Greenhouse effect


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Greenhouse effect

  1. 1. The Greenhouse Effect Environmental Science
  2. 2. Why greenhouse? <ul><li>The term greenhouse effect comes from the idea that the atmosphere traps heat in the troposphere like the glass walls of a greenhouse do </li></ul><ul><li>Without these gases the earth would be frozen like Mars </li></ul>
  3. 3. What are greenhouse gasses? <ul><li>Small amounts of specific gasses act as insulators in the atmosphere </li></ul><ul><li>These are known as greenhouse gasses and include the following: </li></ul><ul><ul><li>Carbon dioxide (CO 2 ) </li></ul></ul><ul><ul><li>Water vapor (H 2 O) </li></ul></ul><ul><ul><li>Methane (CH 4 ) </li></ul></ul><ul><ul><li>Nitrous Oxide (N 2 O) </li></ul></ul>
  4. 4. What do greenhouse gasses do? <ul><li>Sunlight heats up the earth’s surface </li></ul><ul><li>The earth’s surface reflects the heat </li></ul><ul><li>The greenhouse gasses absorb the heat and warm the troposphere </li></ul><ul><li>These greenhouse gasses occur naturally in the atmosphere. </li></ul><ul><li>Without the greenhouse gasses, earth would be cold and lifeless. </li></ul>
  5. 5. Natural Greenhouse Gasses <ul><li>Volcanoes are one source of natural greenhouse gasses </li></ul><ul><li>Swedish chemist Svante Arrhenius first recognized the natural warming effect of gasses in the troposphere. </li></ul>USGS
  6. 6. Carbon Dioxide <ul><li>Next to water, carbon dioxide is the most abundant greenhouse gas in the atmosphere </li></ul><ul><li>Carbon dioxide is controlled by the carbon cycle </li></ul><ul><li>A molecule of carbon dioxide will spend 100-120 years in the atmosphere </li></ul>
  7. 7. Historical Record <ul><li>Bubbles in the ancient ice will contain samples of the ancient atmosphere. </li></ul><ul><li>By analyzing these ancient air samples scientists can discover the greenhouse gas levels in the atmosphere thousands of years ago </li></ul><ul><li>Records exist to describe the atmosphere for the past 160,000 years </li></ul>
  8. 8. More Recently <ul><li>Since 1958 records of atmospheric CO 2 levels have been collected </li></ul><ul><li>Carbon dioxide levels will fluctuate during the year according to the seasons – lower in the summer and higher in the winter </li></ul><ul><li>Even with these fluctuations during the year the average CO 2 levels are rising </li></ul>
  9. 10. Human Impacts <ul><li>Sometimes plants will be buried under silt and compressed over millions of years </li></ul><ul><li>This organic matter is turned into coal, oil, and natural gas </li></ul><ul><li>We burn this for energy and release carbon dioxide into the atmosphere </li></ul><ul><li>As a result most scientists now believe that the extra greenhouse gasses are warming the atmosphere </li></ul>
  10. 11. Human Impacts cont. <ul><li>In addition to carbon dioxide, we are also releasing many other additional greenhouse gasses </li></ul><ul><li>Scientists now believe that the extra greenhouse gasses are warming the atmosphere too </li></ul>
  11. 12. Global Warming <ul><li>Global Warming - an increase in the average global temperature that occurred in the 20 th century </li></ul><ul><li>As the earth warms, there will be several consequences </li></ul><ul><ul><li>Changing weather patterns </li></ul></ul><ul><ul><li>Disruptions of agriculture </li></ul></ul><ul><ul><li>Rising sea levels </li></ul></ul>
  12. 13. Changing Weather Patterns <ul><li>As the earth warms up, so do the oceans. </li></ul><ul><li>Warmer oceans may make hurricanes and typhoons more common </li></ul><ul><li>They may also lead to changes in the pattern of ocean currents </li></ul><ul><li>Droughts could become more frequent and impact agriculture </li></ul>
  13. 14. Melting Ice <ul><li>As the Earth warms, the ice caps and glaciers will start to melt </li></ul><ul><li>This could lead to rising sea levels that have several consequences: </li></ul><ul><ul><li>Coastal wetlands and low-lying areas are flooded </li></ul></ul><ul><ul><li>People who live near the coast loose their homes and livelihood </li></ul></ul><ul><ul><li>Salt water enters coastal aquifers </li></ul></ul>