Geologic Time and Global Warming

What is Geology?

•Geology is “the study of the earth” that arranges Earth's natural events in chronological order and attempts to explain those events.  When studying geology scientists deal with several main ideas:
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•Catastrophism- The belief that the earth’s landscape was developed by great catastrophes.  Canyons, mountains, etc were formed suddenly by unknown causes that no longer exist

•Uniformitarianism- The idea that processes shaping the earth have been consistent through time.  These slow processes have as great an impact as sudden catastrophic events.
(Lutgens 1-2), (Weart 9-10)

 

How does this relate to Global Warming?

By studying the Earth's geology we can see changes and the rate of those changes over time.  What we learn about the past will help us understand the situation we are currently experiencing.

 

Geologic Scale of Time

Cenozoic Era “Age of Recent Life” (70 million years ago-present)
Mesozoic Era “Age of Medieval Life” (225-70 million years ago)
Paleozoic Era “Age of Ancient Life” (600-225 million years ago)
Precambrian  
(Beginning of Earth-600 million years ago)

Watch Continents Through Time

Atmospheric Changes Through Time

Oxygen Levels

•The level of Oxygen in the atmosphere has varied over geological time due to the carbon and sulfur cycle, which involves chemical weathering of continents, the burial of organic matter and photosynthesis.  During periods of increased vegetation, the oxygen levels in Earth's atmosphere increase.

(Berner 10955-1057)

 

 

 

 

 

 

 

Carbon Dioxide

The varying levels of carbon dioxide in the atmosphere can be caused by the carbon cycle, vegetation, and plate tectonics.  As vegetation increases, carbon dioxide levels decrease.  As land masses move and develop carbon dioxide increases.

 

 

Precambrian (600 billion years ago)

  • Atmosphere develops through outgassing

  • •Relatively no oxygen in atmosphere (Lutgens 332-333)

  • •Warm climate with only two ice ages occur

  • 2.7 to 2.3 billion years and .9 to .6 billion years (Buchdahl)

  • •Soft bodied, wormlike organisms and algae are only life forms (Lutgens 33, 262)

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Early Paleozoic (600-350 billion years ago)

 

  • •Early in the era, increased tectonic movement leads to increased Carbon Dioxide in atmosphere and oceans (Buchdahl)

  • •High sea levels bring “maritime” climate (Buchdahl)

  • •Large ice sheet over N. Africa (Buchdahl)

  • •Ocean dwelling plants and animals (Levin 293-94)

  • Animals develop hard shells (Levin 29)

     

Late Paleozoic (350-225 million years ago)

  • •The continents converge to form the Pangaea

  • •With one single continent the climate becomes seasonal

  • •Extremes in climate create extinction (Lutgens 339)

  • •Development of many new fish and amphibians

  • •Development of lush trees and ferns (Lutgens 339-340)

     

Mesozoic (225-70 million years ago)

  • Seasonal climate with some arid areas

  • •Little plate tectonic movement leads to lower sea levels

  • •Deposits of salt and sand are result of arid conditions (Buchdahl)

  • •Conditions perfect for reptiles and coniferous trees to thrive

  • •Dinosaurs unable to adapt and die out rapidly (Lutgens 342-45)

 

Cenozoic (70 million years ago-present)

  • •Significantly cooler than previous eras

  • •Global temperature is still 10-15˚ higher than today

  • •Increased glaciation of poles, (Buchdahl)

  • •“the age of mammals”

  • •“the age of flowering plants” (Lutgens 348)

     

Extinction Events

•Paleozoic Era (270-225 Million Years Ago) Trees, Invertebrates, Marine Life

 

•Mesozoic Era (70 Million Years Ago) Dinosaurs

 

•Cenozoic Era (11,000 Years Ago) Large Mammals

 

•Cenozoic Era (Present time) 844 species over 500 years

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Why does this matter?