(
课件网) Unit 5 When you see the title of this unit, what do you think it is about Why is our world delicate Unit 5 A delicate world To watch a video and answer the questions To look at the satellite images and talk about their changes To reflect on the impact of human activities on the planet View the video and talk about your understanding of the sentence: We were born from nature, and we are part of nature. What is ecosystem An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscapes, work together to form a bubble of life. When we are talking about the ecosystem, most of us would only think about animals and plants. But the truth is our daily activities are playing a vital (极其重要的) role in nature just like everything else. 1. Are humans part of Earth's ecosystems Why 2. In what ways can humans affect ecosystems Watch the video and answer the questions. 1 2. In what ways can humans affect ecosystems Humans can affect ecosystems in positive and negative ways. For example, to have a positive influence on ecosystems, people can plant trees, feed and protect animals, recycle things, etc. However, deforestation, air and water pollution and excessive waste affect ecosystems in a negative way. 1. Are humans part of Earth's ecosystems Why Yes. Humans are part of Earth’s ecosystems. Because all the living things live in ecosystems and people are living things. Watch the video again and discuss what we can do to keep the balance of the whole ecosystem. Look at the satellite images and talk about what you can see in them. 1990: The Aral Sea still appears as a large, dark blue body of water, clearly visible from space. 2000: The sea has shrunk dramatically, especially in the eastern part. 2010: The sea has almost disappeared, with only a thin strip of water remaining. Look at the satellite images and answer the questions. 1. What is happening to the area according to the satellite images Aral Sea is becoming smaller and smaller/ shrinking. 2. What do you think a later satellite image would show The water area will be even smaller. 2 The Aral Sea Crisis The Aral Sea is situated in Central Asia, between Kazakhstan to the north and Uzbekistan to the south. It was once the world's fourth largest lake, and contained 10 grammes of salt per litre. The rivers flowing into the Aral Sea are the river Syr Darya from the north and the river Amu Darya from the south. In the 1960s, the two rivers were diverted away from the Aral Sea so that people could irrigate the surrounding desert region and focus on cotton production. As a result, the Aral Sea has been decreasing in size, and by 1997, it had shrunk to a tenth of its original size, splitting into four lakes. By 2009, the south-eastern lake had disappeared altogether, and the south-western lake had been reduced to a thin strip, with a salinity level of more than 110 grammes per litre. This shrinking of th ... ...
