IELTS Listening Part 4: A Lecture on Urban Heat Islands

Part Four. You will hear a lecture about urban heat islands.

You have some time to look at questions thirty-one to forty.

Now listen carefully and answer questions thirty-one to forty.

Good morning, everyone. Today we're looking at urban heat islands.

Have you ever noticed that cities feel hotter than the countryside?

Well, that's not just your imagination.

On summer nights, a city can be up to ten degrees warmer!

Scientists call this the urban heat island effect.

So, what causes it? There are three main reasons.

First, dark surfaces like roads and roofs absorb heat during the day,

and then they slowly release it again at night.

Second, cities have fewer trees and less open water to cool the air.

And third, there's us! Cars, factories and air conditioners all produce heat.

Ironically, the hotter it gets, the more air conditioning we use.

This matters, because extreme heat can be dangerous.

Elderly people living alone are especially at risk during heatwaves.

Hot cities also use more energy, and the air quality gets worse.

The good news is that there are simple solutions!

Some cities are painting roofs white to reflect the sunlight.

In one study, white roofs cooled the rooms below by up to two degrees.

Green roofs, covered in plants, can work even better.

But the most effective solution is still the oldest one: planting trees.

One large tree can cool the air as much as several air conditioners.

Next week, we'll look at how one city turned itself into a garden.

Thanks, everyone. See you then!

That is the end of Part Four.