PARIS — Scientists sketched a vision on Friday of converting the world’s cities into giant sunlight reflectors to help fight global warming but met with scepticism from fellow academics.
Gradually replacing traditional urban roofs and roads with white or lighter-coloured materials would yield a cooling benefit that, over 50 years, would be the equivalent of a reduction of between 25 and 150 billion tonnes of carbon dioxide (CO2), researchers in Canada said.
At the top end of the scale, this equals the emissions of all the world’s cars over the same period, their study published in Britain’s Institute of Physics’ journal Environmental Research Letters stated.
Light-coloured materials help reflect the Sun’s rays rather than absorb and convert them into heat, a phenomenon known as albedo in scientific terms.
Pavements and roofs make up more than 60 percent of urban surfaces and, by trapping solar energy, are largely to blame for “heat islands”, where cities or districts become local hotspots.
Urban heat islands also gobble up energy in air conditioning and inflict health costs through smog.
The cost of reflectors need not be prohibitive as rooftops and paved surfaces need to be resurfaced every so often anyway, the scientists argued.
“All it means is that when the time comes, they would select a cool roof,” Hashem Akbari of Concordia University in Montreal told AFP.
He conceded that some of the new materials may be slightly more expensive than before, but the cost would still be “lower than the … savings they produce” in cooling.
French climate consultant Jean-Marc Jancovici, however, said the proposals would have only a localised effect.
“If you decrease significantly the temperature in local places with something like painting the roofs in white, it doesn’t ensure that you will have a decrease in the temperature in remote places,” he said.
Alfredo Stein of the Global Urban Research Centre at Britain’s University of Manchester also predicted practical difficulties, particularly for the world’s sprawling slum areas.
“It will require very strong advocacy by whoever will be selling the roofs,” he told AFP, especially considering that about 70 percent of houses worldwide are built by the owners themselves, mainly in informal settlements.
People’s choices for roofing materials are largely determined by affordability and availability, Stein argued.
In a 2009 probe into so-called geo-engineering options to brake global warming, Britain’s Royal Society gave low marks to “white roof” methods.
There would be benefits locally in hot countries, it said.
But only 0.05 to one percent of the world’s land surface would be covered, which meant it would lack effectiveness on a global scale, the prestigious academy said.
And it estimated the cost at “about $300 billion a year, making this one of the least effective and most expensive methods considered.”
Watergate’s John Dean thinks Trump wrote part of his legal team’s brief — because it’s so terrible
Former White House counsel for Richard Nixon, John Dean, explained that the legal brief out of President Donald Trump's White House was so bad that it had to have been dictated by Trump himself.
Saturday evening, Trump's legal team, chaired by Trump lawyer Jay Sekulow and White House counsel Pat Cipollone, filed their own form of a legal brief that responded to the case filed by Democrats ahead of Tuesday's impeachment trial.
The document called the proceedings “constitutionally invalid” and claims House Democrats are staging a “dangerous attack” with a “brazen and unlawful attempt to overturn the results of the 2016 election and interfere with the 2020 election.”
WATCH: Prince Harry explains why he and Meghan are leaving the royal family — but promises ‘a life of service’
Prince Harry posted a video from an HIV/AIDS fundraiser his mother once supported, where he explained his methodology for leaving his profile role as a royal.
"I will continue to be the same man who holds his country dear," said Harry.
He went on to say that he doesn't intend to walk away and he certainly won't walk away from his causes and interests. "We intend to live a life of service."
In the speech, he thanked those who took him under their wing in the absence of his mother
"I hope you can understand that it's what it had come to," he said for why their family intends to step back.
‘You cannot expect anything but fascism’: Pedagogy theorist on how Trump ‘legitimated a culture of lying, cruelty and a collapse of social responsibility’
The impeachment of Donald Trump appears to be a crisis without a history, at least a history that illuminates, not just comparisons with other presidential impeachments, but a history that provides historical lessons regarding its relationship to a previous age of tyranny that ushered in horrors associated with a fascist politics in the 1930s. In the age of Trump, history is now used to divert and elude the most serious questions to be raised about the impeachment crisis. The legacy of earlier presidential impeachments, which include Andrew Johnson and Bill Clinton, provide a comparative historical context for analysis and criticism. And while Trump’s impeachment is often defined as a more serious constitutional crisis given his attempt to use the power of the presidency to advance his personal political agenda, it is a crisis that willfully ignores the conditions that gave rise to Trump’s presidency along with its recurring pattern of authoritarian behavior, policies, and practices. One result is that the impeachment process with its abundance of political theater and insipid media coverage treats Trump’s crimes as the endpoint of an abuse of power and an illegal act, rather than as a political action that is symptomatic of a long legacy of conditions that have led to the United States’ slide into the abyss of authoritarianism.