DEMONSTRATION
CLIMATE CHANGE
9.1 The Natural Greenhouse Effect
Heat and our Atmosphere
9.1 THE NATURAL
GREENHOUSE EFFECT
Recall: infrared radiation is released from Earth’s surface back into
space.
Greenhouse Gases
‣
trap this radiation and radiate it back to Earth’s surface,
making it warmer.
‣
ex. CO2, methane
This is called the greenhouse effect.
‣
without it Earth would be 33°C colder, and life would be
unable to survive.
GREENHOUSE GASES
Greenhouse gases that occur naturally are:
‣
carbon dioxide; water vapour; methane; nitrous oxide; ozone
Greenhouse gases created by humans in last 100 years are:
‣
chlorofluorocarbons (CFC’s); hydrofluorocarbons (HFC’s)
CARBON CYCLE
CO2 gas is released into atmosphere
‣
naturally by cellular respiration
‣
human activities, such as burning fossil fuels, also emit CO2
CO2 is taken out of the atmosphere
‣
by photosynthesis (plants)
WATER VAPOUR
A carbon sink absorbs CO2 from the atmosphere and
stores it in another form.
‣
oceans
‣
forests
About two-thirds of Earth’s
natural greenhouse effect is
caused by water vapour in the
atmosphere
If Earth’s temperature rises,
more water will evaporate to
become water vapour, which
will add to the greenhouse
effect