1 Ozone module prepared by Eugene C. Cordero Lesson 4 "Ozone Depletion: The future?"

2 Ozone module prepared by Eugene C. Cordero Outline  What are current levels of ozone depletion?  Is the ozone hole getting worse?  What has been done about ozone depletion?  What is going to happen in the future?

3 Ozone module prepared by Eugene C. Cordero Global Ozone Trends Most of Australia does not have large negative ozone trends

4 Ozone module prepared by Eugene C. Cordero How has ozone changed over other parts of the Earth?  Globally, ozone has been decreasing over the last 15 years.  Largest ozone change over Antarctica –~ -8% per decade or more  No ozone change over Tropics  Over Australia –Melbourne: decreasing at 2-3%/decade –Darwin: No significant change

5 Ozone module prepared by Eugene C. Cordero Is the ozone hole getting worse?

6 Ozone module prepared by Eugene C. Cordero What is being done about ozone depletion?  Montreal Protocol (1988): international agreement to phase out ozone depleting chemicals  Further amendments accelerated the phase out. –Developed countries have switched to HCFC’s (more ozone friendly) instead of CFC’s. –Developing countries has until 2010 to phase out CFC’s.

7 Ozone module prepared by Eugene C. Cordero Is the Montreal Protocol working?  Observations indicate that chlorine is beginning to decline in the atmosphere. (Good news!)  Still large uncertainties about illegal trade/use of CFC’s (??’s) Future Atmospheric models suggest that:  atmospheric chlorine will return to pre-80’s in next 50 to 100 years. –a slow ozone recovery will follow decreasing chlorine concentrations

8 Ozone module prepared by Eugene C. Cordero What is going to happen in the future?  Model simulations suggest: – atmospheric chlorine will return to pre-80’s in next 50 or more years. –a slow ozone recovery will follow decreasing chlorine concentrations –Still many questions!!!  Phase out and use of CFC’s  Contribution from global warming

9 Ozone module prepared by Eugene C. Cordero Graph of CFC’s levels starting to fall off

10 Ozone module prepared by Eugene C. Cordero Chlorine in the future?

11 Ozone module prepared by Eugene C. Cordero Potential Chlorine growth

12 Ozone module prepared by Eugene C. Cordero Ozone depletion and global warming  No direct connection between these environmental issues.  However: Global warming may enhance ozone depletion –global warming produces  Tropospheric warming & stratospheric cooling –Therefore, if the stratosphere cools, then ozone destroying chemistry (e.g. ozone hole), will increase.

13 Ozone module prepared by Eugene C. Cordero What are the consequences of an ozone depleted world?  With ozone depletion, there will be higher rates of UV radiation.  More UV radiation rates mean –Higher rates of skin cancer –Higher amounts of cataracts –Possible danger to plant and animal life  Recall: Without the ozone layer, life on the Earth’s surface would not exist!!!

14 Ozone module prepared by Eugene C. Cordero Summary  The international community has a plan to phase out CFC’s in the atmosphere. So far, it looks like it’s working!  Current predictions indicate that ozone will recover in next years.