THE  ATMOSPHERE & CARBON CYCLE

Earth’s atmosphere The earth is covered in a blanket of gases called the atmosphere. Without the atmosphere no living thing can survive. The atmosphere gives us warmth by the natural greenhouse effect. It gives us air to breath. It protects us from the Sun’s harmful rays and much much more.     Atmospheric layers & gases Scientists have divided the Earth’s atmosphere into 6 layers. The first layer is the troposphere. The troposphere is 0-17 km high. On top of the troposphere is the stratosphere. The stratosphere is 17-50 km high. After the stratosphere is the mesosphere. The mesosphere is 50-85 km high. Then comes the thermosphere which is 85-300 km. then comes the ionosphere. After that is the exosphere which is more than 500 km high. There are about 5 important gases. Nitrogen (78.1%), oxygen (20.9%), argon (0.9%), carbon dioxide (0.039%) and water vapor (3%). Carbon dioxide Carbon dioxide is necessary for plants to live and it also act as greenhouse gas thereby keeping the Earth warm enough to sustain life. But if the carbon dioxide level goes up more than what it already is it will start to warm up the Earth. more than its normal temperature. If the level of carbon dioxide  keeps on raising it will raise the temperature of Earth which could lead to melting of polar ice cap which then can increase the water level. This can lead to many coastal cities and even many island countries go underwater. Plants use carbon dioxide to produce sugar. This process is called photosynthesis. While producing their food through photosynthesis they generate oxygen which all animals on Earth use for respiration. The Carbon Cycle In the atmosphere, carbon is attached to some oxygen in a gas called carbon dioxide. Plants use carbon dioxide and sunlight to make their own food and grow. The carbon becomes part of the plant. Plants when die and are buried may turn into fossil fuels made of carbon like coal and oil over millions of years. When humans burn fossil fuels, most of the carbon quickly enters the atmosphere as carbon dioxide.  Carbon Cycle Greenhouse effect What blocks the Sun’s energy from escaping from the Earth? Unlike a greenhouse, the Earth does not have a layer of glass over it! Instead, molecules in our atmosphere called greenhouse gasses absorb the heat. Greenhouse gasses include water vapor, methane, ozone, nitrous oxide, and carbon dioxide. There may not be much of some of these gasses in our atmosphere, but they can have a big impact. Each greenhouse gas molecule is made of three or more atoms that are bonded loosely together. These molecules are able to absorb heat, which makes them vibrate. They eventually release the heat energy and it is often absorbed by another greenhouse gas molecule.   The greenhouse effect is useful because trapping some energy keeps the temperatures on our planet mild and suitable for living things. Without its atmosphere and the greenhouse effect, the average temperature at the surface of the Earth would be zero degrees Fahrenheit. However, too many greenhouse gases can cause the temperature to increase out of control. Such is the case on Venus where greenhouse gases are abundant and the average temperature at the surface is more than 855 degrees Fahrenheit (457 degrees Celsius).   End Result Of Human Action On Earth The Earth as we know it is slowly warming up which may result in global warming and climate change leading to extinction of many animal and plant species including humans. And this all is happening due to to increase in carbon dioxide and other green housegasses in the atmosphere. Also due to human actions the ozone layer is breaking and the Sun’s harmful Ultraviolet rays are entering the Earth. If this increase in CO2 and other gases doesn’t stop all living things including humans may become extinct in near future. We must do something to stop global warming as soon as possible.