Published on June 13th, 2023
Authored by Pfizer Medical Team
Record-breaking heatwaves, severe droughts, and flooding affected millions in 2022, resulting in significant loss of human life, threatening food and water security, and causing major economic loss.1 Global temperature increases, due to carbon dioxide and other greenhouse gases, has a significant impact on the climate.2 According to the World Meteorological Organisation, “2022 is the 8th consecutive year that annual global temperatures have reached at least 1°C above pre-industrial levels”.1 In Australia, temperatures have risen by 1.4°C since 1910.3 In New Zealand, temperatures have risen by 1°C over the last century.4 The WHO has gone so far as to call climate change “the single biggest health threat facing humanity” and estimates the associated health costs to be USD $2-4 billion (AUD $3-6 billion) per year by 2030.5
While some of the effects of climate change are obvious, such as the immediate impact of severe weather events, we also need to pay attention to the longer-lasting health implications of a warming planet.
Here are some ways that climate change might affect human health in the future.
Climate change and a rise in severe weather events caused by global warming has the potential to increase vector-borne diseases. These are diseases caused by parasites, bacteria or viruses and are transmitted by infected arthropods (the vector) such as mosquitoes, ticks and sand flies.6 One of the most infamous examples of this is the ‘Black Death’ or plague, that was spread by fleas and ravaged Europe in the late 14th century.7 So how might climate change affect this?
Arthropods do not produce their own body heat and rely on the temperature of the environment to maintain their body temperature. 8 Therefore, environmental temperature directly impacts their ability to survive and reproduce. In turn this affects their population numbers, their distribution and geographic range, and can even affect how quickly these insects mature into adulthood.8 With global warming predicted to bring milder winters and warmer climates, this could improve over-winter survival of some insects and allow them to spread into areas that were previously too cold for them to survive.8
Malaria is a disease spread by mosquitoes and is mainly found in tropical and sub-tropical countries.9 Worldwide, there was an estimated 247 million infections and 619,000 deaths in 2021.9 96% of these deaths were in the African region with 80% in children under five years.9 Malaria is relatively rare in the United Kingdom where most cases are found in return travellers.10 As a result of climate change, one study estimates that malaria transmission will be possible for 2 months of the year in the southern half of Great Britain by 2030 and Southern Scotland by 2080.8 In Australia, climate change could increase mosquito survival and mosquito-transmitted diseases such as Ross-River virus and Murray Valley encephalitis.3
Rising temperatures can also increase rates of climate sensitive diseases such as malnutrition due to threatened crops and livestock. The World Health Organization estimates that between 2030 and 2050, climate change will cause nearly 250,000 additional deaths per year, due to malnutrition, malaria, diarrhea, and heat stress alone.5 Unfortunately, the world’s most vulnerable people are impacted disprortionately by these climate-sensitive health risks, and have little resource to buffer them against the effects of climate change.5 With healthcare costs already pushing 100 million people into poverty every year, this number is expected to rise with increasing temperatures.5
Clean drinking water is vitally important to health and often taken for granted in developed countries. Water-borne diseases, like cholera, spread via contaminated water through drinking, cooking or recreational activities.8 With storms and flooding predicted to increase due to climate change, run-off from flood waters can contaminate clean water sources loading it with harmful bacteria and parasites.8 The likely rise in water temperature owing to prolonged periods of hot weather could also favour bacterial and parasite survival, expand their geographic distribution, and increase reproduction.8 The effect could be an increase in gut and lung infections during periods of heavy rainfall.8
The quality of the air we breathe can also be affected by climate change but isn’t something we usually think of. Clean air is important to prevent serious illness, as inhaled small particles, often invisible to the human eye, in polluted air can get stuck in your lungs or enter the bloodstream.13 This has been linked to serious illness such as heart and lung disease.13
According to a report published by the University of New South Wales, greenhouse gas emissions causing higher carbon dioxide levels could affect flowering plants and increase the amount of pollen in the air, potentially exacerbating allergies, lung disease and increase thunderstorm asthma events.13 With longer summers and an increasing number of extremely hot days predicted with climate change, there could be an increase in bushfires and dust storms in areas that are very hot and arid.13 Bush smoke and dust could increase the levels of particulate matter in the air and be detrimental to health.13 Warmer temperatures can also increase the amount of ground level ozone, particularly in areas with high levels of pollution. 13 While ozone in the atmosphere is protective, at ground-level it is an air pollutant that is toxic to human health.
The effects of climate change are not just physical. Climate change also has a significant impact on mental health. A report published by Doctors for the Environment Australia noted that exposure to natural disasters (flooding, bushfires, storms, extreme heat) have been linked to increased alcohol and substance abuse, domestic violence, anxiety, depression, post-traumatic stress disorder and suicide.15 The impact on mental health is even more pronounced when there is a short period of time between these events, known as compound events.15
Extreme heat has also been linked to an increase in aggression, domestic violence and mental health exacerbations with a rise in mental health emergency presentations on very hot days.15 The report noted that this effect is even more pronounced in people with pre-existing mental health conditions, the elderly, farmers, and our First Nations peoples.15
The threat of climate change and perceived inaction by authorities is also distressing in itself, with a number of terms coined to describe climate-related distress such as eco-anxiety, eco-distress, and ecological grief.15 This is particularly felt amongst our nation’s youth with 93% of people under 30 feeling that the government is not doing enough to address the climate crisis.15
Climate change is more than a weather problem. Here we covered five ways in which the impacts of climate change affect our health, but it also has other far-reaching effects. It impacts livelihoods, food and water security, public safety and civil unrest, health services and the economy. The World Health Organisation has stated that ‘the climate crisis threatens to undo the last fifty years of progress in development, global health, and poverty reduction, and to further widen existing health inequalities between and within populations’.5 Sadly it is also those that contribute least to climate change that are the hardest hit, such as the socioeconomically disadvantaged, indigenous peoples, the very young, and the very old.5,15
It is clear more needs to be done to address the climate crisis at a societal and individual level. The decisions we make every day have an impact. We can reduce our contribution to climate change by driving less, flying less, purchasing fewer items, and eating sustainably, among other choices.16 Collectively we can make a difference in the fight against climate change.