Transcript power point
CLIMATE CHANGE 1. Describe what climate change is. 2. Describe the natural greenhouse effect. 3. Give examples of evidence that our climate has changed. CLIMATE CHANGE CLIMATE CHANGE QUIZ Click on the image above and try out the quiz on climate change and the earth’s natural process of regulating carbon dioxide. CLIMATE CHANGE 1. Describe the natural greenhouse effect. OZONE LAYER The earth’s atmosphere is made up of several layers. One of these is the ozone layer. The ozone layer or ozone shield refers to a region of Earth's stratosphere that absorbs most of the Sun's UV radiation. It contains high concentrations of ozone (O3) relative to other parts of the atmosphere, although it is still very small relative to other gases in the stratosphere. GREENHOUSE GASES Natural greenhouse gases are found in the atmosphere and are essential in keeping the earth warm and habitable. The natural greenhouse gases absorb the heat instead of it escaping into space. It is called the natural greenhouse effect because, just like a greenhouse, it allows the Sun’s heat to become trapped. CLIMATE CHANGE 1. Describe the natural greenhouse effect. The ozone layer is the part of the upper atmosphere where ozone is found in the highest concentrations. The ozone there absorbs ultraviolet radiation, preventing most of it from reaching the ground. This is important because ultraviolet radiation can lead to skin cancer. The destruction of the thin ozone layer allows solar radiation to enter our atmosphere. CLIMATE CHANGE 1. Describe the natural greenhouse effect. • The atmosphere is a mixture of oxygen (21%), nitrogen (78%), carbon dioxide (0.037%) and other gases such as hydrogen, helium, argon, neon, krypton, xenon and ozone. It also contains water vapour. • Only some of the gases in the atmosphere are greenhouse gases – they help to keep the earth warm. There are four main layers in the atmosphere. CLIMATE CHANGE 1. Describe the natural greenhouse effect. Global Heat Budget • The earth is heated by the sun. • When the Earth heats up it releases heat energy. • Some of the heat is absorbed by greenhouse gases rather than escaping back into space. • This keeps the earth warm and is called the natural greenhouse effect. CLIMATE CHANGE 1. Describe the discovery of the OZONE HOLE OZONE HOLE In May 1985 scientists with the British Antarctic Survey shocked the world when they announced the discovery of a huge hole in the ozone layer over Antarctica. Their data, collected at the Halley Research Station in Antarctica, suggested that CFCs were to blame. That's because atmospheric conditions during the cold, dark, Antarctic winters were building stockpiles of CFCs over the South Pole. The ozone hole sits on top of the Antarctic continent and its discovery resulted in the 1987 Montreal Protocol agreement to ban CFC’s which were commonly used in fridges, spray cans and insulation foam. Click on the image to watch a short NASA video that discusses the decreasing size of the hole. Click on the image above to view today’s status of the ozone layer over the Antarctic with a focus upon the ozone hole. (Nasa.gov) Video Question: explain why levels of ozone rise and fall.