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Bangkok, Thailand.

Summers in the city are always a bit more intense. The “urban heat island effect” is produced by man-made concrete and asphalt trapping more heat than natural vegetation and water. The greater density of exhaust spewing cars and humming air conditioners intensifies the heat of big cities even further.

That “heat island effect” will also come into play in the dynamics of climate change, according to a new study from scientists in the United Kingdom, Mexico and the Netherlands.

The urban magnification of heat is predicted to add an additional 2 degrees Celsius to thermometers in the most populated cities by 2050, above and beyond the predicted effects of global warming, according to the study, in the journal Nature Climate Change.

The study of 1,692 cities found that there will be severe economic repercussions – roughly double that of elsewhere on Earth. The end-of-century costs for the largest cities would be 10.9 percent of gross domestic product, compared with the global average of 5.6 percent, according to the paper’s estimates.

“Any hard-won victories over climate change on a global scale could be wiped out by the effects of uncontrolled urban heat islands,” said Richard S.J. Tol, professor of economics at the University of Sussex, one of the authors.

The offset would include planting more urban forests and parks, and fostering more plant coverage on roofs and other surfaces. Another major driver would be installing pavements and roofs to reflect sunlight and absorb less heat, according to the researchers, from Sussex, the Universidad Nacional Autonoma de Mexico and the Vrije Universidad Amsterdam. Such “cool” pavements and roofs could have a significant effect, even at moderate installation rates, they contend. Changing a fifth of a city’s roofs and half of its pavements to the “cool” varieties could save 12 times the cost of putting them in and maintaining them, and reduce ambient temperatures by nearly 1 degree, they explain. The saved energy and labor productivity would offset some of the other effects of increasing temperatures, they added.

“We show that city-level adaptation strategies to limit local warming have important economic net benefits for almost all cities around the world,” added Tol.

Cities cover about one percent of the planet’s surface, but 54 percent of the human population live in them. (They are also expected to grow, encompassing about 66 percent of humanity by 2050). They also are the hub of human productivity: they produce 80 percent of the Gross World Product, and use about 78 percent of the world’s energy.

Other climate change negatives that scientists have identified include reduced water and food sources, sea level rise for coastal metropolises, and potential population-level health effects.

Climate change has been a political football amid major turbulence on the international scene. Most recently, reports have indicated that President Donald Trump will withdraw the United States from its pledges made at the international climate change conference in December 2015 – one point of contention between American leadership and their European counterparts among many.

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