Grade 4 project: Earth in Danger
The greenhouse effect
Earth is kept warm by it's atmosphere, which acts rather like a woolly coat - without it, the average surface temperature would be about -18 degrees Centigrade. Heat from the sun passes through the atmosphere, warming it up, and most of it warms the surface of the planet. As the Earth warms up, it emits heat in the form of infra-red radiation - much like a hot pan emits heat even after it's taken away from the cooker. Some of this heat is trapped by the atmosphere, but the rest escapes into space. The so-called "greenhouse gases" make the atmosphere trap more of this radiation, so it gradually warms up more than it should, like a greenhouse (although a greenhouse actually does this by stopping warm air rising and escaping from it). The greenhouse effect is the process in which the emission of infrared radiation by the atmosphere warms a planet's surface. The name comes from an analogy with the warming of air inside a greenhouse compared to the air outside the greenhouse. The Earth's average surface temperature is about 33°C warmer than it would be without the greenhouse effect.
Greenhouse Gas Emissions
- Burning fossil fuels (coil, oil or gases)
- Clearing land
- Aspects of farming (raising cattle and sheep, growing rice, using fertilizers)
- Producing wast (garbage and sewage)
- Making cement and aluminum
Global warming
Scientists agree the Earth's climate is being directly affected by human activity, and for many people around the world, these changes are having negative effects. Records show that 11 of the last 12 years were among the 12 warmest on record worldwide. Global warming is caused by release of carbon dioxide and other heat trapping gases into the earth's atmosphere.
Endangered rhinoceros
The Rhinoceros lives in Africa and southern Asia. Four of the five species are critically endangered, and the other, the Indian Rhinoceros, is endangered. The African species are the white and black rhinos. Both species have two horns. Asian rhinos include the Indian and the Javan, each with one horn, and the Sumatran, which has two. Rhino habitat ranges from savannas to dense forests in tropical and subtropical regions. Rhinos are herbivores, meaning they eat only plants. White rhinos, with their square-shaped lips, are ideally suited to graze on grass. Other rhinos prefer to eat the foliage of trees or bushes. Rhinos are near extinction because humans used to kill them for their horns. This is what we can do prevent this. Humans can make reserves and have breeding programs.
Bibliography
Wikipedia
Sunday, 04th of May 2008. Melbourne, Australia