The Anthropocene

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The Anthropocene

• Quaternary Seminar
• Fall, 2005
• Bud J. Benneman

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Anthropocene

• Anthropocene The term refers to the most recent
  period of the Earths history starting in the 18
  th century when activities of the human race
  first began to have a significant global impact
  on ecosystems and climate.
• The term Anthropocene was coined by Paul Crutzen.

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Anthropogenic Global Warming

• Describes an increase in the average temperatures
  of the Earths atmospheric and oceans.
• The terms global warming or anthropogenic global
  warming are used to describe the theory that
  increasing temperatures are the result of
  strengthening greenhouse effect caused primarily
  by human actions.

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Major Topics

• Ruddimans Hypothesis.
• Importance of Green House Gases.
• Explanations of pre-industrial Green
• House Gases (GHGs).
• Industrial Revolutions I and II.
• Major Greenhouse Gases.
• Population.

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Major Topics

• Industrial Revolution III.
• Stream Flow Modification.
• The Nitrogen Cascade.
• Solar Radiation and Global Dimming.
• Melting of the Permafrost.
• The Colorado River
• Sea Surface Temperatures.
• Climate Modeling
• Paper Discussion (Joos et al., 2004)

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Ruddimans Hypothesis

• Humans discovered agriculture 12,000 years ago.
• Prior to religion, writing, and great cities
  humans started alerting climate.
• Ruddiman puts forth the hypothesis that through
  the discovery of plant and animal domestication
  the Anthropocene began 8,000 years ago.

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Ruddimans Anthropocene

• CO2 and CH4 are the two most talked about Green
  House Gases.
• CH4 Cycles may be linked to monsoon intensity
  (greater wetland extent) and increases in CH4
  concentrations in the Vostock Ice cores. They
  measured monsoon maxima at 10, 80, 105, and 130
  kyr BP, which corresponds to interglacial
  periods.

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Important Concepts

• Temperature does not control CH4. what is
  important is that temperature controlled the
  aerial extent of wetlands, which releases
  methane.
• Earths orbital variations such as 23,000 orbital
  precession. The tilt varies and changes, thus in
  10,500 years the Earth will have a summer tilt
  when it is closer to the sun resulting in a net
  increase in solar radiation (northern
  Hemisphere).

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Percessional- Wobble Like a TopNorthern
Hemisphere v Southern Hemisphere Facing the Sun
Change in the direction of the Axis of rotation
relative to the Sun
Southern
Northern
25,800 Year Cycle
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Percessional- Wobble
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Obliquity Tilt Variation 2.4 Degree
Milder Winters Cooler Summers
Colder Winters Warmer Summers
40,000 Year Cycle
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Eccentricity
Current 365.4 day orbit around the Sun
Day of the CCSN Field Trip The Earth Was Here
Fall
Summer
Sun
Winter
100,000 Orbital variation eccentricity around the
Sun
Spring
This drawing is not to scale, its not even close
so dont worry man
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• These Earth orbital variations result in normal
  climate change.
• Humans through the introduction of agriculture
  changes and Greenhouse Gases such as CO2 and
  CH4 have resulted in a continuation of a warming
  period.
• According to Ruddiman, we have delayed a
  glaciation.

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• Methane follows the insolation until the
  Holocene.
• CO2 also varies with the orbital cycles
• CO2 reaches a maximum at the height of the
  interglacial
• From Ice core evidence it is apparent that the
  last 10,000 have been different than the last
  100,000

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• There is a seemingly anomalous trend in which CO2
  levels start to increase 8,000 years ago when
  they should be decreasing.

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Hare
Tortoise
8000
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• 9,000-7,800

7,800-6800
9,000-7,800
6,800-5700
gt10,000
Mediterranean Sea
9,000-7,800
10,000-9000
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Solar Radiation
Natural CH4 Trend
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Carbon Based Fuels

• Industrial revolution I and II has caused an
  increase in CO2
• Industrial Revolution III India and China will
  contribute additional CO2

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Carbon Dioxide Variations
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Major Greenhouse Gases
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Industrial Revolution III

• China and India are in the process of
  industrializing.
• The catalyst for this industrialization is
  western investment, inexpensive labor, reduced
  regulations, innovations in communication, and
  transportation.

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World Population 2004
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Stream Flow Modification

• 75 of the worlds rivers have seen some kind of
  stream flow modification.
• Some rivers that had continuous flow now run dry
  every year.
• Other river systems, can no longer provide the
  necessary energy to disperse sediment up and down
  the coast.

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Colorado Delta
Santa Clara Wetland
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Mississippi Delta Spring Runoff
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Stream Flow Modifications

• Some river systems can no longer sweep the
  fine-grained organic matter and mud out of their
  estuaries systems.
• Reservoir storage and impacts of river systems
  varies according to climate.
• This variation results in difficult modeling
  concepts (Syvitski, 2002)

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Stream Flow Modification

• Other rivers that were one dominated by suspended
  load have become bedload-rivers through the
  trapping efficiency of upstream reservoirs.
• Amazon River has an increase in sediment load due
  to deforestation and runoff.
• Amazon soil erosion is a unique and a large
  problem.

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Nitrogen Cascade

• More nitrogen is fixed synthetically and applied
  as fertilizers than in all ecosystems combined
  120Tg/Yr vs 90Tg (McNiell, 2004).
• Of the 120 Tg/year (280,000kg), 100 Tg is wasted,
  discharged into rivers, lakes and subsurface
  reservoirs.
• The result is eutrophication of surface waters.

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• Fossil fuel consumption adds another 25 Tg/
  yr,(25,000 kg) which as NOX is highly reactive ,
  causing photochemical ozone formation.
• The disturbance of the Nitrogen cycle also leads
  to the microbiological production of the
  greenhouse gas NO.
• Oceans, worldwide are releasing increased amounts
  of NO (Galloway, 2002).

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Galloway, 2002
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Solar Radiation

• Widespread decline in solar radiation from
  1960-1990.
• This global decline in solar radiation referred
  to as Global Dimming may have masked some of
  the greenhouse effect and related impacts.
• Since the late 1980s the Northern Hemisphere has
  seen a widespread brightening.

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Global Brightening

• The Brightening seems to conenside with the
  greenhouse signals in the late 1990s
• Whereas, the decline in in solar energy could
  have counterbalanced the increase in down-welling
  of long-wave energy from the enhanced greenhouse
  effect.
• Now beginning to see the true effects of
  greenhouse gases (Wild et al.,2005).

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• Time series of mean annual solar radiation
• AAll Sky conditions BClear Sky

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Melting of the Permafrost

• Rising temperatures in permafrost regions may
  release tons of carbon stored in permafrost
  soils.
• This will influence global climate change.
• Permafrost soils have an average carbon content
  of 2.5 which, equates to 500 gigatons of carbon,
  2.5 times that of all the rainforest combined.

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Permafrost Siberia
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Permafrost Regions

• This carbon is a relatively liable product of
  plant roots that were incorporated from a
  productive steppe vegetation during the
  Pleistocene.
• Upon thaw, microbes will begin converting the
  carbon into CO2 under aerobic conditions, and
  into methane under anaerobic conditions (Nisbet,
  2002).

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Global Warming and Water Resources of Southern
Nevada

• Increased temperature without the influences of
  melting ice equates to dryer conditions.
• Warmer Dryer v. Cooler Wetter

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1927 Compact
1944 Amendment
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1927 1944 Allocations
Odd Years 1961-1970 Glen Canyon Reservoir Filling
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1,138.47 ft Elevation as of 10-22-05
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Southern Nevada allocation 300,000 MAF/year, Use
475,000 due to return credits
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Increasing Sea Surface Temperatures

• Important in the Caribbean and Gulf of Mexico.
• Increased incidence, and intensity of tropical
  storm.

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Sea Surface Temperature
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Melting of Ice

• Since industrialization glaciers have retreated.
• Sea level increase have impacted low lying costal
  areas.

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Sea Level Increases
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Increased Incidence of Costal Flooding
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Higher Tidal Surges
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If Current Trends Continue
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In the Year 2050 some Red States Become Blue
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Climate Modeling

• Significant amount of variation with respect to
  reconstructions of climate and future
  projections.
• Considerable amount of variables.
• Climate modeling is the best alternative for
  future climate predictions.
• In this case the past climates are the key to the
  future.

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Classon, 2002
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Discussion of Paper

• Differences Between this paper and Ruddiman.
• In specific reference to upward revisions of land
  use change.
• Carbon emissions by anthropogenic land use
  changes v. Oceanic Sediment interaction.

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Paper Discussion Continued

• Can the coral reef buildup scenario account for
  CO2 buildup of 40 ppm?
• Do climate forcing models account for CO2
  Holocene increases, and how reliable are these
  models?

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Response to Atmospheric CO2
Figure-1
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Precipitation and Temperature Anomalies
Figure-2
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Changes in Land Availability for Plant Growth
Figure-3
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Simulated Changes in Terrestrial Carbon
Figure-4
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Simulated CO2 v. Holocene Ice Core
Figure-5
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Figure-6 Contribution of CaCO3
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Figure-7 CO2 Increase By CaCO3 Compensation
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Figure-8 Reconstructed v Simulated
Reconstructed v Simulated Atmospheric CO2
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Figure-9 Simulated Delta Carbon 13
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Figure-10 LGM Holocene Changes
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Figure-11 Biome Types
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Figure-12 Biome Distribution
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End of Anthropogenic Climate Change
Punta Gaspareno Baja California, Sur. N22o4722