World Health Day – How does climate change affect human health?

Climate change presents various risks but far too few are known when it comes to our own health. Find out how climate change is affecting the environment and the key health threats this poses.

| 6 min read

Global warming refers to the increase in Earth's average surface temperature from human activities, primarily the increased emission of greenhouse gases from globalised industrialised processes. Carbon dioxide (CO2) is the most common but there are other more potent, albeit less enduring, gasses such as methane (CH4), and nitrous oxide (N2O). These gases trap heat in the Earth's atmosphere, creating a greenhouse effect that leads to a warming planet and a change in climate patterns.

These changes include shifts in weather patterns, more frequent and severe extreme weather events, alterations in precipitation patterns, and changes in ecosystems and wildlife habitats. Human-induced global warming accelerates these changes, leading to far-reaching impacts on the environment, economy, and human societies worldwide. It is important to highlight this linkage because even before we consider how a changing climate has consequences, these industrial processes and human activities have their first impact on human health.

Before diving into how climate change affects our health, we should first appreciate the scientific evidence and research that points to global warming and the key mechanism driving our increasingly warmer planet.

  • It has been nearly two years since the United Nations climate science group Intergovernmental Panel on Climate Change (IPCC) stated that it is “unequivocal that human activities have heated our climate [1]”.
  • Since then, we’ve learnt that 2023 was the warmest year on average where the average global temperature exceeded 1.5⁰C [2].
  • More recently, in February 2024, global sea surface temperatures averaged the highest for any month in the dataset [3], and Antarctic Sea ice registered its third lowest coverage on record at 28% below average.[4]

The impact of climate change on health

1. Air pollution causes respiratory problems

Rolling back to the 19th century, the first industrial revolution and its subsequent advancements were undoubtedly brilliant technological breakthrough moments of change that created the modern economics we now live and breathe. However, the advent of machinery powered by coal caused levels of air pollution and smog in London that were 50x higher [5]than levels known today. Little surprise then that the average life expectancy in the UK in early 1900s was just under 50[6].

Respiratory diseases were rife particularly in the “elderly” and the young with coal emissions having a direct impact on people’s lives at the time. Clearly there was also limited awareness that the CO2 output from continuous coal burning would also be a long-term issue as a key contributor to global greenhouse gases and a changing planet.

Positively, the improvements throughout subsequent industrial revolutions into the 21st century have seen air pollution levels fall, and life expectancy dramatically improve as coal use continues to decline. However, the World Health Organisation recently identified that just seven countries worldwide have safe levels of clean air. [7] In today’s world air pollution is estimated to kill 7 million people globally per year[8] mostly in the developing world where advances in energy generation and cooking are less advanced.

2. Deforestation causes diseases

There is another area that is firmly in the centre of climate change and human health Venn diagram – deforestation. Not only does the removal of our rainforests, trees, and natural capital act as a further contributor global warming but it also poses a very serious direct health risk.

By disturbing natural ecosystems, we force species to migrate from their natural habitats in search of new homes, which increase the likelihood of animal-borne diseases. We have seen examples of this in recent years with SARS in the early 2000s, swine flu in 2009, Ebola in 2013 (and 1970s western Africa), monkey pox in 2022 [9]and most memorably the covid-19 pandemic. These zoonotic diseases, which include coronaviruses, are infections that spread between non-humans and humans. Therefore, the further we probe natural areas, disturb habitat and force species movement, the greater the risk of these diseases crossing over.

Furthermore, as a secondary feedback loop from worsening global warming and climate change, we are seeing increasing incidence of wildfires that is then inadvertently causing animals to flee their habitats, whilst higher temperatures and warmer conditions create the perfect conditions for diseases and viruses to flourish.


It’s clear that climate change has a long-lasting impact on human health as well as the surrounding environment. That’s one of the reasons we pay close attention to initiatives that can reduce carbon emissions via the holdings and fund vehicles in which we invest. It’s also of growing importance that the investment industry pays close attention to nature and deforestation. Investors have the ability and engagement power to encourage companies to restore and protect natural areas.

At Charles Stanley we have taken our first steps in this through being an endorser to the Principles of Responsible Investment’s newly launched Spring Initiative which plays close attention to a specific list of global listed corporates that are closely linked to natural capital.

We also support the development of newly created entities Taskforce for Nature related Financial Disclosures (TNFD) and Nature Action 100 as key initiatives to push for increased attention on Nature to avoid these risks highlighted above.


[1] IPCC:

[2] Financial Times:

[3] Climate Copernicus EU:

[4] Reuters:

[5] The Conversation:

[6] House of Commons Library:

[7] The Guardian:

[8] The Guardian:

[9] National History Museum:

Nothing on this website should be construed as personal advice based on your circumstances. No news or research item is a personal recommendation to deal.

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