Posted
The searing temperatures gripping Europe risk
precipitating the collapse of Notre-Dame de Paris' fire-ravaged vaulted
ceiling, the cathedral's chief architect says.
Key points:
- Rapidly drying masonry and joints may weaken as a result of the heat
- European metropoles have experienced some of their hottest days on record
- The southern Netherlands tipped 40 degrees for the first time on record
The centuries-old Notre-Dame was devastated in April by an inferno that gutted the ceiling and sent the cathedral's towering spire crashing through a part of the ceiling.
"I am very worried about the heatwave," chief architect Philippe Villeneuve said.
"What I fear is that the joints or the masonry, as they dry, lose their coherence, their cohesion and their structural qualities and that all of sudden, the vault gives way."Mr Villeneuve said the vaulted ceiling "could very well" collapse and that unlike the bell towers and other parts of the cathedral, experts had still not been able to access the ceiling from above or below.
Eighty out of mainland France's 96 administrative departments were on Orange alert — the second highest level of warning — on Wednesday as a blistering heatwave intensified.
On Thursday, the mercury in Paris touched 40.6 degrees Celsius, above the previous Paris record of 40.4 C recorded in July 1947.
President Emmanuel Macron has promised Notre-Dame will be rebuilt within five years.
Workmen have erected a giant white tarpaulin over the gutted roof, stabilised the cathedral's pinnacles and placed dozens of sensors to detect any movement.
The blaze at the cathedral, built over nearly 200 years starting in the middle of the 12th century, prompted a global outpouring of grief.
European countries experience record-breaking heat
Europe's current cauldron of hot air has its origins in the Sahara desert, which was drawn northwards by high pressure.
The unusual conditions brought a reduction in French and German nuclear power output, disrupted rail travel in parts of Britain and sent some Europeans, not habitual users of air conditioning in their homes, out to the shops in search of fans.
Health authorities issued warnings to the elderly, especially vulnerable to spikes in temperature.
In Britain, the temperature reached its highest for July, hitting 36.9C, said the Met Office, the national weather service.
The temperature, recorded at Heathrow, London, beat the previously July record of 36C.
In the southern Netherlands, the temperature peaked at 40.4C, topping 40 degrees for the first time on record, Dutch meteorology institute KNMI said.
That broke the national record of 39.3C set the previous day.
Before this week, the national heat record of 38.6C had stood for 75 years.
The heat is expected to persist until Friday.
Heatwave presents urban heat's risks
The earth's increasing temperatures will be sizably felt within urban areas, as cities are prone to the Urban Heat Island effect (UHI), a concept that refers to the heat that urban areas trap.
This is due to the concentration of materials that trap heat, such as glass, dark asphalt and masonry, which raise the temperatures recorded in inner urban areas.
A City of Melbourne report into the UHI from 2012 cited international research that determined that urban areas can add between 1-6C in ambient air temperature.
The council's report found that on a 30C day, the temperature in Melbourne's CBD will rise to 30.8C, while on a 40C day, it rises by 0.5C.
While most city planners know about the risks of heat on citizens' health, there is emerging suite of research that suggests that increasing heat increases crime.
US reports in the 1989 and 1996 found that hotter cities in hotter regions have higher rates of violent crimes than in cooler ones, even after its findings were measured against other factors such as poverty, unemployment, age, and other sociocultural differences.
In 1997, those reports' same authors found that for every 1 degree Fahrenheit rise above 90F (32.2C), the number of violent crimes (murders and assaults) increased by 3.68 per 100,000 people in the United States.
A 2017 Oxford study into the effects of climate change and conflict corroborated the US studies' findings:
"Across studies, however, a general trend seems to emerge: hotter periods of time are more violent, even after controlling for other time-related variables," it read.
Another South African study released last year found a "strong association" between rising temperatures and criminal activity after a study looking into extreme weather's impact on crime in the city of Tshwane.
In Australia's case, the Melbourne report determined that research into temperature-related behaviour effects within the country was "extremely limited".
Driving Melbourne's plan to combat the effect is its urban forest strategy, which aims to increase Melbourne's tree canopy to 40 per cent by 2040.
Trees help to reduce localised temperatures by 2C during summer days, according to the strategy.
Melbourne's move is in stark contrast to Los Angeles — a city which is covered in dark asphalt with little tree cover — prompting city authorities to trial heat-deflective paint on streets and city roofs.
Other cities have sought to avoid implement hard-engineering approaches such LA's, instead opting for green initiatives to combat urban heat absorbed by rooftops.
Chicago City Hall's green roof is a famous example of this urban greening, while some of the design proposals for Notre Dame have incorporated accessible rooftop gardens or green roofs in their design.
ABC/Reuters
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