Lecture 06: Climate & Glaciation Potential Exam Questions

Potential exam question #1:

What are the factors (both climate related, and non-climate related) that lead to rising or falling ocean levels? Explain the difference between eustatic and isostatic changes.

Rising ocean levels caused be water expansion as water temp rises; ice melt from land-based glaciers (not floating ice); and changes in the ocean floor. Eustatic changes are changes to the global sea level; isostatic changes are local or regional.

Potential exam question #2:

Explain (or illustrate) negative and positive feedback, as well as multiple stable states

Negative feedback means that when any situation is influenced away from a stable equilibrium, it will eventually go back to it (like a ball rolling back down to the bottom of a valley if pushed upward from it)
Positive feedback means that when a situation is influenced from an unstable equilbrium, it keeps going farther away from it as a result (like when a ball is pushed off the top of a hill and keeps rolling down it). A good example is the melting sea-ice and subsequent decreasing albedo in the oceans.
Multiple stable states may be two or more stable situations connected by one or more unstable ones; when the unstable situation reaches a tipping point from moving out of a stable situation into an unstable equilibrium, it will either roll back into the first stable situation or roll down into the next stable situation until it reaches a stable equilibrium depending on the direction of the influences at the tipping point (like multiple valleys and hills for a ball to roll into and off of).

Potential exam question #3:

What are Milankovitch Cycles? What causes them?

Milankovitch cycles are periodic variations in earth's orbit and position. They are relevant to environmental science because they are well-correlated with historic changes in the earth's mean temperature, along with the occurrence of glacial periods. However, the exact causal relationships between these cycles and the earth's temperature is unknown.

//Milankovitch cycles have several causes:
• The eccentricity (shape) of the earth's orbit is eliptical. It's periodicity in relation to the sun correlates well with "ice age" occurences.
• The axial tilt (obliquity) of the earth's axis shifts from from 24.5 degree tilt to 21.5 degrees in respect to earth's orbital plane.
• The precession of the earth's axis (aka “precession of the equinoxes”). Like a wobbling top, the Earth's axis of rotation changes in a cone like shape with respect to the fixed position of starts.

page revision: 9, last edited: 16 Nov 2009 16:20