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Climate Crisis

This guide provides information, resources, and data on the climate crisis

Climate Impact on Infectious Disease

The impacts of climate change and global warming go far beyond the environment. Rising global temperatures means milder winters, warmer summers, and fewer days (and locations) of frost. These all contribute to creating a world that while may be more hazardous to humans and other wildlife, it's the perfect environment for many pathogens.

Climate change disrupts the natural complex ecological interactions between humans, animals, and pathogens. As the earth warms, it sets off a chain reaction of consequences.

Climate Hazards of Infectious Disease
Contact with Wildlife

Climate change has altered and destroyed many natural animal habitats, forcing animals to migrate - typically in latitude and/or elevation. This often can move them closer to human population centers. This, coupled with human overpopulation and the constant encroachment and destruction of wildlife habitats, means humans are living in closer proximity to wildlife now than ever before. Many animals can carry certain diseases, that while they do not become ill, can infect humans. Others can become ill and humans subsequently can get infected through contact with the sick or dead animal or animal products.

These zoonotic diseases, crossover from animals to humans and can cause a wide range of infectious diseases.

Extreme Weather

Climate change is increasing the frequency and severity of extreme weather events. Flooding can be caused from a variety of natural disasters, such as excessive rainfall (monsoons), tropical cyclones (also referred to as hurricanes and typhoons), as well as coastal flooding from storm surges and rising sea-levels and even tsunamis due to earthquakes. Urban flooding is also an issue that has been exacerbated due to climate change and overpopulation.

After a weather-related or flood-related disaster, an increased risk of infectious diseases among survivors and displaced persons is often an immediate concern. The degree to which epidemics can occur from these events is associated not only with regional endemic disease population, but also the size and scope of the disaster and the public health infrastructure and disaster response.

A wide variety of pathogens can cause outbreaks and epidemics in the aftermath of extreme weather disasters, including:

  • Water-borne pathogens that can contaminate drinking water and cause gastroenterial infections such as cholera
  • Vector-borne pathogens as mosquito populations typically increase after flooding, causing infections such as malaria and dengue
  • Vaccine preventable diseases such as measles due to overcrowding of refugees after a weather-related disaster
  • Molds and other fungi are more adept to grow in flooded and water-logged areas, leading to various fungal infections
  • Interruption of care and services due to public health and healthcare infrastructure strains, leading to an increased spread of tuberculosis
Warming Waters

As ocean, lakes, rivers, and streams continue to warm with rising temperatures, the impact on marine life can be catastrophic. Warmer waters means increased harmful growth of algae and cyanobacteria.

Algae are microscopic organisms that live in fresh or marine water. They use photosynthesis to produce energy, just like plants. While algae are always present in natural bodies of water (oceans, lakes, rivers, etc), when water temperatures increase the amount of algae increases. The excessive algal growth, or algal bloom, becomes visible to the naked eye and can be green, blue-green, red, or brown, depending on the type of algae. Some types of algae (blue-green algae) can produce toxins, called cyanobacteria. When one of these toxin-producing algae cause an algal bloom it is called a harmful or toxic algal bloom. These toxins end up released into the surrounding water and air, which can harm people, animals, and aquatic life.

Melting Permafrost

Recently scientists made headlines when they revived several ancient viruses that were frozen in Siberian permafrost for tens of thousands of years. So far, the only viruses that have been successfully revived from permafrost samples have been large DNA viruses that infect amoebae and have not been proven to cause illness in humans. However, this research leads to a far more concerning potential consequence. If permafrost is melting and ends up exposing human or animal remains that died of an infectious disease, if the conditions are right an infectious virus may still be lurking, frozen, and end up released to the world.

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