Climate and Climate Change
Climate is what you expect and
weather is what you get
Green Bay 1977-2002
Green Bay 1887-2002
Green Bay 1887-2002
Green Bay 1887-2002
Long-Term Trends
Long-Term Trends
Long-Term Trends
Long-Term Trends
Long-Term Trends
Some Conclusions
• This is not as easy as the media make it
seem
• The fact that it’s not easy doesn’t excuse us
from dealing with it
• The fact that something can’t be proven
conclusively doesn’t protect you if you
make the wrong decision
• Don’t confuse reasoning with reality
Greenhouse Effect
Negative Greenhouse Effect
Positive and Negative
Greenhouse Effects
Positive Greenhouse Effect
• Light enters
• IR trapped: Warming
Negative Greenhouse Effect
• Light Blocked
• IR can leave: Cooling
• Titan
Greenhouse Gases
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Water Vapor
Carbon Dioxide
Methane
Nitrous and Nitric Oxides
Ozone
• Transparent to visible light but
absorb infrared
What Color is Water?
Infrared Absorption
Carbon Dioxide
• Has doubled to 350 ppm since start of
Industrial Revolution
• Coupled to Temperature Rise?
• More Cloud Cover?
• Taken up by biomass?
• Taken up by oceans?
Paleoclimatology
• The present is the key to the past – but
• The past is also the key to the present
• Study of ancient climates
• Have to rely on proxy measurements
• How to convert qualitative data to
numbers?
Ancient Paleoclimatology
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Oxygen 18
Fossils
Evaporites
Glacial Indicators
Air bubbles in amber
Earth’s Climatic History
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Faint Early Sun
Anoxic Atmosphere
Advent of Life – UV Protection?
2.3 by Glaciation
2 b.y. Oxygen Threshold
End of Iron Formations
First Red Sandstones
Snowball Earth
Earth’s Climatic History
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Cambrian Explosion
Ordovician Ice Age
Advent of Forests
Permian Ice Age
Cretaceous Warm Period
Eocene Warm Period
Pleistocene Ice Age
Recent Paleoclimatology
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Historic Records
Tree Rings
Pollen Studies
Oxygen 18
Ice Cores
Holocene Climate
• 11,000 Younger Dryas Cooling
• 9,000-6,000 Mid-Holocene Warm Period
(“Climatic Optimum”)
• 900-1300 AD – Medieval Warm Period
• 1300-1450 Little Ice Age I
• 1450-1550 Recovery
• 1550-1800 Little Ice Age II
Effects of Global Warming
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More Heat Extremes
Drought
Rise in Sea Level
Temporary Severe Cold Spell?
Rapid Migration of Ecological Zones
More Biomass but Lower Nutritional Value
Not a Bad Thing?
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Reduced Energy Demands
Longer Growing Seasons
More Biomass
More Habitable Land
Ozone
Stratosphere – Good
• Absorbs solar ultraviolet
Troposphere – Bad
• Toxic
• Contributes to air pollution
Ozone Depletion
• Cl stripped off synthetic molecules by solar
ultraviolet
• Cl reacts with ozone, acts as catalyst
• Cl – CF3 (Freon)
• Cl – CCl3 (Carbon tetrachloride)
• Cl – H (Hydrochloric Acid)
360
294
431
Smog
Particulate Matter
Long-Term Climatic Trends
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Brightening of the Sun
Capturing of CO2 by carbonate rocks?
Moist greenhouse effect
Runaway CO2 Greenhouse Effect
Venus conditions
The Goldilocks Problem
• Venus is too hot
• Mars is too cold
• Earth is Just Right
Planetary Habitable Zones
• Primarily in the Liquid Water Zone
• Can’t be too warm
• Water Vapor in upper atmosphere broken
down by solar UV and charged particles
(photodissociation)
• Hydrogen escapes to space
The Ultimate Long-Term Forecast
• Slow warming trend for the next billion
years
• Increasing humidity
• CO2 decrease leads to extinction of plants?
• Boiling and evaporation of the oceans
Planetary Habitable Zones
The Oreo Model of Life History
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Micro-organism Earth (0-3 billion years)
Multicellular Earth (3-5 billion years)
Micro-organism Earth (5-6 billion years)
“The white creamy middle”