Thursday, 4 November 2010

DaisyWorld - why we may not have much warning before the Cimate Catastrophe

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These are some simulations I did for fun, as a small extention of the zero dimentional Daisyworld Paper of Watson and Lovelock in '83. The upper graph has temperature on the y axis, and x axis has the poles on the edges and the equator in the centre. The lower graph has population on the y axis while the x axis is the same as above. Green line is the black dasies and blue is the white daisies.

The basic premise is this - there is a planet whose sun's luminosity is increasing linearly. The planet has white daisies that reflect sunlight (and thus reduce local temperature) and black daisies (that absorb sunlight and thus increase local temperatue) both of which grow at some common optimum temperature 300k, with growth rates reducing rapidly away from this temperature. (fairly sharp gaussian in my simulation).

The surprising result is that the black and white daisie populations at every point are such that the optimal temperature is maintained for as long as possible. When finally the daisies cannot regulate temperature any more, we do not see a gradual degredation of populations, we see a catastrophic collapse.

The earth's temperature and chemical regulatory systems are much, much more complex. But this kind of catastrophic transition is fairly common in complex dynamical systems. It is a possibility that has a non neglible probability.

Music Credit - People Are Strange by the Doors. I do not own the rights etc, I just thought it would make a nice sound track for the graphs. Fair Use maybe ? since its not a commercial movie etc etc ? I dont really know.

Typos - in the initial rolling text, it should be first white daisies and then black, instead of black and black. Also excuse the thin lines on the graph. There are around a 1000 graphs making up that video, I cant be bothered to wait the few hours it takes to generate them. Also, the code is a couple of years old, it'd take me ages to make sense of it ! Now on, I will write clean readable code with documentation and comments !

1 comment:

Prajeesh Jayaram L said...

Video is too fast for a non-physicist :)
Had to pause multiple times.
Good work!