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Climate Change
WHAT IS IT AND WHAT ARE SCIENTISTS
DOING TO GATHER INFORMATION ABOUT
IT?
 What is it?
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Weather
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How the atmosphere is CURRENTLY behaving.
How it affects humans TODAY.
Can change from minute to minute, day to day, and
season to season.
 Components
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Temperature
Humidity
Precipitation
Brightness
Visibility
Wind
Atmospheric pressure
 Different kinds of weather
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Sunny or Rainy
Clouds and wind
Hail, snow, or sleet
Floods, blizzards, thunderstorms
Cold front or heat front
Heat wave
Climate
 What is it?
 LONG TERM pattern of weather.
 Average weather for an area.
 Can be local or global.
 Why is it important to study?
 Keeping a record of the weather.
 Deviations from the average could be an
indication of climate change in an area.
What contributes to the climate of an area?
Proximity to oceans and lakes:
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Bodies of water absorb heat when it is
hot and release heat when it is cold,
contributing to the climate of an area.
Heat exchanges between the ocean
and atmosphere cause wind.
Winds drive ocean currents.
Oceans absorb CO2, slowing global
warming.
Evaporation: Hot water from the
tropics evaporates and is carried by
trade winds to the north and south.
Storms often develop over warm
oceans before hitting land.
The ocean, land, and air are all
connected. Changes can have dramatic
effects in interconnected systems (e.g.,
El Nino).
External Forces of Climate Change
 Long term climate cycles (measured in thousands of years) are
driven by astronomical forces.
 Milankovitch cycles: The Earth’s orbit, axial tilt, and other
movements go through long cycles of change which affect climate on
Earth.
 Stretching of orbit
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Elliptical obits cause interglacial periods
Circular orbits cause glacial periods
Occurs every 92,000 years
 Tilt of axis
 Affects polar sunlight
 Changes by about 2 degrees every 41,000 years
 Has great affects on climate
 Wobble of axis
 Like a top spinning the axis of the Earth wobbles
 Causes changes in the intensities of seasons
 Occurs every 21,000 years
CLIMATE IS WHAT YOU EXPECT
WEATHER IS WHAT YOU GET
The Greenhouse Effect
• Why do gardeners use
greenhouses?
• Solar radiation is trapped
inside the glass or plastic
material.
• Gases such as water, carbon
dioxide, methane, and nitrous
oxide absorb and emit the
radiation.
The Greenhouse Effect
Paleoclimatology
 How do scientists know what the climate
was like thousands of year ago?
Sediments
Ice
Cores
Tree Rings
Sediment Cores
 Similar to ice cores
 Taken from oceans or lakes
 Sedimentation rate
 Charcoal
 Pollen
 Diatoms, foraminifera
Foraminifera
-Also know as forams
-Most are benthic: live on the bottom of the sea or lake
-Some live in water column
-Range in size from 1 mm to 200 mm
-Important part of
food chain
-Produce hard shells
made of calcium
carbonate
Foraminifera and Diatoms
 There are thousands of different species.
 Each lives in a particular environment.
 The chemical makeup of their shells depends on the chemical
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makeup of their environment.
The chemical makeup of their
environment depends on the
temperature of the water.
Oxygen has 3 isotopes.
In warmer water, atoms with lighter
isotopes evaporate faster than atoms
with heavy isotopes.
Isotope: Natural variation in the number
of neutrons in the nucleus of an atom.
 Many trees form annual growth rings.
 The width, density, and isotopic composition of tree
rings is influenced by the environment.
 Some trees are thousands of years old.
 To extend chronologies from living trees, scientists
use fossilized wood or wood from old buildings.
 Overlapping patterns found in tree rings allows us to
date tree rings back as far as 11,000 years ago.
Extending chronologies from living trees
http://www.ncdc.noaa.gov/paleo/slides/slideset/18/18_355_slide.html
Ice Cores
 Collected from ice sheets in Greenland and Antarctica.
 Can date as far back as 750,000 years ago.
Information That Can Be Obtained From Ice Cores
 Annual snowfall
 Substances found in snow
 Dust, ash, gas, radioactive substances
 Proxy for
 Temperature
 Precipitation
 Composition of atmosphere
 Volcanic eruptions
How Can Scientists Use Ice Cores To Determine
Past Climate Conditions?
 They use isotopic ratios of water in cores to
determine temperature and precipitation.
 Dust particles can determine atmospheric
circulations, volcanic eruptions, and wind speed.
 Volcanic eruptions help scientists age ice cores
accurately.
 Atmospheric composition is determined by air
bubbles compressed in the ice.
Paleoclimatic data
Vostok Ice Core
How has Florida’s Climate Changed?
 Today, Florida has a subtropical climate
 Approximately 130,000 years ago giant
ground sloths roamed the coasts of Florida
 They are a tropical species, meaning the
climate was warmer and wetter at this time.
 Mastodon fossils found off of the
coast of Florida indicate a colder
climate and lower sea levels.
 Fossils found in Florida date back to
about 13,000 years ago, during the
last ice age.
Climate Change vs. Global Warming
Climate Change
 The climate on Earth and
other planets is constantly
changing over large time
scales.
 Abrupt climate change is
rare but possible.
 Going from a warm period
to an ice age is considered
climate change.
 Climate change occurs with
or without the presence of
humans, or life in general.
Global Warming
 Caused by increases of
greenhouse gas
concentrations in the
atmosphere.
 Occurs naturally due to
astrological phenomena.
 Can occur by disrupting the
natural carbon dioxide
cycle.
 The intensity of effects is
different in different parts
of the world.
Global Warming
Global Warming
Local Changes
 Changes where you live many not reflect global
changes.
 For example, the average yearly temperature of an
area can stay the same, while the seasons may
become more intense.
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Warmer summers and colder winters
Armstrong & Miller-Climate Change
Video