Climate change can propagate diseases in various ways. For example, extreme precipitation and flooding can corrupt water sources and lead to the spread of diarrheal disease and cholera. Rising temperatures can also have an influence on diseases, as they and their vectors thrive in specific climates. For instance, rising temperatures could influence the distribution of mosquitoes carrying disease, such as the Zika virus. Ticks will also find new habitats as temperatures increase and they will be active for longer periods, increasing the risk of tick-borne disease such as Lyme disease.
Another way that climate change can possibly impact the health of humans and animals is by releasing diseases that have remained dormant in ice. Diseases that are trapped in ice have the potential to be released as a result of rising temperatures due to climate change. Such cases have already appeared in recent years, highlighting this danger. In 2016, over twenty people were hospitalized and one boy along with over 2,000 reindeer died, after being infected with anthrax in Siberia. The anthrax was released when a heat wave melted permafrost that had frozen and trapped a reindeer carcass infected with the disease over 75 years ago. The anthrax was released into nearby water and soil, infecting other animals and eventually humans. This incidence has raised fears that other diseases could similarly be exposed through melting ice, including smallpox.
As climate change raises the intensity of weather conditions and events, those in less developed countries will be most at risk of injury and death. Between 1990 and 2015, around half of all deaths from weather-related disasters worldwide occurred in lower-middle-income countries. In the United States, flash floods accounted for the highest portion of deaths due to weather conditions and storms in 2015. The U.S. has also seen deaths due to extreme heat and, in 1995, a record 1,021 people died from such conditions.
In addition to the impact climate change will have on physical health, a recent report from ecoAmerica and the American Psychological Association also emphasized the consequences of climate change on mental health. Trauma and shock, depression, anxiety, post-traumatic stress disorder, and suicide are all expected to impact the mental health of individuals confronted with the consequences of climate change.