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Ozone Depletion
Global Warming Continued:
Simplest Prediction is increase in global mean temperature.
Role of clouds is crucial
Net Cooling or Warming?
There is general consensus that cloud cover will increase as
the capacity for the atmosphere to retain water increases with
increasing temperature.
What does the actual data look like?
All the Data: Global
Warming NCDC Document
Long Term Temperature Trends:
Potential Problems:
- Is the pre-1920 data reliable?
- Increasing number of recording stations since 1950 means
non-uniform data quality
- Southern Hemisphere is more ocean to land area than Northern
Hemisphere
- But, there does appear to be an 0.5 degree Celsius increase per
century in the data
Distribution of Temperature trends on the Earth. Where is it getting
warmest the fastest:
All the historical data
1953-1973
1973-1993
When positional data is combined with temperature data and time-sliced
in this way - it seems clear the Global Warming is occurring.
This conclusion was reached by a National Academy of Science panel
in Sept. 1995 and is accepted by most.
Temperature Variations with
Altitude
What about the US:
Annual US Trends
Max Temperature US Trends
Min Temperature US Trends
Annual Precipitation Trends
Number of Tornadoes
Some Conclusions
Some Internet Resources:
Nice Overview
Comprehensive overview
Another overview
A Dissenting View
(not really - this talks about how we are warming the oceans - same problem!)
Journalistic
view of the problem
Now on to Ozone Depletion Problem:
Ozone Depletion
Oct 30, 1996 Hole size
Oct 23, 1998 Hole Size
Recent years Data
1998 was largest hole
measured due to colder than average temperatures which accelerate the
depletion process.
But CFC concentrations are now finally measured to be going down.
Long Term Evolution:
Latest Results (9/1/96 - 10/14/96)
Latest Results (9/1/97 - 10/14/97)
Overview:
1995 Hole data:
Why do we see the hole in the Antarctic Spring?
Chlorine from CFCs is stored on stratospheric cloud surfaces during the long
polar night and then released to attack ozone when the sun returns in spring. The process involves a series
of unusual chemical reactions taking place at temperatures as low as -85 degrees C (188K). Normal
ozone levels are restored in the summer when the Antarctic atmosphere, isolated during the winter inside
a cold
"polar vortex", becomes mixed with ozone-rich air from other latitudes.
Expectations for this Spring (i.e. right now)
The Antarctic spring of this year is arriving, and with it the annual depletion of ozone within the south
polar vortex. In recent years, the destruction of ozone within the lower stratospheric region from 14 to 20
km has been virtually total.
Where are we Now?
Internet Resources Relevant to the Ozone Problem:
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