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Dr Muiris Houston: How climate change is hurting our health in Ireland

We are at higher risk of emerging diseases, heat-related illnesses and mental-health issues

As we enter the second week of Cop27, the 2022 United Nations Climate Change Conference, in Egypt, and read daily reports from our Science and Environment Editor, Kevin O’Sullivan, I thought it would be timely to devote this week’s column to the health effects of climate change.

First up, like me, you may be confused by the Cop nomenclature. It stands for “Conference of the Parties”. The parties are the attending countries that signed up to the original UN climate agreement in 1992.

Countries and health systems continue to contend with the health, social, and economic impacts of the Covid-19 pandemic, while Russia’s invasion of Ukraine and a persistent fossil fuel overdependence has pushed the world into global energy and cost-of-living crises. Meanwhile, climate change escalates unabated. Its worsening impacts are increasingly affecting the foundations of human health and wellbeing.

At Cop27, a dedicated Health Pavilion will showcase more than 40 events related to climate change and health, at which the World Health Organisation will be promoting the health argument for climate actions.


In the run-up to Cop27, the 2022 report of the Lancet Countdown on Health and Climate Climate was published. It has some dire findings. With an average global surface heating of 1.1 degrees, climate change is increasingly undermining every pillar of good health. The health harms of extreme heat exposure are rising, affecting mental health, undermining the capacity to work and exercise, and resulting in annual heat-related deaths in people older than 65 years increasing by 68 per cent from 2000–2004 to 2017–2021. The changing climate is exacerbating the risk of infectious disease outbreaks and threatening global food security, with heatwave days associated with 98 million more people experiencing food insecurity in 2020 than in the years up to 2010. These health impacts add additional pressure on overwhelmed health systems. We need to adapt at a faster pace to buttress this.

However, the Lancet report found that authorities are not acting fast enough and adaptation funding remains insufficient. The increased use of air conditioning and a scattered implementation of nature-based solutions are not good enough.

How might these trends affect public health in Ireland?

The changing climate is affecting the spread of infectious diseases, putting us at higher risk of emerging diseases. We know that coastal waters are becoming more suitable for the transmission of Vibrio bugs; non-cholera Vibrio bacteria survive in brackish waters, and can cause gastroenteritis if ingested in contaminated food, and potentially lethal wound infections if direct contact is made with contaminated water. Meanwhile, the likelihood of developing dengue fever - a viral infection spread by mosquitoes – has risen in Europe, with France recording a threefold increase in local transmission of the virus in 2022.

As we saw in Ireland this summer, climate change is leading to an increase in the frequency and intensity of heatwaves. Exposure to extreme heat is associated with acute kidney injury, heatstroke, adverse pregnancy outcomes and poor sleep patterns. It also has a negative impact on mental health, and it worsens underlying cardiovascular and respiratory disease. Exposure to extreme heat affects health indirectly by restricting people’s capacity to work and exercise.

Regular physical activity contributes to a healthy bodyweight, improves physical and mental health, and helps to prevent many non-communicable diseases. However, hot weather reduces the likelihood of engaging in exercise, and it increases the risk of heat illness for those who do engage.

We are also seeing an increase in flooding as a result of climate change. Severe flooding can overwhelm sewage systems, endanger sources of drinking water and facilitate the spread of water-borne infectious disease.

With the world projected to heat up by 2.4 to 3.5 degrees by 2100, even more devastating health outcomes are heading our way.

The time for action is now.