WITH IRELAND’S SUMMER temperatures forecast to ratchet up higher as climate change bares its teeth experts say action needs to be taken to protect cities from more-frequent scorching heatwaves.
Climate scientists are unequivocal that the recent record-breaking weather seen in Ireland and the blistering temperatures that have claimed thousands of lives in continental Europe (notably in Spain and Portugal) are set to become increasingly prevalent in the future.
Research has shown that, consistent with global trends, Ireland’s summers are getting warmer while its winters get wetter. Temperatures have ticked upwards by about 0.9 degrees celsius over the course of the last century. This has been accompanied by rising sea levels and more extreme weather events.
Climatologist Peter Thorne told The Journal recently that within the next couple of decades we will likely have heat extremes that are far worse in either duration, extent or magnitude than what was experienced in July.
The comments are echoed by Dr Mary Bourke, an expert in natural hazards from Trinity College Dublin’s geography department.
The earth sciences researcher studies health problems caused by the environment and seeks to find sustainable solutions to natural hazards. One such hazard is sweltering hot cities during heatwaves which carry a health risk, particularly for older people.
Urban heat island effect
Rising temperatures cause an even greater problem in urban areas as cities are hotter than rural parts due to the urban heat island effect. This phenomenon is caused by cities having an abundance of impervious surfaces like roads and buildings.
“The temperature will rise the minute you enter a city and fall as soon as you get out. It’s a place based temperature trend not a meteorological one,” Dr Bourke explains.
“We have built all these urban areas and replaced natural surfaces with concrete and tarmacadam and so on. These materials, especially the colour but also the materials themselves, absorb the incoming solar energy and they hold on to it and then they let it out later in the day.
“Late heat peaks in urban areas after it peaks in rural areas. The city holds heat for longer and it lets it out for longer. So, in general, if you’re living in a city your heat hazard will be higher than the people living in the rural areas.”
Several cities, including New York, Los Angeles and Sydney, have tried to tackle this by ditching dark-coloured surfaces (such as roads and roofs), which absorb and radiate heat, and painting these surfaces white.
Dr Bourke added that urban heat is set to become a greater issue in the future as the population of cities continues to grow. Ireland’s five cities are targeted to grow by 50% by 2040, under the National Planning Framework.
The situation is set to be compounded by the fact that older people face greater danger during heatwaves, as they can struggle to regulate their body temperature, and demographics show that the population is getting steadily older.
“The stats by themselves suggest that the hazard is going to increase as we move through the century. Even if we didn’t have more frequent hot events, just the fact that we have an ageing population increases that standalone hazard,” Bourke added.
Nature based solutions
Dr Bourke focuses much of her research on finding nature-based solutions to the problems posed by climate change.
This approach, which involves the protection, restoration and management of natural ecosystems, is heavily advocated by the UN’s Intergovernmental Panel on Climate Change (IPCC) in its sixth assessment report, which was published this year.
The major report made clear that climate change is causing severe and widespread disruption around the world. The document notes that heatwaves have a greater impact in cities due to higher temperatures.
It says nature-based solutions, including planting and protecting trees, play an important part in reducing greenhouse gas emissions and taking carbon dioxide out of the atmosphere.
Trees and other vegetation have a cooling effect due to water being lost from their leaves through evaporation and transpiration. Because of this, parks, gardens and other green spaces in cities can reduce air temperatures by up to a few degrees.
“The first thing is vegetation. Trees; they create shade, they decrease humidity, they lower the temperature, they are very effective in so many ways,” Dr Bourke told The Journal.
“Cities that have more green spaces in them, and I’m talking about parks – Stephen’s Green, Cabinteely park, that kind of place – they’re generally cooler compared to cities that don’t have those green spaces.”
Parks and green spaces also offer recreation opportunities and spending time in natural surroundings has been shown to be good for people’s physical and mental health.
So-called living walls and green roofs, which are covered in plants and grass, are also effective ways of increasing greenery in cities. As well as having cooling properties, they also help prevent flooding by absorbing rainfall and offer buildings a layer of insulation.
Several prominent cities have created ambitious plans to increase their greenery. Paris is working to “green” 100 hectares across the city while in London mayor Sadiq Khan wants to make the UK capital the world’s first “National Park City” by 2050. The strategy to achieve this involves mass tree planting and park restoration.
What’s Ireland doing?
The Climate Action Plan, released last year, is the roadmap for how the State hopes to reach its goal of cutting greenhouse gas emissions by 51% by 2030.
It does not dictate any urban greening or other nature based solutions to help achieve this. Instead it places the initiative with local authorities which are each required to have a climate action strategy spanning five years.
A spokesperson for the Department of the Environment, Climate and Communications said nature based solutions will also be considered in a forthcoming review of the National Adaptation Framework (NAF), which was published in 2018 and seeks to create a “climate resilient Ireland”.
“Where appropriate, Local Authorities may include urban greening and other nature-based actions in their plans. The review of the NAF, which will be completed later in 2022, will also consider the role of urban greening and other nature-based solutions in national adaptation policy,” the spokesperson said.
National funding programmes, such as the Urban Regeneration and Development Fund, also contribute to the delivery of public green spaces in urban areas.
The IPCC report notes that urban greening alone is far from enough to tackle the range of climate challenges ahead but experts say they have significant potential to make cities more livable for people and other animals.
“Trees, parks, changing the albedo of roads (by brightening the colour of them) they all help. All these micro measures help and change things for the better,” Dr Bourke concluded.
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