Long-term Environmental Change

Geography 430/530: Fall 2022

Tuesday and Thursday, 12:00 to 1:20, in 301 Condon Hall

Instructor:  Prof. Dan Gavin, dgavin@uoregon.edu, office is in 254C Columbia.
Office hours: Thursdays 10:00-11:00. You may meet me by Zoom on office hours if you wish. Send me a message before-hand to arrange the Zoom link.

Why has climate changed over millions of years to decades, how much did it change, what were the effects of the changing climate on biota, biodiversity, and to some extent, people (and vice versa), how do we reconstruct past climate and environments, and what is the relevance of the past with respect to anthropogenic climate change? The class focuses on millennial-scale (ice-age scale) climate change, with an emphasis on the response of ecosystems, especially forests of the Pacific Northwest, to those changes.

Course overview: Climate and the pattern of life on Earth has changed continuously for millions of years resulting in the landscapes we know today. Records of past environmental changes have been assembled from a variety of different paleoenvironmental indicators. This course focuses on the methods used for paleoenvironmental reconstruction, how Earth's climate has varied over a range of different time scales (for example, cycles of glaciation with an emphasis on the last glacial maximium, 20,000 years ago), how the biota, especially vegetation, has varied in concert with climate, and the theories that have emerged to explain those variations. This course is an introduction to the fields of Quaternary paleoclimatology and terrestrial paleoecology, where ecology, geology, and climate science all come together.

Prerequisites: Geog 321 (Climatology) or Geog 322 (Geomorphology) or Geog 323 (Biogeography) or by permission of the instructor.

By the end of this course, students will be able to:

  1. Understand the controls of global and local climate and the scales (temporal and spatial) at which they operate
  2. Identify the sources of information and methods scientists have used the reconstruct past environments, including the biota and climate.
  3. Appreciate how biodiversity today is contingent on past events, and how modern humans have modified certain environments for millennia.
  4. Describe how a knowledge of earth history on late-Cenozoic time scales is relevant to challenges facing humanity today.

Skills taught:

  • Dendrochronology (tree-ring analysis) and reconstruction of climate from tree-ring data.
  • Sediment coring, interpretation of several proxies of climate and vegetation from the natural archives in lake sediment.

Format and grading:  Lectures and discussions in class. We will have a laboratory tour of the paleoecology lab in Pacific Hall, where you will have hands-on experience with tree-ring analysis and can view the coring and sampling process of lake sediments.

Your final grade will be calculated using traditional letter-grade definitions: rounding to integers, A+ 98-100, A 93-97, A- 90-92, etc.. The differential between Geog 430 and 530 is currently being developed. The assignments below tentatively apply to both 430 and 530 students.

  1. Three "mini-reviews" addressing past environmental changes. These will be three to four pages in length and will cite the scientific literature. Examples will be provided. High scoring papers are concise, focused on a single topic, and cite the literature properly. The only criteria for a choice of topic is that it must span before recorded history, thus rely on the geological record. (10%, 20%, 30%)
  2. Visit to the Museum of Natural and Cultural History exhibit "Explore Oregon". Assignment is in development. (15%).
  3. Take-home final exam: 20%
  4. Class participation: 5%

Academic dishonesty policies will be enforced according to the Student Conduct Code.


  • Required: E.C. Pielou. 1992. After the Ice Age. University of Chicago Press.
    Although now 30-years old, this book is still a great introduction to terrestrial paleoecology, written by an ecologist. We will use this book to launch into discussions and to lead into other (more detailed) readings which will be posted on Canvas.
  • Note: We will also use selected material from: W.F. Ruddiman. 2014. Earth's Climate, 3rd Edition. W.H. Freeman & Company.

    Mortiz and Agudo 2013

    Grading rubrics for Mini-reviews. Criteria will be less stringently applied for the first two mini-reviews compared to the third review.

    GEOG 530 students will be longer (and thus more in depth) than those by GEOG 430 students. See below.

    1. Write for a general audience and use no direct quotes. (20 pts)
    2. Begin with a clear statement and/or very short paragraph describing the focus of the review (5 pts).
    3. Have at least four sources relevant to the topic, used and cited properly in your writing (5 pts).
    4. Research depth and thoroughness: Use the most recent relevant sources; do not overly rely on any one source; proper use of citations and in the correct style (15 pts)
    5. The layout, style, and tone of writing should convey the main points with objectivity and little repetition (10 pts).
    6. The writing provides a synthesis of ideas across multiple sources (20 pts).
    7. Your product should be at least 750 words (GEOG 430) or 1500 words (GEOG 530) in good grammar and succinct and brief style (25 pts).

    Detailed weekly course schedule is now in development. All material listed under Readings for each week are available on Canvas (or is in the Pielou Book).

    1. The Ice-house climate of the last 2 million years: Ice-age geography and refugia. The forcing mechanisms of Quaternary climate: greenhouse gases, ice cover, insolation, (and aerosols and vegetation and ...)
      • Readings:
        • Pielou, Chapter 1. The Physical Setting.
        • Ruddiman, Chapter 1. Overview of Climate Science. Note especially concepts of fast and slow responses, feedbacks and the feedback factor.
        • Ruddiman, Chapter 2. This is optional. Please read this for a refresher on the climate system. Most topics here were covered in GEOG 141 (or most any introductory physical geography course). The material on oceans is important (and this was not covered in Geog 141).
        • Lomolino et al. Biogeography. Chapter 9. Glaciation and Biogeographic Dynamics of the Pleistocene. Pages 313-331.
        • Resources on Canvas: Updated maps of North American deglaciation (Dalton et al.)
    2. The fossil evidence. Sediment composition. Pollen and macrofossil analysis, radiocarbon dating, volcanic ash layers.
    3. Tropical vs. northern hemisphere vs. southern hemisphere changes.
    4. Interpreting the evidence. Power and limitations of fossil pollen data. Newer methods (ancient DNA, geochemistry). Ice-age fingerprints in genetics and species distributions.
    5. Migration of vegetation. Seed dispersal. Ecological processes of succession.
    6. Time of maximum ice. Reconstructing past temperatures. Coastal vs. interior climate. Ice-free corridor and megafauna. Mid-Pleistocene rapid climate changes in the northern hemisphere.
    7. Tipping points in the Earth System. Deglaciation and proglacial lakes. The great meltwater pulse. Younger Dryas 'climate reversal'.
    8. Megafauna extinction and potential ecological cascades. Holocene climate changes: early Holocene thermal maximum.
    9. Mid to late Holocene climate changes. Early anthropocene hypothesis. The 'neoglacial' and the Little Ice Age.
    10. Looking further back (and into the future?): Hot house climates of the Mesozoic and Cenozoic. Cenozoic cooling.