Transcript Climate Change

Climate Change
Global Climate Change
• Global climate change: An overall rise or fall
in global temperatures
• Happens slowly over time and has several
causes
• When temperatures rise, there is more
evaporation of water
• When there is more evaporation of water,
there is more precipitation
Questions Scientists are trying to answer…
• Natural vs. Human impact
– Is the global warming that is happening now part of
Earth’s natural cycle?
– Are humans causing climate change?
– CAN humans cause climate change?
– What can humans do to stop climate change?
– Can we control it?
– How will we adapt to climate change?
Natural Causes of Climate Change
1. The Greenhouse effect: gases trapping heat
inside Earth’s atmosphere
Greenhouse Gases
• Greenhouse gas: any gas that absorbs radiation
from the sun
– Carbon Dioxide CO₂
– Carbon Monoxide CO
– Methane CH₄
– Nitrous Oxide N₂O
– Water Vapor H₂O
– Sulfur Dioxide SO₂
Natural Causes of Climate Change
2. Ice Age: The long
term reduction of Earth’s
overall temperature
• Happens every 10,000
to 50,000 years
naturally
Ice Age Data
Natural Causes of Climate Change
3. Solar Activity: Increased solar activity causes
higher temperatures
Solar Cycles
Natural Causes of Climate Change
4. Volcanic Activity: Volcanoes release greenhouse
gases in the atmosphere
– Outgassing releases Water vapor, CO₂, and
sulfur dioxide (SO₂)
Volcanic Activity
• Eruptions release 2000 to 5000 tons of CO₂
into the atmosphere
• Non-active volcanoes release ~100 tons of CO₂
per day
Natural Causes of Climate Change
5. The Milankovitch Theory: variations in earth’s
rotation on its axis and orbit around the sun
causes climate changes over time
• The tilt of the earth changes every 40,000
years
• The earth’s orbit around the sun changes
every 25,000 years
Human Causes of Climate Change
1. Industrialization: burning fossil fuels puts
more CO₂ into the atmosphere
• CO₂ levels have increased in the last 200 years
• Driving cars, electricity, factories
Human Causes of Climate Change
2. Deforestation: Cutting down forests leaves
less plants to take up CO₂
Human Causes of Climate Change
3. Ozone Depletion: The ozone layer is being
depleted by CFC gases
– The hole in the ozone layer allows more UV
radiation into earth’s atmosphere
Measuring Climate Change
1. Fossil Records: tropical plants and
animal fossils are found in Antarctica
• Climates had to have been warmer in
the past
Measuring Climate Change
2. Ice Core Data: Air molecules get trapped
when water freezes
• Scientists analyze the air and can tell what the
climate was like
Measuring Climate Change
3. Sea Floor Sediments: Measuring the chemical
composition of ancient sea life tells us what the
temperatures were like
Measuring Climate Change
4. Tree Rings: Tree ring
width indicates past
climate conditions
• Oldest tree 9550 years
old
Possible Impacts of Climate Change
1. Global Warming: global temperatures have
increased by about 1⁰ C in the past 100 years
2. Changes in Precipitation: some areas will get
more, some areas will get less
3. Weather: severe weather may become more
frequent
• Warmer oceans make it easier for storms to form
• Storms will be more intense and bring more rain
4. Sea level rise: ice at the poles melting could lead
to sea level rise and the melting could cause
flooding in coastal areas