global health and the climate crisis

Tom Davids explores how the health of humans and the planet is intimately connected. Art by Ranuka Tandan

The human body never was, and never will be, sheltered from the climate crisis. One of the most confronting effects of our changing climate, and by far the most direct and experiential, is the global health crisis it will create. The Lancet published a report in 2018 identifying the climate crisis as the biggest threat to global health in the 21st century, and insisting it will be the bodies of those most vulnerable in our globalised society that will bear the brunt of our negligence. This includes, but is not limited to, rural and urbanised poor, the elderly and those with chronic health conditions. There are many ways that this will manifest, but here I will discuss two of the most consequential: increases in diseases like malaria and worsening health outcomes from heat-waves. Soon, our changing environment will test us and our health-care systems in a multitude of ways; the possibilities seem endless and difficult to comprehend, but one thing is certain in this seemingly distant and external crisis - it will hit us in our most personal of spaces: the body itself.

It is now generally accepted that a steady increase in the Earth’s temperature will not just cause a gradual change in ecosystems, but an increase in the frequency and intensity of extreme weather events. One such event is the heatwave. It is common knowledge that heatwaves can have significant impacts upon general health, even when excluding the role of hyperthermia. According to Dr Sari Kovats, they can also cause spikes in mortality and morbidity (the worsening of a certain pre-existing conditions), namely in the elderly and those with respiratory or cardiovascular conditions. Dr Lucy Barard points out that “there is a welldefined value of (daily average) temperature above which mortality risk begins to rise”. This threshold will vary considerably across regions, depending on what their population is already accustomed to. However, in traditionally colder regions, that threshold is markedly low.

In London this threshold is 19°C, with a risk starting to occur if the daily average over a prolonged period of time is at, or above this threshold. During the summer of 1976 in London, heatwaves were attributed to a 15.4% increase in mortality. Again, during the European summer of 2003, a serious heatwave swept over the region, which led to 15,000 deaths in France alone. This represented a 60% increase in mortality on previous figures. The death toll across Europe is believed to have exceeded 30,000.

We, as humans, are very good at adapting to our environment. We’ve created changes in architecture to help with ventilation and air conditioners to blast us with cold air, but there are always limits to our ability to adjust to our environment. Expensive air conditioners and fancy houses with good ventilation to fight against heat waves are a privilege, meaning those who cannot afford these luxuries are further prone to suffer from the environmental

crisis. Add to this that those in poverty are more likely to suffer from diseases whose effects will be made worse during a heat wave, we see that those at most risk will often be the ones unable to protect themselves. This could be particularly relevant for Western Sydney, where many residents of low socio-economic status reside. It’s geography causes the region to experience more days over 35°C than the rest of Sydney, with an additional ten hot days by 2030.

Increases in temperature will not only directly affect disease, but will also increase the capacity of vectors (e.g. insects) to transmit disease. In 1990, WHO identified malaria as the infectious disease most vulnerable to climate change. This vector borne disease is common in tropical areas of the Global South, where poverty is rife. Dr Mercedes Pascual outlines in her research that its latitudinal and altitudinal restrictions are determined by climate, because the vector that carries the disease, the mosquito, flourishes in the warm climates that are restricted to these regions. As the average temperatures of these climates rise, she warns that these higher temperatures “quicken the digestion of the blood meal and maturation of its developing eggs, thus increasing vectoral biting frequency”. The resultant increase in the mosquito population, and therefore how many people they bite, could increase the malaria burden in already affected areas. Further, if the tropical regions that are at a higher altitude experience a rise in average temperature, such as in Ethiopia, where the majority of the population lives in such highlands, malaria will start breaking out of its traditional altitude restrictions and start affecting new areas.

Dr Pascual also outlines that malaria is “predominantly a disease of poverty”, and that many parts of the tropical world are entrenched in poverty partly because of malaria. If eradicating malaria is considered key to the flourishing of these societies, then increasing virulence is not just a problem that resides within the box of global health, but is an issue of social and economic justice as well.

This is by no means a comprehensive list of possible global health challenges that we may face. Drought, unsustainable farming practices and overfishing could all affect our global food security, while climate refugees will face a range of health consequences when they are forced to migrate.

In addition, those who led the charge on creating this climate catastrophe - the rich, and those in positions of power - are leaving many of its adverse consequences to those most vulnerable in our society. This should be seen as one of the grave injustices of our time. In looking at the climate crisis from a global health perspective, it no longer stands as just an environmental crisis, but a deeply human crisis as well.