MET 112 Global Climate Change Lecture 6

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MET 112 Global Climate Change - Lecture 6

• A brief look into the Earths history
• Dr. Eugene Cordero
• San Jose State University

• Outline
• Earths early history
• Evolution of the atmosphere
• Temperature variations
• Activity

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The Earths history can be characterized by
different geologic events or eras.
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Temperature Graph
Source http//www.ruf.rice.edu/leeman/aNR.html
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Timeframe

• We can divide the earths history into two major
  periods
• Note mya stands for millions of years ago

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Timeframe

• We can divide the earths history into two major
  periods
• Precambrian
• Phanerozoic
• Note mya stands for millions of years ago

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The Divisions of Precambrian Time

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The Divisions of Precambrian Time

• Precambrian spans most (7/8) of total history
• Starts with earths formation
• Ends with first presence of animals

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Precambrian

• Hadean time 4.5 to 3.8 billion years ago
• Earth formed during this period.
• Atmosphere likely Hydrogen and Helium
• Archaean 3.8 to 2.5 billion years ago
• First life appeared our oldest fossils date to
  roughly 3.5 billion years ago (microscopic
  bacteria)
• Proterozoic Era 2.5 billion to 543 million ya
• Abundant fossils of living organisms (bacteria)
• Oxygen builds up (breakdown of water?)
• Oxygen (ozone) filter UV radiation
• photosynthesizing plants (absorb CO2)
• Resulting atmosphere

Nitrogen, Water, CO2,
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Precambrian

• Hadean time 4.5 to 3.8 billion years ago
• Earth formed during this period.
• Atmosphere likely Hydrogen and Helium
• Oldest rocks on earth 3.8 billion years old.
• Archaean 3.8 to 2.5 billion years ago
• First life appeared our oldest fossils date to
  roughly 3.5 billion years ago (microscopic
  bacteria)
• Proterozoic Era 2.5 billion to 543 million ya
• Abundant fossils of living organisms (bacteria)
• Earth cools water begins to condense and form
  oceans.
• Oxygen builds up (breakdown of water?)
• Oxygen (ozone) filter UV radiation
• photosynthesizing plants (absorb CO2)
• Resulting atmosphere

Nitrogen, Water, CO2,
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Oxygen formation in the Proterozoic era

• Oxygen appeared to increase fairly rapidly (2.2
  bya)
• Appearance of oxygen killed off a lot of the life
  (bacteria) early pollution (natural)
• However, life evolved to tolerate oxygen
• Cyanobacteria

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Oxygen formation in the Proterozoic era

• Oxygen appeared to increase fairly rapidly (2.2
  bya)
• Appearance of oxygen killed off a lot of the life
  (bacteria) early pollution (natural)
• However, life evolved to tolerate oxygen
• Cyanobacteria
• photosynthetic organisms that produce oxygen
  rise of oxygen

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Evolution of atmospheric oxygen
0xygen in atmosphere
0
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Phanerozoic

• Phanerozoic Eon
• Represents the time during which the majority of
  macroscopic organisms, algal, fungal, plant and
  animal, lived.
• The Phanerozoic consists of three major divisions
• Note the "zoic" part of the word comes from the
  root "zoo", which means animal Paleo mean
  ancient.
• Note (2) these classifications are not strict
  rather generalizations.

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Phanerozoic 543 mya to present

• Phanerozoic Eon
• Represents the time during which the majority of
  macroscopic organisms, algal, fungal, plant and
  animal, lived.
• The Phanerozoic consists of three major divisions
• Cenozoic age of mammals
• Mesozoic age of dinosaurs
• Paleozoic Eras. - age of fishes
• Note the "zoic" part of the word comes from the
  root "zoo", which means animal Paleo mean
  ancient.
• Note (2) these classifications are not strict
  rather generalizations.

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The Paleozoic Era

• The Paleozoic marks two of the most important
  events in the history of animal life.
• Beginning multicelled animals underwent a
  dramatic "explosion" in diversity, and almost all
  living animal species appeared within a few
  millions of years.
• End The largest mass extinction in history
  wiped out approximately 90 of all marine animal
  species.

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The Paleozoic Era 543 to 248 mya

• The Paleozoic marks two of the most important
  events in the history of animal life.
• Beginning multicelled animals underwent a
  dramatic "explosion" in diversity, and almost all
  living animal species appeared within a few
  millions of years.
• End The largest mass extinction in history
  wiped out approximately 90 of all marine animal
  species.
• Atmospheric changes likely played a major role in
  both

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Mesozoic Era

• The Mesozoic is divided into three time periods
• Dinosaurs started in Triassic, dominant during
  Jurassic, and extinct by the end of the
  Cretaceous.

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Mesozoic Era 248 to 65 mya

• The Mesozoic is divided into three time periods
• Triassic (245-208 Million Years Ago),
• Jurassic (208-146 Million Years Ago), and the
• Cretaceous (146-65 Million Years Ago).
• Dinosaurs started in Triassic, dominant during
  Jurassic, and extinct by the end of the
  Cretaceous.

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Cenozoic 65 Million Years ago to present

• Represent the most recent of the three major
  subdivisions of animal history.
• Major development of Flowering Plants, Insects,
  Fish and Birds.

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The Miocene Epoch

• The Miocene was a time of warmer global climates
  than those in the preceding Oligocene, or the
  following Pliocene.
• Global circulation patterns changed as Antarctica
  became isolated and the circum-polar ocean
  circulation became established.

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The Miocene Epoch 23.8 to 5.3 mya

• The Miocene was a time of warmer global climates
  than those in the preceding Oligocene, or the
  following Pliocene.
• Global circulation patterns changed as Antarctica
  became isolated and the circum-polar ocean
  circulation became established.
• This reduced significantly the mixing or warmer
  tropical water and cold polar water.
• Permitted the buildup of the Antarctic polar cap.

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Temperature Graph
Source http//www.ruf.rice.edu/leeman/aNR.html
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The Pliocene Epoch

• The Panamanian land-bridge between North and
  South America appeared allowing migrations of
  plants and animals.
• The accumulation of ice at the poles, leads to
  extinction of most species living there.

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The Pliocene Epoch 5.3 to 1.8 mya

• The Pliocene was a time of global cooling after
  the warmer Miocene.
• The Panamanian land-bridge between North and
  South America appeared allowing migrations of
  plants and animals.
• The accumulation of ice at the poles, leads to
  extinction of most species living there.

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Temperature Graph
Source http//www.ruf.rice.edu/leeman/aNR.html
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The Pleistocene 1.8 million to 11,000 ya

• Pleistocene was characterized by the presence of
  distinctive large land mammals and birds
• Pleistocene had most recent episodes of major ice
  ages (global cooling)
• Much of the world's temperate zones were
  alternately covered by glaciers during cool
  periods and uncovered during the warmer
  interglacial periods when the glaciers retreated.
  
• The Pleistocene also saw the evolution and
  expansion of Homo sapiens
• By the close of the Pleistocene, humans had
  spread through most of the world.

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The Pleistocene 1.8 million to 11,000 ya

• Pleistocene was characterized by the presence of
  distinctive large land mammals and birds
• Pleistocene had most recent episodes of major ice
  ages (global cooling)
• Much of the world's temperate zones were
  alternately covered by glaciers during cool
  periods and uncovered during the warmer
  interglacial periods when the glaciers retreated.
  
• Rapid shifts in climate observed
• The Pleistocene also saw the evolution and
  expansion of Homo sapiens
• By the close of the Pleistocene, humans had
  spread through most of the world.

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Temperature Graph
Source http//www.ruf.rice.edu/leeman/aNR.html
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The Holocene

• The Holocene is time since the end of the last
  major glacial epoch, or "ice age."
• Since then, there have been small-scale climate
  shifts --
• The Holocene generally has been a relatively warm
  period in between ice ages.
• Often termed Anthropogene, or "Age of Man."

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The Holocene The last 11,000 years

• The Holocene is time since the end of the last
  major glacial epoch, or "ice age."
• Since then, there have been small-scale climate
  shifts -- notably the "Little Ice Age" between
  about 1200 and 1700 A.D.
• The Holocene generally has been a relatively warm
  period in between ice ages.
• Often termed Anthropogene, or "Age of Man."
• The climate of the Holocene is being closely
  studied to understand better future climate
  change.

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Activity 3

• Form a group of two with someone youve not
  worked with before.
• Imagine that the history of the earth (4.5
  billions years) could be measured in 24 hours 0
  hours is earths formation (12am), 24 hours is
  present day.
• Around what time did oxygen first experience a
  rapid increase?
• Around what time were dinosaurs around?
• Around what time did homo sapiens first appear?

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Natural Climate Change

• External Forcing
• ___________________________________
• Internal Forcing
• ___________________________________

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Natural Climate Change

• External Forcing
• Internal Forcing

The agent of change is outside of the
Earth-atmosphere system
The agent of change is within the
Earth-atmosphere system itself
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External Forcing

• ___________
• ___________
• ___________

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External Forcing

• Variations in solar output
• Orbital variations
• Meteors

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Solar Variations

• Sunspots correlate with solar activity
• More sunspots, more solar energy

• Sunspots are the most familiar type of solar
  activity.

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SOLAR ACTIVITY

• Sunspots are the most familiar type of solar
  activity.

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THE SOLAR CYCLE

• Sunspot numbers increase and decrease
• Observed for centuries.
• Individual spots last from a few hours to months.
• Studies show the Sun is in fact about

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THE SOLAR CYCLE

• Sunspot numbers increase and decrease
• over an 11-year cycle
• Observed for centuries.
• Individual spots last from a few hours to months.
• Studies show the Sun is in fact about
• 0.1 brighter when solar activity is high.

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SOLAR INFLUENCES ON CLIMATE

• Solar activity appears to slightly change the
  Suns brightness and affect climate on the
  Earth...

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THE MAUNDER MINIMUM

• An absence of sunspots was well observed
• The so-called Maunder minimum coincided with a
  cool climatic period in Europe and North America
  
• The Maunder Minimum was not unique.
• Increased medieval activity

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THE MAUNDER MINIMUM

• An absence of sunspots was well observed
• from 1645 to 1715.
• The so-called Maunder minimum coincided with a
  cool climatic period in Europe and North America
  
• Little Ice Age
• The Maunder Minimum was not unique.
• Increased medieval activity
• correlated with climate change.

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Orbital changes

• Milankovitch theory
• Serbian astrophysicist in 1920s who studied
  effects of solar radiation on the irregularity of
  ice ages
• Variations in the Earths orbit
• Changes in shape of the earths orbit around sun
  
• Eccentricity
• Wobbling of the earths axis of rotation
• Precession
• Changes in the tilt of earths axis
• Obliquity

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Orbital changes

• Milankovitch theory
• Serbian astrophysicist in 1920s who studied
  effects of solar radiation on the irregularity of
  ice ages
• Variations in the Earths orbit
• Changes in shape of the earths orbit around sun
  
• Eccentricity (100,000 years)
• Wobbling of the earths axis of rotation
• Precession (22,000 years)
• Changes in the tilt of earths axis
• Obliquity (41,000 years)

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period 100,000 years
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Eccentricity period 100,000 years
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period 22,000 years
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Precession period 22,000 years
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period 41,000 years
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Axis tilt period 41,000 years
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Internal Forcing

• ____________________________
• ____________________________
• Chemical changes in the atmosphere (i.e. CO2)
• Natural
• Anthropogenic (human produced)
• Ocean changes

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Internal Forcing

• ____________________________
• ____________________________
• Ocean changes
• Chemical changes in the atmosphere (i.e. CO2)
• Natural variations

Plate tectonics/mountain building
Volcanoes
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Temperature Graph
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Question

• Consider the fact that today, the perihelion of
  the Earths orbit around the sun occurs in the
  Northern Hemisphere winter. In 11,000 years, the
  perihelion will occur during Northern Hemisphere
  summer. A) Explain how the climate (i.e.
  temperature of summer compared to temperature of
  winter) of the Northern Hemisphere would change
  in 11,000 years just due to the precession.
• B) How would this affect the presence of
  Northern Hemisphere glaciers?

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Introduction to the Cyanobacteria Architects of
earth's atmosphere

• Cyanobacteria
• Aquatic (live in water)
• Photosynthetic - they manufacture their own food
  through the use of the suns radiation for
  energy.
• Type of bacteria so small and usually
  unicellular,
• Oldest known fossils, (more than 3.5 billion
  years old but still around now!),
• The production of oxygen was generated by
  numerous cyanobacteria during the Archaean and
  Proterozoic Eras.
• Because they are photosynthetic and aquatic,
  cyanobacteria are often called "blue-green
  algae".