Atmosphere and Climate Change ch.13

1. Atmosphere and Climate Changech.13 Why You Should Care: • Popular Issue – interesting • Affects federal policy, global policy • Academic Study • It is a reality • Can we do something about it?

2. Earth and Human Systems

3. Global Temperatures are Increasing http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif

4. Carbon Dioxide Has Increased http://www.esrl.noaa.gov/gmd/ccgg/trends/

5. Global Temperature Change Over Time http://www.scotese.com/climate.htm

6. What is the difference between weather and climate? • Weather – is the state of the atmosphere at a particular place at a particular time • Climate – is the long-term prevailing weather conditions at a particular place based on records taken

7. What Factors Determine the Climate? • Latitude • Atmospheric circulation patterns • Oceanic patterns • Local geography • Solar activity • Volcanic activity

8. 1. Latitude- the distance from the equator in degrees north or south.The amount of solar energy an area of Earth receives depends on its latitude http://www2.gi.alaska.edu/alison/SNW_09B_SolarEnergy.html

9. 2. Atmospheric Circulation • Cold Air sinks because it is denser. As it sinks it compresses and warms. • Warm air rises. It expands and cools as it rises. Warm air can hold more water vapor than cold air can. • Solar energy heats the ground warm air rises cooler air moves in to replace it • This circulation pattern determines Earth’s precipitation pattern

10. Atmospheric circulation driven by uneven heating of the Earth by the SunAtmospheric circulation driven by uneven heating of the Earth by the Sun http://earthguide.ucsd.edu/eoc/middle_school_t/teachers/earth/sp_atmosphere/p_atmo_circulation_explanation.html

11. Atmospheric Circulation, cont’d Prevailing winds – blow predominantly in one direction, not directly northward or southward (because of Earth’s rotation) • Trade winds – blow b/w 30* North and 30* South • Westerlies – produced b/w 30*-60* North and South latitudes • Polar Easterlies – blow b/w 60* to poles both North and South

12. 3. Oceanic Circulation • The ocean currents redistribute heat on the planet. • The Gulf Stream carries warm tropical waters to the polar regions • California current carries cooler polar waters towards the tropics

13. Ocean Circulation

14. Surface Currents that change • El Nino – Southern Oscillation. 6-18 months. • Winds in the western Pacific, which are usually weak, strengthen and push warm water eastward. Effects: • Increased rainfall west coast of S. America and S. eastern U.S. • Drought in Indonesia and Australia • http://www.esrl.noaa.gov/psd/map/clim/sst_olr/el_nino_anim.shtml • La Nina – water in the eastern Pacific is cooler than usual. • Pacific Decadal Oscillation – 20-30 yr. change in location of warm and cold water masses in the Pacific Ocean

15. 4. Topography • Temperatures fall by 11* F for every 1,000 m. increase in altitude • Rain shadow - Rain on West side of Mountain – dry on East. • Water cools and warms faster than land • http://www.newton.dep.anl.gov/askasci/env99/env99395.htm

16. Rain Shadow

17. Other Influences on Earth’s Climate • Solar maximum – the sun emits an increased amount of UV radiation which warms the ozone more hence warming the stratosphere. • Volcanic Eruptions – Sulfur dioxide gas reacts with the smaller amounts of water vapor and dust in the stratosphere forming a bright layer of haze than reflects enough sunlight to cause global temps. to decrease • Aerosols– cool the atmosphere

19. Seasonal Changes in Climate • Seasons are a result of the 23.5* tilt in Earth’s axis. • Because of the tilt, the sun’s rays hit the Earth at different angles thus heating it unevenly. • During summer in the N. Hemisphere, the N. Hemisphere tilts toward the sun and receives direct sunlight

20. Seasonal Changes in Climate

21. POP QUIZ SEC. 1answer on ¼ sheet of paper and turn in • List one reason you should care about climate change. • What is the difference between weather and climate? #3-5 List 3 factors that determine the climate

22. Sec. 2 The Ozone Shield • Ozone – O3 • The ozone layer is in the stratosphere and absorbs harmful UV rays from the sun. • CFC’s – chloroflourocarbons – coolant in refridgerators and air conditioners, and propellent in spray cans. • CFC’s break apart in the stratosphere and destroy ozone • A single chlorine atom from CFC can destroy 100,000 ozone molecules

23. Ozone Hole – a thinning of the ozone layer that occurs over the poles during the spring. http://www.atmos.pku.edu.cn/yhu/ozone.html

24. Ozone Formation • http://www.theozonehole.com/twenty.htm Effects of ozone thinning on humans: • UV damages DNA • can cause skin cancer Effects of ozone thinning on plants and animals: • kills phytoplankton – provides most of the oxygen on earth • Harms amphibian eggs – amphibians are indicators of healthy/unhealthy ecosystem • Interferes with photosynthesis of plants

25. Protecting the Ozone Layer • 1987 Montreal Protocol – nations agreed to put limit on CFC emissions • 1992 – developed countries agreed to eliminate all CFC’s by 1995 • CFC’s remain active in stratosphere for 60-120 years

26. Sec.3 Global Warming • anincreaseintheearth's average atmospheric temperature that causescorrespondingchanges in climate and that may result from the greenhouse effect. • Exacerbated by the greenhouse effect- the radiation of heat given by trapped gases in the atmosphere. • Major greenhouse gases: water vapor, carbon dioxide, chlorofluorocarbons, methane, and nitrous oxide.

28. Measuring Carbon Dioxide in the atmosphere • Measured at Mauna Loa, Hawaii • Most CO2 released is 1) dissolved in the ocean 2) absorbed by plants • CO2 increases acidity in oceans – it combines with water to make carbonic acid • Long term measurements taken from ice cores- shows that levels today are higher than the past 420,000 years.

29. Effects of a Warmer Earth • Rising sea levels • Cycles of plants and animals changing • Tropical diseases, insects and other organisms moving northward • Change in ocean currents causing change in weather patterns • Heat-related deaths • Drought • Food shortages

30. Prevention/Solutions • Scientists use computer models to predict changes in the climate • IPCC – Intergovernmental Panel on Climate Change – a network of 2,500 of the world’s leading climatologists from 70 countries that provide information on climate change, and make predictions on climate change • Kyoto Protocol – requires developed countries to decrease emissions of carbon dioxide and other greenhouse gases by an average of 5% below what it was in 1990’s by 2012.