• Lilla Schottner

How global warming and climate change affect human health?

Updated: Sep 10

My paper for my Environmental Field Study at the University of the District of Columbia. 2019


This paper argues that climate change will have a broad range of direct and indirect impacts on health during this century. The global temperature is rising, hurricanes are getting stronger, heavy rains and longer droughts, wildfires and some other kinds of severe weather—are changing. Extreme weather events can lead to fatalities, injuries and mass migration and competition for resources (water, food). Many areas around the globe are already experiencing health threats. The impacts will increase, like mortality due to stronger and longer heat waves created by urban smog. Air pollution, air quality impacts: respiratory, cardiovascular and increase of cancer, caused by burning fossil fuels (coal, oil, and natural gas) rising the CO2 levels. Malnutrition because of compromised food growing habits and lack of access to water or water related illnesses. Over-use of herbicides and pesticides due to food scarcity. Changing patterns of infectious and insect-borne diseases (Estabrook, 2011).

Quoting from the report of the managing of the health effects of climate change: “Climate change is the biggest global health threat of the 21stcentury.” (Romm, 2018, p.110)!


What is Climate Change and what causes it?

The difference between climate and weather: weather is what occurs day to day, climate is an atmospheric condition measured in the long term, centuries or even longer. Scientists are collecting evidence, observing, analyzing deviations in temperature at different kind of locations around the world for decades. Their findings show that since the Industrial revolution of 1850, humans are emitting heat trapping Green House Gases to the atmosphere; therefore, the earth is warming in an unprecedented rate. When solar radiation hits the surface of the earth and when it strikes dark water or land it gets absorb, when it strikes snow or ice it is reflected back to space. The earth atmosphere is full of gases; these gases absorb some of the radiation coming from the surface therefore rapidly warming it. Scientists measure Carbon dioxide (CO2) in the atmosphere in parts per million (ppm). Before the industrial revolution, this number was 280 ppm; after the discovery of oil and coal this number started to rise, today it is 400 ppm and rising by 2 ppm per year (Robertson, 2017).

Top scientists are proving to the world since1988, since the formation of Intergovernmental Panel on Climate Change (IPCC), that climate change is caused by humans, our over-consumption, energy consumption, eating and driving habits by burning fossil fuels and adding carbon dioxide (CO2), methane (CH4), nitrous oxide (NO2) and other greenhouse gases to the atmosphere causing the earth to warm to levels which will make the earth not livable for humans and other species. In the next century, people will face the following problems:

1. Temperature-related illnesses

2. Air quality impacts

3. Extreme events

4. Vector-borne diseases

5. Water related illnesses

6. Food safety, nutrition and distribution impacts

7. Mental health and well-being issues

8. Population migration

1.Temperature-related illnesses

The growing concentration of greenhouse gases in the atmosphere can lead to extreme temperatures. Higher temperatures over an extended period of time can cause greater evaporation, increase in air temperature which can cause droughts. Droughts which last three decades are called mega droughts. One of those mega droughts has been linked by researchers to what destroyed the Anasazi or Pueblo Peoples in the Colorado Plateau in the 13thcentury (Romm, 2018). The chart below shows that extreme heat conditions can result in all kinds of illnesses including heat cramps, heatstroke and heat exhaustions. Exposures to high minimum temperatures may also reduce the ability of the human body to recover from high daily maximum temperatures (Friis, 2016). Some parts of the earth will experience extreme cold weather conditions, where people will face hypothermia, frostbites, respiratory diseases, cardiovascular diseases, and death.

2. Air Quality Impacts

Climate changes can result in impacts of air quality through three pathways: outdoor air pollution, aeroallergens and indoor air pollution.

Outdoor:Author Bill McKibben in his book Falter claims that, currently New Delhi’s air pollution is the worst in the world and a study found that, 4.4 million children in Delhi have lung damage from breathing the air. “Around the world, pollution kills nine million people a year, far more than AIDS, malaria, TB and warfare combined” (McKibben, 2019, p. 26). In China, a third of yearly deaths is blamed on smog and by 2030, it can claim hundred million worldwide. There is also evidence that climate change will increase the frequency and intensity of wildfires. Wildfires emit fine particulate matters and ozone gases that in turn increase the risk of chronic and acute cardiovascular and respiratory health symptoms and premature deaths (Romm, 2018). The chart above explains the relations between rising temperatures, and ozone related deaths in the United States.

Aeroallergens:Climate change has also led to higher pollen concentration, as well as longer pollen season. Greater concentration of CO2 together, higher temperatures and a changing precipitation increased the quantity of pollen in the air. This increases the allergic sensitization, hay fever, sinusitis, hives and asthma attacks. Especially vulnerable are children and people constantly exposed to it.

Indoor air:In some parts of the world, for example in Australia, people use wood heaters in their home. Burning firewood produces methane and black carbon particles. According to the EPA, inhalation of black carbon can cause respiratory and cardiovascular diseases, birth defects and cancer. Black carbon also contributes to climate change (Robinson, 2011).

3. Extreme Events

Extreme events like precipitations, coastal inundations, hurricanes, droughts and wild fires are projected to increase in frequency and intensity according to “TheThird National Climate Assessment (NCA)” (Friis, 2019). 

Due to climate change, hurricanes, cyclones, costal storms and flooding from stronger precipitations are expected to increase in some parts of the world (see chart below).Therefore, we can expect an increase of exposures to health hazards and health impacts, such as drowning and death during floods and storms. The most vulnerable will be the elderly, children, people who have pre-existing conditions, disabilities and people who rely on medical equipment. Sea level has also risen by about eight inches since 1880, when the record keeping began. In addition, in the next fifty and one hundred years it can rise several feet (six to seven). Such a rise can make coastal cities ungovernable and can create mass migration (Goodell, 2017).

Droughts in the South-west of the United States are expected to be longer, the health impacts could be reduced water quality and quantity, worsening of air quality, infectious diseases and mental health problems. Longer and stronger wild fires are already occurring in the American West, fire season on average is seventy to eighty days longer than it was in the seventies (Kodas, 2017). Wildfire smoke contains carbon monoxide, particulate matters and volatile organic compounds, which can significantly reduce air quality (Romm, 2018). Health risks include death, injury, inhalation related and mental illnesses.

Extreme events will also cause disruptions in essential infrastructures, including power lines, water systems, communication and transportation systems and emergency responders (Ella, 2016).

4. Vector-Borne Diseases

Vector-borne infection is an interaction between the infectious agent and the human host on one hand and the vector on the other. It spreads by biological transmission, which refers to transmission of the infectious agent to a host by bite of blood-feeding vector, as in malaria (Friis, 2019).

Few examples of vector-borne diseases:

Bacterial: Anthrax, Lyme disease, Plague and Salmonellosis.

Viral: Dengue fever, Human monkey pox, Influenza, Avian influenza, Swine flu, West Nile virus, Yellow fever and Rabies.

Parasitic: Leishmaniosis, Malaria, Trichinellosis and Giardiasis (Friis, 2019)

Climate change will have short- and long-term impacts on disease transmissions.

A new study in 2018 by the University of Colorado found, that pests are thriving in a new

heat, causing seven hundred thousand deaths annually (McKibben, 2019).

Tropical climates like in Africa, Southeast Asia, Central and South America, are favorable to most major vector-borne diseases, including malaria, yellow fever and tick-borne

hemorrhagic fevers. These organisms have different sensitivities to temperatures and

precipitations (Bulletin of WHO).

Rising temperatures and increasing rainfalls in the US and in Europe contribute to migration and the growth of the mosquito population. Increased precipitation has the potential to increase the number of breeding sites for vectors such as mosquitos and ticks. The dense vegetations also give shelter and food availability to vectors, could lead to population increase and in turn lead to disease outbreaks. Deforestation in order to create new human settlements or agricultural sites can increase the temperature and can create breading sites for malaria. According to the Center for Disease control and Prevention (CDC), malaria is found in hundred countries putting fifty percent of the world’s population at risk (Friis, 2019).By 2050, seventy percent of the world’s population will live in major cities, and Dengue fever is an urban disease. Cities with poorly managed water control and waste systems will have to face these problems.

5.Water Related Problems and Illnesses

Across the United States, climate change will affect fresh water and will increase people’s exposure to water related illnesses. Few examples of waterborne illnesses are cholera, E. coli and hepatitis A virus. They can cause severe diarrhea, dehydration, fevers and cramps. The most vulnerable groups are children, elderly and patients who are undergoing chemotherapy or have HIV/AIDS (Frees, 2016).

Other problems like runoff from city streets, lands and factories are also major contributors to water contamination. As author, Robertson states “Run off from pesticide applications and from factory/farms sewage introduce pollution in the form of chemicals, antibiotics, and pathogens to lakes and rivers” (Robertson, 2017, p. 232). These chemicals kill all aquatic life on their way, creating dead zones in rivers, lakes and seas.

By 2050, there will be more than nine billion people living on Earth, overshooting its carrying capacity (Robertson, 2017). 70 % of the earth’s surface is covered by seas, but only 0.01% of the world’s water is usable for human consumption. Water scarcity and water stress will be a major problem for humanity in the next decades, especially in sub-Saharan and North Africa, Saudi Arabia and the Persian Gulf countries.

The oceans are carbon sinks; they absorb about 93 % of the extra heat coming from burning fossil fuels. Carbon dioxide is heating and acidifying the seas, killing many key species, reducing diversity and eventually destroying ecosystems. In a 2013 report to the United Nations, scientists stated: “the oceans, over the course of the century, would become hot, sour and breathless”. This situation can create major food shortages in the next decades.

6. Food Safety, Nutrition and Distribution

Climate change will affect food security by disrupting food availability, distribution and nutritional value. Currently, agriculture occupies 35 % percent of the Earth’s land surface. In the 1960s, the green revolution introduced fertilizers, pesticides, irrigation and hybrid seeds that resulted in damage to soils, waters and ecosystems (Robertson, 2017). The increase in the frequency and intensity of some weather patterns will increase the disruption of food distribution by damaging infrastructure or slowing down food transportation. For example, U.S. rivers and canals carry a third of the world’s soy and corn and they had been disrupted before because of flooding (McKibben, 2019). This can lead to food damage, spoilage and contamination, which will limit access to safe food. Rising temperatures will result in longer growing seasons with more pest population; therefore, an increased use of pesticides will be the norm, which can lead to pesticide’s contamination in humans.

As the ocean’s temperatures will rise, so will the potential for fish to uptake higher concentration of mercury. Because of bioaccumulation, the mercury could end up in the human food chain causing serious health problems, including toxicity to the nervous, digestive and immune system (WHO).

Many studies have shown as Carbon dioxide (CO2) continues to rise in the atmosphere, the levels of protein and minerals (calcium, iron) in crops including wheat, rice, barley and potato will be lower and the levels of carbohydrate will be higher (Robertson, 2017). Researchers have grown grains in the expected CO2 levels later in the century and found that the percentage of minerals and protein dropped by eight percent. In the developing world, where most people rely on plants for their protein, this can cause protein deficiency (McKibben, 2019).

7. Mental health and well-being

According to many studies, people who are exposed to natural disasters experience stress, anxiety and serious psychological harm. As weather related events such as hurricanes, droughts, floods and wildfires continue to rise, so will the number of people who are impacted. Elderly, children, women (pregnant and postpartum women), people with preexisting mental illnesses, homeless are at higher risk for distress. Communities living close to the disaster areas are also at increased risk. Elderly and people who take prescription medications will be also at higher risk from extreme heat exposure.

8. Population Migration

Climate change will affect the most the most vulnerable, the very young and the very old, communities of color and low-income, indigenous populations, immigrants, pregnant women, persons with disabilities and persons with chronic and preexisting conditions. We can also expect “large-scale of population migration and the likelihood of civil unrest” (Romm, 2018, p.110). According to the International Organization for Migration (IOM), by 2050 we may see two hundred million climate refugees coming from Africa, South Asia and Latin America, which can destabilize entire regions, as we have seen how refugees coming from Syria poisoned the politics in Europe (McKibben, 2019).


Unfortunately, there are also the climate change deniers, who believe that global warming is a hoax. There is a difference between a denier and a skeptic: “Proper skepticism promotes scientific inquiry, critical investigation and the use of reason in examining controversial and extraordinary claims, it is foundational to the scientific method. Denial, on the other hand, is the priori rejection of ideas without objective consideration” (Romm, 2018, p.197). In the U.S., the climate change became politicized due to a climate change denial activism of the conservative Republican Party and they receive financial support from the fossil fuel industry. In 1946, the leading oil companies had created a “Smoke and Fumes Committee”: their goal was to use science and create public skepticism to prevent environmental regulations; they funneled millions into misinformation campaigns. Similar to the ones Tobacco companies spread about smoking and its cancer-causing debate. Exxon Mobil for example, has known since 1957 that the burning of fossil fuels caused global warming.

Author Joseph Romm in his book, Climate Change claims that the Koch industries, run by the billionaire brothers Charles and David Koch, spent more than $48.5 million from 1997 to 2010 to fund disinformation. Exxon Mobil, from 2005 to 2008, spent $8.9 million to organizations of the climate change denial machine. Dr. Wei-Hock “Willie” Soon is a Malaysian aerospace engineer who didn’t have any training in climatology, had taken more than $1 million from Exxon Mobil and the Koch Industries to spread misinformation, stating that the humans are not the primary cause of global warming, without disclosing that conflict of interest in his scientific papers (Romm, 2018). The Trump administration is as well very anti-science. The National Climate Assessment, which details the future impacts of global warming on the United States, was released on Black Friday, hoping that no one will pay attention to it. The assessment confirms that the climate change poses a major threat to the nation, and its effects are already being felt. For example, the fires in California were not caused by inadequate leaves raking (Trump), but by global warming. As author McKibben in his book Falter sates that “Politicians who don’t’ wish to deal with the issue of global warming often say, “The climate is always changing the earth will be fine; it is humans who are in trouble” (McKibben, 2019, p.66)

There is so much evidence that heat waves will last longer and cover larger regions and climate change makes weather patterns, including droughts, likely to get stuck or blocked, called blocking patterns (Mann, 2016). Nevertheless, the Trump administration and its allies in Congress do and will ignore this. Denying climate change became a Republican principle and it is rooted in ego, opportunism and greed.


The projection for the climate for the next fifty years or the next century, if we continue business-as-usual, meaning we continue burning fossil fuels (oil, coal) and we do nothing about our changing climate, is very alarming! We will experience high temperature rise, longer droughts, dust ball conditions in Southern Europe and in the Southwest of United Sates and areas of the world that are overpopulated and heavily farmed. There will be mega droughts, lasting more than three decades. This will also lead to mass extinctions of flora and fauna. We will also experience much more extreme weather conditions, like major hurricanes, floods and wildfires. The seas are the planet’s carbon sinks, absorbing CO2 and other greenhouse gases, therefore warming and expending its surface, causing sea level rise. By 2050, we can experience a one-foot rise and two feet per decade after 2100. The US East Coast is already experiencing a faster sea-level rise than the rest of the world. Harold Wanless, chair of University of Miami’s Geological Sciences department, told National Geographic in 2013: “I cannot envision Southern Florida having many people at the end of this century” and in 2014, he said, “Miami as we know it today, is doomed. It is not a question of if. It is a question of when” (Room, 2018, p.100). New York was hit by Hurricane Sandy and Hurricane Katrina hit New Orleans, these magnitude of storm surges will become a norm by the mid-century, forcing millions of people to relocate.


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