LAST UPDATE | 19 Sep
HAZARDOUS HEATWAVES in Dublin lasting two to three weeks at a time could become the norm if the world allows global average temperatures to continue to rise at their current projected pace.
The World Resources Institute (WRI) has conducted in-depth analysis of how 996 of the world’s cities would be affected if temperatures remain on course to rise three degrees Celsius above pre-industrial levels.
The research confirms that the effects of that level of global warming on cities and the people who live in them would be extremely difficult to cope with.
In Dublin, the only Irish city included in the research, the duration of the longest annual heatwaves could range from 12 or 14 days up to as high as 24.7 days on average.
Many Irish people might say they wouldn’t mind a little more sun in the summer but the kind of harsh conditions anticipated with climate change are not to be taken lightly – heatwaves that are more intense, more frequent, and more enduring would be uncomfortable at best and deadly at worst.
As well as longer heatwaves, the number of heatwaves Dublin sees in a year could rise to an average of five or six.
London in the UK and New York in the US face similar projections – five to six heatwaves a year with the longest lasting an average of 12 to 16 days for London and six to eight heatwaves a year lasting up to around 18 days on average in New York.
If global warming is limited to 1.5 degrees in line with the Paris Agreement, cities would still experience negative impacts but would be in a much better position to manage them.
The difference in the degrees may appear small on paper but sustained changes in average temperatures that might seem narrow in theory would, in reality, have major impacts.
Under the Paris Agreement signed in 2015, nearly two hundred countries promised to try to limit global warming to within 1.5 degrees of rise compared to pre-industrial times.
However, the latest assessments of progress on climate action show that collectively, the world is on track to see warming of around 2.9 degrees – almost double the Paris Agreement target.
Breaking down the results, the WRI team has explained that “at three degrees Celsius of warming, many cities could face month-long heatwaves, skyrocketing energy demand for air conditioning, as well as a shifting risk for insect-borne diseases – sometimes simultaneously”.
In a statement, Rogier van hen Berg, the Global Director of the WRI Ross Center for Sustainable Cities, said the data should “serve as a wakeup call to every city and national government leader.”
The difference between 1.5 degrees and three degrees has life or death consequences for billions of people worldwide.”
“Now is the time to start preparing cities for a much hotter world, while doing everything we can to slash emissions,” he stated.
With three degrees of warming, most cities can expect longer and more frequent heat waves, with impacts for public health and people’s ability to work.
The longest heatwave each year may last 16.3 days on average with 1.5 degrees of warming, jumping to an average of 24.5 days at three degrees.
16% of cities, which in total are home to 302 million people at present, would be exposed to at least one heatwave that lasted a month or longer every year.
Not only would heatwaves be longer, they’d be more frequent, reaching as many a 6.4 heatwaves in the average city per year.
Dealing with increased temperatures will raise the demand for cooling systems, putting pressure on energy systems.
With 1.5 degrees of warming, the number of people that would face a 100% increase in their cooling demand compared to the period of 1995-2014 would be 8.7 million.
But with three degrees of warming, that number skyrockets to 194 million people seeing their cooling demand double.
As cities become hotter, they would provide the optimal conditions for mosquitoes carrying potentially life-threatening arboviruses like dengue, Zika, chikungunya and yellow fever.
Cities in regions like Europe and North America could also see the risk of malaria increase, though in hotter parts of the world, temperatures may become even hotter than what is optimal for malaria-transmitting mosquitos.
“These findings bear immense consequences for people’s lives, cities’ economies, and infrastructure and public health systems,” a WRI press statement says.
“This is especially important as cities are home to more than half the world’s population — 4.4 billion people — and are expected to grow rapidly over the next two decades.”
Cities in low-income countries will be the worst affected by rising temperatures and the least equipped to try to cope with the impacts.
Cities in sub-Saharan Africa face the worst average increase in heatwave frequency and the number of days with peak conditions for arboviruses, followed by cities in Latin America.
Southeast Asian cities would also be hit hard, with Indonesian cities mentioned in particular as facing “some of the highest compounding risks from both hotter temperatures and greater disease”.
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