Listening Topic: Earth Science – Lecture about desertification
A. Listen to the lecture. Then answer the questions below.
1 What do you think desertification means?
2 What do you think causes desertification?
B. Read through the questions and answer the ones you can. Then listen to the lecture again and complete your answers as you listen.
1 Who is giving this lecture? ___________________
2 How many countries have areas that suﬀer from desertification? ___________________
3 How long does it take for desertification to take place ___________________
4 How can cutting down trees cause desertification? ___________________
5 How are livestock and cattle aﬀected by desertification? ___________________
6 According to the lecture, by 2020, how many people will be forced to leave their homes because of desertification? ___________________
7 What are some of the places where desertification is happening? ___________________
Your own answers
1 Albert Park, from the United Nations Environmental Program (UNEP)
2 Over 100
3 Many years
4 Topsoil gets swept away, so plants can’t grow. This can also lead to bad flooding conditions, which further damages the land. Eventually, the land becomes desert-like.
5 They are left with no vegetation to eat.
6 As many as 60,000,000
7 Africa, Asia, and Latin and North America
A = Albert Park
A: Welcome everyone. My name is Albert Park and I’m from UNEP the United Nations Environmental Program. Today, I’m going to talk to you all a bit about a serious problem affecting over 100 countries. That problem is desertification, the process by which healthy, usable land becomes arid and unusable.
As you might imagine, this process does not happen overnight. It takes many years-in some cases centuries. But it can be stopped, and I’ll talk about how in a moment.
First of all, however, let’s consider what causes desertification to happen. As you’ll see on this slide, it happens for a number of reasons. It takes poor weather conditions like drought, combined with poor land management to create this disastrous situation.
Here’s a common scenario: Let’s say thousands or millions people in a particular region or country need trees-for construction purposes, for making paper, and for other uses. So, of course, forests get cut down. However, if the forests aren’t replaced, soil that was held in place by the tree roots get swept away. This top layer of soil is where plants get nutrients, so if there’s no topsoil, plants won’t grow. Without plants holding the earth in place, these areas also experience more flooding, which destroys even more of the vegetation. Over time, the land continues to suffer degradation, until eventually it becomes barren and desert-like.
Another contributing factor is over-grazing. An example of this is when people settle in one place, their livestock, cattle, goats and sheep, eat food grown on the same piece of land year after year after year, until the minerals in the soil are used up. When that happens, farmers can no longer grow crops there, so the result is that dirt blows away and farmers have to find other places to live. Not only that, but the cattle compact the earth with their hooves so tightly that water from irrigation or rainfall just runs off without penetrating the ground. And if the land is not irrigated properly the level of salt in the soil can rise, thus adding to the degradation of the land.
As I said, this is taking place in over 100 countries around the world, and it’s a problem that is affecting acres and acres of land. And obviously, the loss of usable land affects the animals and people who live in these areas. These barren spots will not support life, which means these people have to go elsewhere to support themselves. In fact, some experts predict that as many as 60 million people will have been displaced because of desertification by the year 2020. And this mass migration will of course put strain on the existing resources in those areas the people move to. This is exactly what’s happening in parts of Africa, in Asia, and in parts of Latin and North America.
So what can be done to stop desertification from happening? Well, there are many things that people and nations are doing to stop the spread of deserts. For instance, one solution is to plant young trees where deforestation has occurred. As the trees grow, the roots will once again hold the earth in place, thus protecting it. People in some areas are planting rows of trees and building fences at the edges of deserts to act as a wind break to stop the approach of the sand. Obviously, proper crop rotation and reseeding will help prevent soil erosion and wise use of irrigation techniques and existing water supplies will also improve conditions.
So all hope is not lost. There is a lot we can do to stop encroaching desertification. But more steps need to be taken immediately. The programs in place in Africa, Asia, and elsewhere need more funding and they need more publicity. That’s one of the reasons that we’re here at this conference. Now if any of you would like to find out more about desertification and what’s being done about it, there are many resources available. For instance, you could visit the UNEP Website or the Website for the USGS-the US Geological Survey. Both sites have plenty of information. Now, I’d like to open up the floor for questions and comments.
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