Case Part I: Geologic History of Earth

The first part of this assignment requires that you consider the history of extinction on our planet as explained in the three tutorials you viewed on the Home page. From the UCMP Geologic Time exercises on the Home page, answer the following questions using full sentences in paragraph form:

1. When you clicked on the "bookmarks," which events were listed and in what order (there were six)?

2. In the Geologic Time Scale section, images of which organisms are included in the Archaean time period?

3. Which three periods of time are described as "Eras"? List the representative organisms included in the photos that appear when you click on each Era.

From the Natural History Museum link to Mass Extinctions:

4. How many mass extinctions are listed? What caused each, and how many species are estimated to have perished?
From the Natural History Museum link to Recent Extinctions:

5. Choose two of the recent extinctions listed on this link and explain how they occurred.

Case Part II: Global Climate Change

Scientists have concerns that human activities are changing our environment at rapid rates that could result in a sixth mass extinction. Let's examine the evidence:

Review this tutorial on the carbon cycle and greenhouse gases.

6. What were listed as human activities related to greenhouse gas production? What does this do to the rate at which carbon is returned to the atmosphere?

7. Opponents of the theory of global climate change propose that extinctions are a normal part of our planet's history and that the temperature of the planet has also historically fluctuated. View this graph demonstrating the rate of greenhouse gas accumulation over the last two thousand years. When do the greenhouse gas emissions drastically increase? Do a Google search using "Industrial Revolution" as your search term. What connections can you make between the Industrial Revolution and this graph?

Next use this Greenhouse Gas simulation. Begin by clicking on the "Simulation Controls" in the upper left-hand corner. Set the greenhouse gas level to the highest, check the boxes "view labels" and "view a possible consequence."

8. What consequence is shown? What effect could this consequence have on animal and plant populations in that region? How much reduction in greenhouse gases is necessary to reduce the extent of this consequence?

9. When you click on the "Graph" menu, what is the relationship between percent (%) of greenhouse gases and temperature? What is the relationship between temperature and ice? Which mass extinction from the Natural History Museum website in Part I does this remind you of?

Part III: Drawing Conclusions

Now provide a Conclusion paragraph that explains what conclusions you can make for yourself based on the evidence provided and what you now know about the geologic time scale of the history of the Earth. What questions are still left unanswered for you?