Daisyworld Lab


Students explore Daisyworld, a model of a self-regulating system incorporating positive and negative feedbacks. Daisyworld is a planet on which black and white daisies are the only things growing. The model explores the effect of a steadily increasing solar luminosity on the daisy populations and the resulting planetary temperature. The growth function for the daisies allows them to modulate the planet's temperature for many years, warming it early on as radiation absorbing black daisies grow, and cooling it later as reflective white daisies grow. Eventually, the solar luminosity increases beyond the daisies' capability to modulate the temperature and they die out, leading to a rapid rise in the planetary temperature. Daisyworld was conceived of by Andrew Watson and James Lovelock to illustrate how life might in part have been responsible for regulating Earth's temperature as the Sun's luminosity increased over time. This exercise guides students through some of the mathematics behind the modeling, and uses STELLA or Fortran 90 code.

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Learning Goals

The Daisyworld modeling exercise has several purposes:
  • To explore a self-regulating system
  • To learn how positive and negative feedbacks work
  • To convey the importance of "subroutines" in decreasing clutter in model structures

Context for Use

This activity was developed for a class introducing dynamical systems modeling to upper level undergraduate students. It builds on a student's understanding of the Earth's climate system. See also the related example Modeling Earths Temperature Balance.

Description and Teaching Materials

Daisyworld_Lab.pdf (Acrobat (PDF) 20kB Jun7 05)
Documented_Daisyworld_Model.STM ( 64kB Jun7 05)
Daisyworld2.f90 ( 7kB Jun7 05)

Teaching Notes and Tips

Instructor Notes (Acrobat (PDF) 22kB Apr10 06)


Daisyworld_Lab_Answer_Key.pdf (Acrobat (PDF) 384kB Jun7 05)
assignment_assessment_5.pdf (Acrobat (PDF) 5kB Jun7 05)

References and Resources

The following is a reading for this exercise:

Watson, A.J., and Lovelock, J.E., 1983, Biological homeostasis of the global environment: the parable of Daisyworld, Tellus, v. 35B, p. 284-289.