1. International Environmental Policy: Controlling Ozone Depletion

2. Ozone: The Basics  Ozone is a naturally occurring gas in the atmosphere.  An ozone molecule contains three oxygen atoms: O 3.  Ozone is found in two layers: –“Bad” ozone: 10% of ozone is in the lower atmosphere (troposphere), where it is a toxic component in smog. –“Good” ozone: 90% is found in the “ozone layer” in the stratosphere (6 to 10 miles above the earth), where it blocks harmful UV-B radiation.

3. Ozone: The Basics

4. Benefits of “Good” Ozone  If the ozone layer did not absorb ultraviolet (UV)-B radiation from the sun, people would suffer more: –Skin cancer –Cataracts –Suppressed immune systems

5. Ozone Depletion  Stratospheric ozone is depleted by reactions with chemicals produced as gases at ground level.  Important ozone-depleting gases: –Chlorofluorocarbons (CFCs) and other chlorine- containing gases, formerly used in refrigeration, air conditioning, and other uses. –Bromine-containing gases (mostly “halons”), originally developed to extinguish fires.

6. Ozone Depletion  Stratospheric ozone concentrations have dropped by about 3%, on average, since the 1980s.  Ozone concentrations have fallen more near the poles, and not at all near the equator.

7. Ozone Depletion Estimated changes in surface UV radiation from 1979 to 1992:

8. Ozone Depletion  The link between man-made chemical emissions and depletion of the stratospheric ozone layer was discovered starting in the mid-1970s.  The most important step in preventing ozone depletion: Montréal Protocol on Substances that Deplete the Ozone Layer (1987)

9. Montréal Protocol  The Montréal Protocol and later amendments required a phaseout of production and consumption of ozone- depleting chemicals.  The Montréal Protocol has been ratified by over 180 nations.  In the US, the Montréal Protocol was implemented in the provisions of the Clean Air Act of 1990.

10. Montréal Protocol Predicted Effects of the Montréal Protocol

11. Montréal Protocol  To facilitate international cooperation in reducing production of ozone-depleting substances, the Montréal Protocol: –allowed trading of emission reduction credits between countries. –established a Multilateral Fund to assist developing countries in the transition toward CFC substitutes.  India’s annual consumption of refrigerators is expected to climb from 6 million in 1989 to 80 million in 2010, so its participation in the Montréal Protocol is crucial.  India ratified the agreement in 1992.

12. Policy Changes in the U.S.  The Clean Air Act of 1990 ended production of CFCs on December 31, 1995.  Rather than calling for an abrupt ban on production, policies were designed to be more cost-effective.

13. Policy Changes in the U.S.  Cost-effective provisions: –Congress enacted an excise tax on production of ozone-depleting chemicals. The tax was gradually raised over time. –Allowances were issued to producers of ozone- depleting chemicals. Over time the number of allowances was reduced. –The 1990 Clean Air Act called for a national recycling program for CFCs. Existing supplies of CFCs could still be legally used.  Policies like these provided incentives for the development of safer alternatives to ozone- depleting chemicals.

14. Costs and Benefits of the CFC Phaseout  The EPA estimated (in 1987) that the costs of phasing out CFCs would be $27 billion through 2075. –For example, the value of CFCs in air- conditioning products was estimated to be $10.9 billion.  The EPA estimated that the benefits of eliminating CFCs (value of health effects and crop damage averted) would be $6.5 trillion.