Dr Muiris Houston: The damage climate change does to global health

Global warming brings wide-ranging, insidious harm to global health, researchers say

Between severe flooding in Belgium and Germany and extensive wildfires in the western US and Canada, the last six weeks have been a dramatic reminder of the perils of global warming. The floods in Germany killed almost 200 people, while in Lytton, British Columbia, Canada, three days of record-breaking 46 degree temperatures saw a small town dramatically combust with the loss of two lives.

Of course natural disasters predate global warming. The Led Zeppelin song, When the Levee Breaks commemorates the Great Mississippi Flood of 1927 and describes how:

“If it keeps on rainin’, levee’s goin’ to break

When the levee breaks, I’ll have no place to stay”


But as well as the acute consequences of flooding and excessive heat there is also a wide range of insidious and ongoing damage to global health. According to the annual Lancet Countdown on Health and Climate Change a child born today will experience a world that is more than four degrees warmer than the pre-industrial average, with climate change impacting human health from infancy to old age.

On Monday, in a report which was the work of more than 200 scientists digesting thousands of studies, the latest scientific assessment from the UN's Intergovernmental Panel on Climate Change warned that the planet will warm by 1.5 degrees in the next two decades without drastic moves to eliminate greenhouse gas pollution.

Jane Lubchenco, deputy director for climate and environment at the White House Office of Science and Technology Policy said the report “draws attention to the immediate benefits of significant reductions in methane, both from an atmospheric concentration point of view, but also the co-benefits to human health from improved air quality”.

A 2019 report for the Department of Health in the Republic says climate change can influence health "through altering exposure to stressors such as extreme weather events; vector-, food- and waterborne infectious diseases; changes in the quality and safety of air, food, and water; and stresses to mental health and well- being."

In practical terms this means we are seeing an exacerbation of respiratory symptoms from wildfire smoke and the spread of vector-borne and water-borne diseases following a flood. Climate change has also influenced the spread of infectious diseases. Parts of Europe are seeing an increase in infections transmitted via mosquitos and ticks – for example Lyme disease, malaria, dengue fever and tick-borne encephalitis.

And the recent German and Belgian floods have put people at increased risk of water-borne diseases, such as typhoid fever, cholera, leptospirosis and hepatitis A.

The urban heat-island effect causes materials that make up streets and buildings cause the air to heat up more than in leafier areas

We know that exposure to high temperatures and heatwaves results in a range of negative health impacts, from heat stress and heatstroke to exacerbations of cardiovascular and respiratory disease. The worst affected are those older than 65 years, those with disabilities or pre-existing medical conditions, and those working outdoors or in non-cooled environments.

Perhaps surprisingly, the World Health Organisation says populations in the European and Eastern Mediterranean regions have been the most vulnerable to the extremes of heat.

Although heatwaves affect people in rural areas, cities bear the brunt of the impact. That’s because of the urban heat-island effect, in which the materials that make up streets and buildings cause the air to heat up more than in leafier areas. On average, central urban areas are several degrees warmer during the day than the surrounding countryside – but they can get much hotter than that.

Many of us here in Ireland, although grateful for the recent prolonged spell of good weather, found it difficult to sleep when nighttime temperatures remained above 20 degrees. Research shows that more people die during stretches of hot weather, most especially when temperatures don't drop much at night.

But according to European research, flooding represents the biggest future threat to Irish people. Demographic changes play a part; with an average increase in the proportion of people living in coastal flood zones of 192 per cent, we are just behind Slovenia when it comes to potential exposure to flooding as a health hazard.

But compared with southern Europe, we will get away lightly, according to the European Commission researchers. Our southern cousins are expected to endure about 700 deaths per million people per year due to weather-related disaster; we can expect some three deaths per million annually by 2100.

As well as immediate deaths from drowning, floods such as the Mississippi disaster cause injuries, hypothermia, infectious disease and psychological distress.

Plus ca change you could say, albeit with a much greater climate- induced frequency.