CLIMATE CHANGE AND OZONE LOSS

1. NAS 215 Presentation CLIMATE CHANGE AND OZONE LOSS Template by: www.itdepartment.biz

2. CLIMATE CHANGE AND OZONE LOSS Our climate is changing more rapidly than it has at any other time in the past 1 000 years. Scientists predict that the global average temperature will rise by 1.4 to 5.8°C by the end of the 21st century. Such drastic warming will affect many other aspects of the weather, including wind patterns, precipitation, and severe weather events, creating serious consequences for humanity and the global environment. Ways to estimate past temperature changes • plankton and isotopes in ocean sediments • ice cores from ancient glaciers • temperature measurements at different depths in boreholes drilled deep into the earth’s surface • pollen from lake bottoms and bogs • tree rings • historical records • temperature measurements since 1860 Template by: www.itdepartment.biz

3. Over the past 900 000 years the average temperature of the atmosphere near the earth’s surface has undergone prolonged periods of global cooling and global warming. PAST CLIMATE CHANGE • During each cold period thick glacial ice covered much of the earth’s surface for about 100 000 years. • Each of these periods was followed by a warmer interglacial period lasting 10 000 to 12 500 years during which most of the ice melted. Template by: www.itdepartment.biz

4. If the natural greenhouse effect acted by itself, the average surface temperature of the earth would be about 54 C. However there is a natural cooling process which takes place at the earth’s surface. This occurs when: THE NATURAL GREENHOUSE EFFECT • large quantities of heat are absorbed by the evaporation of liquid surface water • water vapor molecules rise, condense to form droplets in clouds, and release their stored heat in the higher in the atmosphere Template by: www.itdepartment.biz

5. Human activities which release greenhouse gases: HUMAN INFLUENCE ON EARTH’S CLIMATE • the use of fossil fuels Release: CO2 • deforestation, clearing and burning of grasslandsRelease: CO2 and N2O • cultivation of rice in paddies and use of inorganic fertilizers Release: N2O • production of CFCs Template by: www.itdepartment.biz

6. THE NATURAL GREENHOUSE EFFECT Analysis of the ice core samples, temperature measurements at different levels in several hundred boreholes in the earth’s surface and atmospheric temperature measurements show that: • the concentration of CO2 in the troposphere is higher than it has been in the past 420 000 years and is rising by about 0.5% a year • the 20th century was the hottest century in the past 1 000 years • since 1860 the average global temperature of the troposphere near the earth’s surface has risen from 0.6°C to 0.7°C with most of this increase taking place since 1946 • the 15 warmest years on record since 1860 have occurred in the past two decades Template by: www.itdepartment.biz

7. How might changes in solar output affect the earth’s temperatures? FACTORS AFFECTING THE EARTH’S AVERAGE TEPERATURE • an increase in cosmic rays because of a decrease in the sun’s exterior magnetic field may help cool the earth’s surface by forming more thick, umbrella-like low clouds • a decrease in cosmic rays because of an increase in the sun’s exterior magnetic field may help warm the earth’s surface by forming more high, thin clouds How might changes in the earth’s reflectivity affect atmospheric temperature ? How might the oceans affect climate How do water vapor content and clouds affect climate How might air pollution affect climate How rapidly could climate Shift Template by: www.itdepartment.biz

8. The threat of ozone depletion OZONE DEPLETION IN THE STRATOSPHERE • allows humans and other forms of life to exist on land • helps protect humans from sunburn, skin cancer, eye cataracts, and damage to immune system • prevents much of the oxygen in the troposphere from being converted to photochemical ozone Causes of ozone depletion: • chlorofluorocarbon (CFC) - chemically stable, odorless, nonflammable, non-toxic, non-corrosive compounds Sources of CFC’s • use of CFC as propellants in spray cans • leaks from refrigeration and air conditioning equipment • production and burning of plastic foam products Template by: www.itdepartment.biz

9. Other chemicals causing ozone depletion (Ozone Depleting Compounds - ODCSs): OZONE DEPLETION IN THE STRATOSPHERE • Halons and HBFCs used in fire extinguishers • Methyl bromide-widely used fumigant • Carbon tetrachloride-highly toxic solvent • Hydrogen chloride- emitted into the stratosphere by US space shuttles Why should be worried? • More sunburns • More eye cataracts • More skin cancers Template by: www.itdepartment.biz

10. SOLUTIONS: PROTECTING THE OZONE LAYER It will take 50 years for the ozone layer to return to 1980 levels Can technology save us? Consequences • ozone will continue to be depleted for several decades • return to 1980 levels by about 2050 and to 1950 levels by about 2100, assuming the international agreements are followed and there are no major volcanic eruptions Template by: www.itdepartment.biz

11. OZONE DEPLETION IN THE STRATOSPHERE Possibility of International cooperation for ozone depletion problem: • there was convincing and dramatic scientific evidence of a serious problem • CFCs were produced by a small number of international companies • the certainty that CFC sales would decline unleashed the economic and creative resources of private sector to find even more profitable substances Possibility of international cooperation for projected atmospheric warming • we lack clear-cut and dramatic evidence that there is a serious problem • greenhouse gas emissions result from the actions of hundreds of different large and politically powerful industries and billions of consumers • reducing greenhouse gas emissions will take far-reaching changes within most industries and lifestyle changes for billions of consumers Template by: www.itdepartment.biz

12. Thank you for your attention! Template by: www.itdepartment.biz