The Hidden Impacts of Climate Change 5: Disease

When you hear about climate change, what is the first thing you think about? Deforestation? Rising sea levels? Or global warming? Although the research behind these categories is already daunting, are we being told everything? 

In this series, the hidden impact of climate change, I will be digging deeper into the true effects that climate change has on our planet. Not only on humans, but also on the environment and animals. 

This is part 5 of the Hidden Impacts of Climate Change.

Although it is not obvious, there is a serious link between climate change and disease. We are familiar with infectious diseases, their symptoms and the common impact on human health and that they can affect any part of the human body and new ones are emerging every day. So why would climate change affect disease?

Extreme weather events, heatwaves, droughts and floods are well known consequences of climate change, but what if I told you that these could be dangerous to people that live on another side of the world, away from these events? Initially you would think about diseases relating to temperature or bacteria, but these are not the only diseases included. As climate change causes many chain reactions to occur, we cannot predict the future of how diseases will evolve, as they will constantly adapt to survive in new conditions.

It was common knowledge that climatic conditions affect epidemic diseases long before the role of infectious agents was discovered, late in the nineteenth century. This is exemplified by the fact that Roman aristocrats retreated to hill resorts each summer to avoid malaria. Also, South Asians learnt early that, in high summer, strongly curried foods were less likely to cause diarrhoea. Mosquitoes and other biting insects transmit many of the most important, devastating and neglected human infectious diseases, including malaria, dengue fever, chikungunya and West Nile virus.  But in a world where economic development and cooler temperatures have largely kept mosquito-borne diseases out of wealthier Northern Hemisphere countries, this goes under the radar nowadays. But as evidence of this problem resurfaces, does this issue need to be re-examined?

Image source: https://www.euronews.com/green/2021/07/20/aggressive-tiger-mosquitoes-are-spreading-through-europe-how-can-we-protect-ourselves

What is happening?

Climate change enhances the spread of pests, bacteria and viruses that cause life-threatening illness, and this section highlights how we are affected by climate change and the impact it can have on us.

Vector and Water-borne diseases:

Vectors are living organisms that can transmit infectious pathogens between humans, or from animals to humans. Many of these vectors are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later transmit it into a new host, after the pathogen has replicated. Examples of vectors range from mosquitos to sandflies, which can spread pathogens; parasites, bacteria, viruses or ectoparasites. 

As climate change leads to changing weather conditions, there are many variables that can cause vector-borne diseases to increase. Temperature and precipitation are the most important conditions that affect vectors. For example, the link between malaria and extreme climate events has long been studied in India. Early last century, the river-irrigated Punjab region experienced periodic malaria epidemics. Excessive monsoon rainfall and high humidity was identified early on as a major influence, enhancing mosquito breeding and survival. 

Changes in weather also affect animal and insect behaviour, disrupt habitats and pollute environments. These factors have many repercussions, as water can become contaminated, leading to worse sanitation, resulting in more water-borne diseases such as cholera spreading more. Rainfall can also influence the transport and dissemination of infectious agents, while temperature affects their growth and survival. Globally, temperature increases of 2-3ºC would increase the number of people who, in climatic terms, are at risk of malaria by around 3- 5%, i.e., several hundred million. Furthermore, the seasonal duration of malaria would increase in many currently endemic areas. To analyse the issue, landscape-based modelling has been applied to estimate how future climate-induced changes in ground cover and surface water in Africa would affect mosquitoes and tsetse flies and, hence, malaria and African sleeping sickness. However, Africa is not only affected; as colder countries become warmer, vectors are finding more habitable places to stay which means that they will become a world problem. This is proven by mosquito populations arising in the south of the United States. In the diagram below, we can see that mosquitoes are slowly encroaching into Europe as well.

CURRENT WORLDWIDE DISTRIBUTION OF THE MOSQUITO AEDES AEGYPTI – WHICH CAN SPREAD DENGUE FEVER, ZIKA VIRUS, CHIKUNYUNGA AND YELLOW FEVER – BY DURATION OF TIME IN EACH REGION. Image source: https://earth.stanford.edu/news/how-does-climate-change-affect-disease#gs.ip3m2i

Cardiovascular disease:

This category is all as a result of the harm we impose on ourselves, due to diminishing air quality. Unfortunately, this is overlooked in society as it is a subtle effect of climate change, and is a long-lasting impact that is getting worse by the day. Our air can be less healthy to breathe due to higher temperatures causing an increase in allergens and harmful air pollutants, as longer warm seasons can mean longer pollen seasons- which increase allergic sensitisations and asthma episodes. Ozone, also a harmful pollutant, would be more prevalent on ground-level. Ground-level ozone (a key component of smog) is associated with many health problems, including diminished lung function, increased hospital admissions and emergency department visits for asthma, and increases in premature deaths.

Another way climate change can affect our health is through wildfires. These can arise from drought, human negligence and high temperatures, and the worrying issue is not the damage we know large wildfires can cause, it is the smoke. Exposure to it increases acute (or sudden onset) respiratory illness, respiratory and cardiovascular hospitalizations, and medical visits for lung illnesses. This is a component that is well-known, as smoke has caused many illnesses and complications to occur in a wide range of events from house fires to volcanoes. But when the consequences are paired up with already existing health issues, they can turn out to be deadly. If respiratory health deteriorates as a result of smoke, viruses and infections become more dangerous, not to mention chronic diseases, especially for people of young age. When sensitive individuals are simultaneously exposed to allergens and air pollutants, allergic reactions often become more severe. The increase in air pollutants make the effects of increased allergens associated with climate change even worse, e.g.- People with existing pollen allergies may have increased risk for acute respiratory effects.

Air pollution is estimated to account for around 7 million premature deaths per year globally and more than 28,000 per year in the UK, but according to the facts and impending danger, air quality is not a topic that has been taken seriously by developed countries.

Cancer:

There are many ways cancer can arise from factors relating to climate change. Firstly, returning to the topic of cardiovascular disease, air quality can lead to higher risk of lung cancer. This is as a result of toxic chemicals being breathed in and cell mutations occurring, which can become a malignant tumour if they uncontrollably divide. Wildfire smoke and debris generate huge amounts of climate-warming gases and fine particles that contain carcinogenic poly-aromatic hydrocarbons, benzene, and formaldehyde. High temperatures, poor air quality, and wildfire pollutants cause rising rates of respiratory and cardiovascular diseases in children and increase the risk of developing lung cancer later in life; this is the most obvious way cancer may occur. But cancer due to temperature and food is also a problem that we face, furthermore treatment availability is likely to be affected by weather. 

Skin cancer is an example of how temperature can cause cancer and with increasing heatwaves, poses a risk to a larger proportion of people. Most skin cancers are caused by exposure to ultraviolet (UV) rays. When you don’t protect your skin, UV rays from sunlight or tanning beds can damage your skin’s DNA.  However, temperature has not only been linked to skin cancer, but with breast cancer. A surprising link has been found through the MCC-Spain study, who conducted their own investigation. They found that DNA can be damaged due to heat stress and have its repair system inhibited, not only this, but there was also a correlation between heat exposure and breast cancer. Nonetheless, this is only one of a few studies which explore this case, so cannot be concluded as heat exposure being a causation of breast cancer in the long-run. But it is an alarming trend that requires more investigations.

Another way cancer is affected is through food. Depending on what we eat and how we eat it, cancer is at higher risk for some communities and groups. Our diet is the defining driver, as normally a healthier diet leads to lower risk of cancer. But with climate change, eventually we will all be affected by water and food insecurity; a prerequisite to unhealthier diets. For example, if a natural disaster occurred in places with ideal climates, this may affect the production and transport of tropical fruits to the UK. Therefore, the UK would suffer as well as countries with ideal climates, as there would be limited alternatives to eat, leading to poorer diets. Although this is a theoretical case, this could be a reality around the corner. In addition, natural disasters are preventing the necessary treatments for patients with cancer in developing countries, where hospital supplies are extremely volatile. Unfortunately, this inevitably leads to more people dying.

Natural disasters are not the only threat though. As the planet continues to warm and polar ice melts, otherwise inert chemicals, such as DDT and lindane, which might become carcinogenic at higher temperatures, are being released and could enter the food chain, increasing lifetime cancer risk. Food security concerns might precipitate the increased use of more intensive farming practices, including greater use of carcinogenic pesticides. 

Prevention will always be superior to solutions, but the damage already done cannot be reversed. We currently live in a situation where prevention is not an option for the bigger issues climate change imposes on us, still, so much can be done to protect us from an ugly dystopia. But maintaining a healthy environment, encouraging healthier eating and better sanitation are things that are in our control, and for the sake of ourselves should be prioritised in an attempt to avoid the full wrath climate change has.

Any… Positives?

As I continued my research, I realised that it would be very hard to find anything to be optimistic for regarding disease. I’ve done everything; put my head in my hands, shaken my head, even done both while chuckling with it as well, so are there any positives? This article is intended to not be a political diatribe, leaving you angry and frustrated, but as this is not a mainstream topic, you still may feel this way. Honestly, I don’t blame you.

Anyways, with this situation, climate change is not the reason for this issue arising – it has always been a problem: Disease is a main cause of death. But climate change is a factor that can only make disease more prevalent. So, in this unique problem, the impacts of climate change have been hidden from the wider public, where misconceptions are bound to arise, due to climate change altering many day-to-day processes, causing confusion. But as I said before, disease and climate change are overlooked as a pair. So what can be done? We cannot control how animals and vectors behave, the weather, or whether our cells mutate. So even if world governments come together, what can they do? They can only work to continue to prevent climate change getting any worse. On the other hand, we are familiar with the sheer number of charities, movements, and mass donations continually arising, devoted to a specific cause. But this is not enough. So, one way to counteract the impending dangers we face due to worsening climate change is to personally support small groups working to fund a better future for people in dire and unfortunate positions. But we are unable to know how much of that money is actually going towards the cause, consequently leaving us sceptical to donate out of our own pocket. Also, our desire to help directly is dependant on our disposable income, meaning it is extremely difficult to make substantial impact in places of our choice. So, these options are unviable for many people. 

Changing our lifestyle is another solution, which is easier said than done. We have heard this one before, many times, but regarding disease, this would be a personal goal rather than a large-scale impact objective. So, eating healthier, exercising and overall being stronger against diseases is a solution to us avoiding any illness. It will require personal commitment of course, but there will not be any bystander-like effect when it comes to taking action in this case. 

Lastly, this solution is less of a concrete one. If you have a burning passion for something, you should pursue one way or another; fortune favours the brave. This has turned motivational now. But just taking action somehow, such as, spreading awareness about an issue, creating a group of equally driven people regarding the same cause, or simply making a GoFundMe page. Even if is seems somewhat uncomfortable, every day is a chance to change your life and if you embrace this passion, you will definitely reap the benefits.

Closing words

This article’s purpose turned out to be more informative and motivational than educational in the end. But as this was more about climate change exacerbating an issue, making it more serious, there not a whole lot humans can do against it apart from protect ourselves when it comes to disease. It is certainly something to be aware of though, and it needs to be monitored so we are prepared for the potential of diseases becoming more rampant. 

This is the last part of the Hidden Impacts of Climate Change, and I hope you have enjoyed and learnt something from the series.

If you are interested in studies about climate change and disease, the links below contain more information:

Thank you for reading!

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