Essential Question: How is Earth's climate connected to its geological, biological and cultural systems?
ENGAGE
Creating a Nice Atmosphere
Soft jazz and candle light may be one way to create a nice atmosphere, but don't imagine anything like that 4 billion years ago when our first atmosphere was forming on Earth. Something more like screaming heavy metal and blast furnaces comes to mind.
The proto-Earth formed from the bits and pieces of an ancient star that went supernova and exploded, spewing forth its periodic table mixture of stellar guts. As these bits of stardust were drawn together by their mutual gravitational attraction, they clumped and grew larger in snowball fashion.
And just as occurs in the present day ocean and atmosphere, the denser materials in the hot, molten Earth settled in the center of the planet while less dense matter was rafted upwards toward the surface. Heat created by enormous pressure, radioactive decay and chemical changes in the interior of the Earth caused gases to erupt from the surface of the slowly cooling planet, much in the manner as they do today from volcanoes, geysers and hydrothermal vents.
The early Earth lacking a protective magnetic shield at the time, lighter gases like Hydrogen and Helium were blow away by the intense solar winds. Those gases with sufficient mass to be captured by Earth's gravity clung to the surface of the planet, creating a dense early atmosphere of water vapor, carbon dioxide and ammonia, among others - greenhouse gases. No free Oxygen yet. Sound nice?
Interestingly, the early Sun forming at the same time was considerably cooler than today, so the clouds of dense greenhouse gases on the early Earth helped to keep the planet warm enough for the spark of life to begin the amazing evolutionary processes that have brought you to reading these words today.
EXPLORE
Teachers 'Domain
Humans aren't the first life form on Earth to change its atmosphere. Let's go back in time when early lifeforms on the planet changed it's atmosphere in this TD video, Life Before Oxygen.
While we're on the topic of the role of microbial metabolism on Earth, check out this TD video on recent Arctic studies relating Soil Microbes and Global Warming.
Life Before Oxygen
Soil Microbes and Global WarmingHelpful Hint: NOVA Part of the PBS collection of high quality educational materials includes NOVA's media on cosmic evolution. Check out NOVA's Origins website for a fascinating collection of digital media for use in your classroom.
OriginsEXPLAIN
- What was Earth's earliest atmosphere like?
- Where did most free Oxygen on Earth come from?
- How did the early atmosphere help to foster the first life on Earth?
- How have microbes affected the composition of Earth's ancient and present atmosphere?
- What is a positive feedback loop?
EXTEND
- What other atmospheric variables and processes influence climate?
EVALUATE
- What's the utility of any of these resources in your or your students' learning; or how you might use any of them in your final project for this course.
