Alongside other man-made and natural factors, climate change is capable of influencing human health in various important ways.
This article discusses the influence of climate change on human health, based on the following aspects of the topic;
Definition of Climate Change
Climate change is the modification or complete change of the average weather conditions over a period of time, in any region.
Climate change can be identified and measured, based on some unique atmospheric conditions and environmental events which take place in the world today. These include;
-Global rise in Average Temperature
-Increase in Precipitation
-Thawing of frost and glaciers in polar regions
How Climate Change Affects Human Health
As a result of climate change, various existing health challenges have grown more intense and widespread, while other new challenges have arisen. However, the impacts of this on the human population may vary with geographic location, economic conditions, as well as age .
The mechanism by which climate change leads to public health problems, can be explained in a simple manner. Because the climate directly influences how biological, ecological, chemical and physical systems operate, it can also control the quality, availability and distribution of important materials like air, water, energy, and food.
Severe cases of climate change (as we are experiencing in several parts of the world), generally reduce the quality of the environment, and its natural resources. We can observe this effect in the form of food insecurity, drought, global warming, ozone layer depletion famine, air, water, and soil pollution, and natural hazards like landslides, heatwaves, flooding, among others.
Because the human population depends directly on the environment for its survival, replenishment, nourishment and productivity, public health soon declines. Some common examples of this effect include;
-Injuries (due to natural disaster and environmental degradation)
-Cardiovascular and Respiratory Diseases (as a result of pollution)
-Increases prevalence of Water-borne Diseases (due to sea level rise, flooding and water pollution)
-Increase in prevalence of Vector-borne Diseases (due to increase in global temperature, allowing disease vectors like tse-tse fly and mosquito, to breed in a wider geographic range of environments)
-Increased Mortality rate (due to natural hazards and diseases)
-Increase in prevalence of Mental Illnesses (due to lack of economic resources and the resultant rise in rates of joblessness, poverty, homelessness, and social isolation)
Further Explanation of the Health Challenges of Climate Change
Decline in crop yield could result in hunger, increased cost of food materials, and under-nutrition. Obviously, each of these conditions have negative ripple effects on health.
Climate change involves the greenhouse effect, whereby gases like carbon dioxide occur in large atmospheric concentrations. This increases the potential of atmospheric pollution and acid rain, which are capable of reducing the yield, quality and nutritional value of crops.
You may recall that we earlier linked mental illnesses to social and economic issues like joblessness, poverty, social isolation and homelessness. In addition to these issues, natural disasters like droughts, heatwaves and floods, result in trauma that could cause depression, anxiety, and isolation, and could ultimately increase suicide rates.
In extreme weather conditions, power outages may occur due to damaged electrical infrastructure. This is capable of crippling important public facilities like transport and health systems.
Increase in humidity, temperature and rainfall, can increase the spread of ticks and mosquitoes, alongside the diseases which they cause.
More environmental heat may lead to respiratory ailments and allergies.
The quality and effectiveness of labor (especially in construction and agriculture) may decline due to extreme weather conditions and potential occupational hazards like heatstroke. This will in turn cause a decline in economic conditions.
The very young and the old within the human population, will become even more vulnerable to climate-related ailments.
Dengue fever, caused by mosquitoes, is known to have multiplied in recent decades, in terms of its prevalence, spreading to the Asia-Pacific. This is mainly due to climate change effects like humidity and temperature rise.
Saltwater intrusion into freshwater systems, may become more frequent and widespread as a result of climate change and sea level rise. Flooding may increase the rates of chemical pollution by industrial effluents, and overflow of sewage systems.
Increased rainfall implies that disease-causing microorganisms like bacteria and fungi will become more prevalent.
In addition to the above, it is important for us to acknowledge that climate change is already affecting public health in several ways. Specifically, there has been a sharp, recent rise in rates of illness and death resulting from extreme weather conditions. Examples of such conditions are storms, floods, and heatwaves.
Climate change and its corresponding extreme-weather conditions, are directly and negatively affecting several of the factors that determine public health, such as equality, livelihood, as well as access to social infrastructure and health care systems .
As we will soon understand from the concept of climate injustice, these impacts are felt most severely by the vulnerable members of our society, including ethnic minorities, economically disadvantaged people, poor individuals, the elderly and children, migrants, women and displaced persons, aa well as individuals with already-existing health problems.
While it is widely accepted, already, that climate change affects human health, there is not much available information with which we can measure the level of impact, or the scale of the effects of climate change on health. Through scientific research, however, it has been shown that global warming and its related issues, are related to increases in mortality and morbidity rates .
It is predictable that the major way by which the health effects of climate change will be determined is based on the level of vulnerability of the human population, as well as the degree of their resilience and adaptation.
Also, the long-term effects of climate change on health, depend on the degree and effectiveness of steps taken to reduce greenhouse gas emissions and mitigate global temperature rise.
Also, research has shown that the health problems which are directly affected by climate change are fairly numerous. They include Ebola, Tuberculosis, Avian Influenza (or bird flu), Plague, and Cholera . These illnesses can either be worsened or made to spread at a faster rate, by extreme climatic conditions.
Social Inequalities, Climate Justice, and Climate-related Health Problems
Climate justice is a very important topic, which seeks to address the influence of social inequality on how climate change affects the human population.
It highlights the imbalance between the socially privileged (including the wealthy, urban dwellers, and people in well-developed countries), and the less-privileged (including the poor, homeless, illiterates, rural dwellers, and inhabitants of underdeveloped countries) with respect to their vulnerability to the problems arising from climate change.
Although the entire human population faces the risks posed by climate change, the individuals who face the greatest risk are those who make the least contribution to the causes of climate change.
These individuals are exposed due to lack of resources, and are least protected. They include the categories of people which we have already mentioned- such as low-income households.
In order to achieve climate justice, it is also important for us to acknowledge that the climate change problem has undermined the efforts made to improve the quality of life for the human population. These efforts include advances in technology to aid all sectors of the economy.
By resulting from these very efforts to improve the human condition, climate change serves as a notable challenge to the overall growth of our society.
Efforts to achieve universal health coverage have also been hindered by climate change. This is due to the imbalance in access to healthcare, economic resources, and other factors that reduce the impact of climate change.
Up to 12% of the global population spends at least 10% of their overall income on health care . Considering the rising prevalence of economic challenges in the world, it is very likely that more of the human population will be exposed to both climate-related illnesses and poverty in the coming years.
Health Challenges of Climate Change: Major Diseases Caused by Climate Change
Before proceeding, it will be helpful to clarify, as we have earlier shown, that climate change itself is not solely responsible for the CAUSE of any major human disease.
This means that there are other factors that cause the diseases which are discussed in this section. However, climate change has been found to be a major driver in the recent rise in the rate and severity of such illnesses.
This is especially in the area of increasing infections, mortality and morbidity. Having said this, we can proceed to discuss some major examples of climate change-related human health problems;
Babeiosis is a disease which bears similarity to malaria. It is transmitted by ticks and prevails mainly in the tropical regions of the world.
However, of recent, Babeiosis infections have grown more widespread, affecting parts of Europe such as Italy. Although the disease is relatively rare among the human population, there are speculations that issues of global warming will likely cause a rise in the prevalence of the disease .
The reason behind these speculations, is the fact that climate change has been found to increase the spread of tick-borne diseases. This is because the increase in global temperature and humidity, makes more regions of the world to be conducive to the survival of these and other disease vectors .
2). Avian Influenza
Also known as ‘bird flu,’ this illness is associated with birds, especially domestic poultry, across the globe.
The avian influenza is caused by viruses, and has led to more than 200 human deaths and huge economic losses worth up to $100 billion. Avian influenza infections in humans, occur in a seasonal manner. Studies have shown that the environmental factors that cause outbreaks of the disease include topography, population density, and topography.
With respect to climate, the conditions which favor the spread of avian influenza, include high temperature, increased variability of the weather, and high humidity .
The Ebola virus is well-known for its fatal effects on humans and primates in general. In spite of several scientific efforts so far, there appears to be no reliable, known, or approved, cure for the disease .
The symptoms of Ebola infection include vomiting, external or internal bleeding, and fever .
While there is not much available and reliable information on the primary host of the virus, much speculation suggests that it could be transmitted chiefly by fruit bats. However, there is no doubt that the spread of Ebola is related to climate change.
Past outbreaks of the Ebola virus have been observed to mainly occur alongside extreme environmental conditions like droughts or storm events. Based on these observations, it is believed that climate change will increase the risk of;
1). More frequent outbreaks
2). Wider geographic spread of the virus
At the present, Ebola outbreaks usually prevail within Central Africa and its surrounding regions . The climate change crisis is capable of increasing the rate of transmission and spread by 3.2-fold, by the year 2070.
At the same time, climate change presents the risk of outbreaks in other parts of Africa in the coming years. Such conditions imply that the risk of rapid spread to other continents will increase greatly as well.
To further help us visualize the possible ways by which climate change can worsen Ebola spread, we can consider how increased rainfall is capable of leading to increased production of fruits. This will provide food supply to the fruit bat population, which is considered to be a potential disease vector .
Drought conditions, on the other hand, may reduce crop yield significantly. Especially in rural areas, this may cause an increase in the dependence on wild animals and vegetation for food. Such a dependence would obviously increase the exposure of humans to the animal vectors of the virus such as apes and bats.
4). Lyme Disease
In the United States, Lyme disease is one of the most common diseases spread by a vector. About 30,000 cases of this disease are confirmed annually within the country alone. This is even less than the actual incidence rate, since some of these cases are unreported.
The transmission of Lyme disease occurs as a result of the bite of deer ticks (a term used to refer to the specie of ticks that carries the disease).
The deer tick is basically an ecto-parasite, known to live on birds, deer and rodents, among other animals .
It has been confirmed through studies, that climate change has led to a spread in the geographical range of occurrence; of ticks. This is evident in the fact that ticks now occur in regions like Canada, where they were previously unable to survive.
Temperature rise, and increasing humidity may both account for the growing prevalence of ticks. At temperatures of 45°F and above, with corresponding humidity of 85% and above, deer ticks have been found to be most active.
These conditions are typical of climate change, yet they contribute to increased breeding, migration and survival rates of disease vectors like the deer tick.
The cholera bacterium is known to breed rapidly in warm, humid regions. Diarrhea is a major consequence of cholera infection, and is often very severe, resulting in death within a period of approximately seven days . The most fatal stages of cholera usually occur within a few hours.
Based on observations so far, of the pattern of incidence of cholera across the globe, it is believed that incidence rates will multiply with further rise in global temperature.
Hundreds of millions of people have already been infected and a great percentage (~70%) of these have died as a result of cholera since its first outbreak from the Gange delta of India in 1817. These deaths include the fatalities from about seven global cholera pandemics.
While the general opinion relates cholera bacterium to sewage and filth, recent studies have rather shown that the disease is supported mainly by hydrological conditions, weather variations and the nature of the environment . Since climate change is associated with extreme weather, environmental and hydrological variability, it is likely that the rate of incidence of cholera will increase.
Although cholera outbreaks typically result from different factors, there has been much interest so far, in the role of global warming in spreading the disease.
A piece of evidence to support this rising interest is the increase in cholera incidence in Bangladesh, following El Nino (temperature rise of the Pacific Ocean surface water) events in the Bay of Bengal .
Because plague is transmitted mainly by rodents, it is not difficult for us to predict the role of climate change in driving this disease.
Changes in weather conditions, as may be observed in terms of temperature and precipitation, are bound to affect the dynamics of rodent populations across the world. In the same manner, these changes will affect the populations of the infectious flees which the rodents play host to.
Since the early stages of investigation and research surrounding plague incidence, it has been implied that climate change could be a major factor involved.
It was observed that seasonal changes in humidity and temperature, accompany the seasonal trend of plague outbreaks. This observation was similarly made in India, Central and West Africa.
It has been shown, for instance, that in Africa, plague occurrence is at its peak in between seasons of extreme heat or cold. In parts of Asia, plague has been found to occur at higher rates in relatively hot and dry weather.
7). Rift Valley Fever
Rift valley fever is a relatively new viral disease, transmitted by mosquitoes .
The symptoms include fatigue and fever, and it is prevalent in the Middle East and Africa. Victims of the disease so far include cattle of all species, as well as humans.
As is the case with malaria and other insect-borne diseases, climate change will potentially widen the geographic span of infection, of Rift Valley Fever. This is likely to occur because, with global warming, the disease vector (mosquitoes) will be enabled to survive in several other regions.
8). Red Tides
Red tides are caused by poisonous blooms of algae in waters along the coast .
The condition has harmful effects on aquatic animals and the entire ecosystem. For example, in the southwestern coast of Florida, several marine organisms including manatees, dolphins, sea turtles and fish have been found dead along beaches, mostly as a result of algal poisoning.
Red tides affect humans as well, who come in contact with poisoned water.
Aside climate change, other human activities are capable of increasing the rate and severity of poisonous algal blooms in coastal waters.
On of such activities is the use of nitrogenous fertilizer, or allowing nitrogen-rich chemicals to flow as run-off, into the ocean. Such materials provide nutrients that support the rapid growth of algae.
Climate change also affects the growth and survival as well as geographic spread, of poisonous algal blooms .
As we are aware already, human activity is contributing greatly to the process of climate change, especially in terms of global warming and the greenhouse effect, both of which are the result of greenhouse gas emissions into the atmosphere.
The rise in aquatic and atmospheric temperature has been found to increase the rate of growth of toxic algal blooms, as we have earlier implied.
Although these algae are more restricted to saltwater, with increasing temperatures, there is also an increase in the risk of their occurrence in freshwater as well.
This is a very huge risk indeed, since the human population depends directly on freshwater for domestic purposes.
Additionally, studies have revealed that toxic algae such as K. brevis, not only thrive at warmer temperature, but also with higher concentrations of carbon dioxide (CO2).
Considering the rise in global sea levels- caused by climate change -it is obvious that this creates more marine habitat for red tides to occur.
Higher temperatures and seasons of drought may dry up some fresh and brackish water bodies. In the absence of sufficient precipitation, this will cause an increase in the concentration of nitrogen and salts in the water, further favoring the spread of toxic algal blooms and red tides, to freshwater systems.
9). Sleeping Sickness
Climate change and global warming will affect the geographical distribution of tse-tse flies, which are the primary vector of sleeping sickness.
The last few decades have seen the prevalence of sleeping sickness in parts of Africa, where at least 300,000 humans are infected on a yearly basis.
Trypanosomiasis, as the disease is called, is usually transmitted when the tse-tse fly feeds on the blood pf its victims. Although humans are primarily affected, other vertebrate animals like cattle are also vulnerable.
The typical symptoms of sleeping sickness include lethargy and swelling of the nymph nodes. Provided no treatment is administered, it may lead to coma and death. Over 30 countries in Sub-Saharan Africa are known to be affected, although the highest concentration occurs in the Democratic Republic of Congo, which recorded up to 70 percent of all known cases in the past decade.
The effects of sleeping sickness affect the economy. This is because it affects livestock and may cause significant expenditure on public health care.
10). Yellow Fever;
Is likely to spread as a result of climate change, which will affect the distribution of mosquitoes in coming years.
The tendency of more droughts means that livestock and humans will likely come into close contact with wildlife in the effort to harness water bodies. This increases the risk of spread of both livestock and human variants of tuberculosis.
Ways to Address the Health Challenges of Climate Change
It is predicted that future climate change scenarios alongside lower socioeconomic development and higher rates of population growth, can result in an increased potential of epidemic outbreaks by at least 1.6 times.
The measures which we can take to address the health challenges of climate change can be carried out on individual or collective levels. Some of them are listed below;
1). Reduction of the Dependence on Automobile Vehicles for Transport
Especially in the case of relatively short distances, opting for alternative, active means of transport like cycling and walking, is capable of reducing the risk of illnesses such as heart disease, obesity, and diabetes. At the same time, his will reduce the emission of carbon and other greenhouse gases into the atmosphere.
2). Increase of the Consumption of Plant-based Food Materials
The consumption of more plant-based food materials like seeds, nuts, vegetables, grains and fruits, will improve on the environment by reducing nitrogen oxide emissions that are associated with animal farming . This is also beneficial to general human health.
3). Public Transport Systems and Policies
In place of active methods of transport, relying more on public transport, than private vehicles, will also reduce the rate and volume of greenhouse emissions in the atmosphere. At the same time, the rates of asthma, stroke, and lung diseases will also be reduced.
4). Reduction of the Consumption of Highly Processed Foods
This will help to check the level of consumption of energy, and the associated environmental challenges like carbon emission.
In general, highly processed foods contribute to excessive waste production, and energy consumption, due to the complexity of the methods used to process them.
5). Efficient Energy Management
Energy efficiency in homes, industrial and commercial facilities can be achieved by the use of well-managed energy distribution, cooling and hearing systems
6). Policies and Regulations
The challenge of climate change itself must be addressed in order to reduce the risk of health problems associated with it.
Policies and regulations will help to enforce several of the required measures for ensuring that industrial, domestic and commercial practices are sustainable, and do not harm the environment. This is useful in checking environmental pollution, waste management, and greenhouse gas emissions.
7). Technological Innovation
In order to reduce the disease outbreaks and associated risks of climate change, innovation is required. This innovation may be in form of healthcare technological improvements, or infrastructure to manage emissions from industrial processes.
Examples of innovations which are capable of reducing the incidence of diseases as a result of climate change, include smart building development, energy efficient systems, renewable energy technology, and carbon capture technology.
As we have seen in this article, health problems may arise as a result of climate change.
The health problems include water, air and vector-borne diseases, as well as some direct outcomes of extreme weather conditions, such as floods and heatwave events.
Addressing and mitigating these problems will require measures that tackle not only the risk of the diseases themselves, but also the primary problem of climate change.
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