Atmosphere

1
Chapter 13

• Atmosphere
• And
• Climate Change

2
The Ozone Shield

• The ozone layer is an area of the stratosphere
  where ozone is highly concentrated.
• The ozone layer is important because it shields
  the Earths surface from most of the ultraviolet
  rays of the sun.

3
How are UV rays dangerous?

• Damages the DNA of humans sometimes resulting in
  skin cancer.
• Can kill single cell organisms possibly
  disrupting ocean food chains.
• Amphibians can experience mutations and death of
  eggs.

4
A hole in our protective ozone layer?

• In 1985 the scientific journal Nature reported a
  50 98 reduction of the ozone layer above the
  South Pole.
• From data collected by a NASA satellite
  scientists were able to detect a thinning in the
  ozone layer since 1978.
• The ozone layer over the Arctic has grown as well.

5
How did the hole in the ozone layer get there?

• CFCs or chlorofluorocarbons go high into the
  atmosphere and break down into chlorine atoms in
  the polar stratospheric clouds.
• These chlorine atoms rapidly break apart the
  ozone.
• CFCs were used in aerosol cans and refrigerants
  such as refrigerators and air conditioners.

6
Why cant ground level ozone repair the hole?

• Ozone (O3) is very reactive and never reaches the
  stratosphere in tact.

7
Can we stop ozone depletion?

• The Montreal Protocol is an agreement made in
  1987 by many nations, including the US and Canada
  to sharply limit the use of CFCs.
• The production of CFCs has gone way down proving
  success of the Montreal Protocol.
• Unfortunately CFCs remain active in the
  stratosphere for 60 to 120 years.

8
Global Warming

• Why does Earths atmosphere act like a
  greenhouse?
• Why do scientists think the Earths climate may
  becoming warmer?
• How is carbon dioxide produced?
• What are the possible consequences of global
  warming?
• What is the Kyoto Protocol?

9
Why does Earths atmosphere act like a
greenhouse?

• Sunlight heats the Earth.
• Some of the heat eventually escapes the
  atmosphere and dissipates into space.
• The rest of the heat is absorbed by gases in the
  troposphere heating the Earth like a greenhouse.
• These gases are called greenhouse gases.
• The major greenhouse gases are water vapor,
  carbon dioxide, chlorofluorocarbons, methane, and
  nitrous oxide.
• (absorb most of the heat)

10
(No Transcript)
11
Why do scientists think the Earths climate may
becoming warmer?

• CO2 levels naturally rise and fall
• Decrease in summer as plants absorb more CO2
• Increase in winter as dying grasses and fallen
  leaves decay releasing CO2
• In 1958 Charles David Keeling recorded CO2
  levels far from forests and human activities.
• What did he find?..........

12
Keelings discovery

• Carbon dioxide levels were changing beyond the
  natural fluctuations.
• Each winter the levels of CO2 in the winter
  became higher and each summer the levels of CO2
  did not fall as low.

13
(No Transcript)
14
How is carbon dioxide produced?

• Natural causes
• Respiration of living things
• Decaying plants
• Volcanic activity
• Other causes
• Burning of fossil fuels
• deforestation

15
What are the possible consequences of global
warming?
16
What is the Kyoto Protocol?

• 1997 160 countries met to address the problem of
  global warming
• Developed countries are required to decrease CO2
  and other greenhouse gas emissions by 5 below
  their 1990 levels by 2012.
• The United States did not ratify this treaty.