Abstract
There’s a strong interconnectedness between climate change and public health. It is my intent, with this paper, to raise some awareness on the topic, especially within the framework of infectious diseases. Ever since the 1980s, global warming has become a prominent topic in public debate, contributing to greater awareness about environmental problems and the warming of the planet.
By and large, climate change holds big coverage in the media and in national and international narratives, especially in light of recent international commitments within the environmental global governance framework, such as the 2030 Agenda for sustainable development, adopted by world leaders in 2015.
Despite widespread awareness of the direct effects of climate change, its indirect repercussions on public health often fade in the background.
Monica Gambardella (Junior Researcher – GEO Ambiente)
Introduction
The analysis will begin with a general overview of the interplay between climate change and public health, followed by a detailed discussion about the responsibilities of environmental change in exacerbating the proliferation of infectious diseases. Two major effects will be examined: the alteration of the ecosystems and the melting of the ices. In the second part of this essay, two case studies – Dengue and Malaria - will be presented. Finally, the solutions that have been put forward by the governments will be discussed.
In conclusion the present analysis will highlight the need for a multidisciplinary approach, while underlining the intersectionality required to tackle climate change challenges.
Climate change and the emergence and exacerbation infectious diseases
As the effects of climate change keep worsening and global warming increases, progressively more scientific evidence appears pointing out the close link between the rise of global temperatures and the emergence of viruses. The impact climate change has on the transmission of diseases needs to be observed from multiple angles. Although there is a gap in research, several studies substantiate the claim that infectious diseases must be regarded as a serious threat to public health, considering the long-term effects that climate change exerts on both human health and life on earth (Mora et al. 2022).
In assessing the interplay between climate change and public health, global heating is what mostly triggers viruses to proliferate. As a matter of fact, as global temperature increases, vectors spread more rapidly and the emergence of new diseases will become a chronic occurrence. Data suggests that roughly 50% of infectious diseases have been directly affected by climate change (Ali et al. 2024).
Pre-existing conditions and higher vulnerability to climate hazards
Despite climate change being a universal burden, the degree of its damages is uneven, subject to a variety of factors. Pre-existing conditions are a decisive factor in determining the degree and the extent the damages global hazards produce on different countries. Compared to high-income countries, emerging economies and low-income countries suffer from more violent repercussions, as they begin from a disadvantaged position due to systemic deficiencies. Lack of resources, political instability, poor health services are among the compounding factors aggravating hygiene conditions and increasing the likelihood of disease transmission. The above illustrate how socioeconomic inequalities are deeply intertwined with the ability of countries to address climate hazards, suggesting that adaptation and mitigation strategies are of little use, without proper prior social and economic assessment. Due to the malfunctioning of their health systems, fragile communities are affected the most. This in turn, is connected to the malfunctioning of local health institutions and lack of funding, personnel and medical equipment (Ahmed 2025).
In light of the above, prevention of climate driven infectious diseases is possible, provided that proper mitigation and adaptation strategies are put in place. This highlights severe systemic deficits that fuel a vicious cycle: the implementation and effectiveness of adaptation strategies require properly functioning public infrastructures. In conclusion, when analysing the connection existing between climate change and infectious diseases, a plurality of factors must be considered, among which environmental, but also biological and ecological. The outcome of the measures adopted will be determined by a careful weighting of these different aspects (Çeleğen, İ., Sarıöz, A., 2025).
Effects of climate change on proliferation of pathogenic diseases
As anticipated, climate change bears significant responsibility in exacerbating pathogens’ transmission.
Narrowing the scope, it ultimately comes down to the alteration of the biological cycles of disease vectors. Depending on the group they belong to, whether it is vector-borne, foodborne or water-borne, diseases vectors respond differently to environmental changes. Despite the divergent reactions vectors may have, the rising of global temperatures is the one condition valid for most of them. In fact, rising temperatures facilitate the growth and reproduction of vectors, regardless of their nature. This said, it would be misleading to assume that higher temperatures are always beneficial for pathogens, as extreme heat might actually pose a barrier to the transmission of sicknesses. To gain a comprehensive understanding of the issue, we must look at it from various standpoints. It is not merely about the effects global warming has on vectors and their transmissibility.
Firstly, all climate hazards, regardless of their nature, significantly impact the biological cycles of the hosts. By way of example, heavy precipitation and flooding as well as periods of prolonged drought, affect the hosts’ life forcing them to migrate.
Moreover, one must consider viruses transmitted by other animals, whose lives can be very much impacted by sudden climate events. Sudden changes in temperature are among the primarily causes of increased interactions between humans and the animal world. Lastly, the perspective of human beings. It is not unusual, especially considering recent events, to hear about forced displacements caused by an array of different factors. Whether war-driven or climate-induced disasters, displaced people are at greater risk of catching a disease.
Following the incident of such events, people are forced to live in emergency shelters and temporary housing whose poorly sanitary conditions facilitate the proliferation of bacteria. By way of example, this is what happened following the flooding in Pakistan and Brazil, respectively in 2023 and 2024 (“Headlines from a Warming World: Extreme Weather and Climate Breakdown” 2021).
For a long time, global warming has been regarded exclusively as an environmental problem. It is only in recent times that many have become aware of its responsibility for irreversibly altering the pattern of infectious sicknesses (Ahmed R. 2025).
An increased likelihood of the occurrence of pandemics is expected in the next decades. Although climate change holds most of the responsibility, this is also partially ascribable to the augmented ineffectiveness of vaccines, that is in turn connected to an increased resistance of mosquitoes to insecticides. Pesticides are the first measure people resort to, for disease mitigation. However, due to the delivery of sublethal doses of poison, in each population of insects, some units have developed an immunity to most of the insecticides present on the market. Combined with the effect of rising temperatures, already analysed, this is yet another factor worth considering when assessing real threats to public health (Richards et al. 2020).
Zombie viruses and permafrost as a pathogen habitat
Climate change’s most visible effect is the melting of the ice in the arctic region, which has strong repercussions on human health. By definition, permafrost is a soil that has been frozen for more than two years. However, most of it goes back to the glaciation era. Human activities bear the main responsibility for the defrosting of the ices. Permafrost represents the biggest carbon supply on earth and is currently heating at unmatched speed. As for the last decade, temperature has risen by approximately 2 degrees. The melting of the ices is among the effects of climate change that affect the proliferation of viruses, since the thawing of the arctic could release a large amount of microorganisms, many of which - unheard of. Most of the microbes identified so far are not life-threatening to human beings. Despite this, it is worth noting that just as many others have not been identified yet and could be fatal for human life. It is still uncertain whether permafrost preserves viruses' qualities and their transmissibility or makes them lose their bacterial load. Another hypothesis advanced is that once unfrozen, viruses will get their bacterial load back. (Wu et al. 2022)
Despite this being an unexplored area, there is agreement within the scientific community that most of the frozen DNA viruses are bacteriophages, which by nature can only contaminate other bacteria of the same species and thus not pose a threat to human life. Bacteriophages aside, some other types of bacteria could make a reappearance due to thawing of ices, however the number of those detected so far does not reach the threshold required for being listed as harmful to human health.
Such pathogenic organisms have been referred to as “zombie viruses” and they are believed to be carriers of dangerous diseases. That of the “zombie viruses” is an unexplored realm, however the Siberian permafrost has been designated as a potential reservoir of them. Tens of millions of years old latent viruses are expected to be present beneath the thick ice layer.
Just as zombies, these viruses are invisible pathogens, whose presence will be unveiled once the repercussions on health become manifest. As permafrost, that accounts for one quarter of the northern hemisphere, keeps melting, the researchers forecast the incidence of pandemics to dangerously rise, as more viruses will be freed from the ices in the upcoming years. The biggest concern is the inextricable link between all ecosystems,
The unfreezing of glaciers and consequent release of microorganisms in the environment is evidence of the fact that what happens in the Arctic has severe repercussions everywhere (Popat Mohite et al. 2023).
Case studies: global rise in Malaria and dengue outbreaks
Most of the existing research focuses on malaria and dengue. This should not come as a surprise when considering the scaring number of cases worldwide and the fact that they are among the deadliest vector-borne diseases. As extensively discussed, climate is responsible for negatively impacting public health. In the next three decades, it is expected for climate hazards to inflict 250.000 casualties, most of which will come from low-income countries. The paradox is that the number of victims of a country to climate change and the greenhouse gas emissions of said countries are inversely related. Taking the African continent as an example it accounts only for 4% of global emissions, yet it figures among the most vulnerable countries to climate change. Conversely, industrialized countries, whose global emissions represent more than 80%, do not suffer from climate change effects as much, due to the well preparedness of their health infrastructures.
Hazardous climate events are creating suitable conditions for the expansion of contagious diseases in places where it was once unanticipated. Unprecedented outbreaks of dengue fever were documented in several African countries. The World Health Organization has reported dengue and malaria outbreaks to expand beyond their once known geographical boundaries. On top of this, the global fight against malaria has recently been undermined by the appearance of new mutations of malaria-transmitting mosquitoes. To the present day, the biggest obstacle for the eradication of the disease is climate change. Roughly half a million individuals die prematurely each year, after contracting the disease. The African health system is poorly equipped to respond to health crises, requiring combined support from various actors (Kaseya et al. 2024).
Closer look at Malaria and Dengue Fever
Malaria is a vector-borne disease affecting billions of individuals worldwide. The Malaria pathogen can be transmitted through humans and female anopheles’ mosquitoes, and its cycle begins when an infected mosquito bites a human being (Kaseya et al. 2024). Global warming is dangerously impacting the lifecycle and development of vectors. Rising temperatures hastens larval development facilitating their reproduction resulting in more frequent malaria epidemics. Climate hazards not only jeopardise the measures implemented for the eradication of the disease but on the contrary they affect the geographical distribution of the viruses. As mentioned above, Africa is the continent with the highest incidence of malaria cases, with the horn of Africa being the most affected region. When discussing the occurrence rate of malaria cases, it is worth mentioning the non–weather-related features, such as population density. It has been observed that the disease finds fertile soil in densely populated areas. Furthermore, contemporary phenomena such as globalization and migration flows are among the key factors aggravating its effects, making it a persistent threat to humanity (Megersa and Luo 2025).
Dengue fever is the most common tropical sickness worldwide, taking millions of lives every year.
People contract the virus when they get in contact with two species of mosquitoes, Aedes albopictus and Aedes aegypti. The exothermic nature of mosquitoes is what explains the proliferation of the virus when temperature rises. Despite indisputably being an aggravating factor, environmental change is not the only variable to consider when observing the aggressive spread of dengue fever. As with the case of Malaria, a wide array of factors is to be taken into account, such as urbanization and global travel. (Borunda 2024)
Conclusion
As extensively analysed, human induced climate change is heating the planet at an unprecedented rate, making the occurrence of epidemics expected to dangerously increase. Tackling the consequences of climate-driven disasters has been a priority on the agenda of both international and national bodies ever since the acknowledgement of the severity of the problem. Given the unpredictability of the issue, the most successful response so far in dealing with the problem revolves around mitigation and adaptation strategies, among which training programs for health work force, afforestation and tree-planting programs and the raise awareness in civil society. The major obstacle is financial support, without which neither of the solutions remains a viable option. Considering the universal nature of the problem, unilateral responses and national strategies have long proved to be insufficient, enhancing the need for international bodies to converge their strategies.
What led most of the strategies adopted so far to be unsuccessful is the negligence of important non-meteorological factors, such as migrations, wars, shortages of resources, all of which dictate the spread of diseases among communities. It is not only about standardizing health data sets but rather recognizing the weight of human factors in this context. Ultimately, effective outcomes depend on tight cooperation between state actors, non-state actors and transnational bodies (Ali et al. 2024).
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