiple organ systems. Children breathe more rapidly than adults do, so they absorb more pollutants at a time when their developing organs are more vulnerable. As a result, air pollution causes an estimated 600,000 deaths each year in children under five, mostly from pneumonia. There is also emerging evidence that air pollution compromises children’s cognitive development and can increase their risk of behavioral disorders.


In adults, pollution contributes to a wide range of respiratory and circulatory diseases, and may accelerate cognitive decline in seniors. Most air-pollution-related deaths are due to heart attacks and strokes, but ambient air pollution also accounts for a significant number of pneumonia, asthma, emphysema, and lung cancer deaths.

In addition to air pollution, emissions are responsible for rising global temperatures. These in turn lead to increased humidity and cause more frequent and intense heat waves that worsen hypertension and mental health problems, and can limit the effectiveness of certain medications. When a person’s body temperature rises to 104 degrees Fahrenheit or above, systematic organ failure occurs. Heat waves this summer killed 1,435 people in France alone, the only country to have published statistics on heat-related deaths. As many of the world’s major population centers grow hotter and more humid, more people will die from simply overheating.

The WMO Statement on the State of the Global Climate in 2018, its 25th anniversary edition, highlights record sea level rise, as well as exceptionally high land and ocean temperatures over the past four years. This warming trend has lasted since the start of this century and is expected to continue.

Source: United Nations

Perhaps fear was the main motivator for the public and private sectors around the world to seek public cooperation in responding to the COVID-19 pandemic by implementing guidelines and restrictions for the affected areas. It was indeed an unprecedented level of cooperation that helped control the spread of pandemic and it produced some meaningful results. At the same time, it was depressing to observe that climate change never got a friction of the attention to inspire and stimulate public interest in dealing with the devastating, damaging, and determintal situations caused by climate change.

The good news is that the enormous efforts invested around the world to control the pandemic, helped indirectly to reduce global emissions.  For instance:

  • The International Monetary Fund projected CO2 emissions would fall 5.7 percent this year, off a 3 percent drop in GDP and the International Energy Agency estimated an 8 percent fall. No one has yet estimated how much further emissions could fall in case a second wave of Covid-19 infections forces another global lockdown like the one in April;
  • Grounded flights, emptied highways and shuttered factories caused global CO2 emissions to fall to levels not seen since 2006 as stay-at-home orders peaked last month.  On April 7, global CO₂ emissions were 17 percent lower compared to the same time last year. That’s the conclusion of a new analysis by climate researchers who estimated this year’s CO₂ data across 69 countries, covering 97 percent of global emissions;
  • Before the pandemic, scientists had been expecting there to be little or no change in emissions this year. Countries hit their nadir at different times during the coronavirus pandemic, with CO₂ emissions bottoming out at 26 percent lower than the 2019 daily average in some places, according to the study published on recently; and
  • If pandemic-containment measures lift early this summer, emissions may fall 4 percent this year over last. Should they persist in a less strict form throughout the year, 2020 may finish 7 percent lower. Annual CO₂ pollution was stable in 2018 and 2019, approaching 37 billion metric tons. 

Here are some more observations:

  • According to Marshall Burke from the Department of Earth System Science at Stanford University: In China, just two months of reduced pollution has saved the lives of 4,000 children under the age of 5 and 73,000 adults over the age of 70. Perhaps, this is not a question of whether the virus is “good” or “bad” for the climate, but instead if we can create a functional economic system that supports people without threatening the life of Earth;
  • The first thing to consider, says Kimberly Nicholas, a sustainability science researcher at Lund University in Sweden, is the different reasons that emissions have dropped. Take transport, for example, which makes up 23 percent of global carbon emissions. These emissions have fallen in the short term in countries where public health measures, such as keeping people in their homes, have cut unnecessary travel. Driving and aviation are key contributors to emissions from transport, contributing 72 percent and 11 percent of the transport sector’s greenhouse gas emissions respectively; and
  • According to Steven Davis, Associate Professor in the Department of Earth System Science at the University of California, in recent years, we have generated around 500 tons of CO2 per $1 million of the world’s GDP. In 2019, 40 billion tons of CO2 were emitted per $88 billion of the world’s GDP. If this correlation persists, a decrease of the world’s GDP due to the imminent economic recession might generate a reduction in the global CO2 emissions in a similar proportion.

This public health crisis may serve as a turning point for another well-known crisis that, even though it may be perceived as slow, has the potential of significantly impacting humanity. As the Secretary-General of the United Nations, António Guterres, indicated the threat of COVID-19 is temporary, meanwhile, the threat of droughts, floods, and extreme storms linked to climate change will remain for years and will require constant action.

Kanata, Ontario, Canada 1 June 2020