GEOG 203 1nd Edition Lecture 13 Outline of Last Lecture I Intro to the dynamic earth changing climates and shifting continents II Changing Climates a Louis Agassiz the theory of a great ice age in the past and some types of evidence for climate change b Reconstructing climate history c What causes climate change Outline of Current Lecture I Changing climates a What causes climate change b Climate change vegetation and humans Current Lecture These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute What causes climate change Milutin Milankovitch changes in the earth s orbital parameters causes change Changes in Earth s tilt would effect seasonality Milankovitch proposed that the places of less seasonality would be more conducive for glacier formation o Warmer air in the winter aids the formation of snow o Cooler summers lead to less melting o Each year more and more snow pile on to eventually form a glacier Procession of equinoxes varies as the earth wobbles on its axis o Aphelion occurs in the northern hemisphere summer leading to cooler summers in the northern hemisphere o Perihelion occurs when the northern hemisphere is in winter leading to a warm winter Low albedo on glaciers cause high amounts of radiation to be reflected causing glaciers not to melt much even if the sun is radiating on them in the summer Low temperature of glaciers cause climate to have lower temperatures feedback Climate Thermohaline circulation cooler water is more dense than hot water and salty water is more dense than fresh water as water moves north and evaporates it cools o cool and salty water keeps Gulf Stream going change vegetation and humans Today we should be headed back into the next glaciation In the short term we are in a warming period but long term we are cooling Greenhouse gas emissions have overall warmed the earth up but long term effects are hard to predict CO2 numbers should have followed the natural trend of declination but begin to increase rather than decrease years ago Some say that anthropocene is more appropriate than Holocene