Class 11 wednesday july 21 earth s changing climate
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Class #11: Wednesday July 21 Earth’s changing climate. Chapter 16. The earth's changing climate. Chapter 16. Reconstructing Past Climates. Techniques Glacial landscapes CLIMAP Ice cores Otoliths Dendrochronology Climate Throughout the Ages Earth 8-15ºC warmer than it is today

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Class 11 wednesday july 21 earth s changing climate

Class #11: Wednesday July 21Earth’s changing climate

Chapter 16

Class #11 Wednesday, July 21


The earth s changing climate

The earth's changing climate

Chapter 16

Class #11 Wednesday, July 21


Reconstructing past climates
Reconstructing Past Climates

  • Techniques

    • Glacial landscapes

    • CLIMAP

    • Ice cores

    • Otoliths

    • Dendrochronology

  • Climate Throughout the Ages

    • Earth 8-15ºC warmer than it is today

    • Ice Age/Interglacials

    • Younger-Dryas, mid-Holocene maximum

Class #11 Wednesday, July 21


Class #11 Wednesday, July 21

Fig. 16-CO, p. 438


Class #11 Wednesday, July 21

Fig. 16-1, p. 440






Reconstructing past climate
Reconstructing Past Climate

  • Climate During the past 100 years

    • Little Ice Age

    • Modern warming

  • Topic: Ocean Conveyor and Climate Change

    • Cold, salty water sinks near Greenland driving warm water north .

    • If the conveyor stops much colder over Europe.

Class #11 Wednesday, July 21




Stepped Art

Class #11 Wednesday, July 21

Fig. 1, p. 444


Class #11 Wednesday, July 21

Fig. 16-6, p. 445


Reconstructing past climate1
Reconstructing Past Climate

  • Temperature Trend During the Past 100+ Years

    • Largest increase in temperature of any century during the past 1000 years

    • 0.6ºC is significant when compared to the last 1000 years

    • Scientists point to carbon dioxide and greenhouse gases as the cause

Class #11 Wednesday, July 21



Possible causes of climate change
Possible Causes of Climate Change

  • External Causes

    • Change in incoming radiation

    • Change in composition of the atmosphere

    • Change in Earth’s surface

  • Feedback Mechanisms

    • Water vapor-greenhouse gas feedback (+)

    • Snow-albedo feedback (+)

    • Infrared radiation (-)

Class #11 Wednesday, July 21



Possible causes of climate change1
Possible Causes of Climate Change

  • Plate Tectonics and Mountain Building

    • Theory of plate tectonics

    • Ridge and subduction

    • Mountain interaction with airflow and ocean currents

  • Variation on the Earth’s Orbit

    • Milankovitch Theory

      • Eccentricity

      • Precession

      • Obliquity

Class #11 Wednesday, July 21







Possible causes of climate change2
Possible Causes of Climate Change

  • Atmospheric Particles

    • Aerosols = natural + anthropogenic

    • Aerosols in the troposphere (sulfate) may cause cooling die to reflection of radiation

    • Topic :Nuclear winter

      • Explosions cause debris to rise and circulate absorbing sunlight creating darkness and cold.

    • Volcanic Explosions: ash and dust in the stratosphere reflect light and cool

Class #11 Wednesday, July 21


Class #11 Wednesday, July 21

Fig. 16-14, p. 451


Class #11 Wednesday, July 21

Fig. 16-15, p. 453




Possible causes of climate change3
Possible Causes of Climate Change

  • Variations in Solar Output

    • Sunspots cause more radiation to be generated by the sun

    • Maunder minimum

  • Topic: Climate Models

    • General circulation models (GCMs) are not perfect but extremely sophisticated and serves as the most reliable current predictive tool.

Class #11 Wednesday, July 21



Global warming
Global Warming

  • Recent Global Warming: Perspective

    • Since the beginning of the 20th century average global surface temperature has increase 0.8ºC

  • Radiative Forcing Agents

    • Carbon dioxide and other greenhouse gases disrupt radiative equilibrium, forming an increase in temperature

Class #11 Wednesday, July 21


Global warming1
Global Warming

  • Advanced Topics:

  • Radiative Forcing

    • Any change in average net radiation that occurs at the top of the atmosphere which is due to some change in the climate system is called radiative forcing.

  • Climate Models and Recent Temperature

    • It is difficult to unequivocally prove greenhouse forcing due to the noise in the system.

    • Model well sulfate aerosols, greenhouse gases, change in solar radiation

Class #11 Wednesday, July 21


Class #11 Wednesday, July 21

Fig. 16-19, p. 457




Global warming2
Global Warming

  • Future Global Warming: Projections

    • Double carbon dioxide levels will cause a surface warming of 2-4.5ºC

    • Uncertainties:

      • The effect of water and land on rising levels of carbon dioxide

      • Amount or greenhouse gases

    • Question of Clouds

      • Clouds reflect radiation and emit infrared radiation, positive and negative feedbacks.

Class #11 Wednesday, July 21



Global warming3
Global Warming

  • Consequences of Global Warming

    • Land areas warm faster

    • Rise in sea level

    • Fertilize plants

  • Land Use Change

    • Desertification

    • Plagues and climate

Class #11 Wednesday, July 21


Class #11 Wednesday, July 21

Table 16-1, p. 460


Class #11 Wednesday, July 21

Fig. 16-21, p. 461


Class #11 Wednesday, July 21

Fig. 16-21a, p. 461


Class #11 Wednesday, July 21

Fig. 16-21c, p. 461






Global warming4
Global Warming

  • Topic: The Sahel

    • Recent studies suggest that the dry periods were due to a cooler North Atlantic Ocean and aerosols from North America may exacerbate desertification

  • Efforts to Curb

    • Kyoto Protocol

      • Target emissions, credits, sinks

      • US has yet to sign protocol

      • California implementing protocol

Class #11 Wednesday, July 21