Download Unit 3 Notes Part 4: Climate Change

Unit 3 Notes
Part 5: Climate Change
What are natural causes that could result in
global climate change?
• Plate tectonics – when the
continents move they may
receive different amounts
of sunlight
• Earth’s orbit and tilt –
more elliptical orbits cause
large variations in seasons
• Volcanic activity – ash from
eruptions can reflect solar
energy and decrease global
temperatures
Mount Pinatubo June 1991
How are past climate changes
studied?
• Paleoclimatologists find clues in
natural records.
• These records offer natural clues
to past climate that are:
– buried in sediments at the bottom of
the oceans
– locked in coral reefs
– frozen in glaciers and ice caps
– preserved in the rings of trees
– fossils
How are past climate
changes studied?
Sea-Floor Sediments measure:
-concentrations of oxygen isotopes in shells
-Charcoal trapped in sediments can indicate past
fire events.
-Remains of microorganisms such as diatoms,
foraminifera, microbiota, and pollen within
sediment can indicate changes in past climate,
since each species has a limited range of
habitable conditions.
-When these organisms and pollen sink to the
bottom of a lake or ocean, they can become
buried within the sediment. Thus, climate
change can be inferred by species composition
within the sediment.
How are past climate
changes studied?
Ice cores can be
analyzed for
trapped gas (CO2),
stable isotope
ratios, and pollen
trapped within the
layers to infer
past climate.
How are past climate
changes studied?
Fossils measure
changes in pollen
type, leaf shapes,
and animal
adaptations
How are past climate
changes studied?
•
Tree Rings can be counted
to determine age.
•
The thickness of each ring
can be used to infer
fluctuations in temperature
and precipitation, since
optimal conditions for the
particular species will
result in more growth, and
thus thicker rings for a
given year.
•
Scars and burn marks can
indicate past natural events
such as fire.
What is the relationship
between the emissions of
carbon dioxide, and the
average global
temperature over the
past 150 years?
• As carbon dioxide
levels have risen so
have global
temperatures
Trends in surface
temperatures
& CO2 over the past
1,400 years
Given data on the annual trends of CO2
concentration increase, what could the
global temperature be by 2100?
• Global temperatures
are predicted to
rise 2-4 C
What are the consequences of warmer
oceans and changing climatic zones?
• If oceans become warmer it will lead to an increase in
evaporation.
• This could cause more cloud formation and precipitation
in areas that normally have drier conditions.
• Sea levels would rise around the world causing flooding.
• Ocean currents could be changed causing climates
around the world to be altered
• Ice reflects sunlight, so with less of it Earth would
heat up