GFX / Visual Explainer: Urban Heatwaves -- WEB
Metadata
- GFX / Visual Explainer: Urban Heatwaves -- WEB
- July 20, 2022
- Content Type Package
- Language English
- Transcript/Script Urban Heatwaves HEADLINE: Cities Unprepared for More Intense and Frequent Heat Waves TEASER: Current urban infrastructure leaves cities vulnerable to climate change emergencies PUBLISHED: 07/19/2022 at 8:25 pm BYLINE: Luyi Cheng CONTRIBUTOR: DATELINE: VIDEOGRAPHER: PRODUCER: Yass Monem SCRIPT EDITORS: Reifenrath, Sharon Shahid GFX Artist: Chin Park VIDEO SOURCE (S): VOA Graphics PLATFORMS (mark with X): WEB __ TV __ RADIO __ TRT: 6:13 VID APPROVED BY: mia TYPE: Visual Explainer EDITOR NOTES:)) The world is bracing for more intense heat waves fueled by climate change this summer, and urban centers across the world are unprepared to face these brutal natural disasters. Many emerging global climate risks, such as heat stress, will be concentrated in urban areas, according to reports by the Intergovernmental Panel on Climate Change. Heat waves can hit hard in cities, partly because of urban infrastructure that both exacerbates and fails to handle extreme heat. With over 50% of the world's population residing in densely populated urban areas, experts expect heat-related deaths, economic consequences and infrastructural damage to become a growing concern. Here's how cities are impacted by extreme heat. Urban Heat Islands Urban heat island' is a name given to the city, because typically they are hotter than suburban areas," said Hashem Akbari, professor, department of building, civil and environmental engineering, Concordia University in Montreal. "Most urban surfaces are man-made, and as a result of that, they are dark, typically, and they absorb a lot of the sun's energy. And if a surface absorbs the sun's energy, it heats up the air adjacent to it, and as a result, the temperature in the city will be warmer." Closely packed buildings and streets also mean fewer trees and plants and a potential reduction in shade. Plants normally absorb water through their roots and use surrounding heat to evaporate and emit the moisture as vapor from their leaves. With less greenery, that natural cooling effect is also gone. Energy Demands In these scenarios, to avoid the heat, urban populations turn on air conditioners and fans, which rely on electricity to run. "As our temperature rises, we turn on our ACs to make a comfortable indoor environment, but that requires more electricity,” said Sayanti Mukherjee, assistant professor, department of industrial and systems engineering, University at Buffalo in New York. “And on the other side, if there is less supply of electricity, it's a cascading impact, right?" And when the demand exceeds the amount of electricity an energy grid can generate and deliver, the system overloads and the flow of power shuts off. "Over the years, we are also seeing more and more people migrating to these urban areas, which is also increasing the load on the existing system," Mukherjee said. Materials in Infrastructure Heat has another effect on urban infrastructure: It makes all kinds of building materials expand. Power lines, typically made of copper or aluminum, help transmit electricity to buildings and transportation systems. A combination of heat from the weather and the overloaded power lines can cause the metal to expand and sag. These hot, drooping lines could then touch trees, vehicles or people and possibly cause fires or deaths. Heat can affect concrete. “What we really get concerned about with heat is big variations at a quick time scale, so if you're going from cold to hot and back to cold, that can kind of shock the concrete,” said Matthew Adams, assistant professor, department of civil and environmental engineering, New Jersey Institute of Technology. “It's a very insulative material, and it really holds heat or holds cold, so it takes a long time to heat up or cool down. And so, if the surface changes temperature much faster than the interior part, it can crack, because you get sort of these differential expansions on the surface, and so that any cracks in concrete will speed up the deterioration of the system." Something similar happens with asphalt. “As you heat up the asphalt, the oil-based binder becomes softer, and then the whole system is expanding, right, because it's heating up,” Adams said. “So what happens is you end up with these places that push up because now it's softer, so it can't handle being pushed together from the rest of the asphalt that's expanding." Then there's steel. A movable bridge roasting under the sun, for example, can swell where the joints of two steel parts meet and push against each other. Without room to shift, they can get stuck when trying to lift the bridge to allow boats to pass under. Similarly, rail tracks can expand to create curves and kinks that force trains to run slower, or even stop, to avoid accidents. Preparing for Climate Change Besides encouraging lowering greenhouse emissions to reduce climate change, researchers are also offering other suggestions to help urban populations endure extreme heat. "If you have vegetation, the vegetation will also be able to shade the pavement and create a more comfortable environment for the pedestrians," Akbari said. Updating structures with materials that are lighter in color and more reflective can also lower temperatures and save energy. There are also ways to address energy demands. "Introducing renewables, such as solar power in the Southwest of the U.S. or wind in the North, then encouraging utilization of these renewables into this existing system, would be very helpful, as well," Mukherjee said. Introducing smart grids with computer-based operators to control the multiple components of a power system can also help utilities respond efficiently to weather events. With experts now saying that the world's carbon emissions have pushed climate change past a tipping point, cities will have to learn to adapt to handle future heat waves.
- NewsML Media Topics Arts, Culture, Entertainment and Media
- Network VOA
- Embargo Date July 19, 2022 20:57 EDT
- Byline Luyi Cheng
- Brand / Language Service Voice of America - English