–By Loretta Okonkwo


Climate Change refers to a change in the state of the climate that can be identified by changes in the variability of its properties (temperature, rainfall), and that persists for an extended period. It may be due to natural internal processes or external forcing- persistent human activities causing changes in the composition of the atmosphere or in land use.

Globally, climate change has become one of the most visible environmental concerns of the 21st century. Climate change directly affects five components of the environment: water, air, weather, oceans, and ecosystems.The changing climate impacts society and ecosystems in a broad variety of ways. For example climate change can increase or decrease rainfall, influence agricultural crop yields, affect human health, cause changes to forests and other ecosystems, or even impact our energy supply.  Weather and climate play a significant role in people’s health. Changes in climate affect the average weather conditions that we are accustomed to.

Science shows that climate change will affect human health across the world. From diminished air quality and decrease of food and water supplies to increasing levels of allergens and catastrophic weather events.

All human societies, from primitive to advanced, have had to adapt to the challenges posed by climate. It affects where people live, how they make a living, what they eat, the abundance or lack of fresh water and even what they do in their leisure time. Deeply embedded in this fundamental relationship between climate and human life are the many ways in which climate has always played a role in human health. Climate defines health concerns such as the direct effects of excess heat or cold, the lack of sufficient water during drought, impacts on air quality, and the risk of various waterborne or vector-borne diseases based on conditions favorable to their spread.

Some variation in climate has long been recognized, such as a series of especially cold winters or seasonal drought. But climate has historically been seen as a consistent characteristic of particular areas.Though it is clear that shifts in climate have occurred over time in the past, these changes have occurred very slowly and gradually, and the human response has been similarly gradual over generations.It is now established that climate changes are occurring at an increasingly rapid rate. These changes require active monitoring and coordinated responses in all aspects of their impacts on human society, including health. Malnutrition, particularly during the prenatal period and early childhood as a result of decreased food supplies, as well as exposure to toxic contaminants and bio-toxins released during extreme weather events, increased pesticide use for food production, may all affect normal human development.

Climate change is one of the most serious public health threats facing the nation, but few people are aware of how it can affect them. Children, the elderly, and communities living in poverty are among the most vulnerable. Changes in the greenhouse gas concentrations and other drivers alter the global climate and bring about myriad of human health consequences. Climate change endangers human health, affecting all sectors of society, both domestically and globally. The environmental consequences of climate change, both those already observed and those that are anticipated, such as sea-level rise, heat waves, more intense hurricanes and storms, and degraded air quality, will affect human health both directly and indirectly.The changes in temperature and rainfall, as well as droughts and floods, will likely affect agricultural yields and production. These impacts may compromise food security and threaten human health through malnutrition, the spread of infectious diseases, and food poisoning.

Climate changes also are directly associated with many pest habitats and disease vectors, and changes in temperature can extend or reorient habitats such that organisms are introduced to new geographic areas or life cycles are altered, requiring increases in pesticide use or use in new areas to achieve the same yields. Global warming is also causing shifts in the ranges of disease vectors that require specific environments to thrive and increasing the threat and incidence in humans of waterborne, vector borne and zoonotic diseases.It also affects air movement and quality by increasing airborne allergens and pollution, thereby expanding or changing patterns of human exposure and resulting health effects.

Categories of human health consequences of climate change include: Asthma, Respiratory Allergies, and Airway Diseases, Cancer, Cardiovascular Disease and Stroke, Foodborne Diseases and Nutrition, Heat-Related Morbidity and Mortality, Human Developmental Effects, Mental Health and Stress-Related Disorders, Neurological Diseases and Disorders, Vectorborne and Zoonotic Diseases, Waterborne Diseases, Weather-Related Morbidity and Mortality.

The impacts of climate change on health may depend on many factors. These factors include the effectiveness of a community’s public health and safety systems to address or prepare for the risk and the behavior, age, gender, and economic status of individuals affected. In addition, the impacts of climate change on public health around the globe could have important consequences.  For example, more frequent and intense storms may require more disaster relief and declines in agriculture may increase food shortages.


While much is known about the actual and potential human health impacts of climate change, many effects are speculative and targeted research efforts are needed to address them. Addressing the effects of climate change on human health is especially challenging because both the surrounding environment and the decisions that people make influence health. For example, increases in the frequency and severity of regional heat waves as likely outcomes of climate change have the potential to harm a lot of people. Certain adverse health effects can probably be avoided if decisions made prior to the heat waves result in such things as identification of vulnerable populations such as children and the elderly and ensured access to preventive measures.

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