With the summer sun baking up the earth and cities growing in number, hot cities will grow even hotter, says a new study. It is known that cities retain more heat than rural areas, and the above finding suggests that the increasing temperature in urban areas would take a toll on the comfort and health of people who live in cities around the world, especially those who don’t have access to air-conditioning.

If you’ve been exposed to hot temperatures during the day and you expect relief over night, that becomes increasingly difficult as temperatures at night get warmer. We have to prepare to live in a warmer world,” Discovery News quoted Richard Betts, a climate scientist at the UK’s Met Office, as saying.In a concrete jungle, roads and buildings absorb sunlight and trap heat, which also flows as waste out of cars, air-conditioning units and even just the breathing of millions of people crammed into a busy grid of streets.

Thus, cities create their own, warmer microclimates — a phenomenon called the urban heat island effect.In the Middle East, where the effect will likely be most extreme, the study predicted that CO2 emissions will lead to a night time rise of about 5.4 degrees Fahrenheit both inside and outside of cities, with an extra 5.4 degrees Fahrenheit rise within city limits.Among other places, nights will also get significantly warmer in the urban areas of East Africa, Central Asia and the western United States.