Are climate effects on health a reality? Climate can indeed facilitate disease emergence and spread through pathogen survival, development and dissemination.
Although it is not proved that climate will have a critical role in massively promoting the appearance of new pathogens, climate change caused a dramatic alteration of ecosystems, leading to a gradual substitution of species, shrinking of ecosystems and decrease in species diversity. Climate extremes, acting on a much shorter timescale, can also directly or indirectly affect the frequency and intensity of forest fires, floods, famines and migrations, equally influencing animal epizootic infectious diseases that may jump from an animal to a human.
Together with other natural and human-made health stressors, climate influences human health and disease in numerous ways. Some existing health threats will intensify and new health threats will emerge.
Factors such as temperature, atmospheric carbon dioxide, and cloud cover are having a direct impact on the growth of plants and trees, affecting natural habitats and ecosystems. Even subtle adjustments can have a great impact on the species living within an ecosystem.
Public health can be affected by disruptions of physical, biological, and ecological systems with increased respiratory and cardiovascular disease, injuries and premature deaths related to extreme weather events, changes in the prevalence and geographical distribution of food- and water-borne illnesses and other infectious diseases and threats to mental health.
Higher pollen concentrations and longer pollen seasons cause more people to suffer stronger health effects from pollen and other allergens, triggering various allergic reactions like hay fever. Allergic conjunctivitis is found in up to 30% of the general population and as many as seven out of 10 patients have allergic rhinitis.
Extreme rainfall and rising temperatures can also contribute to indoor air quality problems, like the growth of mold, leading to worsened respiratory conditions for people with asthma and/or mold allergies and heightened challenges in maintaining adequate asthma control.
Climate is one of the factors that influence the distribution of diseases borne by vectors, such as fleas, ticks, mosquitoes, which spread pathogens causing illness, as well as diarrheal diseases related to water and food pathogens.
Influenced by climate changes, heat waves with extreme temperatures and wildfires, leading to smoke exposure, result in a dramatic increase of death rates, from heat strokes, cardiovascular, respiratory and cerebrovascular diseases.
COVID-19 and climate change
Was climate change a causal factor of the COVID-19 outbreak?
In January of 2021, a paper published in the journal Science of the Total Environment revealed evidence that climate change may have played a direct causal role in the emergence of the virus responsible for the COVID-19 pandemic. An international team of scientists from the UK, Germany and the US stated that they were able to link climate change directly to COVID-19.
COVID-19 is not the only infectious disease that has been linked to climate change. For many years, the World Health Organization (WHO) has highlighted the link between changing environmental conditions and epidemic diseases.
At the time the COVID-19 outbreak was declared a global pandemic, climate change was at the forefront of political agendas. It was considered to be a crucial time to take decisive action to protect the future of the planet. The impact of the pandemic moved the spotlight away from climate change.
A 2020 report by The Lancet highlighted the need to align responses to both crises, the COVID-19 pandemic and climate change, in order to address them optimally. Because of the common factors of the pandemic and climate change, as both are linked to human activity and both lead to the degradation of the environment, it is rational to converge responses.
Climate change and infectious disease cause preventable loss of human life, but strategic adjustments can stop further loss of life.
Over the coming years, we will likely see more strategies implemented to amend human behaviour so that it has less impact on the environment and, consequently, on the spread of infectious diseases.
Climate change impacts our response to the pandemic
The World Health Organization (WHO) has stated there is no evidence of a direct link between climate change and the emergence or transmission of COVID-19.
However, it adds that almost all recent pandemics originated in wildlife and points to evidence that disease emergence could be partly driven by human activity.
What is more certain, WHO says, is that climate change can indirectly affect responses to the pandemic by undermining the environmental determinants of health and placing extra stress on health systems.
Measures such as improved surveillance of infectious diseases in wildlife and humans, and greater protection of the natural environment could help reduce the risk of future outbreaks.
While public concerns about climate change have risen in recent years, there still seems to be a widespread lack of knowledge about how rising global temperatures impact infectious diseases like the coronavirus.
The COVID-19 pandemic can possibly be a big turning point in 2021, as it has had significant economic impact and made us aware that, as humans, we are vulnerable.
But the public health emergency of climate change is an even more complex global danger to our health and our healthcare systems.
▪ Climate change affects the social and environmental determinants of health: clean air, safe drinking water, sufficient food and secure shelter.
▪ Between 2030 and 2050, climate change is expected to cause approximately 250,000 additional deaths per year, from malnutrition, malaria, diarrhoea and heat stress.
▪ The direct damage costs to health are estimated to be between €2-4 billion/year by 2030, excluding costs in health-determining sectors such as agriculture, water and sanitation
▪ Reducing emissions of greenhouse gases through better transport, food and energy-use choices can result in improved health, particularly through reduced air pollution.
A lack of awareness is not allowing humans to see that they must not continue to disrespect nature … our time is up!
Best health wishes,
By Dr Maria Alice
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Dr Maria Alice is a consultant in General and Family Medicine. General Manager/Medical Director – Luzdoc International Medical Service. Medical Director – Grupo Hospital Particular do Algarve/ Hospital S. Gonçalo de Lagos