2. Definition of Climate Change
• “ It is a change which is attributed directly or
indirectly to human activity that alters the
composition of the global atmosphere and
which is in addition to natural climate
variability observed over comparative time
periods”
3. Major Causes of Climate
Change
Natural Causes
• the arctic tundra and wetlands
release methane, a greenhouse gas
• Earth naturally has a cycle of
climate change that occurs every
40, 000 years
• the sun’s solar energy output is
changing and naturally increases
Earth’s average temperature by
about 1ºC every century
• Earth’s orbit and tilt alter in relation
to the sun, which changes solar
energy output
Human Causes
• Increasing green house gas
emissions from burning fossil fuels-
oil, coal, gas
• Pollution, smog from factories
• Large forests have been cut down
(trees absorb CO2 and pollution,
deforestation creates about 6 billion
tons of CO2 per year)
• Increasing world population-more
people requires more food, energy,
transportation, etc. Farms animals
release methane from their wastes.
• More people also means more CO2
production from respiration and less
trees to make room for human
population
16. Some Effects of Climate Change
• An average increase in Earth’s temperature during the last century
• Melting of polar ice—polar bears and other animals are drowning
• Migrating birds are forced to change their time and place of migration
• Melting of glaciers will lead to higher sea level, which will cause floods and
put many low-elevation regions at risk of disappearing under water
• Longer summers can disrupt animal habitation
• New and widespread diseases because of warm climate
• Damaged crops due to sudden climate change and floods
• Average precipitation increase around the world
• Droughts, heat waves, extreme winters and storms, hurricanes, typhoons
• More wildfires
17. Effects of Climate Change
RISE IN SEA LEVEL
Melting ice sheets Sea level rise
24. Carbon dioxide acidifies
seawater
• CO2 and carbonate (which plankton use
to make shells) combine in the ocean.
• The ocean is already more acidic than it
was 50 years ago.
Source: Alfred-Wegener-Institute
CO2 CO2
Ocean
Atmosphere
“shelled-critters”
