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Many places in the northern half of the world are currently facing record-breaking heat.
北半球的许多地方目前正遭受破纪录的高温。
Several countries in the Middle East, including Iran, Kuwait, Oman and the United Arab Emirates, recorded days over 50 degrees Celsius in recent months.
最近几个月，包括伊朗、科威特、阿曼和阿拉伯联合酋长国在内的几个中东国家的气温都超过了50摄氏度。
Moscow and Helsinki, Finland also reported their hottest June temperatures on record.
据报道，莫斯科和芬兰的赫尔辛基也出现了有记录以来最高的六月气温。
Several weeks ago, there was a record-breaking heat wave in the Pacific Northwest of the United States and western Canada.
几周前，美国西北太平洋地区和加拿大西部出现了破纪录的热浪。
Oregon and Washington state reported almost 200 heat-related deaths.
俄勒冈州和华盛顿州报告了近200例与高温有关的死亡。
Jennifer Vanos is an assistant professor at Arizona State University.
Jennifer Vanos是亚利桑那州立大学的助理教授。
She said: "(Heat) is different than other extremes because...it's invisible."
她表示：“(热浪)不同于其他极端天气，因为…… 它是无形的。”
She added that when "it's something people have never experienced before, then it becomes a lot more dangerous."
她补充说，如果“这是人们从未经历过的事情，它就会变得异常危险。”
A United Nations group on climate change says cities can be dangerous places during heat waves.
联合国气候变化组织表示，出现热浪时，城市可能是危险之地。
City buildings and streets can make temperatures rise.
城市里的建筑和街道会让气温上升。
And with more than 50 percent of the world's population living in cities, experts fear that heat-related health problems will become more common.
世界上有超过50%的人口居住在城市，专家担心与高温有关的健康问题会变得更加普遍。
Cities can be several degrees hotter than rural environments.
城市的温度可能比农村高出几摄氏度。
This effect is known as the urban heat island.
这种效应被称为城市热岛效应。
Hashem Akbari studies urban heat islands at Concordia University in Montreal.
Hashem Akbari在蒙特利尔的康考迪亚大学研究城市热岛效应。
He said building materials in cities take in heat and hold it.
他说，城市里的建筑材料会吸收并储存热量。
Asphalt, for example, is a petroleum-based mixture used in streets and on the tops of buildings.
例如，沥青是一种以石油为原料的产出混合物，通常用在街道表面和建筑物顶部。
Its dark surface reflects little light and absorbs heat.
它黑色的表面几乎不反光，还会吸收热量。
At the same time, buildings are often close together, which means there are fewer trees and plants.
与此同时，建筑物之间通常间距较小，这意味着树木和植被较少。
Plants provide valuable cover from the sun.
植被是重要的遮阳物体。
Plants also absorb water through their roots and use surrounding heat to evaporate the water from their leaves.
植被还可以通过根部吸收水分，并利用周围的热量从叶子上蒸发水分。
With fewer plants, this natural cooling effect is gone, Akbari said.
Akbari表示，随着植被的减少，这种自然冷却效应也会随之消失。
Energy demands
能源需求
To avoid the heat, people living in cities use electricity to power air cooling systems and fans.
为了祛除高温，城市居民会用电力来驱动空气冷却系统和风扇。
On a very hot day, those technologies use a lot of electricity.
在非常炎热的天气里，这些技术会消耗大量的电力。
Sayanti Mukherjee is an assistant engineering professor at the University at Buffalo, New York.
Sayanti Mukherjee是纽约布法罗大学的工程学助理教授。
She said cities have "a higher population to serve, so the infrastructure is working at a higher capacity because of the demand."
她说，城市有“更多的人口需要服务，这种需求要求基础设施有更强的工作能力。”
But sometimes the electricity system is unable to supply enough power to meet the demand.
但有时电力系统无法提供足够的电力来满足居民需求。
If that happens, the system shuts down and the power shuts off.
如果出现这种情况，电力系统就会崩溃，电源也会被切断。
Extreme weather events, however, are unusual.
然而，极端天气事件并不常见。
That makes it difficult for city planners and engineers to prepare for conditions that might not happen very often.
所以城市规划者和工程师很难为罕见的情况做好充分准备。
Materials in infrastructure
基础设施的用料
The materials used to make urban infrastructure also are affected by high heat.
城市基础设施所用的材料也受到了高温的影响。
Heat makes metal materials expand.
热量会让金属材料膨胀。
Power lines, for example, are usually made with metal.
例如，电线一般是用金属制成的。
Hot temperatures and high electricity demands cause the metal to expand and fall lower to the ground.
高温和高电力需求导致金属膨胀并出现下坠。
The falling lines can touch trees or people and can cause fires or injuries.
坠下的电线可能触碰到树木或人，并引起火灾或造成伤害。
Concrete and asphalt expand with heat too.
混凝土和沥青也会因受热而膨胀。
Quick changes in temperature can create cracks in concrete and can cause buildings, streets or bridges to weaken.
温度的快速变化会导致混凝土出现裂缝，并让建筑物、街道或桥梁的功能减弱。
Finding solutions
寻找解决方案
Researchers are looking for ways to help urban populations live through extreme heat.
研究人员正在寻找帮助城市居民度过极端高温的方法。
Vanos said cities should keep better records of heat-related deaths.
Vanos表示，城市应该认真记录好与高温有关死亡案例。
She said these kinds of deaths are often underreported.
她说，这类死亡往往会被低估。
Vanos added that city governments can help identify populations that are at risk and improve emergency services.
Vanos补充说，市政府可以帮助鉴别处于危险中的人群，并改善应急服务。
Akbari said more trees and grass are needed to cool cities.
Akbari说，城市需要更多树木和草地来降温。
He added that structures should be built with new materials that are lighter in color and reflect more light.
他补充道，建筑结构应该用颜色更浅、能反射更多光线的新材料建造。
That would also lower temperatures and save energy.
这也可以降低温度，节约能源。
To supply energy demands, Mukherjee said cities need to use more wind and solar power.
Mukherjee说，为了满足能源需求，城市需要更多地使用风能和太阳能。
Experts say the heat-trapping carbon gasses have pushed the world's climate to an extreme.
专家表示，温室气体已经将全球气候推向了一个极端。
"The more frequent and intense heat waves are showing that we need to prepare ourselves more to address this problem in the future," Mukherjee said.
Mukherjee表示：“越来越频繁和强烈的热浪表明，我们需要为未来解决这一问题做更多准备。”
I'm Dan Novak.
丹·诺瓦克为您播报。
译文为可可英语翻译，未经授权请勿转载！
