Glaciers Are Coming!

 

Scientist are trying to determine why an ice age began about 30 million years ago.

Earth’s climate was normally warm at this time.

They looked for things that happened in/to the world at that time.

They knew that Himalayas were formed at that time when Indian plate pushed upward into Asia forming Tibetan Plateau.

 

1^st supposition- Did huge elevation change of this plateau have any effect?

Large landmass elevated to 15 000 feet would cause air masses coming from west to go upward, resulting in cooling which would cause large amounts of rainfall.

  Would these lower global temperatures enough to start glaciation process?

 

 2^nd supposition - What other global change could change the temperature enough for glaciation?       

 CO₂ amounts:  or the Greenhouse effect.    If large amounts of CO₂ were taken out          of the atmosphere the heat retention of the atmosphere would decrease thus lowering the global temperature  -  but what could do this?

 When Himalayas were pushed up this exposed a vast amount of rock.    When the tremendous rain that was created by the elevation of the air masses passing over the plateau started falling the water combined with CO₂ in the atmosphere to form a weak carbonic acid which dissolved much of the rock.

  Was there enough depletion of the CO₂ in the atmosphere for this to happen?    How could this be proven?

 

3^rd supposition - When rock is decomposed (chemical weathering) by carbonic acid a product is strontium-87.   These scientist looked at the amount of strontium-87 in core samples of off-shore ocean sediments.     Approximately 30 million years ago the amount of strontium-87 increased dramatically.

 

Your job is to try to put all this information together into one cause-effect relationship (may include several steps in the process) that would explain why the planet went into a glacial period at this time.   We will discuss the scientific conclusion in class.