Earth’s Seasonal and Milankovitch Climate Cycles


Annual and Milankovitch climate cycles on Earth.




Russell Deitrick


POISE DistOrb DistRot

Approx. runtime

5 minutes

This example validates VPLanet’s 1-D climate model with dynamic ice sheets over annual and Myr timescales. On annual timescales, the seasons cycle back and forth on the northern and southern hemispheres. On longer timescales, ice sheets grow and retreat due to changes in eccentricity, obliquity and precession angle (the angle orthogonal to obliquity), which are caused by perturbations from other bodies. Note that we assume every latitude grid is 75% water, 25% land so the latitudinal extent of the ice sheets does not exactly match the geologic record, but the frequencies and intensities do.

To run this example

python <pdf | png>

Expected output


Insolation (upper left), surface temperature (upper right), ice mass balance (lower left), and out-going longwave radiation (lower right), for Earth over a single year, as modeled by POISE. Note that negative values in ice mass balance represent potential melting, i.e. this value is calculated even in the absence of ice on the surface.


Earth’s orbital, rotational, and climate evolution over 1 Myr. The orbital and rotational evolution are modified by all the planets in the Solar System, and the Moon is included by forcing the Earth’s precessional frequency to match the observed rate. CPP is the “climate precession parameter.” The bottom four panels show key properties of the climate state, as indicated by the color bars and axes on the right. Compare to Fig. 4 in (Huybers & Tzipermann 2008).