Lecture: Desertification: Narrator: Listen to part of a lecture in a class on environmental studies. Professor: Often when we think about deserts, we imagine vast uninhabitable wasteland that are basically, um, well, uninhabited. But actually dry lands comprise over 40 percent of the Earth and over two billion people across the globe live within these very tough ecological zones. Obviously, the scarcity of water is a huge issue for any population, big or small. And to survive, people in dry lands, that these kinds of societies often will utilize too much of what little resources they have. It's an unsustainable process, leading to an eventual degradation and intensification of environmental conditions. The whole process is known as desertification. The land basically deteriorates over time, becoming a harsher and harsher desert. But I should mention that desertification does happen naturally. Severe and persistent droughts occur, and well, they're basically unavoidable, unfortunately. But the intensification of the process has become alarming. Let me walk you through how human activity has affected desertification. Throughout history, the populations of arid and semi-arid regions were small and basically nomadic, balancing survival techniques, like hunting and gathering with farming and herding. They moved around a lot in ... in their attempts to navigate the irregular seasons. The population growth led to less movement and more farmland, and that farmland needs to be irrigated. Now all life is essentially dependent on healthy soil. Plants can't grow without it. And without plants, there are ... there aren't any crops for people or for that matter, grazing animals. Healthy soil is the result of a few concerted efforts, like heavy composting, rotating crops and using chemical fertilizers sensibly and correctly. And for truly rich soil, there needs to be fungi and microorganisms in the Earth by products of organic decay. The breakdown of dead plants and animals provides nutrients like carbon, nitrogen, and um, so her and phosphorus. Now those components need to be maintained in the soil in order to farm effectively. That's true anywhere, not just in dry areas. Without proper conservation of healthy soil, we begin to see desertification. Too often, chemical fertilizers are overused. That is what little water is available, sapping the topsoil of those fundamental nutrients. If plants can't draw nutrients from the Earth, they don't grow, which means there are fewer root systems absent of those groups. The soil becomes too compact or too loose, resulting in erosion, and that leads to even further desertification. But, um, there are also a few other causes. Um, grazing animals can be responsible as well. Livestock like cows and sheep are obviously very important to any robust farming society. But the problem with permitting animals to feed uncontrolled in dry regions with few predators and no migration is that they can quickly eliminate all plant life. And like before, without vegetation cover top soil is exposed. So we see erosion starting when heavy wind or ... or storms sweep the land. And here's another cause that I know some of you are already thinking of, the reckless clear cutting a forest, that too can set off the desertification process. Trees are needed for securing topsoil and reducing wind erosion. Again, balance. I mean, sustainability is too often disregarded, resulting in still more degradation. And keep in mind that a region without grasses and trees only gets hotter and hotter over time. The process doesn't stop with erosion. The star surface reflects sunlight back into the atmosphere, leading to greater evaporation and less rainfall. So how exactly can desertification be stopped? A big part of the problem is that these societies living in these kinds of harsh zones are usually marginalized and um, very poor. Some are even war refugees on the run from invading militias. They're well desperate sometimes. It's only through education, the teaching of sustainable agricultural techniques that desertification can be slowed or stopped. Common sense treatment of topsoil is key and crop rotation has to be practiced. The planting of cover crops, like um beans and lentils that's been shown to boost nitrogen and topsoil, responsible irrigation should also coincide with building terraces on hilly areas. Those terraces, uh, they look kind of like stairs, built into the side of a hill. They help to prevent runoff and erosion. Planting more trees in specifically chosen locations can also lessen environmental degradation and help to stabilize the soil. And we're still developing ways to adapt. Conservation ingenuity has resulted in something called arid agriculture, a method of breeding fish in the salty ponds of certain dry lands. So as bleak as all this might seem, there's still plenty of opportunity to overcome it.